Itatlonal Bureau of Standi

Library, &M MTM"'

DEC 3 0 1970

NBS MONOGRAPH 113, VOLUME 3

Research and Development

in the Computer

and Information Sciences

U.S.

RTMENT

OF

AMERCE

National

Bureau

of

tandards

Volume 3. Overall System Design Considerations—

A Selective Literature Review
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards ' was established by an act of Congress March 3, 1901. Today,

in addition to serving as the Nation's central measurement laboratory, the Bureau is a principal

focal point in the Federal Government for assuring maximum application of the physical and

engineering sciences to the advancement of technology in industry and commerce. To this end

the Bureau conducts research and provides central national services in four broad program

areas. These are: (1) basic measurements and standards, (2) materials measurements and

standards, (3) technological measurements and standards, and (4) transfer of technology.

The Bureau comprises the Institute for Basic Standards, the Institute for Materials Research, the

Institute for Applied Technology, the Center for Radiation Research, the Center for Computer

Sciences and Technology, and the Office for Information Programs.

THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United

States of a complete and consistent system of physical measurement; coordinates that system with measurement systems of other nations; and furnishes essential services leading to accurate and

uniform physical measurements throughout the Nation's scientific community, industry, and commerce. The Institute consists of an Office of Measurement Services and the following technical

divisions:Applied Mathematics—Electricity—Metrology—Mechanics—Heat—Atomic and Molecular Physics—Radio Physics - —Radio Engineering - —Time and Frequency '-' —Astrophysics -'—Cryogenics.

THE INSTITUTE FOR MATERIALS RESEARCH conducts materials research leading to im- proved methods of measurement standards, and data on the properties of well-characterized

materials needed by industry, commerce, educational institutions, and Government; develops,

produces, and distributes standard reference materials; relates the physical and chemical properties of materials to their behavior and their interaction with their environments; and provides

advisory and research services to other Government agencies. The Institute consists of an Office of Standard Reference Materials and the following divisions: Analytical Chemistry—Polymers—Metallurgy—Inorganic Materials—Physical Chemistry.

THE INSTITUTE FOR APPLIED TECHNOLOGY provides technical services to promote

the use of available technology and to facilitate technological innovation in industry and Government; cooperates with public and private organizations in the development of technological

standards, and test methodologies; and provides advisory and research services for Federal, state, and local government agencies. The Institute consists of the following technical divisions and

offices: Engineering Standards—Weights and Measures — Invention and Innovation — Vehicle Systems Research—Product Evaluation—Building Research—Instrument Shops—Measurement Engineering—Electronic Technology—Technical Analysis.

THE CENTER FOR RADIATION RESEARCH engages in research, measurement, and application of radiation to the solution of Bureau mission problems and the problems of other agencies and institutions. The Center consists of the following divisions: Reactor Radiation—Linac Radiation—Nuclear Radiation—Applied Radiation. THE CENTER FOR COMPUTER SCIENCES AND TECHNOLOGY conducts research and

provides technical services designed to aid Government agencies in the selection, acquisition,

and effective use of automatic data processing equipment; and serves as the principal focus

for the development of Federal standards for automatic data processing equipment, techniques,

and computer languages. The Center consists of the following offices and divisions: Information Processing Standards—Computer Information — Computer Services — Sys- tems Development—Information Processing Technology.

THE OFFICE FOR INFORMATION PROGRAMS promotes optimum dissemination and

accessibility of scientific information generated within NBS and other agencies of the Federal Government; promotes the development of the National Standard Reference Data System and a system of information analysis centers dealing with the broader aspects of the National Measure- ment System, and provides appropriate services to ensure that the NBS staff has optimum accessibility to the scientific information of the world. The Office consists of the following

organizational units:

Office of Standard Reference Data—Clearinghouse for Federal Scientific and Technical Information ' —Office of Technical Information and Publications—Library—Office of Public Information—Office of International Relations.

1 Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted; mailing address Washington, D.C. 20234.

- Located at Boulder, Colorado 80302.

'' Located at 5285 Port Royal Road. Springfield, Virginia 22151.
UNITED STATES DEPARTMENT OF COMMERCE • Maurice H. Stans, Secretary

NATIONAL BUREAU OF STANDARDS • Lewis M. Branscomb, Director

Research and Development in the

Computer and Information Sciences

3. Overall System Design Considerations

A Selective Literature Review

Mary Elizabeth Stevens

Center for Computer Sciences and Technology

National Bureau of Standards

•Washington, D.C. 20234

U- 5 'National Bureau of Standards, Monograph 113, Vol. 3

r » » Nat. Bur. Stand. (U.S.) Monogr. 113 Vol. 3, 147 pages (June 1970) CODEN: NBSMA

Issued June 1970

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 (Order by SD Catalog No. C 13.44:113, Vol. 3), Price SI. 25
NATIONAL BUREAU OF STANDARDS

FEB 1 2 1971

i ^

o

n

Library of Congress Catalog Card No. 70-603263
Foreword

The Center for Computer Sciences and Technology of the National Bureau of Standards has

responsibility under the authority of Public Law 89-306 (the Brooks Bill) for automatic data processing standards development, for consultation and technical assistance to Federal agencies, and for supporting research in matters relating to the use of computers in the Federal Government.

This selective literature review is one of a series intended to improve interchange of information among those engaged in research and development in the fields of the computer and information sciences. Considered in this volume are the specific areas of overall system design

considerations, including the problems of requirements analysis, system networking, terminal

design, character sets, programming languages, and advanced hardware developments.

Names and descriptions of specific proprietary devices and equipment have been included

for the convenience of the reader, but completeness in this respect is recognized to be impossible.

Certain important developments have remained proprietary or have not been reported in the open

literature; thus major contributors to key developments in the field may have been omitted.

The omission of any method or device does not necessarily imply that it is considered unsuitable or unsatisfactory, nor does inclusion of descriptive material on commercially available instru- ments, products, programs, or processes constitute endorsement.

Lewis M. Branscomb, Director

in
I

I

I
Contents

Page

1. Introduction 1

2. Requirements and resources analysis 1 2.1. Requirements analysis 3

2.1.1. Clientele requirements 3

2.1.2. Information control requirements 3

2.1.3. Other system design requirements 5

2.2. Resources analyses 5

2.2.1. System modularity, configuration and reconfiguration 6

2.2.2. Safeguarding and recovery considerations 6

3. Problems of system networking 7

3.1. Network management and control requirements 7

3.2. Distribution requirements 8

3.3. Information flow requirements 8

4. Input-output, terminal design, and character sets 9

4.1. General input-output considerations 9

4.2. Keyboards and remote terminal design 10

4.3. Character set requirements 12

5. Programming problems and languages and processor design considerations 13

5.1. Programming problems and languages 13

5.1.1. Problems of verv large programs and of program documentations 14

5.1.2. General-purpose programming requirements 14

5.1.3. Problem-oriented and multiple-access language requirements 16

5.1.4. Hierarchies of languages rfnd programming theory 17

5.2. Processor and storage system design considerations 18

5.2.1. Central processor design 19

5.2.2. Parallel processing and multiprocessors 20

5.2.3. Hardware-software interdependence 20

6. Advanced hardware developments 21

6.1. Lasers, photochromies, holography, and other optoelectronic techniques 21

6.1.1. Laser technology 21

6.1.2. Photochromic media and techniques 22

6.1.3. Holographic techniques 23

6.1.4. Other optoelectronic considerations 24

6.2. Batch fabrication and integrated circuits 25

6.3. Advanced data storage developments 26

6.3.1. Main memories 26

6.3.2. High-speed, special-purpose, and associative or content-addressable memories 27

6.3.3. High-density data recording and storage techniques 28

7. Debugging, on-line diagnosis, insirumentation, and problems of simulation 29

7.1. Debugging problems 29

7.2. On-line diagnosis and instrumentation 30

7.3. Simulation 31

8. Conclusions 33 Appendix A 35 Appendix B 129

List of Figures Page Figure 1. A generalized information processing system 2 Figure 2. Photochromic data reduction 23 V
1

!
Research and Development in the Computer and Information Sciences

3. Overall System Design Considerations:

A Selective Literature Review

Mary Elizabeth Stevens

This report, the third in a series on research and development efforts and requirements in the computer and information sciences, is concerned with a selective literature review involving overall system design considerations in the planning of information processing systems and networks. Specific

topics include but are not limited to: requirements and resources analysis, problems of system net- working, input/output and remote terminal design, character sets, programming problems and lan- guages, processor design considerations, advanced hardware developments, debugging and on-line diagnosis or instrumentation, and problems of simulation. Supplemental notes and a bibliography of over 570 cited references are included.

Key words: Data recording; debugging; holography; information control; input-output; integrated

circuits; lasers; memory systems; multiprocessing; networks; on-line systems; programming; simulation; storage.

1. Introduction

This is the third in a planned s,eries of reports

involving selective literature reviews of research

and development requirements and areas of continuing R&D concern in the computer and information sciences and technologies. In the first report,*

the background considerations and general purposes

intended to be served by the series are discussed.

In addition, the general plan of attack and certain caveats are outlined.**

In the first two reports in this series, we have been

concerned with generalized information processing

systems as shown in Figure 1, more particularly

these reports were concerned respectively with in- formation acquisition, and sensing, and input operations and with information processing, storage, and

output requirements. In this report we will be con- cerned with some of the overall system design considerations affecting more than one of the processes

shown, such as programming languages, remote

terminals used both for input and output, and ad- vanced hardware developments generally.

Affecting all of the system design requirements for specific functions of generalized information proc- essing systems are those of hierarchies and inter- action of systems, and of effective access-response

languages; the client, system-configuration, and

system-usage considerations (especially in terms of multiple-access, time-shared systems), and of sys- tem evaluation, including such on-going "evaluations" as debugging aids and on-line instrumented

checking or monitoring facilities. Under overall system design requirements, we

are concerned with input-output capabilities and

terminal display and control equipment, with processor and storage systems design, with advanced

technological developments, with programming

language requirements, and with problems of online debugging, client protection, instrumentation,

and simulation.

First, however, let us consider some of the overall system design considerations involved in requirements and resources analysis and in problems of

system networking.

2. Requirements and Resources Analyses

The introduction of automatic data processing

techniques has not changed the kind of fact-finding,

analysis, forecasting, and evaluation required for

•Information Acquisition. Sensing, and Input: A Selective Literature Review. ••Appendix A of this report contains notes and quotations pertinent to the running

text. For the convenience of the reader, notes and "»- 2 " recapitulate some of the considerations discussed in the first report. Appendix B provides a bibliography of

cited references.

effective systems planning and implementation; it has changed the degree, particularly with respect to extent, comprehensitivity, detail in depth, and

questions of multiple possible interrelationships.

For example, a "single information flow" concept 21 becomes realizable to an extent not possible before. On the other hand, distributed 22 and decentralized

1
1. Information

Acquisition

r

3. Prep rocessing

4. Processing

Operations

2. Information)

Sensing anc Input

1 2. Retrieval

5. Direct

Outputs

13. Postprocessing

14. Outputs

15. Use and

Evaluation

I

I

7. Processing

Client Service

Requests

!. Preprocessing — H

9. Processing

Specifications

J

Legend: process flow

feedback flow

FIGURE 1. A generalized informatioti iJiucessing system.

2
systems also become more practical and efficient because of new possibilities for automatic control

of necessary interactions.

A major area of continuing R&D concern with

respect to both requirements and resources analysis

is that of the development of more adequate methodologies.2 - 3 Nevertheless, the new business on the

agenda of the national information scene — that is, the challenge of system networking — offers new

possibilities for a meshing of system design criteria that have to do with where and how the system is to be operated and with where and how it is to be used.

2.1. Requirements Analysis

Requirements analysis, as an operational sine qua

non of system design, begins of course with suitable

assessment of present and potential user needs.

Elsewhere in this series of reports, some embarrassingly critical commentaries with respect to actual or prospective usage are selectively covered.2 - 4 Assuming, however, that there are definitive needs

of some specifiable clientele for processing system

services that can be identified, we must first attempt some quantifiable measures of what, who, when,

where, and why, the information-processing-systemservice requests are to be honored.2 - 5 In particular,

improved techniques of analysis with respect to clientele requirements, information control requirements, and output and cost/benefit considerations

are generally desired.

2.1.1. Clientele Requirements

It is noted first that "lack of communication be- tween the client, that is, the man who will use the

system, and the system designer is the first aspect

of the brainware problem." (Clapp, 1967, p. 3). Considering the potential clients as individual users

of an information processing system or service, the

following are among the determinations that need

to be made: 2 6

1. Who are the potential users?

2. Where are they located? 2 7

3. If there are many potential users, user groups, and user communities, how do needs for in- formation and for processing services differ among them? 2 8

4. What are the likely patterns and frequencies of

usage for different types of potential clients?

5. To what extent are potential clients both motivated and trained to use the type of facilities and services proposed? 2 - 9 However obvious these and other requirements

analysis considerations may be, a present cause of

critical concern is the general lack of experimental

evidence on user reaction, user behavior, and user

effectiveness.210

2.1.2. Information Control Requirements

Detailed consideration and decision-making with

respect to controls over the quality and the quantity

of information input, flow, processing, storage, re- trieval, and output are essential to effective system

design. Davis in a late 1967 lecture discussed many

of the multifacetted problems involved in information control — in both system planning and system

use. The varied aspects range from questions of

information redundancy in information items to be

processed and stored to those of error detection and

correction with respect to an individual item record

as received, processed, stored, and/or retrieved.

Among these information control requirements

are: input and storage filtering and compression;

quality control in the sense of the accuracy and

reliability of the information to be processed in the

system; questions of file integrity and the deliberate

introduction of redundancy; problems of formatting,

normalization, and standardization, and error de- tection and error correction techniques.

More particularly, Davis (1967) is concerned with

problems of information control in a system with

the following characteristics:

"1. It has several groups of users of differing

administrative levels. "2. The information within the system has imposed upon it varying privacy, security and/or

confidentiality constraints.

"3. The information entering the system is of

varying quality with respect to its substantive

content; that is, it may be raw or unevaluated,

it may have been subjected to a number of

evaluation criteria or it may be invariant

(grossly so) as standard reference data.

"4. The user audience is both local and remote.

"5. Individual users or user groups have individ- ual access to the information contained within

the system.

"6. The information within the system is multi- source information."

(Davis, 1967, p. 1-2).

We may note first the problems of controls that

will govern the total amount of information that is to be received, processed, and stored in the system.

These may consist of input filtering operations 211 as in sampling techniques applied to remote data

acquisition processes 212 or in checking for duplications and redundancies in the file.213 Other information control requirements with re- spect to the total amount of information in the sys- tem relate to problems of physical storage access, withdrawals and replacements of items to and from

the store, maintenance problems including questions

of whether or not integrity of the files must be pro- vided (i.e., a master copy of each item accessible at

all times),214 provisions for the periodic purging of

obsolete items,215 revisions of the file organization

in accordance with changing patterns of usage,216 response requirements 217 and requirements for display of all or part of an item and/or indications of

its characteristics prior to physical retrieval.218 Another important area of information control is that of identification and authentication of material

3
entering the system, with special problems likely to be involved, for example, in the dating of reports.

(Croxton, 1955). As Davis (1967) also points out, the

timeliness of information contained in the system

depends not only on the time of its input but also upon the date or time it was recorded or reported

and the date the information itself was originally ac- quired, including the special case of the "elastic

ruler" (Birch, 1966).2 19 Another typical problem is that of transliterations and transcriptions between

items or messages recorded in many different

languages.2 - 20 A crucial area of R & D concern is that of the accuracy, integrity, and reliability of information in the

system, although these questions are all too often

neglected in system design and use.2 - 21 Again, Davis

emphasizes the importance of information content

controls. These may be achieved, on input, either by

error-detecting checks on quantitative data or by

"correctness control through 'common sense' or

logical checks." (Davis, 1967, p. 10.) 2 22 Thus, the use of reliability indicators and automatic inference

capabilities may provide significant advantages in improved information handling systems in the

future.2 - 23 One of the obvious difficulties in controlling accu- racy and reliability of the information content of

items in the system is that of correction and up- dating cycles.2 - 24 More commonly, however, errors

affecting the accuracy and reliability of information

are those of human errors in observation, recording,

or transcription and those of transmission or equipment failure during communication and input. The

incidence of such errors is in fact inevitable and

poses a continuing challenge to the system designers

which becomes increasingly severe as the systems

themselves become more complex.2- 25

It is to be noted, of course, that a major area of R&D concern in the communication sciences is that of information theoretic approaches to error

detection, correction, and control. In terms of generalized information processing systems, however, we

shall assume that advanced techniques of message

encoding and decoding are available to the extent

required, just as we assume adequate production

quality controls in the manufacture and acceptance

testing of, say, magnetic cores. Thus our concern

here is with regard to the control, detection, and

(where feasible), correction, of errors in information content of items in an information processing

system or network, regardless of whatever protective encoding measures have been employed.

It should be recognized first of all that any formulation of an information-carrying message or record

is an act of reportage, whether it is performed by

man or by machine. Such reportage may itself be

in error (the gunshots apparently observed during

riot conditions may have been backfiring from a

truck, the dial indicator of a recording instrument

may be out of calibration, and the like). The recording of the observation may be in error: misreading of, say, the dial indicator, transposition of digits in

copying a numerical data display, and accidental or inadvertent misspellings of names are obvious

examples.

With respect to errors introduced by transmission,

examples of R & D requirements and progress were

cited in the first report in this series ("Information

Acquisition, Sensing, and Input", Section 3.4). Two

further examples to be noted here include the dis- cussion by Hickey (1966) of techniques designed to handle burst-type errors 2 - 26 and a report by Menkhaus (1967) on recent developments at the Bell Telephone Laboratories.2 - 27 For checking recording

and/or transmission errors, a variety of error detection devices (such as input interlocks,2 - 28 parity

information 2 29 check digits,2 - 30 hash totals,2 - 31 for- mat controls and message lengths 2 - 32

) have been

widely used.2 - 33 Problems introduced by alphanumeric digit trans- positions or simple misspellings can often be

attacked and solved by computer routines, provided

that there is some sort of master authority fist, or

file, or the equivalent of this in terms of prior conditional matching.2 - 34 For example, Alberga (1967)

discusses the comparative efficiency of various

methods of detecting errors in character strings.

The use of contextual information for error detection and possible correction in the case of auto- matic character recognition processes has been

noted in a previous report in this series, that on

information acquisition, sensing, and input. This is, of course, a special case of misspelling.2 - 35 Some of

the pertinent literature references include Edwards

and Chambers (1964), Thomas and Kassler (1967)

and Vossler and Branston (1964). The latter investi- gators, in particular, suggest the use of lookup

dictionaries specialized as to subject field and analysis of part-of-speech transitions.2 - 36 Context analysis is important, first, because for the human such capabilities enable him to predict

(and therefore skim over or filter out) message

redundancies and to decide, in the presence of

uncertainties between alternative message readings,

the most probably correct message contents when

noise, errors, or omissions occur in the actual

transmission of the message.2 - 37 Context analysis also provides means for auto- matic error detection and error correction in the

input of text at the character level, the word

level, and the level of the document itself such

as the detection of changes in terminology or the

emergence of new content in a given subject field. For example, "various levels of context can be

suggested, ranging from that of the characters

surrounding the one in question to the more nebulous concept of the subject class of the document

being read." (Thomas and Kassler, 1963, p. 5). In automatic character recognition, in particular,

consideration has been given to letter digrams,

trigrams, and syllable analysis approaches 2 38 as well as to dictionary lookups.

Special problems, less amenable to contextual

considerations, arise in the case of large files

4
containing many names (whether of persons or

of drugs, for example) which are liable to misspellings or variant spellings or which are homonymous.2 - 39 Information control requirements in such cases may involve the use of phonetic indexing

techniques 2 40 as well as error detection and

correction mechanisms.2 - 41 Automatic inference and consistency checks

may be applied to error detection and error cor- rection as well as to identification and authentication procedures. Waldo and DeBacker (1958) give an early example as applied to chemical structure

data.2 - 42 A man-machine interactive example has

been described by North (1968). 2 43 For the future,

however, it can be predicted that: "Ways must be

found for the machine to freely accept and use

incomplete, qualitative information, to mix that information with internally-derived information,

and to accept modifications as easily as the original

information is accepted." (Jensen, 1967, p. 1-1).

Finally, we note that, in its broadest sense, the

term "control" obviously implies the ability to predict whether a given machine procedure will or will not have a solution and whether or not a given computer program, once started running,

will ever come to a halt. The field of information

control may thus include the theories of automata,

computability, and recursive functions, and questions of the equivalence of Turing machines to other formal models of computable processes.

2.1.3. Other System Design Requirements

Other system design considerations with respect

to requirements analysis include questions of

centralization or decentralization of functions

and facilities, including compromises such as

clusters; 2 44 questions of batch-processing as

against time-sharing or mixtures of these modes,2 - 45 and questions of formatting, normalization,2 - 46 and

standardization.2 - 47 A final area of requirements analysis involves

the questions of system design change and modification 2 - 48 and of system measurement. 2 - 49 In particular,

information on types of system usage by various

clients provides the basis for periodic re-design

of system procedures and for appropriate re- organization of files. Such feedback information

may also provide the client with system statistics that enable him to tailor his interest-profile or search strategy considerations to both the available

collection characteristics and to his own selection

requirements. As Williams suggests, 2 - 50 this kind

of facility is particularly valuable in. systems where

the client himself may establish and modify the

categories of items in the files that are most likely

to be of interest to him.

2.2. Resources Analysis

Collateral with comprehensive analyses of

potential system clienteles, their needs and requirements, their locations and the probable workloads

(both as to types and also as to throughputs re- quired), are the necessary analyses of the resources

presently or potentially available. Resources

analysis typically involves considerations of

manpower availabilities, technological possibilities,

and alternative procedural potentialities.

The question may well be raised with respect to an obvious spectrum of R & D requirements.

Certainly there will be continuing areas of R & D

concern with respect to advanced hardware tech- nologies in processor and storage system design,

and in materials and techniques that are related

to these requirements. Next there are problems of

"software" — that is, of programming techniques

to take full advantage of parallel processing capabilities, associative memory accessing and organization, multiprogrammed and multiple-access

system control. Certain requirements are obviously overriding

because they permeate the total system design

and because they interact with many or all of the

sub-systems involved. These include the problems

of comparative pay-offs between various possible

assemblies of hardware and software, the questions

of programming languages and of suitable

hierarchies of such languages, and the problems

of man-machine interaction especially in the case

of time-shared or multiple access systems.

Similarly, the requirements for handling a variety

of input and output sensing modalities and for processing more than one I—O channel in an effec- tively simultaneous operation clearly indicate needs

for continuing research and development efforts in the design and use of parallel processing tech- niques, multi-processor networks, time-shared

multiple access scheduling, and multi-programming.

Hierarchies of languages are implied, ranging

from those in which the remote console user speaks

to the machine system in a relatively natural lan- guage (constrained to a greater or lesser degree) to those required for the highly sophisticated executive control, scheduling, file protection, accounting,

monitoring, and instrumentation programs. For the

future, increasing consideration needs to be given

not only to hierarchies of languages for using sys- tems, but to hierarchies of systems as well.2 - 51 There are, of course, concurrent hardware re- search, development, and effective usage requirements in all or most of these areas. Improvements in microform storage efficiency, lower per bit information-representation costs, communication channel

utilization economies, improved quality of facsimile

reproduction and transmission of items selected or

retrieved, are obvious examples of directly fore- seeable future demands. Some of the above considerations will be discussed in later sections of this report. Here we are concerned in particular with resources analysis in terms of system modularity,

configuration and reconfiguration, and with provisions for safeguarding the information to be handled

in the system.

5
2.2.1. System Modularity, Configuration, and

Reconfiguration

Today, in increasingly complex information proc- essing systems, there are typically requirements for considerable modularity and replication of system

components in order to assure reliable, dependable,

and continuous operation.2 - 52 The possibilities for the use of parallel processing techniques are re- ceiving increased R&D attention. Such techniques

may be used to carry out data transfers simultaneously with respect 2 - 53 to the processing operations,

to provide analyses necessary to convert sequential

processing programs into parallel-path programs,2 - 54 or to make allocations of system resources more

efficiently because constraints on the sequence in which processing operations are executed can be

relaxed.2 - 55 In terms of system configuration and reconfiguration, there is a continuing question of the extent of

desirable replication of input-output units and other

components or sub-assemblies. This maybe particularly important for multiple-access and multiple-use

systems.2 - 56 A particularly important system configuration feature desired as a resource for largescale information processing systems is that of

open-endedness.2 - 57 System reconfigurations, often necessary as changing task orders are received, are particularly

important in the area of shifting the system facilities for system self-checking and repair.2 - 58 Thus Amdahl

notes that "the process of eliminating and introducing components when changing tasks is reconfiguration. The time required to reconfigure upon occur- rence of a malfunction may be a critical system

parameter," (Amdahl, 1965, p. 39) and Dennis and

Glaser emphasize that "the ability of a system to adapt to new hardware, improved procedures and new functions without interfering with normal sys- tem operation is mandatory." (Dennis and Glaser,

1965, p. 5.)

2.2.2. Safeguarding and Recovery Considerations

A first and obvious provision for "fail-safe" (or, more realistically, "fail-softly") 2 59 operation of an

information processing system network is that of

adequate information controls (for example, as discussed above) on the part of all member systems

and components in the network.2 - 60 This requirement reflects, of course, the familiar ADP aphorism of 'garbage in, garbage out'. Again, the total system must be adequately protected from inad- vertent misuse, abuse, or damage on the part of

its least experienced user or its least reliable component. Users must be protected from unauthorized

access and exploitation by other users, and they also must be protected from the system itself, not only

in the sense of equitable management, scheduling,

and costing but also in the sense that system

failures and malfunctions should not cause intoler- able delays or irretrievable losses.2 - 61 Tie-ins to widespread communication networks

and the emergence of computer-communication

networks obviously imply some degree of both

modularity and replication of components, pro- viding thereby some measure of safeguarding and

recovery protection.2 - 62 An extensive bibliographic

survey of proposed techniques for improving system

reliability by providing various processes for intro- ducing redundancy is provided by Short (1968).2 - 63 Protective redundancy of system components is, as we have seen, a major safeguarding provision

in design for high system reliability and availability.2 64 In terms of continuing R&D concerns, however, we note the desirability of minimizing

the costs of replication 2 65 and the possibilities for development of formal models that will facilitate the choice of appropriate trade-offs between risks

and costs.2 - 66 Finally, there are the questions of resources

analysis with respect to the safeguarding of the

information in the system or network — that is, the provisions for recovery, backup, rollback, and

restart or repeat of messages, records, and files. 2 - 67 The importance of adequate recovery techniques

in the event of either system failure or destruction

or loss of stored data, can hardly be overestimated.2 - 68 The lessons of the Pentagon computer installa- tion fire, in the early days of automatic data process- ing operations, still indicate today that, in many

situations, separate-site replication of the master

files (not only of data but also often of programs)

is mandatory.2 - 69 Otherwise, the system designer

must determine whether or not the essential contents of the machine-usable master files can be

recreated from preserved source data.2 - 70 If the

file contents can be recreated, then the designer

must decide in what form and on what storage

media the backup source records are to be

preserved.2 - 71 In terms of system planning and resource analysis

for information processing network design, we note

the following questions:

Can the network continue to provide at least minimal essential services in the case of one or more accidental or deliberate breaks in the links?

What are the minimal essential services to be maintained at fail-safe levels? To what extent

will special priorities and priority re-scheduling

be required?

Must dynamic re-routing of information flow be applied, or will store-and-forward with delayed

re-routing techniques suffice?

There are known techniques for evaluating

optimum or near-optimum paths through complex

paths in the sense of efficiency (economic, workload balancing, and throughput or timeliness

considerations). Can these techniques be re- applied to the fail-safe or fail-softly requirements

or must new methods and algorithms be

developed?

What are the fallback mechanisms at all levels and nodes of the system for: (a) specific failures

6
at a particular node, (b) breaks of one or more

specific link(s), (c) massive failures, such as the

New York area power blackout?

In general, with respect to areas of R & D

concern affecting safeguarding and recovery provisions, we may conclude with Davis that "Rarely,

if ever, are measurements made of the ability of the system to respond when partially destroyed

or malfunctioning, of the length of time required

for changing the system response to internal change

in direction or to external stimuli, of the length of time necessary for a newcomer to be inserted into

his assigned role in the system, of the redundancy,

backup, or alternatives available at times of partial or total system destruction, and so forth. Clearly,

there will be no adequately constructed system until such measures of effectiveness are understood and

incorporated into system design." (Davis, 1964,

p. 28).

3. Problems of System Networking

Steadily mounting evidence of the nearly

inevitable development of information-processingsystem networks, computer-communication utili- ties, and multiply-shared, machine-based, data

banks illuminates a major and increasingly critical area of R & D concern. In this area, the problems

of "organized complexity" 31 are likely to be at least an order of magnitude more intractable than

they are today in multiprogrammed systems, much

less in those systems requiring extensive manmachine interaction.

It is probable, in each of these three fields of

development, that there has been and will continue

to be for some time to come: (1) inadequate requirements and resources fact-finding and analysis,3 - 2

(2) inadequate tools for system design,3 - 3 and (3) the utter lack of appropriate means for evaluation

in advance of extensive (and expensive) alternatives

of system design and implementation. 3 - 4 Certainly

the problems of system networking will involve

those of priority scheduling and dynamic allocation and reallocation in aggravated form. 3 - 5 Moreover, the extensive prior experience in, for example,

message-switching systems, is likely to be of rela- tively little benefit in the interactive system

network. 3 - 6 In particular, the practical problems of planning

for true network systems in the areas of documentation and library services have scarcely begun to be

attacked.3- 7 Nevertheless, the development of computer-communications networks has begun to emerge as the result of some or all of the following

factors:

(1) Requirements for data acquisition and collec- tion from a number of remote locations. 3 - 8

(2) Demands for services and facilities not readily

available in the potential user's immediate

locality.

(3) Recognized needs to share data, programs and

subroutines, work loads, and system re- sources.3 9 In addition, various users may share

the specialized facilities offered by one or more

of the other members of the network.310

Similar requirements were considered by various

major members of the aerospace industry as early

as 1961, as follows:

"a. Load sharing among major computer centers . . . "b. Data pick-up from remote test sites (or from

airborne tests). In some cases real-time proc- essing and retransmission of results to the

test site would be desirable.

"c. Providing access for Plant A to a computer

center at Location B. Plant A might have a medium-scale, small-scale, or no computer of

its own.

"d. Data pick-up from dispersed plants and offices for processing and incorporation in overall

reports. The dispersed points might be in the same locality as the processing center, or possibly as much as several thousand miles

away." (Perlman, 1961, p. 209.)

Three special areas of system network planning

may be noted in particular. These are the areas of

network management and control, of distribution

requirements, and of information flow requirements.

3.1. Network Management and Control

Requirements

Effective provisions for network management and

control derive directly from the basic objectives and

mission of the network to be established. First,

there are the questions with respect to the potential users of the system such as the following:

1. What are the objectives of the system itself? Is

it to be a public system, free and accessible to

all? 311 Is it to serve a spectrum of clientele

interests, privileges, priorities, and different levels of need-to-know? Is it subject, in the

provision of its services, to constraints of national security, constitutional rights (assurance

of protection of the individual citizen's right to the security, among other things, of his "papers" from unreasonable searches and

seizures), laws and regulations involving penalties for violation such as "Secrecy of Communications," and copyright inhibitions?

2. What are the charging and pricing policies, if any, to be assessed against different types

of service, different types of clients, and

7
different priorities of service to the different

members of the clientele? 3 12

3. What different protections may be built into the system for different contributors with

varying degrees of requirements for restric- tions upon access to or use of their data? 313

4. What are the priority, precedence, and inter- rupt provisions required in terms of the

clientele? 314 Next are the questions, in terms of the potential

client-market, of the location, accessibility, cost, volume of traffic, and scheduling allocations for some determinate number of remote terminals, user stations, and communication links. Then there are the questions of the performance

and technological characteristics required with

respect to these terminals, stations, and links. 3 - 15 Are the central system and the communication

network both capable of handling, effectively

simultaneously, the number of individual stations or links required? Does the communication system

itself impose limitations on bandwidths available,

data transmission rates, number of channels

operable effectively in parallel? Are alternate

transmission modes available in the event of channel

usurpation or nonavailability for other reasons?

Is effectively on-line responsiveness of the communication system linkages required and if so to what

extent? More generally, the following design and planning

questions should be studied in depth if there is to be effective management and control:

"1. What is the scope of the network?

a. Its geographical coverage

b. Services to be provided by and to whom

c. Location and facilities of participants

d. Existing capabilities available

e. Required rate of development

"2. What are the relevant software and data

characteristics?

a. Privacy requirements

b. Accessibility and/or availability of program services

c. System management programs

"3. What are the network management and

control requirements?

a. Standardization 316

b. Membership

c. Information and program manipulation

d. Feedback 317

e. Documentation

f. Cost of services

"4. What are the pertinent legal regulations and

practices?

a. FCC regulations

b. Carrier rate structure

c. Common carrier use

d. Responsibilities for information content

e. Privacy versus broadcast methods

f. Federal agency jurisdiction . . . "5. What are the technological constraints?

"6. What are the budgetary constraints and

financially allowable rate of development?"

(Davis, 1968, p. 4-5).

The factors of geographical coverage, location

and facilities of participants, and membership

point to some of the distribution requirements,

to be considered next.

3.2. Distribution Requirements

A major area of concern with respect to distri- bution requirements in information processing net- work planning is that of the question of the type

and extent of centralization or decentralization of

the various system functions. There is first the

possibility of a single master, supervisory, and

control processing center linked to many geo- graphically dispersed satellite centers (which carry

out varying degrees of preprocessing and postprocessing of the information handled by the

central system) and terminals. Secondly, several

interconnected but independent processors may

interchange control and supervisory functions as workload and other considerations demand.318

Still another possibility is regional centralization

such has been recommended for a national documentation network, for example.319 Different compromises in network and system

design to meet distribution requirements are also obviously possible.3 20 However, a variety of special

problems may arise with respect to distribution

requirements when some of the network functions

are decentralized.3 - 21 Then there is the question of whether or not

the network is to be physically distributed — that

is, "the term 'distributed network' is best used to delineate those communications networks based

on connecting each station to all adjacent stations,

rather than to just a few switching points, as in a centralized network." (Baran, 1964, p. 5). This

distribution requirement consideration is closely

related to information flow analysis and planning,

especially with respect to assurance of continuing

productive operation when certain parts of the

network are inoperative.3 - 22 It should be noted, moreover, that "solving the data base management

problem has been beyond the state of the art." (Dennis, 1968, p. 373).

3.3. Information Flow Requirements

In general, it may be concluded that "to determine

the correct configuration, certain basic factors

must be investigated. These factors generally

relate to the information flow requirements and

include the following:

1. The kind of information to be transmitted

through the communications network and the

types of messages.
2. The number of data sources and points of

distribution to be encompassed by the network

and their locations.

3. The volume of information (in terms of messages and lengths of messages) which must

flow among the various locations.

4. How soon the information must arrive to be

useful. What intervals the information is to be transmitted and when. How much delay

is permissible and the penalty for delays.

5. The reliability requirements with respect to the accuracy of transmitted data, or system

failure and the penalty for failure.

6. How the total system is going to grow and the

rate of growth."

(Probst, 1968, p. 19). More specifically, overall system design considerations with respect to information flow requirements

typically involve calculations of average daily

volume of message and data traffic, peak loads

anticipated, average message length, the number of messages to be transmitted in given time intervals,

total transmission time requirements, and questions of variable duty cycles for different system

and network components.3 - 23 Examples of relatively recent developments in

this area include RADA (Random Access Discrete

Address) techniques 3 24 and a "hot-potato" routing

scheme for distributed networks.3- 25 A continuing R&D challenge in terms of scientific and technical

information services has been posed by Tell (1966)

by analogy with the techniques of input-output

economics.3 - 26 Of major concern is the problem of

high costs of communication facilities necessary to meet network information flow requirements.3 - 27

4. Input-Output, Terminal Design, and Character Sets

The area of input-output, especially for two- dimensional and even three-dimensional information processing, is currently receiving important

emphasis in overall information processing sys- tem design. One reason for this, as we have seen,

is the increased attention being given to remotely

accessed, time-sharing, or man-machine interaction

systems. In particular, as noted by Tukey and Wilk:

"The issues and problems of graphical presentation

in data analysis need and deserve attention from

many different angles, ranging from profound psy- chological questions to narrow technological ones. These challenges will be deepened by the evolution

of facilities for graphical real-time interaction."

(Tukey and Wilk, 1966, p. 705).

4.1. General Input/Output Considerations

Since a multiplicity of input and output fines are assumed for a variety of types of information to be processed (including feedback information from

users and from the system itself), development re- quirements with respect to both equipment and

sortware processing operations include batching of various input units, buffering of at least some

types of input (as required, for example, to provide

necessary reformatting), and multiplexing of input

operations. Such considerations also apply even more forcefully to interfaces between the various

nodes of a network involving more than one type of

participating system.4 - 2 Format control is typically needed both into

and out of the system, preferably under dynamic

program control. The format control subsystem,

by means of address storage registers or other

techniques, should enable the input data itself to determine where it should go in storage, and other means of "self-addressing" should be provided

without the need for elaborate or inefficient pro- gramming and related software requirements.4 3 The overall output capability design should

provide ability to reformat conveniently and effi- ciently 44 as well as to select certain character

sequences. Because of the variety of equipments

needed for various tasks, provision should be made

for reversal of the bit order of input and output

data so that either high or low order bits can be

processed first. In the case of displays, special

provisions may be required to prevent overlapping

of symbols.4- 5 Related to format control is the question of vari- able byte size for input and output. For the future,

system design will require ASCII (American Standard Code for Information Interchange) code sorting

and ordering capabilities, but in many circumatances

it will also be necessary to handle collapsed subsets of ASCII and other codes, longer byte lengths

such as 10- and 14-bit codes for typesetting, and

even longer codes for monotype, numeric process

control, data logging, and equipment control. Analog-digital and digital-analog convertibility

is needed for experimental applications in source

data automation, measurements automation, map

analysis, map and contour plotting, pattern processing, and the like. One example of convergent efforts

in the field is provided by Ramsey and Strauss

(1966) who discuss interrupt handling in the area

of hybrid analog-digital computers as representative of more general on-line scheduling problems.

For some of these investigations, at least virtual

real-time clocks will be needed.46 This implies

processor main frame and transfer trunks versatile

enough to handle these requirements whether implemented by software or built into the hardware.

Another important requirement is for versatile

and varied graphic input and output capability,

9
including light pen, microfilm, FOSDIC-type

scanning, mark-sensing, OCR (Optical Character

Recognition), MICR (Magnetic Ink Character

Recognition), color-code input (such as Lovibond

color network), and three-dimensional probe data

in (see the first report in this series), and largevocabulary character and symbol generation;

diagram retrieval, construction and reconstruction,

and perspective or three-dimensional projection

capabilities out (as discussed in the second report

in this series). Photographic and TV-type input

and output with good resolution, hard-copy re- production capability, varying gray-scale facility,

and at least the possibility of handling color input

or output display techniques will be required in future system design.4 7 Audio input-output capabilities should include dataphone, acoustic signal

inputs, and voice, with speech compression on

output, requiring controlled timing of "bursts" or

"slices." In many system design situations, we should

be able to switch peripheral equipment configurations around for special purposes and we may

need to have multiple access to various types of

peripheral devices simultaneously during the same processing run, e.g., to be able to shift between character recognition and graphic scanning

tasks for input of material where text and graphics

are intermixed.

Related to these problems of input, output, and

on-line responsiveness (especially for clients in- volved in problem-solving applications), is the

concept of graphical communication generally.48 This presupposes, first, a suitable language for the

exchange of both pictorial data and control infor- mation between the designer and the machine, and

secondly, provisions for the dynamic manipulation

of data and controls.4- 9 Recent programming techniques under investi- gation for the display of two-dimensional structure information are exemplified in work by Forgie,410 by Hagan et al. (1968) 411

, and at the University of

Michigan (Sibley et al., 1968).4 12 Then there is the

DIALOG programming system developed at the ITT

Research Institute in Chicago for graphical, textual,

and numeric data input and display, online and off- fine programming facilities, and hard-copy options.

(Cameron et al., 1967). A special feature is a character-by character man-machine interaction mode,

so that the programmer may use only those

input symbols that are syntactically correct. For more efficient machine use in production-type

operations, a DIALOG compiler for the IBM

7094 has been prepared following the "Transmographer" of McClure.4 13 (McClure, 1965).

Then we note that "in the area of displays, determining the information to be displayed and

generating the procedures for retrieval and formatting of the information are the difficult problems."

(Kroger, 1965, p. 269). Further, as of today, "too many systems are designed to display all the

data, and not to display only the data needed for the

decisions the system is called upon to make."

(Fubini, 1965, p. 2). In general, the client of the on-line, graphical

input-output, and problem-solving system needs

convenient means for the input of his initial data,

effective control of machine processing operations,

effectively instantaneous system response, dis- plays of results that are both responsive to his needs and also geared to his convenience, and

handy means for the permanent recording of the

decisions and design choices he has made.

With respect to these client desiderata, the identifiable R&D requirements relate to keyboard

function key overlay design; 414 improvements in both problem-oriented and client-oriented languages

for man-machine communication and interaction; 415

fast, high-resolution, flicker-free display generation; 416 ability to selectively emphasize various areas of display,4 17 further development of the combination of static displays (such as maps) with computer-controlled dynamic displays,418 and rapid

responsivity of the system to feedback from the

client. Since remote, reactive terminals are an in- creasingly important factor in systems involving

dynamic man-machine interaction, the question

of design of remote inquiry stations and consoles

necessarily raises problems of human engineering

for whose solution there is inadequate experimental

cost-benefit, and motivational data 419 available

to date. Also involved are questions of acceptance

and interactive response by the client to feed- back outputs from the system, including requests

for further information or additional inputs and

display of re-processed results.

4.2. Keyboards and Remote Terminal Design

Where graphic input and output facilities are to be available to on-fine users, there are unresolved

questions of interrelated and interlocking system

and human factors. How clumsy are light pens

or pointers to use? Are they heavy or difficult to aim? 4 - 20 Should light-pen imputs be displayed

a little to the left or to the right of the actual lightpen location so that the active part of the input

is not blocked from view by the moving light-pen

itself? 4 21 Can flicker-rate be kept to a tolerable

level without undue and costly regeneration de- mands on a multiply-accessed central processor

used by the many clients, or must the remote

terminal have storage and display re-generation

capabilities at added cost and design complexity? 4 22 For graphic input and display should

the input surface be flat, upright, or slanted? 4 23

It has been pointed out, in the case of the recent development of a solid state keyboard, that "the

requirements of today's keyboards are becoming more complex. Increased reliability and more

flexibility to meet specialized demands are essential. Remote terminals are quite often operated by

10
relatively untrained personnel and the keyboard

must be capable of error-free operation for these

people. At the same time it should be capable

of high thru-put for the trained operator as will be

used on a key tape machine.

"Some of the limitations of existing keyboards are: • Mechanical interlocks which reduce operator

speed. • Excessive service (increasingly important for remote terminals). • Contact bounce and wear of mechanical

switches. • Non-flexible format." (Vorthmann and Maupin,

1969. p. 149).

For automatic typographic composition applications, it is emphasized that "the application of

computers to typesetting only emphasizes the

scope and the need for a radical re-thinking on

keyset design," and that, although "one may imagine that the keyboard is a relatively simple piece

of equipment ... in fact, it presents a unique

combination of mechanical, electrical and human

problems." (Boyd, 1965, p. 152). Current R&D

concerns with respect to keyboard redesign in- volve consideration of principles of motion study

as applied to key positioning, key shape, key

pressures required, and the like.4 - 24 Nevertheless, it is to be emphasized that "in- put-output devices are still largely the result of an

ingenious engineering development and a somewhat casual and often belated attention to operator,

system attachment, and programming problems"

and that ". . . no input-output device, including

all terminals combined, has yet received the careful and competent human factors study afforded

the cockpit of a military aircraft." 4 25 (Brooks,

1965. p. 89). Beyond this are questions of design requirements

for dynamic on-line display. Thus we are con- cerned with requirements for improved remote

input console and terminal design.4 - 26 Relatively recent input-output terminal developments, especially for remote consoles or dynamic man-machine

interaction, have been marked by improved potentialities for two- and even three-dimensional

data processing and by further investigation of

prospects for color, as discussed, for example, by

Rosa (1965),4- 27 Mahan (1968) 4 28 and Arora et al. (1967), among others. Van Dam (1966) has provided

an informative state-of-the-art review of such scan- ning and input/output techniques. Vlahos (1965)

considers human factor elements in three-dimensional display. Ophir et al. (1969) discuss computergenerated stereographic displays, on-line.4- 29

In the area of input-output engineering and sys- tem design, what is needed for more effective manmachine communication and interaction will include

the provision for remote consoles that are truly

convenient for client use. Hardware, software, and

behavioral factors are variously interrelated in

terms of desired display and console improvements.4 - 30 The desirable design specifications for remote

inquiry stations, consoles, and terminals and dis- play devices as discussed in the literature variously

include: economy, dependability, and small enough

size for convenient personal use.4 - 31 Some misgivings continue to be expressed on this score. Thus,

it is reported that Project Intrex will consider the

design of much more satisfactory small consoles 4 - 32 and Wagner and Granholm warn that "at the moment, it is difficult to predict whether remote

personal consoles can be economically justified to the same extent that technological advances will make them feasible." (1965, p. 288). Cost certainly

appears to be a major factor in the limited nature

of the use that has been made of remote terminals

to date.4 - 33 A second requirement is for the provision of

adequate buffering facilities including, for at least some recent systems, capabilities for local display

maintenance.4 - 34 From the hardware standpoint, it is noted that "the major improvements in displays

will be in cost and in the determination and implementation of the proper functions from the user

standpoint. The cathode-ray tube will probably

be dominant as the visual transducer for console

displays through 1970, but there are several new

techniques for flat-panel, digitally addressed dis- plays presently under development that may eventually replace the CRT in many applications.

The advances in memory and logic component

technologolies will permit significant improvements

in the logic and memory portions of console dis- plays." (Hobbs, 1966, p. 37). Other features that are desirable may include a capability for relatively persistent display, for example, up to several hours or several days,4 - 35 and the capability, as in the Grafacon 1010 (a commercially available version of the RAND Tablet)

for the tracing of material such as maps or charts to be superimposed on the imput surface, or the Sylvania Data Tablet ET 1, which also allows a modest

third axis capability.

As in the case of system outputs generally,

hard-copy options are often desired through the

terminal device. For example, the console "should

have a local storage device on which the user can build up a file of the pieces of information he

is retrieving, so that he can go back and forth in referring to it. It should have means of giving him

low-cost hard copy of selected material he has been

shown and temporarily stored." (King, 1965, p. 92). The use of markers and identifiers for on-line

text editing purposes should be simplified or elimi- nated to the maximum extent possible. If, for ex- ample, elaborate line and word sequence identi- fications must be used both by the machine system

and by the client, then the virtues of machine

processing for this type of application will be largely

lost. Such systems should not only be easy to use, but easy to learn how to use.

376-411 O - 70 - 2
An important question to be asked by the sys- tem designer is whether the output responses will be of the types and in the formats that the client

will expect to receive. It is noted in particular that "the closer the correspondence of the computer

output is to the methods of presenting textual

and tabular material familiar to the user, the greater

his information absorption rate will be." (Morenoff

and McLean, 1967, p. 20). Thus, in engineering

applications, for example, the client may want

results to be displayed in a familiar format such

as a Nyquist plot.4 - 36 Similarly, in operations on

files or data banks, the user should be able to struc- ture and sequence files and subfiles for display

and selection to suit his own purposes.4 - 37 For effective online operation, the system should

provide responses within the reading rates of typical users, and with good resolution, little or no flicker,

and with both upper and lower case.4 - 38 A some- what more specific and stringent list of remote terminal desiderata is provided by Licklider, with particular reference to the requirements of multiple access to the body of recorded knowledge. His de- sired features include, but are not limited to, color, or at least gradations of gray scale; 4- 39 terse or abbreviated modes of expression to the

machine with full or "debreviated" response; 4 40 selective erasibility of the display by either program

or user command, 4 41 and capabilities such as the

following: "Shortly thereafter, the system tells me: 'Response too extensive to fit on screen. Do

you wish short version, multipage display, or typewriter-only display?'." (Licklider, 1965, p. 50). Another design criterion affected by the factor of

client convenience is that of the extent of display on the console face of meta-information.4 - 42 Continuing needs for technological developments

have also been indicated for improved terminal

and output display design. Examples include the

development of new, fast phosphors and other

materials,4- 43 use of analog predictive circuitry to improve tracking performance,4 - 44 and variable

sequencing of processor operations in computation and display.445 A number of advanced tech- niques are also being applied to large-screen

displays,4 - 46 although some continuing R&D dif- ficulties are to noted.4 - 47 Multiplexing of graphic

display devices may also be required.4 - 48 Returning, however, to the human behavioral

factors in input-output and terminal design, we note

that man-machine relationships require further

investigation both from the standpoint of human

engineering principles and also from that of attitudes

of clients and users,4 - 49 that there are continuing

requirements for research and development efforts on both sides of the interface 4 50 and that, in all probability, "industry will require more special

prodding in the display-control area than in the

other relevant areas of computer technology."

(Licklider, 1965, p. 66). We note further an area of R & D concern that

will recur in many other aspects of information

processing system design and use, and especially

in information selection and retrieval applications.

More specifically: "The major problem today in the design of display systems is that we cannot

specify in more than qualitative terms such critical criteria as 'context' and 'meaning'." (Muckler and

Obermayer, 1965, p, 36). Swanson adds: "Other

restrictions derive from the need of programs to solve hidden line problems, to recognize context,

and to make abstractions." (Swanson, 1967, p. 39). Finally, we note the specific problem in documentary and library applications that large character

repertoires are important to input and output

representations of various levels of reference and

emphasis in technical texts (especially, for example,

in patent applications with multilevel referrals to accompanying drawings and diagrams) and to delineation of different types of possible access points

in indexes and catalog cards.4- 51 In addition, a wide

variety of special symbols and/or exotic alphabets

are typically employed in texts dealing primarily

with mathematical, logical or chemical subjects. A

text written principally in one particular language

and alphabet may frequently use the alphabet set of one or more other languages, as in reference to proper names, citations, and quotations.

4.3. Character Set Requirements

For multiple-access systems "most creative users want large character sets with lower-case as well as capital letters, with Greek as well as Latin

letters, with an abundance of logical and mathematical signs and symbols, and with all the common

punctuation marks." (Licklider, 1965, p. 182). In

addition, subscripts, superscripts and diacritical marks may be required.4 - 52 Attacks on problems of character-set requirements for output begin with on-line printer varia- tions to provide larger output character-set vocabularies at the expense both of output printing

speed and of prior input precedence-coding and/or

of processor programming. Larger characterset vocabularies are provided both by photocomposition techniques and by electronic charactergeneration methods, but again at the expense of

either pre-coding or programming requirements.4 - 53

It should be noted, of course, that the internal

language of most general-purpose information proc- essing systems is limited to no more than 64 dis- crete characters, symbols, and control codes.

Thus there must be extensive provision for multiple table lookups and/or for decoding and re- encoding of precedence codes or transformation

sequences, on both input and output, if any internal

manipulations are to be performed on the textual material. In general, the larger the character set, the more elaborate the precoding and/or programming efforts that will be required.

Then there is the problem of setting up keyboard character sets that are adequate for application requirements and yet within reasonable

12
human engineering limitations. One proposed solution, the use of keyboard overlays and control codes

to enable rapid shifting from one character subset

to another, is exemplified by developments at Bunker-Ramo.4 - 54 Another possible solution to the

character set problem as related to human engineering factors that is receiving continuing R&D

concern is to provide multiple inputs via a single

keystroke, such as "chord" typewriters or Stenotype devices.4 - 55 Regardless of what may be available through

various conversion, transliteration, or translation

processes on either input or output, there remains

the question of the effects of internal character

set upon sorting, ordering, filing and interfiling

operations for a specific processor-storage system.

For example, "other control elements which are frequently required in the design of information

systems are special sorting elements. In a directory

of personal names, such as those which might be

found in an author bibliography, if names beginning with 'Mc' and those beginning with 'Mac'

are to sort together, then special sorting codes

must be entered into the computer for this purpose."

(Austin, 1966, pp. 243-244)4 - 56 The size of an adequate character set is a particularly critical problem in at least two signifi- cant areas: those of automatic typographic-quality

typesetting and of library automation.4 - 57 Complex

character set requirements are also to be noted

in such multiple-access applications as computeraided-instruction (CAI).4 - 58 Avram et al., considering

automation requirements at the Library of Congress, stress that "keyboard entry devices must be

designed to facilitate the input of a variety of lan- guages and diacriticals." (1965, p'. 4). These authors

point out further that "if the problems associated

with the design of input keyboards and photocomposition printing devices can be resolved for the

multiplicity of alphabets, there still will remain

the formidable task of searching in a machine file which contains them." (Avram et al,, 1965, p. 89). Similarly, Haring (1968) points out that the 128

symbols provided in the ASCII code is inadequate

for the augmented catalog under development at Project INTREX.4 59 The very number and diversity of varied but

realistic cataloging, filing, and search considerations in terms of character-set and sort-order

requirements that exist today may indeed surprise

the typical computer scientist facing library auto- mation implementation problems. Nevertheless,

particular problems of sorting, filing, and reassembly orders in terms of practical usage needs and

acceptability to the clients of mechanized systems

and services should be subjects of concern to designers of machine languages, machine character-sets, and of the processors as such.4 - 60 The even more difficult case of extensive mathematical, chemical, and other special symbols de- sired on output imposes additional hardware re- quirements, whether for high speed printers,

photocomposition devices, or character generators. 4 - 61 This, then, is the area that has been called

"Caligraphy by Computer." 4 62 A final example of

unusual character set requirements is provided by

"Type-A-Circuit" developments.4- 63

5. Programming Problems and Languages and Processor

Design Considerations

The questions of design and development of

appropriate programming languages and of proc- essor design are obviously pertinent to all of the

operations shown in Figure 1. As of 1967-68, however, special emphasis in terms of research requirements lies in three principal areas: user-oriented

input, response and display languages; symbol

manipulation languages capable of handling ar- rays of multiply interrelated data, and increasing

interpenetration of hardware and software considerations in both system design and system use.51 For example, in the operations of developing

processing specifications from client requests for service (Boxes 8 and 9 of Fig. 1), we need: new and more powerful problem-oriented languages; versatile supervisory, executive, scheduling, and accounting programs; hierarchies of programming lan- guages; multiprogramming systems; improved

microprogramming; new approaches to increasing

interdependence of programming and hardware;

and more versatile and powerful simulation lan- guages.

The overall system design requirements of the

future indicate R&D concerns with programming

languages, and especially with hierarchies of such

languages at the present time.5 - 2 Controversies

certainly exist as between advocates of more and more "universal" languages and proponents of problem-oriented or user-oriented machine communication techniques.

5.1. Programming Problems and Language

Continuing R&D requirements for programming language improvements represent two

contradictory requirements: on the one hand,

there is recognized need for increasingly uni- versal, common-purpose languages compatible

with a wide variety of systems, hardware configurations, and types of applications; and on the other

hand for hierarchies of language systems. In

addition, a number of special requirements for more flexible, versatile and powerful languages

are just beginning to emerge, especially in such

13
areas as graphical communication, on-line problem

solving, multiple access and multiprocessor control systems, simulation, and on-line instrumentation. We are concerned here, then, with generalpurpose language and compatibility requirements;

with special-purpose requirements such as problem-oriented programs, list-processing and other

techniques for non-numeric data processing;

with special problem areas such as very large

programs and the requirements of multiple-access

and multiprogrammed systems; with hierarchies

of programming languages, and with the increasing

interdependence of software and hardware considerations.

5.1.1. Problems of Very Large Programs and of Program

Documentation

In terms of continuing R&D concern, we

note first the problems of handling very large

programs, defined as those that demand many

times the available main storage capacity and

that are sufficiently complex in structure to require more than ten independent programmers to work

on them.5 - 3 An obvious requirement is to develop

efficient techniques for segmentation: "When

many programmers are involved, there is the problem of factoring the system into appropriate

subtasks. At the present time this is an art rather

than a science, and very few people are good at

its practice, because of the inability to find useful

algorithms for estimating the size and degree of

difficulty of programming tasks." (Steel, 1965,

p. 234). The questions of automatic segmentation,

although recognized as critical and difficult problems, have therefore been raised.5 - 4 In particular, the checkout of very large pro- grams presents special problems.* For example,

"another practical problem, which is now beginning to loom very large indeed and offers little prospect of a satisfactory solution, is that of checking the correctness of a large program." (Gill, 1965, p. 203). Further, "the error reporting rate from a program system of several million instructions is sufficient to occupy a staff larger than most

computing installations possess." (Steel, 1965,

p. 233).

Other specific requirements in the programming

problem areas include improved provision for adequate program documentation and related controls.5 - 5 For example, Pravikoff (1965) presents

cogent arguments for the improved documentation for programs generally. Mills (1967) points

to the special documentation problems in multiple access systems where users are less and less apt

to be trained programmers.5 - 6 Dennis (1968) points

to the present high costs of large-scale programming

efforts as due to inadequate documentation that prevents taking advantage of programming already

achieved,5 - 7 while Kay (1969) considers the advan-

*See also Section 7.1 of this report, on debugging problems generally.

tages of on-line documentation systems.5 - 8 Thus the area of program documentation requires further

study and concern. A related difficulty is that of inadequate means

for translation between machine languages, al- though some progress has been made.5- 9 An in- triguing possibility deserving further investigation

has been raised by Burge (1966, p. 60) as follows: "Presented here is a problem and a framework for

its solution. The problem is as follows: Can we

get a computer program to scan a library of pro- grams, detect common parts of patterns, extract them, and re-program the library so that these

common parts are shared?"

Another current question of R & D concern

with respect to programming problems is of the

generality with which a given language system

can or cannot cope with a wide variety of system

configurations and reconfigurations over time.510 The questions of development of more effective

common-purpose or general-purpose languages

involve very real problems of mutually exclusive

features and of choices as between a number of means of achieving certain desirable built-in features.511 Areas of continuing R&D concern in programming language developments reflect, first, the

need for increasing generality, universality, and

compatibility (these objectives are followed in general-purpose language construction and standardization, on the one hand, and by increasing

recognition of the needs for hierarchies of language, on the other); secondly, the special requirements of

multiple-access, multiprogrammed, multiprocessor,

and parallel processing systems; thirdly, requirements for problem-oriented and other special-purpose languages, and finally, needs for continuing

advances in hardware-software balances and in fundamental programming theory.

5.1.2. General-Purpose Programming Requirements

The presently indicated transition from exclusively batch or job-shop operation to on-line, multiple access system management 512 sharply

aggravates the problems of programming language

requirements in a number of different ways. First,

there are very real difficulties in translating from

programming languages and concepts geared to sole occupancy and use of system facilities to those required in the multiple-access, and multiprogrammed, much less the multiprocessor and

network environment.513 As Brooks (1965) points out: "Today's excite- ment centers chiefly around (1) multiprogramming

for time-sharing, (2) multiple-computer systems

using a few computers for ultra-reliability, and

(3) multiple-computer systems using a highly parallel structure for specialized efficiency on highly

structured problems." 514 In all of these cases, moreover, the R&D requirements are typically

14
aggravated by a persistent tendency to underestimate the difficulties of effective problem solution. 515 An obvious first common-purpose requirement is for truly efficient supervisory, accounting, and

monitoring control programs 516 that will effectively

allocate and dynamically reallocate system re- sources, that will be secure from either inad- vertent or malicious interference, and that will be

flexible enough to accommodate to changing cli- entele needs, often with new and unprecented

applications.5 - 17 Also in the area of general-purpose programming

requirements are the various emerging programs

for generalized file or data base management,

maintenance, and use.

518 The first requirement,

here, is for reconciliation of variable input, file storage, and output formats, together with flexible means for dupe checking on input, combinatorial

selection, and output reformatting.519 Closely re- lated are the questions of the so-called "formatted

file systems." 5 20 A first approach to such general-purpose pro- gramming systems was undoubtedly that of the

Univac B—O or Flow-Matic system developed in the mid-1950's.5 - 21 More recent examples include

General Electric's GECOS HI (General Comprehensive Operating Supervisor III) 5 22 and Inte- grated Data Store concepts; 5 23 the TDMS (rimeShared Data Management System) at System De- velopment Corporation 5 24 and GIS (Generalized

/nformation System) of IBM.5,25 Heiner and Leish- man (1966) describe a generalized program for record selection and tabulation allowing variable

parameters for sort requirements, selection cri- teria, and output formats.5- 26 In 1965, comparative operation of file management was demonstrated by different systems

including COLINGO (Mitre Corporation), Mark

III (Informatics, Inc.), BEST (National Cash Register), Integrated Data Store (G.E.), and an on-line

management system of Bolt, Beranek, and Newman, Inc.5 - 27 It was concluded that: "All of these

systems were able to accompbsh the processing

required, but their approaches varied considerably,

particularly in the file structures chosen for the

application, executive control procedures, and level

of language used in specifying the processing to be

performed." (Climenson, 1966, p. 125). In addition, we may note the examples of a file organization executive system,5 - 28 a program management system involving a two-level file,5 - 29 and

a file organization scheme developed for handling

various types of chemical information.5 - 30 Another

documentation application involving a list-ordered

file is provided by Fossum and Kaskey (1966)

with respect to word and indexing term associations for DDC (Defense Documentation Center)

documents.5 - 31 In the area of common-purpose languages,

also, there is need to reconcile the differing re- quirements with respect to different classes

of data structures,5 - 32 from those of numerical

analysis processing through those of alphanumeric

file management to those of list and multi-list processing.5 - 33 List structures have been noted

in several of the file management systems mentioned

and it is to be noted further that: "Linked indexes

and self-defining entries are an extension of list processing techniques." (Bonn, 1966, p. 1869).

For non-numeric data processing applications, in general, symbol string manipulation, list processing

and related programming techniques have been of

particular concern. 5 - 34 While many advantages of list-processing tech- niques have been noted, a number of disadvantages

are also reported. Among the major advantages are the recursive nature of list processing languages 5 35 and adaptability to dynamic memory allocation and

reallocation. 5 - 36 Also, languages of this type are "well suited to symbol manipulation, which means

that it is possible to talk about the names of vari- ables, and perform computations which produce

them" (Teitelman, 1966, p. 29), and "by means of

list structures ... a three-dimensional spatial net- work can be modeled in computer memory."

(Strom, 1965, p. 112).

Typical disadvantages to be noted include lack

of standardization,5 - 37 degree of programming

sophistication required,5 - 38 and wastage of stor- age space.5 - 39 Major difficulties are often encountered in updating and item deletion operations 5 - 40 and in dealing with complex data structures.5 - 41 We may ask also to what extent the available

list-processing and symbol manipulation programming languages are adequate for current application needs? 5 42 To what extent are they useful for the investigation of further needs? In particular,

it is noted that "unfortunately, while these lan- guages seem in many ways directly tailored to the

information retrieval work, they are also in other

respects very awkward to use in practice." (Salton,

1966, p. 207).

List-processing languages and structures are

particularly clumsy, moreover, for multiply inter- related and cross-associated data.5 - 43 Short of

truly large-scale associative memories, effective

compromises are needed as between list struc- tures, including multilist programming languages,

and file organizations that will provide economy

of both storage and access.5 - 44 Beyond list processing procedures there are

trees, directed graphs, rings, and other more complex

associative schemes.5 - 45 A relatively early example

is that of "Rover" with "up links" and "side

links" as well as "down links". 5 - 46 Savitt et al., 1967,

describe a language, ASP (Association-Storing

Processor), that has been designed to simplify the

programming of nonnumeric problems, together

with machine organizations capable of high-speed

parallel processing.5 - 47 Ring structure language systems are represented

by Sketchpad developments 5 48 and the work of

Roberts at M.I.T. for graphical data processing 5 - 49 and by systems for use in question-answering

15
and similar systems, such as Project DEACON.5 - 50

Still other associative structure developments are discussed for example, by Ash and Sibley (1968),5 - 51 Climenson (1966),5 - 52 Craig et al, (1966),5 - 53 Dodd

(1966),5 - 54 and Pankhurst (1968). 5 - 55 There are certainly those who need far more

generalized multipurpose languages and, with

equivalent force, those who advocate specialized,

man-oriented, and special-purpose languages.

A specific current design problem has to do with an appropriate compromise between these apparently contradictory comments. A future R&D

requirement is to seek more effective solutions.

Thus Licklider insists upon the need to bring

on-line "conversational" languages more nearly

abreast with the more conventional programming

languages as an R & D challenge. 5 - 56

5.1.3. Problem-Oriented and Multiple-Access Language

Requirements

Increasing needs for advanced special-purpose

program language developments have been recog- nized for the areas of man-machine interactive

problem-solving and computer-aided instruction

applications, graphical manipulation operations,

and simulation applications, among others. It is noted in particular that "their power [that of

problem-oriented languages] in the extension

of computing lies in the fact that the expert knowledge of skilled analysts in particular fields can

be incorporated into the programs, together with

a language which is native to the field, or nearly so, and can thereby break down the barriers of eco- nomics, of lack of familiarity with the computer,

and of time." (Harder, 1968, p. 235).

Important requirements in programming lan- guages reflect, predictably, those of multiple- access and time-shared systems involving a suitable

hierarchy of languages so that the relatively un- sophisticated user may converse freely with the

machine without interference to other users or

to the control and monitor programs and yet also draw upon common-use programs and data. The effective use of such systems in turn demands

extremely tight and sophisticated programming

to keep "overhead" to a minimum 5 - 57 and to provide

dynamic program and data location and relocation.

Relatively recent developments in this area are discussed by Bauer, Davis, Dennis and Van Horn,

Licklider, Clippinger, Opler, and Scherr among

others.5 - 58 Bauer (1965, p. 23) suggests in particular

that: "Entirely new languages are needed to allow flexible and powerful use of the computer

from remote stations."

Multiple-access systems and networks obviously

require R&D efforts in the development of lan- guage systems "optimized for remote-on-line

use" (Huskey, 1965, p. 142). Opler points out,

first, that "for the most difficult areas — telecommunication, process control, monitors, etc.—

real-time languages have provided little assistance,"

and, secondly, that "the task of developing a complete new real-time language would be inter- esting and challenging since it would require

reconsideration of the conventional procedure

and data defining statements from the viewpoint

of the real-time requirements." (Opler, 1966,

p. 197).

Further, on-line problem-solving applications re- quire dynamic and flexible programming capabilities. 5 59 Experimentation with the working program

should be permitted with due regard for system

protection and control. 5 - 60 Generalized problemsolving capabilities should be available in the

language system without necessary regard to specific applications.5 - 61 Such programs should be

extensively self-organizing, self-modifying, and

capable of adaptation or tentative "learning." 5 - 62 Then it is to be noted that languages for on-line use should be relatively immune to inadvertent user

errors. 5 - 63 Teitelman comments, for example, that "in languages of this type, FORTRAN, COMIT,

MAD, etc., it is difficult to write programs that construct or modify procedures because the communication between procedures is so deeply embedded

in the machine instruction coding, that it is very

difficult to locate entrances, exits, essential vari- ables, etc." (1966, p. 28). In language systems such as TRAC,5 64 the powerfulness is largely buried in specific machine proc- essors for this language — the user is freed from

learning a number of arbitrary exceptions, he is not able to "clobber" the underlying processor by

inadvertent goofs, he is able iteratively to name and rename strings and procedures he wishes to use

largely in terms of his own convenience, and he is able to make use of the language and system with

minimal training or prior experience.

Related problems affect the design of specialpurpose languages ("the design of special-purpose

languages is advancing rapidly, but it has a long

way to go," Licklider, 1965, p. 66), the interaction

of executive and console languages ("wherever

remote consoles are used, we find the users enthusiastic. However, they always hasten to add that there is much to learn about the design of executives and processors for console languages,"

(Wagner and Granholm, 1965, p. 287), the provision

of adequate debugging aids ("the creation of large

programming systems using remote facilities re- quires a number of debugging aids which range in complexity from compilers to simple register contents request routines." Perlis, 1965, p. 229), and

the development of effective modularity in programs

and compilers ("it will be necessary for the soft- ware to be modular to the greatest extent possible

because it will need to work up to the next level of

software." Clippinger, 1965, p. 211). In connection with the latter requirement Lock

discusses the desirability of an incremental compiler which is characterized by its ability "to compile each statement independently, so that any

local change in a statement calls only for the re-
compilation of the statement, not the complete

program." (1965, p. 462).

Time-sharing or time-slicing options and graphical

communication possibilities cast new light not only

upon the problem-oriented but also upon the user- oriented languages and improved possibilities for man-machine communication and interaction. Ef- fective compromises between the system design,

the programmer, and the client have not yet been

met, even although the demands of modern systems

are increasing in complexity.

The problems of effective programming and uti- lization reach back beyond specific routines, specific languages, and specific equipment. They are involved in all the many questions of systems planning, systems managment and systems design. For

example, in time-shared operations, "considerably

greater attention should be focused on questions of

economy in deciding on the tradeoff between hard- ware and software, in using storage hierarchies, and

in determining the kind of service which the timesharing user should be offered." (Adams, 1965, p. 488). Finally, the critical problems reach farther

back than the potentialities of hardware, software

and systems planning combined, to fundamental

question of why, how, and when we should look to machines for substantial aid to human decisionmaking and problem-solving processes, "An analysis of the various requirements that a programming language must satisfy (to be known

both by the job-originator and the job-executor

and to be capable of expressing both what the

first wants to be done and what the second is capable

of doing) involves basic researches on the linguistic nature of programming languages." (Caracciolo di Forino, 1965, p. 224).

5.1.4. Heirarchies of Languages and Programming

Theory

Direct machine-language encoding and pro- gramming was the first and obvious approach

to both numeric and non-numeric data processing

problems. In both areas, forms of communication

with the machine that are more congenial to the

human user have been developed, as formal

"programming languages" (FORTRAN, ALGOL,

COBOL, and the like). 5- 65 In addition, special

program languages to facilitate either problemsolving and question-answering systems, or textual

data processing, or both; (such as list-processing

techniques, IPL-V, LISP, COMIT, SNOBOL,

more recently TRAC, and others) 5 66 have been

developed. More and more, however, it is beginning

to be recognized that hierarchies of language are

essential to present and foreseeable progress.5 - 67 Burkhardt (1965, p. 3) lists a spectrum of pro- gramming languages on the basis of the "declarative

freedom" available to the user, from absolute

machine languages with none, to "declarative

languages" which provide a description of the

problem and freedom of both procedure and solution. Certainly, for the future, "the entire spec- trum of language from binary machine code to the

great natural languages will be involved in man's

interaction with procognitive systems." (Licklider,

1965, p. 104). In the area of desired hierarchies of languages, we note such corroborating opinions as those of

Salton who asks for compiling systems capable of

handling a variety of high-level languages, specifically including list processing and string manipulations 5 68 and of Licklider who points out that in each of many subfields of science and technology

there are specific individual problems of terminology, sets of frequently used operations, data struc- tures, and formulas, indicating a very real need for many different user-oriented languages.5 - 69 However, in his 1966 review, the first ACM Turing Lecture, Perlis concludes: "Programmers should never be satisfied with languages which permit them to program everything, but to program nothing of

interest easily. Our progress, then, is measured by

the balance we achieve between efficiency and

generality." (1967, p. 9). Moreover, even in a single system, it may be

necessary not only to reconcile but to combine the

contradictory advantages and disadvantages of dif- fering levels of programming language in various

ways. Thus Salton states "it is possible to recognize

five main process types which must be dealt with

in an automatic information system: string manipulation and text processing methods, vector and

matrix operations, abstract tree and list structure manipulations, arithmetic operations, and finally

sorting and editing operations." (Salton, 1966, p. 205). A second complicating factor relates to the

still unusually fluid situation with respect to hard- ware developments, logical design, and the increasing interdependence of hardware-software factors

in the consideration of future system and network

design possibilities.

Beyond the investigation, development, and

experimental application of advanced programming

languages for specific types of application such as graphical data processing, simulation, or on-line

question-answering and problem-solving systems,

study is needed of fundamental problems of pro- gramming theory.5 - 70 For example Halpern notes

". . . the increasingly wide gulf between research

and practice in the design of programming lan- guages." (1967, p. 141), while Alt emphasizes that "we do not yet have a good theory of computer

languages, and we are nowhere near the limit of

the concepts which can be expressed in such lan- guages." (1964, p. B.2-1).

There is also to be noted in the current state of the

art in the computer and information sciences an

increasing concern for the relationships between

formal modelling techniques, generally, the questions of formal languages, and the development

of powerful, general-purpose programming lan- guages.5 - 71 Karush emphasizes that "the development of an integrated language of mathematical

17
and computer operations is part of a more general

problem associated with the automation of control

functions. This is the problem of formalism which

embraces both mathematical representations of

systems and representations of the processes of

actual execution of systems, by computer or other- wise." (1963, p. 81). A similar concern is expressed by Gelernter: "Just as manipulation of numbers in arithmetic is the fundamental mode of operation in contemporary computers, manipulation of symbols in formal

systems is likely to be the fundamental operating

mode of the more sophisticated problem solving

computers of the future. It seems clear that while

the problems of greatest concern to lay society

will be, for the most part, not completely formalizable, they will have to be expressed in some sort of formal system before they can be dealt with by

machine." (1960, p. 275).

High-order relational schemes both in languages

and in memory structures will thus be required.5 - 72 For example, "the incorporation in procedural

programming languages of notations for describing

data structures such as arrays, files, and trees,

and the provision to use these structures recursively together with indications of the scope of

definition, will help greatly with the storage alloca- tion problem and assist the programmer organizationally . . ." (Barton, 1963, p. 176). In this connection, Press and Rogers (1967) have described

the IDEA (inductive Data Exploration and Analysis)

program package for the detection of inherent

structure in multivariate data. 5 - 73 We note also that "even in the more regular

domain of formal and programming languages,

many unsolved practical and theoretical problems remain. For example, the matter of recovery

from error in the course of compilation remains

in a quasi-mystical experimental state, although some early results, applicable only to the simplest

of languages suggest that further formal study

of this problem could be worth while." (Oettinger,

1965, p. 16). Requirements for continuing research and

development activities in the area of computing

and programming theory are increasingly seen as directly related to needs for more effective multi- access time-sharing, multi-programmed, and multiprocessor systems. It can be foreseen that "Organizational generality is an attribute of underrated

importance. The correct functioning of on-line

systems imposes requirements that have been

met ad hoc by current designs. Future system

designs must acknowledge the basic nature of

the problems and provide general approaches

to their resolution." (Dennis and Glaser, 1965,

p. 5). What are some of the difficulties that can be

foreseen with respect to the further development

of hierarchies of systems? Scarrott suggests

that "the problems of designing and using multilevel storage systems are in a real sense central

to the design of computing systems" (1965, p. 137), and Burkhardt warns: "As long as actual

computers are not well understood there will not be much hope for very successful development

of useful universal processors." (1965, p. 12).

5.2. Processor and Storage System Design

Considerations

In the area of information processing systems

themselves, current trends have been marked

not only by new extensions to the repertoires

of system configurations available for the large,

high-cost, high-speed processors but also by a continuing tendency to the development of computer system "families." Increasing attention

is being given to both "upward" and "downward"

compatibility — that is, to means by which pro- grams operable on a large system may also operate on a smaller, slower, or less expensive member

of the same family, and vice versa. Increasing attention has also been given to pro- viding adjuncts to existing and proposed systems

which will give them better adapatability to timesharing and on-line multiple-access requirements.

Similarly, the requirements for handling a variety

of input sensing modalities and for processing more than one input channel in an effectually

simultaneous operation clearly indicate needs for continuing research and development efforts in the design and use of parallel processing tech- niques, multiprocessor networks, time-shared

multiple access scheduling and multiprogramming.

Hierarchies of languages are implied as we have

seen, ranging from those in which the remote console user speaks to the machine system in a rela- tively natural language (constrained to a greater or lesser degree) to those required for the highly so- phisticated executive control, scheduling, file protection, accounting, monitoring, and monitoring

instrumentation programs.

Tie-in to various communication links, generally,

should include remote consoles, closed circuit TV,

facsimile, voice quality circuits, and the like, with

capability for real-time processing. Message security

protection facilities are often required, including

encoding and decoding. Access to error detection

and error correction mechanisms are also necessary. Overall system design requirements indicate also the necessary exploitation of new hardware technologies, new storage media, associative-memory

procedures for file and data bank organization and

management, the use of dynamic reallocations of

.space and access to both programs and files or data

banks in multiple-access systems, protective and

fail-safe measures, and the development of hier- archies of languages of access and usage, hier- archies of stored data files, and hierarchies of

systems.5 - 74 Many of the above factors are discussed in other

sections of this report or in other reports in this series. Here, we will consider briefly some of the

18
problems of central processor design, parallel processing, and hardware-software interdependence.

5.2.1. Central Processor Design

With regard to the central processing system, it is noted that it should be operable in both time-sharing

and batch processing modes, and that it provide

simultaneous access to many users. Efficient multiple access should be provided to the hierarchies of

storage with the user having, in effect, virtually unlimited memory.5- 75 There should be a capability for accessing either internal or auxiliary associative

memory devices.

A continuing problem in processor-storage system

design is that of address-circuitry.5 - 76 Closely related

to this problem are questions of content-identification-matching whether for sequential or parallel access. Indirect addressing and multiple relative addressing via a number of index registers is an

important consideration.5 - 77 Moreover, direct program access to all registers

by ordinary instructions and with interlock protection features is often required. If the index registers can be simultaneously and interchangeably used as

instruction counters, there are additional parallel

processing benefits. For example, such capabilities can provide for jumping to the nth. instruction from

the present one, determining whether an instruction

has been executed or not, and other flexible capabilities for debugging, diagnostic, and evaluation

purposes. It should be possible to manipulate index

registers several at a time.

System users may need a relatively long word

length to provide numerical accuracy in long floating

point values, for manipulation of large matrices, to provide duplex operations on two sections of the

word simultaneously as in complex number processing, and the like. Automatic unpacking of word

subsets in variable sized bytes is also recommended

for future processor design. Salton indicates needs

for "flexible instructions operating on individual

bits and characters, and flexible branching orders.

Pushdown store instructions, such as 'pop' or 'push'

should also be useful for the list operations."

(1966, p. 209).

Also desirable is the ability to access a word

simultaneously from more than one computer sys- tem or component with automatic protection inter- locks in case of conflicts. Power-failure protection

systems should be available and protection should

also be provided against unauthorized access to various memory and data bank sections.

More flexible pagination 5 78 is needed for some

important applications. For example, in graphic data

processing, dynamic memory reallocation proce- dures requiring fixed pagination would be awkward to use and highly inefficient. Storage allocation should

be under programmer control. For example, if pictorial data overflows the boundaries of a page, at least 4 and as many as 9 pages may be required since

such data must be processed as a two-dimensional

array. The system designer needs to avoid as far as possible the problems of unnecessary and

clumsy programming in order to apply a single

procedure to such arrays. For example, Wunderlich

points out in connection with sieving procedures

for computer generation of sets and sequences that "there are obvious programming difficulties con- nected with sieving on a field of bits." (1967, p. 13). Another hardware-software desideratum here is obviously the need for efficient bit-manipulation

capabilities. For example, the user would like to find, for a given gray-level representation of a graphic

input that, at a given location and blackness level, some or all or none of the neighboring locations have

the same blackness level recordings (this is important in eliminating "fly specks" from further

processing, in filling-in "holes" that result from imperfect printing impressions, and also in deter- mination of the relative locations of centers of

blackness when attempting to reconstruct three- dimensional imaging for serial sequences of two- dimensional image representations).

Problems of computer design as well as programming for array processing are discussed by Senzig

and Smith (1965) in terms of a worldwide weather

prediction system and by Roos (1965) in terms of

the ICES (integrated Civil Engineering System) at M.I.T.5 - 79 Association matrices present a special

form of data arrays requiring efficient manipulation

and processing. Such considerations are particularly

important in the experimental research or on-line

instrumentation situations. 5 - 80 In addition, bit- manipulation and array-processing requirements

are severely constrained in commercially available

systems.

A requirement of major future importance (especially for chemical information searching, file, organization, mapping functions and graphic data

processing) is for efficient bit manipulation capabilities, including convenient Boolean processing

and transplant features. Again, bit manipulation

capabilities are important because many operations

require consideration of all the orthogonal neighbors

of a single bit position. In future system designs, increasing needs for multivalued logic approaches can also be foreseen.

In general, a binary (two-valued) logic pervades in- formation processing system design and the basic

methods of information representation as of today.

For the future, however, attention needs to be di- rected toward multivalued logic systems and to direct realizations of the ra-ary relations between the

data elements of stored information. There are new

technological possibilities that point in this direction (e.g., new devices that are capable of at least ternary response,5 - 81 or multiple response by color- coding techniques from a single "bit" recording on advanced storage media). In addition, parallel processing, associative processing, and iterative circuit techniques point the way to new complexities of

program command and control and to new, multivalued, processing opportunties as well.

19
Then, as Wooster comments: "Radically different

types of computers may well be needed. At present,

the best way of building these seems to be through

the creation of logical structures tending more and more in the direction of distributed logic nets,

wherein vast numbers of processes occur simultaneously in various parts of the structure. Right now,

the best building blocks for such systems seem to be

multifunctional microprogramable logic elements."

(1961, p. 21). Increasing complexity of central processor design

is indicated by developments in advanced hardware

technologies; 5 82 while increasing flexibility is dic- tated by dynamic reconfiguration requirements.5 - 83 Modularity is an important consideration.5 - 84 The

critically challenging, interacting problems of both

design, programming and utilization of multiproc- essors and of parallel processing are emphasized by

Brooks (1965), Amdahl (1965), Burkhardt (1965), and

Opler (1965), among others. Thus: "The use of multicomputers implies intercommunication, with the

associated implications of interconnection, reconfiguration and interlocking." (Amdahl, 1965, p. 38).

5.2.2. Parallel Processing and Multiprocessors

The possibilities for the use of parallel processing

techniques should receive increased R&D attention. Such techniques may be used to carry out data

transfers asynchronously with respect to the proc- essing operations,5 - 85 to provide analyses necessary

to convert sequential processing programs into

parallel-path programs,5 - 86 or to make allocations of

system resources more efficiently because constraints on the sequence in which processing operations are executed can be relaxed.5 - 87 Applications

to the area of pattern recognition and classification research and to other array processing operations

are obvious.5 - 88 However, there are problems of effective use of

parallel processing capabilities. Some examples

of the discernible difficulties with respect to current

parallel-processing research and development

efforts have been noted in the literature as follows:

(1) "Multiprogrammed processors will require more explicit parallel control statements in languages than now occur." (Perlis, 1965,

p. 189.)

(2) "Much additional effort will have to be put

into optimizing compilers for the parallel

processors that may dominate the computer

scene of the future." (Fernbach, 1965, p. 84).

(3) "Computers with parallel processing capabilities are seldom used to full advantage."

(Opler, 1965, p. 306).

There are also problems of R & D concern in programming language developments involved with

increased use of parallel processing capabilities.

The possibilities of "Do Together" provisions in compilers, first raised by Mme. Poyen in 1959,5 - 89 add a new dimension of complexity for analysis, construction, and interpretation. Fernbach comments

on the sparcity of attempts made to date on the

potentials of parallel processing in programs for many problems. He states further that while the

tasks of segmenting the problem itself for parallel

processing attack are formidable, "they must be

undertaken to establish whether the future development lies in the area of parallel processing or

not." 5 90 Then there is need for judicious inter- mixtures of parallel and sequential processing

techniques in specific design, programming, or application situations. 5 - 91 Parallel processing potentials are also closely

related to, and may be interwoven with, multiprocessing systems which involve: "The simultaneous operation of two or more independent

computers executing more-or-less independent

programs, with access to each other's internal

memories . . ." (Riley, 1965, p. 74). In particular,

the Solomon Computer and Holland Machine con- cepts may be noted.5 - 92 For another example,

increasing parallelism of operation of a multiple access processing system has been investigated at the Argonne National Laboratory in terms of an

"Intrinsic Multiprocessing" technique consisting of n time-phased "virtual" machines which time-share

very high speed execution hardware (Aschenbrenner

et al., 1967), while ILLIAC III has been designed

for parallel processing of pictorial data.5 - 93

5.2.3. Hardware-Software Interdependence

The earlier dichotomy as between "hardware"

and "software" considerations is beginning to yield, not only to the increasing interdependence of the

two factors in many information processing application requirements, but also to technological de- velopments in "firmware" (in effect, wired-in

microprogramming 5 - 94

) and to growing recognition of

the critical importance of more precise and comprehensive "brainware" in systems planning, design,

specification, and implementation.5 - 95 Is it currently possible to separate computer and

storage system design considerations from those of

programming language design and of programmed

executive control? Several experts testify that, if it is still possible today, it will soon be so no longer.5 - 96

It can be quite clearly seen that the areas of computer theory and program design are becoming

increasingly interdependent with those of adequate

programming languages, "software", and user- tolerance levels. At the same time, new possibilities for multicommunicator, multiprocessor, and multi- user networks are increasingly coming to the fore. The growing interdependence is stressed, for example, by Schultz (1967),5 - 97 and by Lock (1965)

who notes the strongly increasing influence of

multiprogrammed, on-line systems upon the or- ganization of the storage facilities. Scarrott (1965,

p. 137) for another example, insists that "the

problems of designing and using multilevel storage

systems are in a real sense central to the design of computing systems."

20-
Thus, "as we enter an era of bigger and more

complex systems some new requirements are coming to be of major importance.

• Will we be able to minimize the program handling by proper allocation to primary, e.g., core, or secondary, e.g., drum or disk, storage? • Will we be able to incorporate changes to the

functional operation of the system?

• Will we be able to modify the system to accom- modate new or additional hardware? • Will we be able to add a completely new function to an already operating system?" (Perry,

1965, p. 243). In the next section, therefore, we will consider some of the advanced hardware developments

before discussing such overall system design considerations as debugging, on-line instrumentation

and diagnosis, and simulation.

6. Advanced Hardware Developments

Certain obvious overall system design requirements have to do with the further extensive development and application of advanced hardware

technologies, especially opto-electronics generally

(and lasers and holography in particular), with

integrated circuit techniques, and with improved

high-density storage media.

Recurrent themes in current progress toward

very-high-speed, computer-controlled access to primary, secondary and auxiliary storage banks,

from the standpoint of hardware technology, include

the questions of matching rates of data-and/orinstruction access to those of internal processing

cycles, and of the prospects for integrated circuit and batch fabrication advantages in design and

construction.

These new technologies may also be combined in various ways. For example, Lockheed Electronics

has been using deflected laser beams to scan photochromic planes very rapidly and very ac- curately,61 laser and holographic techniques are conjoined in equipment designed to photograph fog

phenomena in three dimensions,6- 2 and it has been

reported that "laser devices show promise of very

fast switching which together with optical inter- connections could provide digital circuits that are

faster than electronic circuits." (Reimann, 1965,

p. 247).

6.1. Lasers, Photochromies, Holography,

and Other Optoelectronic Techniques

New hardware developments that are technically

promising in terms of the long range research and

development necessary to support future improvements in information processing and handling sys- tems include the development of special laser tech- niques for switching, storage, and other purposes,

and the possible use of holograms or kinoforms for 3-dimensional pattern recognition and storage.

6.1.1. Laser Technology

Writing in 1965, Baker and Rugari have pointed

out that "a wide variety of lasers have been dis- covered and developed since the first laser device was operated five years ago.

6- 3 Lasers can be classed

into three basic types: solid-state, semiconductor,

and gaseous. Typical examples are the ruby solid- state laser, gallium arsenide semiconductor laser,

and the neon-helium gas laser." (1966, p. 38). Certainly, lasers, whether of the gas, fluorescent

crystal, or semiconductor type,6 - 4 are finding many

new possibilities of application in computer, communication, and information processing systems.6 - 5 As sources of illumination they can provide greater

display efficiency 6 6 and greater resolution with

respect to display systems involving lightbeam

deflection techniques (Soref and McMahon, 1965,

p. 60),6 - 7 and they provide an effective aid to the

boundary and contrast enhancement techniques for image processing developed at the National Physical

Laboratory at Teddington, England. More specifically, this technology promises new developments in space communications,6 - 8 in memory construction

and design,6- 9 in the development of analytical

techniques such as Raman spectroscopy and photomicroscopy,610 in the identification of fingerprints,611 in quantization of high resolution photographs 612 and in the use of holograms for collection,

storage, and regeneration of two- and three-dimensional data.613 Small, very high-speed memories may be driven

by laser beams,614 and laser components contribute

to the design of "all-optical" computers 615 and

computer circuits and components.616 Laser in- scribing techniques are being investigated for such

applications as large screen real-time displays,617 and for highly compressed data recording, for example, at Precision Instrument Company.618 As of March 1969, it could be reported that orders

had been placed for UNICON systems by Pan

American Petroleum Corporation, and were under

consideration by several other organizations, in- cluding U.S. Government agencies.619 In particular,

the National Archives and Records Service has

been studying the possibilities of converting present

magnetic tape storage to this system.6 - 20

Investigations of future technical feasibility of

using laser devices for high speed data storage and/

or processing have thus been complemented by

exploration of possibilities for recording onto very

large capacity storage media as also in developments at Honeywell,6 - 21 at the Itek Corporation,6 - 22

21
and at RCA,6 - 23 an IBM system designed for and now

in operation at the Army Electronics Command as well as IBM developments in variable frequency

lasers,6 - 24 and a recording system from Kodak that uses fine-grained photographic media, diffraction

grating patterns, and laser light sources. 6 - 25 Holographic techniques may also be applied to the de- velopment of associative memories with possible

analogies to human memory-recall systems.6 - 26 Kump and Chang (1966) describe a thermostrictive recording mechanism effected on uniaxial

Permalloy films by the application of a local stress induced by either a laser or an electron beam,

promising large capacity memories of better than

106 bits per square inch storage efficiency.6 - 27 Then

there are combined optical and film techniques for

digital as well as image or analog recording and

storage. Specific examples include IBM photo-chip

developments,6- 28 thermal recording developments

at the NCR research laboratories,6- 29 Precision Instrument's UNICON System,6 - 30 and, in general,

the area of photochromic storage technology.

Areas of continuing R&D concern with respect

to laser communications possibilities include

questions of modulation and transmission,6 - 31 acquisition and tracking problems,6 - 32 isolation from

atmospheric interferrence conditions,6 33 and

possibilities for controlled atmosphere systems.6- 34 Vollmer (1967) notes that an experimental short- range laser communication system has narrow beam

width with significant advantages for privacy. In

particular, "operation at 9020 A enhances this privacy by virtue of its invisibility." (p. 67.) Some

examples of the experimental use of lasers for communications purposes were given in an earlier report in this series,6 - 35 and it was noted that the

most successful ventures to date have been at opposite ends of the distance spectrum.6- 36 However,

laser scanning techniques combined with other means of communication may offer important gains

in high-resolution facsimile transmission. For ex- ample, a system developed by CBS Laboratories uses a laser beam to scan photographic film, convert

to video signals, and transmit, via satellite, military

reconnaissance pictures from Viet Nam to Washington.6 - 37 Continuing requirements for further developments

in the application of lasers in display systems

involve, for example, efforts directed toward less expensive high quality semiconductor lasers 6 38 and

toward solving problems of deflection, modulation,

and focusing.6 - 39 Kesselman suggests that results

to date in terms of laser displays are inconclusive

and that practical applications are not likely in the near future (1967, p. 167). As in the case of laser versus electron beam display,6- 40 the absence of

requirements for vacuum techniques favors the

eventual use of laser rather than electron beam

techniques in many high density data storage

recording applications.6- 41

6.1.2. Photochromic Media and Techniques

By definition, photochromic (or phototropic)

compounds exhibit reversible effects or color

changes, resulting from exposure to radiant energy

in the visible or near visible portions of the spec- trum.6 - 42 Such media give excellent resolution and

reduction characteristics, and because of the

reversibility property, they can theoretically be

erased and rewritten repeatedly,6 - 43 although a continuing area of R & D concern is that of problems

of fatigue.6- 44 They also enable storage of images

with a wide range of gray scale.6 - 45 Such materials

have been known for at least a hundred years or more (Smith, 1966). In fact, as Smith suggests, they

may have provided the means for achieving the

world's first "wrist-watch." 646

Tauber and Myers (1962) and Hanlon et al. (1965)

offer summaries of NCR efforts to provide commercial applicability to photochromic recording

techniques for large-capacity micro-image storage

files. 6 - 47 A British example of application is the Technical Information on Microfilm Service.6 - 48 A less favorable characteristic of the photochromic material appears in the case of storage

files — the permanency of recording depends on

ambient temperature, ranging from only a few

/lours at normal room temperatures to perhaps

several years under rigid temperature controls.6 49 Therefore, for mass and archival storage, the

NCR system involves transfer from the photochromic images to a high-resolution photographic

emulsion for permanent files. 6- 50 The remaining

advantages are two-fold. First, the reduction is impressive: 1,400 pages of the text of the Bible on

an approximately 2" x 2" film chip is the widely

demonstrated example (Fig. 2). Secondly, 'spot' erasure and rewriting provides an important in- spection and error correction capability. It is claimed that: "Instantaneous imagery followed by

immediate inspection permits the production of

essentially 'errorless' masters for the first time".

(Hanlon et al., 1965, p. 10). In the area of internal memory and switching

design, Reich and Dorion (1965) report of the photochromic techniques that: "The photochromic

medium has extremely large storage capacity

latently available in physically small dimensions.

The basic photochromic switches are the molecules

themselves . . . Photochromic media can be employed for many write-erase-rewrite cycles and

give almost nondestructive read . . . Appropriate

photochromic systems can retain stored data with- out power consumption . . . The memory can

probably be designed to be stored for quite a long

time." (p. 572) 6 51 A photochromic medium in the form of trans- parent silicate glass containing silver halide particles

has been suggested for such applications as eras- able memories, displays for air traffic control

operations, and optical transmission systems.6- 52

22
N C R MICRO-IMAGE PROCESS

WORLD PUBLISHING CO., BIBLE No. 714

FIGURE 2. Photochromic data reduction.

In addition, it is to be noted that photochromic

films may be activated by CRT phosphors for use in information display systems (Dorion et al., 1966)6 - 53 and may also be used for real-time target tracking. 6 - 54 Recent developments suggest the use of photochromies for digital data storage.6- 55 Finally, the properties of photochromic materials

might be used for improved performance of holo- graphic recording, reconstruction and display

systems. 6 - 56 Thus, "the use of self-developing photochromic devices in the place of the photographic

plate would enhance the value of wavefront reconstruction microscope by permitting nearly real-time

operation and eliminating the chemical development process." (Leith et al., 1965, p. 156).

6.1.3. Holographic Techniques

Holography is a new information processing

technique, but it is, in fact, highly illustrative of

needs for truly long-range R&D planning in many

areas of computer and information sciences and

technology, since it is by no means a recent area of

investigation, the principles having been announced

by Gabor as early as 1948.6 - 57 The basic holographic

phenomena are described by Cutrona (1965, p. 89) as follows: "A hologram is produced by recording on

photographic film the interference pattern resulting

from the illumination of some object with a wavefront from the same source".6- 58

Leith et al. (1965, p. 151) point out further that "by combining conventional wavefront reconstruction techniques with interferometry, it has been

possible to produce holograms from which highquality reconstructions can be obtained. These

reconstructions bear close likeness to the original

object, complete with three-dimensional characteristics . . . The object can be a transparency, or

it can be a solid, three-dimensional object".6- 59

23
Armstrong (1965) emphasizes that, in general, no

lenses are required and the reconstructed image

can be magnified or demagnified as desired.6 - 60 As of early 1969, however, the question has been

raised that holograms may be already outdated.6 - 61 A new wavefront reconstruction device — the kinoform— is a computer-generated device intended to provide a reconstructed three-dimensional image

of various objects with greater efficiency than is available with holographic procedures (Lesem et al., 1969).6 - 62 In addition to the use of holographic techniques

for three-dimensional image storage and recall (including rotation 6 - 63

), these techniques are also being explored for bandwidth compression in pictorial data storage 6 64 the production of highly

magnified images,6 65 and other novel applications. 6 - 66 In particular, it has been claimed that

holographic techniques offer a new potential for high-quality-image capture in regions of the electro- magnetic spectrum extending beyond those that

have been achieved by optical recording techniques

in the the region of visible light.6 - 67 Then it has been reported that "General Electric's

Advanced Development Laboratories, Schenectady,

build a laser holograph reader — a device capable of

reading characters in several ways. It can detect a

single object out of many without scanning, or if scanning is used, can recognize up to 100 different

characters. The holographic reader is said to show

wide tolerance for variations in type font and is expected to find applications in the computer field." (Veaner, 1966, p. 208.)

Laser and holographic techniques in combination

are also being investigated for high density digital

data storage, for example, at the Bell Telephone

Laboratories,6- 68 at Carson Laboratories,6 - 69 and at IBM.6 70 Some special areas where advanced optoelectronic

techniques and improved materials or storage media

continue to be needed include "certain operations,

such as two-dimensional spatial filtering (that) can

be readily accomplished, in principle, with coherent

light optics. Problems under consideration include:

the effect of film-grain noise on the performance of a coherent optical system; the relation of film thick- ness and exposure; techniques for the making of

spatial filters; and the effect on the reconstructed

picture of various operations (such as sampling,

quantization, noise addition) upon the hologram."

(Quarterly Progress Report No. 80, Research

Laboratory for Electronics, M.I.T., 221 (1966).)

McCamy (1967) reports recent extension of pre- vious R&D investigations into fading and aging

blemishes in conventional microforms to the effect of formation of such blemishes on information stored

by means of holograms. It is to be noted further that certain types of holograms have an important immunity to dust and scratches.6 71 Possibilities for a holographic read-only store are under investigation at IBM (Gamblin, 1968), RCA

(Viklomerson et al., 1968), and at the U.S. Army

Electronics Command, Fort Monmouth. In particular, "it is intended that a hologram of a binary data

array would constitute the card-like removable

media. Upon insertion into the memory read unit,

the hologram would continuously focus a real image

on the data onto a photodetector matrix. Such an arrangement can permit electronic random access

to the information within the array while eliminating

the stringent optical requirements on the detectors

involved." (Chapman and Fisher, 1967, p. 372).6 - 72 Other R&D possibilities of interest include ex- perimentation with acoustic 6 73 and computer-generated holograms.6 74 The computer generation of

holographic or kinoform recordings is thus another

development in this area of advanced technology.

For example, digital holograms may be generated

by computer simulation of wave fronts that would

emanate from particular optical elements arranged

in specific geometrical relationships (Hirsch et al., 1968).6 - 75 An interesting area of investigation is that

of computer synthesis of holograms of three-dimensional objects which do not, in fact, physically

exist.6 - 76

6.1.4. Other Optoelectronic Considerations

In general, it is emphasized that increasing in- terest has been evident in the use of optoelectronic

techniques for both computer and memory design

for a wide variety of reasons. Scarrott (1965) and

Chapman and Fisher (1967) point to the high densities achievable with photographic media.6- 77 Reich and Dorion (1965) suggests a photochromic

film memory plane, 2" x 2", with 645 subarrays in- dividually accessible and a total capacity, assuming

only 50 percent utilization of the film area, of better

than 12 million bits. 6 - 78 Potentially, then, many of

these techniques promise significant advances in data storage, in logic and processing circuitry, in alternative communications means, in computing

or access speed, and in data collection with respect

to two- and three-dimensional object representation, including spatial filtering. 6- 79 Bonin and Baird (1965, p. 100) list other applications of optoelectronic techniques for tape and card

readers, position indicators, and recognition equipment. In addition, important new areas will include use in communication and transmission systems.

Here it is noted that optical techniques as applied

to advanced communication systems planning relate also to continuing theoretical investigations. Thus,

"preliminary studies of communication systems employing optical frequencies have indicated three

topics to which the concepts and techniques of

modern communication theory may most profitably

by addressed. They are (i) the import of quantum

electrodynamics for the characteristics of efficient communication systems, (ii) the relevant description of device noise as it affects the performance of

communication systems, and (hi) the statistical characterization of the atmosphere as a propagation

channel at optical frequencies." (Quarterly Progress

24
Report No. 80. Research Laboratory- for Electronics,

M.I.T. 178(1966).)

For use as computer logical elements, somewhat

less attention has been paid to date to the optoelectronic techniques. However. Ring et al. (1965.

p. 33) point out that "it well may be that optical

devices which do not appear at all suitable as binary

computer elements may be very- effective computing

devices in the context of some other logic structure

i e.g.. majority logic, multivalued logics)."

Reimann adds: "T\ ith the advent of the laser,

efficient light-emitting diodes, and high-speed

photodetectors. interest in the application of higher

speed opto-electronic circuits to digital logic has

increased. . . . \5 e may in the future expect to see opto-electronic circuits which will combine

laser amplifiers with other high-speed semiconductor devices." (1965. p. 248).

Then we note that optoelectronic techniques may

also be used to attack some of the problems that increasingly plague the circuit designer.6 - 80 Possibilities for circumventing interconnection limitations

which become more severe as physical area per

component is reduced are also stressed by Reimann

(1965. p. 247). He states: "The possibility of signal

connection between parts of the system without

electrical or actual physical contacts are very

attractive for integrated circuit techniques. With

optical signals, a totally new approach to the inter- connection of digital devices is possible."

Optoelectronic techniques as .applied to the problems of large, inexpensive memories are not only

promising as such,6 - 81 they also may be used to attack the noise problems still posed by integrated

circuits.6- 82 Thus Merryman savs "one attractive

property of optoelectronic devices is their potential

for isolation: they can get rid of the noise that is generated when two subsystems are coupled. The

noise problem is even tougher in integrated circuit systems, because the transformers used in tradi- tional methods of isolation are too bulky." (1965.

p. 52).

6.2. Batch Fabrication and Integrated

Circuits

In very recent years, it has been claimed that integrated circuitry is the most significant advance

in computer hardware technology' since the introduction of the transistor: 6 83 that it will bring important

changes in the size, cost, reliability and speed of

system design components,6- 84 and that advanced

high-speed techniques paradoxically also indicate

eventual lower costs.6- 85 Many potential advantages of increased usage of

LSI techniques are cited in the literature. These

include, for example, applications in improved

central processor unit speed or capacity performance, in system control and reliabihty, and in content-addressable (associative) memory construction and operation.6 - 86 Wilkes suggests that parallelism achieved by use of these techniques may

overcome present-day deficiencies of processing

systems in such applications as pattern recognition.6 - 87 In terms of relatively recent R&D literature,

Minnick (1967) provides a review of microcellular

research, with emphasis upon techniques useful

for batch-fabricated circuit design; Bilous et al. (1966) discuss IBM developments of large scale

integration techniques to form monolithic circuit arrays, where on only nine chips it was possible to replicate a specific System/360 computer model,

and, under RADC auspices. Savitt et al. (1967) have

explored both language development and advanced

machine organization concepts in terms of large

scale integration (LSI) fabrication techniques.6 - 88 That is. in general, where integrated circuits based

on etched circuit board techniques had replaced

discrete components, the LSI techniques of fabri- cation produce sheets of integrated logic components as units. 6- 89 To what extent do integrated fabrication tech- niques hold promise for future developments in very large yet inexpensive memories? Rajchman

suggests that "the dominance of non-integrated

memories is likely to be finally broken or at least seriously challenged by integrated memories, of which the laminated-ferrite-diode and the super- conductive-thin-sheet-cryotron memories are promising examples." (Rajchman, 1965, p. 128.) And,

further, that "it appears certain that energetic

efforts will continue to be devoted towards inte- grated technologies for larger and less costly

memories, as this is still the single most important

hardware improvement possible in the computer

art." (Rajchman. 1965, p. 128.) Other advocates

include Gross,6 - 90 Hudson,6 - 91 Van Dam and

Michener,6 - 92 Pyke,6 - 93 and Conway and

Spandorfer. 6 - 94 Hobbs says of silicon-on-sapphire circuits that

their fabrication is suitable for large arrays and that they are indeed "promising, but presently being

pursued by only one company." (1966, p. 38.) Of

active thin-film circuits, he concludes: "Potentially

cheaper and easier to fabricate very large arrays. Feasibility is not proven and utilization much further

away." (Hobbs, 1966, p. 38.) The same reviewer

continues: "Costs are expected to range between 3

and 5 cents per circuit in large interconnected

circuit arrays . . . However, the ability to achieve

these costs is dependent upon the use of large inter- connected arrays of circuits and, hence, upon the

computer industry's ability to develop logical design

and machine organization techniques permitting

and utilizing such arrays." (Hobbs, 1966, p. 39.)

Continuing R&D problems in terms of LSI

technology include those of packaging design,6 - 95 error detection and correction with respect to malfunctioning components; 6 96 the proper balance

to be achieved between flexibility, redundancy, and

maintenance or monitoring procedures, and questions of segmentation or differentiation of functional

logic types.6 - 97 One example of many special prob25
lems is reported by Kohn as follows: "In all batch

fabricated memories, the problem of unrepairable

element failures is predominant ... It is an open

question how complex and expensive the additional

electronic circuits will be, which will disconnect the

defective elements and connect the spare ones." (Kohn, 1965, p. 132.) On the other hand, special

advantages of LSI techniques for self-diagnosis and

self-repair have been claimed. 6 - 98

6.3. Advanced Data Storage Developments

In the area of advanced hardware, the prospects

for much larger, much faster, and more versatile

storage systems must of course be a major R&D

consideration. Current technological advances indi- cate the desirability of increasing use of integrated

construction methods using ferrite aperture plates,

thin films, laminated-diode combinations, field-effect transistors, and superconductive thin film systems,

among other recent developments. 6 " For another

example, possible applications of echo resonance

techniques for microwave pulse delay lines that

would be suitable for high-speed memories are being

explored at the Lockheed Palo Alto Research Laboratory. (Kaplan and Kooi, 1966).

Advanced hardware developments for improved

data storage emphasize both higher speeds of access and readout and larger capacities at higher densities

of storage. There are the small capacity, ultra-highspeed, memories of the read-only, scratchpad, and

associative type. These typically supplement significantly larger capacity and slower speed "main

memories". Next, there are continuing prospects

for high density, very large capacity stores. There is finally the question of R & D requirements in the area where the development of

"artificial" memories are designed to replicate, so

far as possible, known neurophysiological phe- nomena. For example, Borsellino and his colleagues

at the University of Genoa are studying physicalchemical simulation, such as collagen "memories",

in terms of possible mechanisms of axon action,

connectivity of pulses, and currents through membranes. (Stevens, 1968, p. 31). We may thus conclude with Licklider that "insofar as memory media are concerned, current research and development present many possibilities. The most immediate prospects advanced for primary memories are thin magnetic films, coated

wires, and cryogenic films. For the next echelons,

there are magnetic disks and photographic films and

plates. Farther distant are thermoplastics and

photosensitive crystals. Still farther away — almost

wholly speculative — are protein molecules and

other quasi-living structures." (Licklider, 1965,

pp. 63-64).

6.3.1. Main Memories

Questions of advanced tehcnological developments related to data and program information

storage and recall concern first of all the problems

of "main memory" — that is, the preloaded, immediately accessible, information-recording space

allocated at any one time to necessary system

supervision and control, to user(s) programs and

data, and to temporary work space requirements.

It is to be noted that "this 'main' memory size is related to the processing rate; the faster the arith- metic and logic units, the faster and larger the memory must be to keep the machine busy, or to enable

it to solve problems without waiting for data."

(Hoagland, 1965, p. 53). Further, "this incompatibility between logic and

memory speeds has led to increased parallel operation in processors and more complex instructions as an attempt to increase overall system capability."

(Pyke, 1967, p. 161).

As of current technology, main memories are still usually magnetic core, with typical capacities of a

million bits and cycle times of about one microsecond.6100 One relatively recent exception is the

NCR Rod Memory Computer, which is claimed to have "about the fastest main memory cycle time of

any commercial computer yet delivered — 800

nanoseconds." (Data Processing Mag. 7, No. 11, 12 (Nov. 1965).) This is a thin-film memory, con- structed from beryllion-copper wires plated with

magnetic coating.6101 Petschauer lists the following trends which may

be expected in magnetic memory developments in the near future:

"1. Trend toward simple cell structures — 2 or 3

wire arrays.

"2. More automated assembly and conductor

termination or batch-fabricated arrays.

"3. More fully automated plane testing. "4. More standardization.

"5. Extended use of integrated or hybrid circuits. "6. Improved methods of packaging for stack and

stack interface circuits to reduce packaging

and assembly costs.

"7. Reduced physical size." (Petschauer, 1967,

p. 599).

With respect to current prospects for much larger,

much faster main memories, Rajchman (1965)

reviews possibilities for integrated construction

methods using ferrite aperture plates, thin films,

laminate-diode combinations, field-effect transistors,

and superconductive thin film cryotrons.6102 It

is noted further that "planar magnetic film memories

offer many advantages for applications as main

computer storage units in the capacity range of

200K to 5M bits." (Simkins, 1967, p. 593), and that "perhaps the most significant system advantage

available to users of plated magnetic cylindrical

thin film memory elements is a nondestructive

readout capability. For main memory use, NDRO

with equal Read-Write drive currents is most ad- vantageous. It allows the greatest possible flexibility

of organization and operation. For maximum econ- omy, many memory words (or bytes) may be ac- 26
cessed by a single word drive line without need for more than one set of sense amplifiers and bit current drivers. The set contains onlv the number of

amplifiers needed to process the bits of one word

(or byte) in parallel." (Fedde, 1967, p. 595). Simpson

(1968) discusses the thin film memory developed at Texas Instruments.6103 Nevertheless, the known number of storage

elements capable of matching" ultrafast processing

and control cycle times (100-nanosecond or less) are

relatively few,6104 and there are many difficulties to be encountered in currently available advanced

techniques.6105 Some specific R&D requirements

indicated in the literature include materials research

to lower the high voltages presently required for fight-switching in optically addressed memories

(Kohn, 1965),6 106 attacks on noise problems in inte- grated circuit techniques (Merryman, 1965), 6107 and

the provision of built-in redundancy against element

failures encountered in batch fabrication techniques

(Kohn, 1965). In the case of cryotrons used for memory design, Rajchman (1965) notes that the

"cost and relative inconvenience of the necessary

cooling equipment is justified only for extremely

large storage capacities" (p. 126), such as those

extending beyond 10 million bits, and Van Dam and

Michener (1967) concur.6108 Considerations of

"break-even" economics with respect to cryogenicelement memories such as to balance high density

storage and high speed access against the "cooling"

costs has been assessed at a minimum randomaccess memory requirement of 10 7 bits. 6109 As of

1967-68, however, practical realizations of such

techniques have been largely limited to small-scale,

special-purpose auxiliary and content-addressable

memories, to be discussed next.

6.3.2. High-Speed, Special-Purpose, and Associative or

Content-Addressable Memories

Small, high-speed, special-purpose memories

have been used as adjuncts to main memories in computer design for some years.6110 One major

purpose is to provide increased speed of instruction access or address translation, or both. The "readonly-stores" (ROS) in particular represent relatively recent advances in "firmware," or built-in microprogramming.6111

It is noted that "the mode of implementing ROM's

spans the art, from capacitor and resistor arrays and

magnetic core ropes and snakes to selectively

deposited magnetic film arrays." (Nisenoff, 1966,

p. 1826.) An Israeli entry involves a two-level

memory system with a microprogrammed "Read

Only Store" having an access time of 400 nanoseconds. (Dreyer, 1968.) A variation for instruction- access processes is the MYRA (MYRi Aperture)

ferrite disk described by Briley (1965). This, when

accessed, produces pulses in sequential trains on

64 or more wires. A macro instruction is addressed

to an element in the MYRA memory which then

produces gating signals for the arithmetic unit and

signals for fetching both operands and the next

macro instructions. Further, "Picoinstructions are stored at constant radii upon a MYRA disk, in the

proper order to perform the desired task. The

advantages of the MYRA element are that the picoinstructions are automatically accessed in se- quence . . ." 6112 Holographic ROM possibilities are also under consideration.6113 In the area of associative, or content-addressable

memories,6114 advanced hardware developments to date have largely been involved in processor design

and provision of small-scale auxiliary or "scratchpad" memories rather than for massive selectionretrieval and data bank management applications.6115 "Scratchpad" memories, also referred to as "slave"

memories, e.g., by Wilkes (1965),6116 are defined by

Gluck (1965) as "small uniform access memories

with access and cycle times matched to the clock

of the logic." They are used for such purposes as reducing instruction-access time, for microprogramming, for buffering of instructions or data

that are transferable in small blocks (as in the

"four-fetch" design of the B 8500),6117 for storage of

intermediate results, as table lookup devices,6118 as index registers and, to a limited extent, for content addressing.6119 Another example is the modified "interactive"

cell assembly design of content-addressable memory

where entries are to be retrieved by coincidence of

a part of an input or query pattern with a part of

stored reference patterns, including other variations on particular match operations (Gaines and Lee,

1965).6 120 In addition, we note developments with

respect to a solenoid array 6121 and stacks of plastic

card resistor arrays,

6122 both usable for associative

memory purposes; the GAP (Goodyear Associative

Processor), 6123 the APP (Associative Parallel

Processor) described by Fuller and Bird (1965), 6 124 the ASP (Association-Storing Processor) machine

organization,6125 and various approaches which

compromise somewhat on speed, including bit- rather than word-parallel searching 6126 or the use

of circulating memories such as glass delay lines.6127 Cryogenic approaches to the hardware realization

of associative memory concepts have been under

investigation since at least the mid-1950's (Slade

and McMahon, 1957), while McDermid and Peterson

(1961) report work on a magnetic core technique as

of 1960. However, the technology for developing

high-speed reactivity in these special-purpose memories has been advanced in the past few years. On

the basis of experimental demonstration, at least,

there have been significant advances with respect

to parallel-processing, associative-addressing, in- ternal but auxiliary techniques in the form of memories built-into some of the recently developed large

computer systems.6128 The actual incorporation of such devices, even

if of somewhat limited scale, in operational computer system designs is of considerable interest,

whether of 25- or 250-naraosecond performance. For

example, Ammon and Neitzert report RCA experiments that "show the feasibility of a 256-word

27

376-411 O - 70 - 3
scratchpad memory with an access time of 30 nano- seconds . . . The read/write cydle time, however,

will still be limited by the amplifier recovery so that with the best transistors available it appears that 60 nanoseconds are required". (1965, p. 659). RCA

developments also include a sonic film memory in which thin magnetic films and scanning strain waves

are combined for serial storage of digital information. 6 - 129 Crawford et al. (1965) have claimed that an IBM

tunnel diode memory of 64 48-bit words and a read/

restore or clear/write cycle time of less than 25

nanoseconds was "the first complete memory sys- tem using any type of technology reported in this size and speed range", (p. 636). 6 130 Then there is an IBM development of a read-only, deposited magnetic

film memory, having high-speed read capability

(i.e., 19ns access time) and promising economics

because the technique is amenable to batch fabrication.6131 (Matick et al, 1966). Catt and associates of Motorola describe "an in- tegrated circuit memory containing 64 words of 8

bits per word, which is compatible in respect to both speed and signal level with high-speed current- mode gates. The memory has a nondestructive read

cycle of 17 nanoseconds and a write cycle of 10 nano- seconds without cycle overlap." (Catt et al., 1966,

p. 315). 6132 Anacker et al. (1966) discuss 1,000-bit

film memories with 30 nanosecond access times.6133 Kohn et al. (1967) have investigated a 140,000 bit, nondestructive read-out magnetic film memory

that can be read with a 20-nanosecond read cycle

time, a 30-nanosecond access time, and a 65-nanosecond write time. More recently, IBM has an- nounced a semi-conductor memory with 40 nano- second access.6134 Memories of this type that are of somewhat larger

capacity but somewhat less speed (in the 100-500

nanosecond range) are exemplified by such commercially-announced developments as those of

Electronic Memories,6135 Computer Control Company,6136 and IBM.6 137 Thus, Werner et al. (1967)

describe a 110-nanosecond ferrite core memory with

a word capacity of 8,192 words,6 138 while Pugh et al. (1967) report other IBM developments involving a 120-nanosecond film memory of 600,000-bit capacity.

McCallister and Chong (1966) describe an experimental plated wire memory system of 150,000-bit

capacity with a 500-nanosecond cycle time and a 300-

nanosecond access time, developed at UNIVAC.6-139 Another UNIVAC development involves planar thin

films. 6 140 A 16,384-word, 52-bit, planar film memory

with half-microsecond or less, (350 nanosecond)

cycle time, under development at Burroughs lab- oratories for some years, has been described by

Bittman (1964).6 141 Other recent developments have

been discussed by Seitzer (1967) 6 142 and Raffel

et al. (1968),6 143 among others. For million-bit and higher capacities, recent IBM

investigations have been directed toward the use of

"chain magnetic film storage elements" 6144 in both DRO and NDRO storage systems with 500-

nanosecond cycle times.6145 It is noted, however,

that "a considerable amount of development work is

still required to establish the handling, assembly,

and packaging techniques." (Abbas et al., 1967,

p. 311).

A plated wire random access memory is under

development by UNIVAC for the Rome Air Development Center. "The basic memory module consists

of 107 bits; the mechanical package can hold 10

modules. The potential speed is a l-to-2 microsecond word rate. . . . Ease of fabrication has been

emphasized in the memory stack design. These

factors, together with the low plated wire element

cost, make an inexpensive mass plated wire store a

distinct possibility." (Chong et al., 1967, p. 363).6 146 RADC's interests in associative processing are also reflected in contracts with Goodyear Aerospace

Corp., Akron, Ohio, for investigation and experimental fabrication of associative memories and

processors. (See, for example, Gall, 1966).

6.3.3. High-Density Data Recording and Storage

Techniques

Another important field of investigation with

respect to advanced data recording, processing, and

storage techniques is that of further development of

high-density data recording media and methods and

bulk storage techniques, including block-oriented

random access memories. 6147 Magnetic tech- niques—cores, tapes, and cards — continue to be

pushed toward multimillion bit capacities. 6148 A

single-wall domain magnetic memory system has

recently been patented by Bell Telephone Laboratories.6149 In terms of R & D requirements for these

techniques, further development of magnetic heads,

recording media, and means for track location has

been indicated,6150 as is also the case for electron

or laser beam recording techniques. 6151 Videotape

developments are also to be noted. 6152 In addition to the examples of laser, holographic,

and photochromic technologies applied to high

density data recording previously given, we may

note some of the other advanced techniques that are being developed for large-capacity, compact

storage. These developments include the materials

and media as well as techniques for recording with

light, heat, electrons, and laser beams. In particular,

"a tremendous amount of research work is being

undertaken in the area of photosensitive materials. Part of this has been sparked by the acute shortage

of silver for conventional films and papers. In October, more than 800 people attend a symposium in Washington, D.C., on Unconventional

Photographic Systems. Progress was described in a number of areas, including deformable films,

electrophotography, photochromic systems, unconventional silver systems, and photopolymers."

(Hartsuch, 1968, p. 56). Examples include the General Electric Photocharge,6153 the IBM Photo-Digital system,6154 the

UNICON mass memory,6155 a system announced

28
by Foto-Mem Inc. 6156 and the use of thin dielectric

films at Hughes Research Laboratories.6157 At

Stanford Research Institute, a program for the U.S. Army Electronics Command is concerned with in- vestigations of high-density arrays of micron-size

storage elements, which are addressed by electron

beam. The goal is a digital storage density of 108

bits per square centimeter.6158

Still another development is the NCR heat-mode

recording technique. (Carlson and Ives, 1968).

This involves the use of relatively low power CW

lasers to achieve real-time, high-resolution (150 : 1) recording on a variety of thin films on suitable substrates.6159 In particular, microimage recordings can

be achieved directly from electronic charactergeneration devices.6160 Newberry of General Electric has described an electron optical data storage

technique involving a 'fly's eye' lens system for which a "a packing density of 108 bits per square

inch has already been demonstrated with 1 micron

beam diameter." (1966, p. 727-728).

Then there is a new recording-coding system,

from Kodak, that uses fine-grained photographic

media, diffraction grating patterns, and laser fight sources.6161 As a final example of recent recording developments we note that Gross (1967) has

described a variety of investigations at Ampex,

including color video recordings on magnetic film plated discs, silver halide film for both digital and

analog recordings, and use of magneto-optic effects

for reading digital recordings.6162 Areas where continuing R&D efforts appear to be

indicated include questions of read-out from highly

compact data storage,6163 of vacuum equipment in the case of electron beam recording,6164 and of

noise in some of the reversible media.6165 Then it is noted that "at present it is not at all clear what compromises between direct image recording and holo- graphic image recording will best preserve high

information density with adequate redundancy, but

the subject is one that attracts considerable re- search interest." (Smith, 1966, p. 1298).

Materials and media for storage are also subjects of continuing R&D concern in both the

achievement of higher packing densities with fast direct access and in the exploration of prospects

for storage of multivalued data at a single physical

location. For example: "A frontal gttack on new

materials for storage is crucial if we are to use the

inherent capability of the transducers now at our

disposal to write and read more than 1 bit of data

at 1 location . . . "One novel approach for a multilevel photographic store now being studied is the use of color

photography techniques to achieve multibit storage

at each physical memory location . . . Color film can store multilevels at the same point because both

intensity and frequency can be detected." (Hoagland,

1965, p. 58). "An experimental device which changes the color

of a laser beam at electronic speeds has been

developed . . . IBM scientists believe it could

lead to the development of color-coded computer

memories with up to a hundred million bits of infor- mation stored on one square inch of photographic

film." (Commun. ACM 9, 707 (1966).)

Such components and materials would have

extremely high density, high resolution characteristics. One example of intriguing technical possibilities is reported by Fleisher et al. (1965) in terms

of a standing-wave, read-only memory where n color sources might provide n information bits, one for each color, at each storage location.6166 These

authors claim that an apparently unique feature of

this memory would be a capability for storing both

digital and analog (video) information,6167 and that

parallel word selection, accomplished by fiber-optic

light splitting or other means, would be useful in associative selection and retrieval.6168

7. Debugging, On-Line Diagnosis, Instrumentation, and Problems of Simulation

Beyond the problems of initial design of information processing systems are those involved in the

provision of suitable and effective debugging, self- monitoring, self-diagnosis, and self-repair facilities in such systems. Overall system design R&D

requirements are, finally, epitomized in increased concern over the needs for on-line instrumentation,

simulation, and formal modelling of information

flows and information handling processes, and with

the difficulties so far encountered in achieving

solutions to these problems. In turn, many of these

problems are precisely involved in questions of

systems evaluation.

It has been cogently suggested that the area of

aids to debugging "has been given more lip service

and less attention than any other" 71 in considerations of information processing systems design.

Special, continuing, R&D requirements are raised

in the situations, first, of checking out very large

programs, and secondly, of carrying out checkout

operations under multiple-access, effectually online, conditions.7 - 2 In particular, the checkout of

very large programs presents special problems.7 - 3

7.1. Debugging Problems

Program checkout and debugging are also problems of increasing severity in terms of multiple- access systems. Head states that "testing of many

non-real-time systems — even large ones — has all too often been ill-planned and haphazard with numerous errors discovered only after cutover. . . . In most real-time systems, the prevalence of errors

after cutover, any one of which could force the

29
system to go down, is intolerable." (1963, p. 41.)

Bernstein and Owens (1968) suggest that conventional debugging tools are almost worthless in the

time-sharing situation and propose requirements

for an improved debugging support system. 7 - 4 On-line debugging provides particular challenges

to the user, the programmer and the system designer. 7 - 5 It is important that the console provide

versatile means of accomplishing system and pro- gram self-diagnosis, to determine what instruction

caused a hang-up, to inspect appropriate registers

in a conflict situation, and to display anticipated

results of a next instruction before it is executed.

A major consideration is the ability to provide inter- pretation and substitution of instructions, with

traps, from the console. A recent system for on-line

debugging, EXDAMS (Extendable Debugging and

Monitoring System), is described by Balzer (1969). 7 6 Aids to debugging and performance evaluation

provided by a specific system design should therefore

include versatile features for address traps, in- struction traps, and other traps specified by the

programmer. For example, if SIMSCRIPT programs

are to be run, a serious debugging problem arises

because of the dynamic storage allocation situation

where the clients needs to find out where he is and

provide dynamic dumping, e.g., by panel interrupt

without halting the machine. Programmers checking

out a complex program need an interrupt-and-trapto-a-fixed location system, the ability to bounce out

of a conflict without being trapped in a halt, to jump

if a program accesses a particular address, to take

special action if a data channel is tied up for ex- pected input not yet received, or to jump somewhere

else on a given breakpoint and then come back to scheduled address, e.g., on emergence of an over- flow condition. 7 - 7 Problems of effective debugging, diagnostic,

and simulation languages are necessarily raised. 7 - 8 For example, McCarthy et al. report: "In our

opinion the reduction in debugging time made possible by good typewriter debugging languages and

adequate access to the machine is comparable to that provided by the use of ALGOL type languages

for numerical calculation." (McCarthy et al., 1963,

p. 55). Still another debugging and diagnostic R&D

requirement is raised with respect to reconfigurations of available installations and tentative evaluations of the likely success of the substitution of one

configuration for another. 7 9 In at least one case, a combined hardware-soft- ware approach has been used to tackle another

special problem of time-shared, multiple-user sys- tems, that of machine maintenance with minimum

interference to ongoing client programs. The

STROBES technique (for Shared-rime-repair of

6ig electronic systems) has been developed at the

Computation Center of the Carnegie Institute of

Technology.710 This type of development is of significance because as Schwartz and his co-authors

report (1965, p. 16): "Unlike more traditional sys- tems, a time-sharing system cannot stop and start

over when a hardware error occurs. During timesharing, the error must be analyzed, corrected if possible, and the user or users affected must be

notified. For all those users not affected, no sig- nificant interruption should take place."

7.2. On-Line Diagnosis and Instrumentation

Self-diagnosis is an important area of R & D con- cern with respect both to the design and the utiliza- tion of computer systems.711 In terms of potentials

for automatic machine-self-repair, it is noted that "a self-diagnosable computer is a computer which

has the capabilities of automatically detecting and

isolating a fault (within itself) to a small number

of replaceable modules." (Forbes et al., 1965, p. 1073).7 12 To what extent can the machine itself be

used to generate its own programs and procedures?

Forbes et al. suggest that: "If the theory of self- diagnosing computers is to become practical for a family of machines, further study and development

of machine generation of diagnostic procedures is necessary." (1965, p. 1085).

Several different on-line instrumentation* techniques have been experimentally investigated by

Estrin and associates (1967), by Hoffman (1965),

Scherr (1965) and by Sutherland (1965), among

others.713 Monitoring systems for hardware, soft- ware, or both are described, for example, by

Aviziensis (1967, 1968),714 Jacoby (1959),7 15 and

Wetherfield (1966),716 while a monitoring system for the multiplexing of slow-speed peripheral equipment

at the Commonwealth Scientific and Industrial

Research Organization in Australia is described by

Abraham et al. (1966). Moulton and Muller (1967)

describe DITRAN (D/agnostic FORTRAN), a compiler with extensive error checking capabilities that can be applied both at compilation time and during

program execution, and Whiteman (1966) discusses

"computer hypochondria". 717 Fine et al. (1966) have developed an interpreter

program to analyze running programs with respect to determining sequences of instructions between page

calls, page demands by time intervals, and page

demands by programs. In relatively early work in this area, Licklider and Clark report that "Program

Graph and Memory Course are but two of many

possible schemes for displaying the internal proc- esses of the computer. We are working on others

that combine graphical presentation with symbolic

representation ... By combining graphical with

symbolic presentation, and putting the mode of

combination under the operator's control via light

pen, we hope to achieve both good speed and good

discrimination of detailed information." (1962, p. 120). However, Sutherland comments that: "The

information processing industry is uniquely wanting

in good instrumentation; every other industry has

meters, gauges, magnifiers — instruments to measure

^'Instrumentation" in this context means diagnostic and monitoring procedures which are applied to operating programs in a "subject" computer as they are being executed in order to assemble records of workload, system utilization, and other

similar data. 30
and record the performance of machines appropriate 1 to that industry." (Sutherland, 1965, p. 12). More

effective on-line instrumentation techniques are thus

urgently required, especially for the multiple-access

processing system.

Huskey supports the contentions of Sutherland

and of Amdahl that: "Much more instrumentation of

on-line systems is needed so that we know what is going on, what the typical user does, and what the

variations are from the norms. It is only with this information that systems can be 'trimmed' so as to optimize usefulness to the customer array."

(Huskey, 1965, p. 141).

Sutherland in particular points out that plots of

times spent by the program in doing various subtasks, can tighten up frequently used program and

sub-routine loops and thus save significant amounts

of processor running-time costs. 718 He also refers

to a system developed by Kinslow in which a pictorial representation of "which parts of memory

were 'occupied' as a function of time for his timesharing system. The result shows clearly the small

spaces which develop in memory and must remain

unused because no program is short enough to fit into them." (Sutherland, 1965, p. 13). In general, it is hoped that such on-line instrumentation tech- niques will bring about better understanding of the

interactions of programs and data within the proc- essing system. 719 Improved techniques for the systematic analysis

of multiple-access systems are also needed. As

Brown points out: "The feasibility of time-sharing

depends quite strongly upon not only the timesharing procedures, but also upon . . . the following

properties, characteristic of each program when it is run alone:

(1) The percentage of time actually required for execution of the program . . . (2) The spectrum of delay times during which the

program awaits a human response . . . (3) A spectrum of program execution burst

lengths . . . A direct measurement of these properties is diffi- cult; a reasonable estimate of them is important,

however, in determining the time-sharing feasibility of any given program." (1965, p. 82). However, most

of the analyses implied are significantly lacking to date, although some examples of benefits to be

anticipated are given by Cantrell and Ellison (1968)

and by Campbell and Heffner (1968).

Schwartz et al. emphasize that "another researchable area of importance to proper design is the

mathematical analysis of time-shared computer

operation. The object in such an analysis is to pro- vide solutions to problems of determining the user

capacity of a given system, the optimum values for the scheduling parameters (such as quantum size) to be used by the executive system, and, in general,

the most efficient techniques for sequencing the

object programs." (Schwartz et al., 1965, p. 21). Continuing, they point to the use of simulation

techniques as an alternative. "Because of the large

number of random variables — many of which are interdependent — that must be taken into account in a completely general treatment of time-sharing

operation, one cannot expect to proceed very far with analyses of the above nature. Thus, it seems

clear that simulation must also be used to study

time-shared computer operation." (Schwartz et al., 1965, p. 21). A 1967 review by Borko reaches similar

conclusions.7 - 20

7.3. Simulation

The on-going analysis and evaluation of information processing systems will clearly require the

further development of more sophisticated and more

accurate simulation models than are available

today. 7 - 21 Special difficulties are to be noted in the case of models of multiple access system where

"the addition of pre-emptive scheduling complicates

the mathematics beyond the point where models

can even be formulated" (Scherr, 1965, p. 32) and

in that of information selection and retrieval applications where, as has been frequently charged, "no

accurate models exist". (Hayes, 1963, p. 284). In these and other areas, then, a major factor is the inadequacy of present-day mathematical tech- niques. 7 - 22 In particular, Scherr asserts that "simulation models are required because the level of detail necessary to handle some of the features studied is beyond the scope of mathematically tractable

models." (Scherr, 1965, p. 32). The importance of

continuing R&D efforts in this area, even if they

should have only negative results, has, however

been emphasized by workers in the field. 7 - 23 Thus, for example, at the 1966 ACM-SUNY

Conference, "Professor C. West Churchman . . . pointed to the very large [computer] models that can now be built, and the very much larger models

that we will soon be able to build, and stated that the models are not realistic because the quality

of information is not adequate and because the right

questions remain unasked. Yet he strongly favored

the building of models, and suggested that much

information could be obtained from attempts to build several different and perhaps inconsistent

models of the same system." (Commun. ACM 9,

645 (1966).)

We are led next, then, to problems of simulation.

There are obvious problems in this area also. First there is the difficulty of "determining and building

meaningful models" (Davis, 1965, p. 82), especially

where a high degree of selectivity must be imposed

upon the collection of data appropriately representative of the highly complex real-life environments and

processes that are to be simulated.7 - 24 Beyond the questions of adequate selectivity in simulation-representation of the phenomena, operations, and possible system capabilities being

modelled are those of the adequacy of the simulation

languages as discussed by Scherr, Steel, and

others. 7 - 25 Teichroew and Lubin present a compre31
hensive survey of computer simulation languages

and applications, with tables of comparative characteristics, as of 1966.726 In addition, IBM has

provided a bibliography on simulation, also as of

1966. Again, as in the area of graphic input manipulation and output, the field of effective simulation has

specific R&D requirements for improved and more versatile machine models and programming

languages. Clancy and Fineberg suggest that "the

very number and diversity of languages suggests

that the field [of digital simulation languages] suffers from a lack of perspective and direction." (1965,

p. 23). The area of improved simulation languages is one

that has a multiple interaction between software and

hardware, especially where a computer is to be used

to simulate another computer, perhaps one whose

design is not yet complete 7 27 or to simulate many

different scheduling, queuing and storage allocation

alternatives in time-shared systems (see, for example, Blunt 1965). Such problems are also dis- cussed by Scherr (1965) and by Larsen and Mano

(1965), among others, while Parnas (1966) describes

a modification of ALGOL (SFD-ALGOL, for "System Function Description") applicable to the

simulation of synchronous systems.

However, there are difficult current problems in that languages such as SIMSCRIPT do not take

advantage of the modularity of many processing

systems, that conditional scheduling of sequences

of events is extremely difficult 7 28 and that "we are

still plagued by our inability to program for simultaneous action, even for the scheduling of large

units in a computing system." (Gorn, 1966, p. 232). In addition, for simulation and similar applications,

heuristic or ad hoc programming facilities may be

required. Thus, "a computer program which is to serve as a model must be able to have well-organized

yet manipulatable data storage, easily augmentable

and modifiable. The program must be self-modifying

in a similarly organized way. It should be able to handle large blocks of data or program routines

by specification of merely a name." (Strom, 1965,

p. 114.)

For simulations or testings with controls, and with- out discernible interruption or reallocation of normal

servicing of client processing requests, compilers

must be available that will transform queries

expressed in one or more commonly available

customer languages to the language(s) most effec- tively used by the substituted experimental system

and to the format(s) available in a master data base.

Then there are problems in the development of an

appropriate "scenario", or sequence of events to be

simulated.7 - 29 Burdick and Naylor (1966) provide a survey account of the problems of design and

analysis of computer simulation experiments.

The problems of effective simulation of complex,

interdependent processes are another area of

increasing concern. Suppose, for example, that we

are seeking to simulate a process in which many

separate operations are carried out concurrently or

in parallel, and that the simulation technique

requires a serial sequencing of these operations.

Depending upon the choice of which one of the

theoretically concurrent operations is processed

first in the sequentializing procedure, the results of the simulation may be significantly different in one case than in another.7 - 30 For example, the SL/1 language being developed

at the University of Pisa under Caracciolo di Forino

(1965) is based in part on SOL (Simulation-Oriented

Language, see Knuth and McNeley, 1964) and in part on SIMULA (the ALGOL extension developed

by O. J. Dahl, of the Norwegian Computing Center,

Oslo).7 - 31 A second version, SL/2, now under

development, will provide self-adapting features to optimize the system. Caracciolo emphasizes that, for any set of deterministic processes that are to be

applied simultaneously, but where problems of

incompatibility may arise, the problems can be

reduced to a set of probabilistic processes. Otherwise, if one sequentializes parallel, concurrent

processes actually dependent upon the order of

sequentialization, then hidden problems of incompatibility may vitiate the results obtained.

Despite difficulties, however, progress has been

and is being made. Thus computer simulation has

been investigated as a means of system simulation

for determination of probable costs and benefits

in advance of major investments in equipment or procedures.7 - 32 Then, as reported by Gibson (1967),

simulation studies have been used to determine

that block transfers of 4 to 16 words will facilitate reduction of effective internal access times to a few

nanoseconds. Other programs to simulate digital

data processing, time-shared system performance,

and the like, are discussed by Larsen and Mano

(1965) and by Scherr (1965). Simulation studies in terms of multiprocessor systems are represented by

Lindquist et al. (1966) 7 33 and by Huesmann and

Goldberg (1967). 7 - 34 Other advantages from research and development

efforts to be anticipated from computer simulation

experiments are those of transfer of applications

from a given computer to another not yet installed or

available, 7 - 35 advancements in techniques of pictorial data processing and transmission,7 - 36 advance

appraisals of performance of time-shared systems,7 37 and investigations of probable performance of

adaptive recognition systems. 7- 38

Finally, we note prospects for system simulation

as a means of evaluation and of redesign, including

the alteration of scheduling priorities to meet

changing requirements of the system's clientele. Three examples from the literature are as follows:

(1) "Use of a simulator permits the installation to continue running its programs as reprogramming proceeds on a reasonable schedule."

(Trimble, 1965, p. 18).

(2) "Effective response time simulation can be

32
easily modified to provide operating costs of

retrieval." (Blunt, 1965, p. 9). (3) "When large systems are being developed

another set of programs is involved to perform

a function not required for simpler situations. These are the simulation and analysis pro- grams for system evaluation and —for semiautomated systems having a human com- ponent—system training." (Steel, 1965, p. 232).

On the other hand, as Davis warns: "It is obvious

that there is some threshold beyond which the real environment is too complex to permit meaningful

simulation." (1965, p. 82). For the future, therefore, a system of multiple-working-hypotheses might well

be developed: "The benefits and drawbacks of empirical data gathering vs. simulation vs. mathematical analysis are web1 documented. What we

would really like to be able to do is a little of all three, back and forth, until our gradually increasing

comprehension of the problem becomes the desired

solution." (Greenberger, 1966, p. 347). Similarly, it may be claimed that simulation models ". . . are often cumbersome and difficult to adapt to new

configurations, with results of somewhat uncertain

interpretation due to statistical sampling variability.

Ideally, simulation and analytic techniques should

supplement each other, for each approach has its advantages." (Gaver, 1967, p. 423).

8. Conclusions

As we have seen, major trends in input/output,

storage, processor, and programming design relate

to multiple access, multiprogrammed, and multiprocessor systems. On-line simulation, instrumentation, and performance evaluation capabilities are necessary in order to effectively measure and test proposed techniques, systems, and networks of

broad future significance to improved utibzation of

automatic data processing techniques.

We may therefore close this report on overall system design considerations with the following

quotations:

(1) "In rating the completeness, clarity, and

simplicity of the system diagnostics, com- mand language and keyboard procedures, we

found their 'goodness' was inversely related

to the running efficiency of the system . . . System developers should examine this condition to determine whether inefficient execution is an inherent feature of system[s]

supplying complete and easily understood

diagnostics, or a function of the specific

interests and prejudices of the developers."

(O'Sulhvan, 1967, p. 170).

(2) "An engineer who wishes to concern himself

with performance criteria in the synthesis of new systems is frustrated by the weakness

of measurement of computer system behavior."

(Estrin et al., 1967, p. 645.)

(3) "The setting up of criteria of evaluation . . . demands user participation and provides an

indication of whether the user understands the reason for the system, the role of the system

and his responsibilities as a prospective sys- tem user." (Davis, 1965, p. 82.)

(4) "Today, and to an even greater extent tomorrow, the use of multiple functional units

within the information processing system, the

multiplexing of input and output messages, and

the increased use of software to permit multiprogramming will require more subtle measures to evaluate a particular system's perform- ance." (Nisenoff, 1966, p. 1828.)

(5) "Broad areas for further research are indi- cated . . . Comparative experimental studies

of computer facihty performance, such as

online, offline, and hybrid installations, sys- tematically permuted against broad classes of

program languages (machine-oriented, pro- cedure-oriented, and problem-oriented lan- guages), and representative classes of

programming tasks." (Sackman et al., 1968.

p. 10), and

(6) "Improved methods of simulation, optimizing

techniques, scheduling algorithms, methods

of dealing with stochastic variables, these are the important developments that are pushing

back the hmits of our ability to deal with very

large systems." (Harder, 1968, p. 233.)

Finally we note that the problems of the information processing system designer, then, are today

aggrevated not only by networking, time-sharing,

time-slicing, multiprocessor and multiprogramming

potentiabties, but also by critical questions involving

the values and the costs of maintaining the integrity of privileged files. By the terminology "privileged

files", we suggest the interpretation of all data

stored in a machine-useful system that may have

varying degrees of privacy, confidentiality, or security restrictions placed upon unauthorized

access. Some of the background considerations

affecting both pobcy and design factors will be

discussed in the next report in this series.

33

Appendix A. Background Notes on Overall System Design Requirements

In this Appendix we present further discussion and background material intended to highlight currently identifiable research and development requirements in the broad field of the computer and

information sciences, with emphasis upon overall system design considerations with respect to information processing systems. A number of illustrative examples, pertinent quotations from the literature, and references to current R and D efforts have been assembled. These background notes have been

referenced, as appropriate, in the summary text.

1. Introduction

1.1 There are certain obvious difficulties with

respect to the organization of material for a series of

reports on research and development requirements

in the computer and information sciences and technologies. These problems stem from the overlaps

between functional areas in which man-machine

interactions of both communication and control

are sought; the techniques, tools, and instrumentation available to achieve such interactions, and the

wide variety of application areas involved.

The material that has been collected and reviewed

to date is so multifaceted and so extensive as to require organization into reasonably tractable

(but arbitrary) subdivisions.- Having considered some of the R and D requirements affecting specific

Boxes shown in Figure 1 (p. 2) in previous reports, we will discuss here some of the overall system

design considerations affecting more than one of

the processes or functions shown in Figure 1. Other topics to be covered in separate reports in

this series will include specific problems of information storage, selection and retrieval systems and the

questions of maintaining the integrity of privileged

files (i.e., some of the background considerations

with respect to the issues of privacy, confidentiality,

and/or security in the case of multiply-accessed,

machine-based files, data banks, and computercommunication networks).

In general, the plan of attack in each individual

report in the series will be to outline in relatively

short discursive text the topics of concern, sup- plemented by background notes and quotations and

by an appendix giving the bibliographic citations of

quoted references. It is planned, however, that there

will be a comprehensive summary, bibliography,

and index for the series as a whole.

Since problems of organization, terminology, and

coverage have all been difficult in the preparation of

this series of reports, certain disclaimers and observations with respect to the purpose and scope of this report, its necessary selectivity, and the problems

of organization and emphasis are to be noted. Obviously, the reviewer's interests and limitations will emerge at least indirectly in terms of the selectivity that has been applied.

In general, controversial opinions expressed or implied in any of the reports in this series are the

sole responsibility of the author(s) of that report and

are not intended in any way to represent the official policies of the Center for Computer Sciences and

Technology, the National Bureau of Standards, or the Department of Commerce. However, every

effort has been made to buttress potentially controversial statements or implications either with

direct quotations or with illustrative examples from

the pertinent literature in the field.

It is especially to be noted that the refer- ences and quotations included in the text of this report, in the corroborative background notes, or in the bibliography, are necessarily highly selective. Neither inclusion nor citation is intended in any

way to represent an endorsement of any specific

commercially available device or system, of any

particular investigator's results with respect to those

of others, or of the objectives of projects that are mentioned. Conversely, omissions are often in- advertent and are in no sense intended to imply

adverse evaluations of products, materials and

media, equipment, systems, project goals and

project results, or of bibliographic references not

included.

There will be quite obvious objections to this necessary selectivity from readers who are also R&D workers in the fields involved as to the repre- sentativeness of cited contributions from their own

work or that of others. Such criticisms are almost

inevitable. Nevertheless, these reports are not intended to be state-of-the-art reviews as such, but,

rather, they are intended to provide provocative

suggestions for further R&D efforts. Selectivity

must also relate to a necessarily arbitrary cut-off date in terms of the literature covered.

These reports, subject to the foregoing caveats, are offered as possible contributions to the understanding of the general state of the art, especially

with respect to long-range research possibilities in a variety of disciplines that are potentially applicable

to information processing problems. The reports

are therefore directed to a varied audience among

whom are those who plan, conduct, and support

35
research in these varied disciplines. They are also addressed to applications specialists who may hope

eventually to profit from the results of current re- search efforts. Inevitably, there must be some

repetitions of the obvious or over-simplifications of

certain topics for some readers, and there must also be some too brief or inadequately explained discussions on other topics for these and other readers.

What is at best tutorial for one may be difficult for another to follow. It is hoped, however, that the notes and bibliographic citations will provide

sufficient clues for further follow-up as desired. The

literature survey upon which this report is based

generally covered the period from mid-1962 to mid1968, although a few earlier and a few later refer- ences have also been included as appropriate.

1.2 Certain features of the information flow and

and process schema of Figure 1 are to be noted. It is assumed, first, that the generalized information

processing system should provide for automatic

access from and to many users at many locations.

This implies multiple inputs in parallel, system

interruptibility, and interlacings of computer pro- grams. It is assumed, further, that the overall scheme involves hierarchies of systems, devices

and procedures, that processing involves multistep

operations, and that multimode operation is possible, depending on job requirements, prior or tentative results, accessibility, costs, and the like.

It should be noted, next, that techniques sug- gested for a specific system may apply to more than one operational box or function shown in the

generalized diagram of Figure 1. Similarly, in a

specific system, the various operations or processes

may occur in different sequences (including itera- tions) and several different ones may be combined

in various ways. Thus, for example, questions of remote console design may affect original item input,

input of processing service requests, output, and

entry of feedback information from the user or the

system client. The specific solutions adopted may be

implemented in each of these operational areas, or combined into one, e.g., by requiring all imputs

and outputs to flow through the same hardware.

2. Requirements and Resources Analysis

2.1 "The single information flow concept . . . is input-oriented. The system is organized so that essential data are inserted into a common reservoir

through point-of-origin input/output devices. User

requirements are then satisfied from this reservoir

of fundamental data about transactions.

"Thus, the single information flow concept is characterized by random entry of data, direct access

to data in the system, and complete real-time

processing . . . fast response, a high degree of

reliability, and an easily expansible system."

(Moravec, 1965, p. 173). 2.2 "In a highly distributed system, however,

information on inputs to the organization flow

directly to relatively low-level way stations where

all possible processing is done and all actions are taken that are allowed by the protocol governing

that level. In addition to the direct actions that

it takes, the lowest, or reflexive, level of information

processing ordinarily generates two classes of

information. These are, first, summaries of actions

taken or anticipated and, second, summaries of

information inputs that, because of their type,

salience, or criticality, fall outside the range of

action that policy has established as appropriate for that level. ...

"In computer terms, a highly distributed system

involves a primary executive program that adds and

subtracts subroutines to various primary libraries from which alternative subroutines are to be drawn

and combined. Secondary executive programs,

responding to separate inputs and conditions, select and organize subroutines from each of these primary

libraries and add and subtract subroutines to various

secondary libraries from which tertiary executive

programs select alternative subroutines for use at

their level and for controlling the library one level down, and so forth. The flexibility of a distributed

system is an outgrowth of the ability of each of the

lower executive programs to organize its program

on the basis of separate inputs reaching it directly."

(Bennett, 1964, pp. 104-106).

"By a distributed implementation of an information

service system we mean that the data processing activity is carried out by several or many installa- tions . . . The data base is now distributed among

the installations making up the information network

for this service system . . . "The distributed information network should offer considerable advantage in reducing the cost of terminal communications by permitting installations

to be located near concentrations of terminals."

(Dennis, 1968, p. 373). 2.3 "A large number of factors (user communities, document forms, subject disciplines, desired

services, to name but a few) compete for the attention of the designer of information service systems.

A methodology for the careful organization of these

factors and the orderly consideration of their

relationships is essential if intelligent decisions are

to be made." (Sparks et al., 1965, pp. 1—2).

"The lack of recognition of the nature and even,

in some cases, the existence of the problems facing

the information systems designer has meant that there has been little or no orderly development of

generally agreed upon system methodology."

(Hughes Dynamics, 1964, p. 1-7).

"To the best of our knowledge, no one has yet

developed a completely satisfactory theory of in- formation processing. Because there is no strong

theoretical basis for the field, we must rely on intui- tion, experience and the application of heuristic

36
notions each time we attempt to solve a new information processing problem." (Clapp, 1967, p. 4). 2.4 Additional examples are as follows: "Preliminary data support the previous indications (Werner, Trueswell, et al.) that the introduction of new services is not followed by an immediately high level use of them. The state-of-theart of equipment, personnel, and documentation

still offers continuing problems. Medical researchers

in the study do not seem to look upon the system as being an essential source of information for their work, but as a convenient ancillary activity."

(Rath and Werner, 1967, p. 62). "A major study recently conducted by Auerbach

Corporation into the manpower trends in the

engineering support functions concerned with

information . . . which involved investigations

of a large number of company and government

operations, was both surprising and disconcerting

because it showed that there are large areas of

both government and industry in which there is very little concern about, or work underway toward,

solving the information flow and utilization problem." (Sayer, 1965, p. 24). 2.5 "There are seven properties of a system that can be stated explicitly by the organization requesting the system design: WHAT the system should

be, WHERE the system is to be used, and WHERE,

WHEN, WITH WHAT, FOR WHOM, and WITH

WHOM the system is to be designed." (Davis,

1964, p. 20). 2.6 Consider also the following:

"Consequently, it appears that two early areas

of required investigation are those of determining:

1) who are the potential users of science and/or

engineering information systems, where are they

located, what is their sphere of activity? and 2) What is the real nature and volume of material

that will flow through a national information sys- tem? . . . "In undertaking a program to establish information service networks it is necessary to know:

1. Who are the users?

2. What are the user information needs?

3. Where are these users?

4. How many users and user groups are there,

and how do their needs differ?

5. What information products and services will meet these needs?

6. What production operations are necessary to produce these information products and

services?

7. Which of these products and services are

really being produced now; by whom and where

and how well is an ultimate purpose already

being achieved?

8. How will any new system best integrate with

existing practices?

9. What are the operations best performed from

a standpoint of quality and timeliness of

service to users, economy of costs and overall

network operations, available trained manpower, and ability to respond to change?"

(Sayer, 1965, pp. 144-145).

"Some of the details the user must determine are the number and location of remote points, frequency

of use, response time required, volume of data to be

communicated, on line storage requirements, and

the like." (Jones, 1965, p. 66). 2.7 "Neglect of 'WHERE the system is to be

used' is the most frequent cause of inadequate sys- tem designs." (Davis, 1964, p. 21). 2.8 Thus Sayer points out the need for "population figures describing the user community in detail,

its interest in subject disciplines, and the effect of

this interest on the effective demand on the system

from both initiative and responsive demands."

(Sayer, 1965, p. 140).

Sparks et al. raise the following considerations:

"There are certain basic dimensions of an information service system which it is appropriate to recognize in a formal way. One of these is the spectrum of selected disciplines which are to be represented in the information processed by the system. Another

of these is the geographical area to be served by the

system and in which the user population will be

distributed . . . "The number of user communities into which the user population is divided determines (or is deter- mined by) the number of direct-service information

centers in the system. Thus, it has a major effect on system size and structure." (Sparks et al., 1965,

pp. 2-6, 2-7).

2.9 "In structuring shiny, new information sys- tems, we must be careful to allow for resistance to change long before the push buttons are installed,

especially when the users of the systems have not been convinced that there is a real need for change."

(Aines, 1965, p. 5.) "Examine the various systems characteristics

such as: user/network interface; network usage

patterns; training requirements; traffic control; service and organization requirements; response

effectiveness; cost determinations; and network

capacity." (Hoffman, 1965, p. 90-91.)

"As an appendage to a prototype network, some

experimental retraining programs would be well

advised . . . "A massive effort directed at retraining large

numbers of personnel now functioning in libraries

will be required to produce the manpower necessary

for a real-time network ever to reach a fully operational status." (Brown et al., 1967, p. 68). "Where do experimental studies of user perform- ance fit into burgeoning information services? The

answer is inescapable: the extent of experimental

activity will effectively determine the level of ex- cellence, in method and in substantive findings,

with which key problems regarding user perform- ance will be met. If experimental studies in mancomputer communication continue to be virtually

nonexistent, the gap in verified knowledge of user behavior will continue to be dominated by immediate

37
cost and narrow technical considerations rather

than by the users' long range interests. Everyone will be a loser. Neither the managers of computer utili- ties, or the manufacturers, or the designers of central systems will have tested, reliable knowledge of

what the user needs, how he behaves, how long it takes him to master new services, or how well he

performs. In turn, the user will not have reliable,

validated guidance to plan, select, and become

skilled in harnessing the information services best

suited to his needs, his time, and his resources. Since he is last, the user loses most." (Sackman,

1968, p. 351).

2.10 "Everyone talks about the computer user, but virtually no one has studied him in a systematic,

scientific manner. There is a growing experimental

lag between verified knowledge about users and

rapidly expanding applications for them. This

experimental lag has always existed in computer

technology. Technological innovation and aggressive marketing of computer wares have consistently outpaced established knowledge of user performance — a bias in computer technology

largely attributable to current management outlook

and practice. With the advent of time-sharing

systems, and with the imminence of the muchheralded information utility, the magnitude of this scientific lag may have reached a critical point.

If unchecked, particularly in the crucial area of

software management, it may become a crippling

humanistic lag— a situation in which both the

private and the public use of computers would be

characterized by overriding concern for immediate

machine efficiency and economy, and by an en- trenched neglect of human, needs, individual

capabilities, and long-range social responsibilities."

(Sackman, 1968, p. 349).

"Quite often the most important parameter in a system's performance is the behavior of the

average user. This information is very rarely known

in advance, and can only be obtained by gathering

statistics. It is important to know, for example,

how long a typical user stays on a time-sharing

system during an average session, how many lan- guage processors he uses, how much computing

power he requires during each 'interaction' with

the system, and so forth. Modeling and simulation can be of great help in pre-determining this infor- mation if the environment is known, but in many

commercial or University time-sharing systems

there is little control over or prior knowledge of

the characteristics of the users." (Yourdon, 1969,

p. 124).

"The lag in user studies is a heritage which stems

mainly from the professional mix that originally

developed and used the technology of man-computer

communications. For two critical, formative

decades, the 1940's and the 1950's — comprising

the birth and development of electronic digital

computers — social scientists, human engineers

and human factors specialists, the professionals

trained to work with human subjects under experimental conditions, were only indirectly concerned

with man-computer communications, dealing largely

with knobs, buttons and dials rather than with the

interactive problem-solving of the user. In all fairness, there were some exceptions to this rule,

but they were too few and too sporadic to make a

significant and lasting impact on the mainstream

of user development. Since there was, in effect, an applied scientific vacuum surrounding mancomputer communication, it is not at all surprising

that there does not exist today a significant, cumulative experimental tradition for testing and evaluating

computer-user performance." (Sackman, 1968,

p. 349).

"The problem is, of course, to get the right

information to the right man at the right time and

at his work station and with minimum effort on

his part. What all this may well be saying is that the

information problem that exists is considerably more subtle and complex than has been set forth . . . The study for development of a Methodology for Analysis of Information Systems Networks arrives,

both directly and by implication at the same conclusion as have a number of other recent studies.

That conclusion is that much more has to be known

about the user and his functions, and much more

has to be known about what the process of RDT & E

actually is and how can information, as raw material

input to the process, flow most efficiently and most

effectively." (Sayer, 1965, p. 146).

"The recurrent theme in general review articles concerned with man-computer communication is the glaring experimental lag. Innovation and unverified applications outrace experimental evaluation on all sides. "In a review of man-computer communication,

Ruth Davis points out that virtually no experimental

work has been done on user effectiveness. She

characterizes the status of user statistics as inadequate and 'primitive', and she urges the specification and development of extensive measures of user performance. . . . "Pollack and Gildner reviewed the literature on

user performance with manual input devices for man-computer communication. Their extensive

survey — covering large numbers and varieties of

switches, pushbuttons, keyboards and encoders —

revealed 'inadequate research data establishing

performance for various devices and device characteristics, and incomplete specification of operator

input tasks in existing systems.' There was a vast experimental gap between the literally hundreds

of manual input devices surveyed and the very

small subset of such devices certified by some form

of user validation. They recommended an initial program of research on leading types of task/device

couplings, and on newer and more natural modes of manual inputs such as speech and handwriting."

(Sackman, 1968, p. 350). 2.11 "Information control at input can be used

to achieve improved system efficiency in several

different ways. First, a reduction in the total 38
volume of information units or reports to be received,

processed, or stored can be gained through the use

of filtering procedures to reduce the possible re- dundancies between items received. (Timing considerations are important in such procedures, as noted elsewhere, because we won't want a delayed

and incorrect message to 'update' its own correction notice.)

"Secondly, input filtering procedures serve to reduce the total bulk of information to be processed

or stored — both by elimination of duplicate items

as such and by the compression of the quantitative

amount of recording used to represent the original

information unit or message within the system.

"A third technique of information control at input is directed to the control of redundancy within

a single unit or report. Conversely, input filtering

procedures of this type can be used to enhance the

value of information to be stored. For example, in pictorial data processing, automatic boundary contrast enhancements or 'skeletonizations' may improve both subsequent human pattern perception

and system storage efficiency. Another example is natural text processing, where systematic elimination of the 'little', 'common', and 'non-informing'

words can significantly reduce the amount of text

to be manipulated by the machine." (Davis, 1967,

p. 49). 2.12 In this area, R&D requirements for the

future include the very severe problems of sifting

and filtering enormous masses 'of remotely collected

data. For example, "our ability to acquire data is so

far ahead of our ability to interpret and manage it that there is some question as to just how far we

can go toward realizing the promise of much of this remote sensing. Probably 90% of the data gathered

to date have not been utilized, and, with large multi- sensor programs in the offing, we face the danger of

ending up prostrate beneath a mountain of utterly

useless films, tapes, and charts." (Parker and Wolff,

1965, p. 31). 2.13 "Purging because of redundancy is ex- tremely difficult to accomplish by computer program

except in the case of 100% duplication. Redundancy

purging success is keyed to practices of standardization, normalization, field formatting, abbreviation

conventions and the like. As a case in point, document handling systems universally have problems

with respect to bibliographic citation conventions,

transliterations of proper names, periodical title abbreviations, corporate author fisting practices and

the like." (Davis, 1967, p. 20). See also Ebersole (1965), Penner (1965), and

Sawin (1965) who points to some of the difficulties with respect to a bibliographic collection or file, as

follows:

"1. Actual errors, such as incorrect spelling of

words, incorrect report of pagination, in one

or more of the duplicates. The error may be

mechanically or humanly generated; the error may have been made in the source bibliography, or by project staff in transcription

from source to paper tape. In any case, error

is a factor in reducing the possibility of

identity of duplicates.

"2. Variations among bibliographies both in style and content. A bibliographical citation gives several different kinds of information;

that is, it contains several 'elements,' such

as author of item, title, publication data, re- views and annotations. Each source bibliography more or less consistently employs one

style for expressing information, but each

style differs from every other in some or all of the following ways:

a. number of elements

b. sequence of elements

c. typographical details" (1965, p. 96).

2.14 "File integrity can often be a significant

motivation for mechanization. To insure file integrity in airline maintenance records, files have been

republished monthly in cartridge roll-microfilm

form, since mechanics would not properly insert

update sheets in maintenance manuals. Freemont

Rider's original concept for the microcard, which was a combination of a catalog card and document

in one record, failed in part because of the lack of

file integrity. Every librarian knows that if there wasn't a rod through the hole in the catalog card they

would not be able to maintain the integrity of the

card catalog." (Tauber, 1966, p. 277).

2.15 "Retirement of outmoded data is the only

long-range effective means of maintaining an

efficient system." (Miller et al, 1960, p. 54). With respect to maintenance processes involving

the deletion of obsolete items, there are substantial

fact finding research requirements for large-scale

documentary item systems in terms of establishing

efficient but realistic criteria for "purging". Kessler

comments on this point as follows: "It is not just a matter of throwing away 'bad' papers as 'good' ones come along. The scientific literature is unique

in that its best examples may have a rather short

life of utility. A worker in the field of photoelectricity need not ordinarily be referred to Einstein's

original paper on the subject. The purging of the

system must be based on criteria of operational

relevance rather than intrinsic value. These

criteria are largely unknown to us and represent

another basic area in need of research and invention." (1960, pp. 9-10).

"Chronological cutoff is that device attempted

most frequently in automated information systems.

It is employed successfully in real-time systems

such as aircraft or satellite tracking or airline reservations systems where the information is useless after very short time intervals and where

it is so voluminous as to be prohibitive for future

analyses . . . "That purging which is done is primarily replace- ment. Data management or file management

39
systems are generally programmed so that upon

proper identification of an item during the manual

input process it may replace an item already in the system data bank. The purpose of replacement

as a purging device is not volume control. It is for purposes of accuracy, reliability or timeliness

controls." (Davis, 1967, p. 15). "The reluctance to purge has been a leading reason for accentuating file storage hierarchy considerations. Multi-level deactivation of information

is substituted for purging. Deactivation proceeds

through allocating the material so specified first to slower random-access storage devices and then

to sequentially-accessed storage devices with

decreasing rates of access all on-fine with the

computer. As the last step of deactivation the

information is stored in off-line stores . . . "Automatic purging algorithms have been written

for at least one military information system and for SDC's time-sharing system ... In the military

system . . . the purging program written allowed

all dated units of information to be scanned and

those prior to a prescribed date to be deleted and

transcribed onto a magnetic tape for printing. The

information thus nominated for purging was re- viewed manually. If the programmed purge decision was overridden by a manual decision the falsely

purged data then had to be re-entered into system

files as would any newly received data." (Davis,

1967, pp. 16-18).

"Automatic purging algorithms have been ex- plored for the past three years. The current scheme

attempts to dynamically maintain a 10 percent

disc vacancy factor by automatically deleting the

oldest files first. User options are provided which

permit automatic dumping of files on a backup,

inactive file tape . . . prior to deletion." (Schwartz

and Weissman, 1967, p. 267).

"The newer time-sharing systems contemplate

a hierarchy of file storage, with 'percolation'

algorithms replacing purging algorithms. Files

will be in constant motion, some moving 'down'

into higher-volume, slower-speed bulk store, while others move 'up' into lower-volume, higherspeed memory— all as a function of age and refer- ence frequency." (Schwartz and Weissman, 1967,

p. 267).

2.16 "Some computer-oriented statistics are provided to assist in monitoring the system with

minimum cost or time. Such statistics are tape

length and length of record, checks on dictionary

code number assignment, frequency of additions

or deletions to the dictionary, and checks to see

that the correct inverted file was updated." (Smith

and Jones, 1966, p. 190).

"Usage statistics as obsolescence criteria are commonly employed in scientific and technical

information systems and reference data systems . . . "Usage statistics are also used in the deactivation

process to organize file data in terms of its refer- ence frequency. The Russian-to-English automated

translation system at the Foreign Technology Division, Wright-Patterson AFB had its file system

organized on this basis by IBM in the early 1960's.

It was found from surveys of manual translators that the majority of vocabulary references were

to less than one thousand words. These were isolated

and located in the fastest-access memory: the rest of the dictionary was then relegated to lower priority

locations . . ." (Davis, 1967, pp. 18-19).

"The network might show publications being

permanently retained at a particular location. This

would allow others in the network to dispose of

little-used materials and still have access to a copy if the unexpected need arose . . . "Such an 'archival' copy could, of course, be

relocated to a relatively low-cost warehouse area

for the mutual benefit of those agencies in the net- work. Statistics on frequency of usage might be

very helpful in identifying inactive materials, and

the network could also fill this need." (Brown et al., 1967, p. 66). "Periodic reports to users on file activity may

reveal possible misuse or tampering." (Petersen

and Turn, 1967, p. 293).

2.17 "Accessibility. For a system output a measure of how readily the proper information was made available to the requesting user on the

desired medium." (Davis, 1964, p. 469).

2.18 Consider also the following:

"The system study will consider that the document-retrieval problem lies primarily within

the parameters of file integrity; activity and activity

distribution; man-file interaction; the size, nature and organization of the file; its location and workplace layout; whether it is centralized or decentralized; access cycle time; and cost. Contributing

factors are purging and update; archival considerations; indexing; type of response; peak-hour,

peak-minute activity; permissable-error rates; and publishing urgency." (Tauber, 1966, p. 274).

Then there are questions of sequential decisionmaking and of time considerations generally. "Time

consideration is explicitly, although informally,

introduced by van Wijngaarden as 'the value of a

text so far read'. Apart from other merits of van

Wijngaarden's approach and his stressing the inter- action between syntax and semantics, we would like

to draw attention to the concept of 'value at time t', which seems to be a really basic concept in pro- gramming theory." (Caracciolo di Forino, 1965, p. 226). We note further that "T as the time a fact assertion is reported must be distinguished from the

time of the fact history referred to by the assertion."

(Travis, 1963, p. 334).

Avram et al., point more prosaically to practical

problems in mechanized bibliographic reference

data handling, as in the case of different types of

searches on date: The case of requesting all works

on, say, genetics, written since 1960 as against that of all works on genetics published since 1960 with

respect to post-1960 reprints of pre-1960 original

texts. For the future, moreover, "In some instances, the

40
search request would have to take into account

which data has been used in the fixed field. For

example, should one want a display of all the books

in Hebrew published during a specific time frame,

an adjustment would have to be made to the date

in the search request to compensate for the adjustment made to the data at input time." (Avram et al., 1965, p. 42). 2.19 "Here you run into the phenomenon of the

'elastic ruler'. At the time when certain data were

accumulated, the measurements were made with

a standard inch or standard meter . . . whether

researchers were using an inch standardized before

a certain date, or one adopted later." (Birch, 1966,

p. 165).

2.20 "Large libraries face the problem of converting records that exist in many languages. The

most complete discussion of this problem to date is by Cain & Jolliffe of the British Museum. They suggest methods for encoding different languages and

speculate on the extent to which certain translitera- tions could be done by machine. The possibility of

storing certain exotic languages on videotapes is suggested as a way of handling the printing problem.

At the Brasenose Conference at which this paper was presented, the authors analyzed the difficulties

in bibliographic searching caused by transliteration

of languages (this is the scheme most generally sug- gested by those in the data processing field)."

(Markuson, 1967, p. 268). 2.21 "The question of integrity of information

within an automated system is infrequently addressed." (Davis, 1967, p. 13). "No adequate reference service exists that would

allow users to determine easily whether or not rec- ords have the characteristics of quality and compatibility that are appropriate to their analytical

requirements." (Dunn, 1967, p. 22). 2.22 "Controls through 'common sense' or

logical checks . . . include the use of allowable

numerical bounds such as checking bearings by

assuming them to be bounded by 0° as a minimum

and 360° as a maximum. They include consistency

checks using redundant information fields such as

social security number matched against aircraft type and aircraft speed. They also include current awareness checks such as matches of diplomat by name against reported location by city against

known itinerary against known political views."

(Davis, 1967, p. 36). "A quite different kind of work is involved in examing for internal consistency the reports from

the more than 3 million establishments covered

in the 1954 Censuses of Manufacturers and Business. If these reports were all complete and self- consistent and if we were smart enough to foresee

all the problems involved in classifying them, and

if we made no errors in our office work, the job of getting out the Census reports would be laborious

but straightforward. Unfortunately, some of the

reports do contain omissions, errors, and evidence

of misunderstanding. By checking for such inconsistencies we eliminate, for example, the large

errors that would result when something has been

improperly reported in pounds instead of in thousands of pounds. Perhaps one-third to one-half of

the time our UNIVACs devote to processing these

Censuses will be spent checking for such inconsistencies and eliminating them. . . . "Similar checking procedures are applied to the

approximately 7,000 product lines for which we

have reports. In a like manner we check to see whether such relationships as annual man hours

and number of production workers, or value of

shipments and cost of labor and materials, are within reasonable limts for the industry and area

involved. . . . "For example, the computer might determine

for an establishment classified as a jewelry repair

shop, that employees' salaries amounted to less than

10 percent of total receipts. For this kind of service

trade, expenditures for labor usually represent the

major item of expenses and less than 10 percent

for salaries is uncommonly low. Our computer

would list this case for inspection, and a review

of the report might result in a change in classifi- cation from 'jewelry repair shop to retail jewelry

store', for example." (Hansen and McPherson,

1956, pp. 59-60).

2.23 "The use of logical systems for error control is in beginning primitive stages. Questionanswering systems and inference-derivation

programs may find their most value as error control

procedures rather than as query programs or problem-solving programs." (Davis, 1967, p. 47). "A theoretically significant result of introducing source indicators and reliability indicators to be

carried along with fact assertions in an SFQA

[question-answering] system is that they provide

a basis for applying purifying programs to the fact assertions stored in the system — i.e., for resolving

contradictions among different assertions, for culling out unreliable assertions, etc. . . . "Reliability information might indicate such

things as: S's degree of confidence in his own

report if S is a person; S's probable error if 5 is a measuring instrument; S's dependability as determined by whether later experience con- firmed S's earlier reports; conditions under which

5 made its report, etc." (Travis, 1963, p. 333).

2.24 "Another interesting distinction can be

made between files on the basis of their accuracy. A clean file is a collection of entries, each of which was precisely correct at the time of its inclusion

in the file. On the other hand, a dirty file is a file that contains a significant portion of errors. A re- circulating file is purged and cleansed as it cycles —

a

utility-company billing file is of this nature. After

the file 'settles down,' the proportion of errors imbedded in the file is a function of the new activity

applied to the file. The error rate is normalized

with respect to the business cycle." (Patrick and

Black, 1964, p. 39). 41
"When messages are a major source of the

information entering the system corrections to a previously transmitted original message can be

received before the original message itself. If entered on an earlier update cycle the correction

data can actually be 'corrected' during a later update cycle by the original incorrect message."

(Davis, 1967, p. 24). 2.25 "Errors will occur in every data collection

system, so it is important to detect and correct

as many of the errors as possible." (Hillegass and

Melick, 1967, p. 56). "The primary purpose of a data communications

system is to transmit useful information from one

location to another. To be useful, the received copy

of the transmitted data must constitute an accurate

representation of the original input data, within

the accuracy limits dictated by the application

requirements and the necessary economic tradeoffs. Errors will occur in every data communications

system. This basic truth must be kept in mind

throughout the design of every system. Important

criteria for evaluating the performance of any communications system are its degree of freedom from

data errors, its probability of detecting the errors

that do occur, and its efficiency in overcoming the

effects of these errors." (Reagan, 1966, p. 26). "The form of the control established, as a result of the investigation, should be decided only after considering each situation in the light of the three

control concepts mentioned earlier. Procedures,

such as key verification, batch totals, sight verification, or printed listings should be used only when

they meet the criteria of reasonableness, in light

of the degree of control required and the cost of

providing control in relation to the importance and

volume of data involved. The objective is to establish appropriate control procedures. The manner

in which this is done — i.e., the particular combination of control techniques used in a given set circumstances — will be up to the ingenuity of the

individual systems designer." (Baker and Kane,

1966, pp. 99-100).

2.26 "Two basic types of codes are found

suitable for the burst type errors. The first is the

forward-acting Hagelbarger code which allows

fairly simple data encoding and decoding with

provisions for various degrees of error size cor- rection and error size detection. These codes,

however, involve up to 50 percent redundancy

in the transmitted information. The second code

type is the cyclic code of the Bose-Chauduri type

which again is fairly simple to encode and can detect

various error burst sizes with relatively low redundancy. This code type is relatively simple to decode

for error detection but is too expensive to decode

for error correction, and makes retransmission the

only alternative." (Hickey, 1966, p. 182).

2.27 "Research devoted to finding ways to further reduce the possibility of errors is progress- ing on many fronts. Bell Telephone Laboratories

is approaching the problem from three angles:

error detection only, error detection and correction

with a non-constant speed of end-to-end data

transfer (during the correction cycle transmission

stops), and error detection and correction with a constant speed of end-to-end data transfer (during

the correction cycle transmission continues)."

(Menkhaus, 1967, p. 35). "There are two other potential 'error injectors'

which should be given close attention, since more

control can be exercised over these areas. They

are: the data collection, conversion and input devices, and the human being, or beings, who collect the data (or program a machine to do it) at the

source. Bell estimates that the human will commit

an average of 1,000 errors per million characters

handled, the mechanical device will commit 100 per

million, and the electronic component, 10 per

million. . . . "Error detection and correction capability is a 'must' in the Met Life system and this is provided

in several ways. The input documents have Honeywell's Orthocode format, which uses five rows of

bar codes and several columns of correction codes

that make defacement or incorrect reading virtually

impossible; the control codes also help regenerate

partially obliterated data. . . . "Transmission errors are detected by using a dual

pulse code that, in effect, transmits the signals for a message and also the components of those signals,

providing a double check on accuracy. The paper

tape reader, used to transmit data, is bi-directional;

if a message contains a large number of errors, due

possibly to transmission noise, the equipment in the

head office detects those errors and automatically

tells the transmitting machine to 'back up and start over'." (Menkhaus, 1967, p. 35). 2.28 "Input interlocks — checks which verify that the correct types and amounts of data have been

inserted, in the correct sequence, for each transaction. Such checks can detect many procedural

errors committed by persons entering input data

into the system." (Hillegass and Melick, 1967, p. 56). 2.29 "Parity— addition of either a 'zero' or 'one'

bit to each character code so that the total number

of 'one' bits in every transmitted character code

will be either odd or even. Character parity checking can detect most single-bit transmission errors, but

it will not detect the loss of two bits or of an entire

character." (Hillegass and Melick, 1967, p. 56). "Two of the most popular error detection and cor- rection devices on the market — Tally's System 311

and Digitronics' D500 Series — use retransmission

as a correction device. Both transmit blocks of

characters and make appropriate checks for valid

parity. If the parity generated at the transmitter

checks with that which has been created from the

received message by the receiver, the transmission

continues. If the parity check fails, the last block is retransmitted and checked again for parity. This

method avoids the disadvantages of transmitting

42
the entire message twice and of having to compare

the second message with the first for validity."

(Davenport, 1966. p. 31). "Full error detection and correction is provided.

The telephone line can be severed and reattached

hours later without loss of data . . . Error detection

is accomplished by a horizontal and vertical parity

bit scheme similar to that employed on magnetic

tape." (Lynch, 1966, p. 119).

"A technique that has proven highly successful

is to group the eight-level characters into blocks

of eighty-four characters. One of the eighty-four

characters represents a parity character, assuring

that the summation of each of the 84 bits at each

of eight levels is either always odd or always even. For the block, there is now a vertical parity check

(the character parity) and a horizontal parity check

(the block parity character). This dual parity

check will be invalidated only when an even number of characters within the block have an

even number of hits, each at the same level. The

probability of such an occurrence is so minute

that we can state that the probability of an undetected error is negligible. In an 84-character block,

constituting 672 bits, 83 + 8 = 91 bits are redundant.

Thus, at the expense of adding redundancy of 13.5 per cent, we have assured error-free transmission.

At least we know that we can detect errors with

certainty. Now, let us see how we can utilize this knowledge to provide error-free data at high

transmission rates. One of the' most straightforward

techniques is to transmit data in blocks, auto- matically checking each block for horizontal and

vertical parity at the receiving terminal. If the

block parities check, the receiving terminal delivers the block and an acknowledgment character

(ACK) is automatically transmitted back to the

sending terminal. This releases the next block and

the procedure is repeated. If the block parities do

not check, the receiving terminal discards the

block and a nonacknowledgment character (NACK)

is returned to the sender. Then, the same block is retransmitted. This procedure requires that storage

capacity for a minimum of one data block be

provided at both sending and receiving terminals."

(Rider, 1967, p. 134).

2.30 "What then can we say that will summarize

the position of the check digit? We can say that it is useful for control fields — that is, those fields we access by and sort on, customer number, employee number, etc. We can go further and say

that it really matters only with certain control

fields, not all. With control fields, the keys by

which we find and access records, it is essential

that they be correct if we are to find the correct

record. If they are incorrect through juxtaposition

or other errors in transcription, we will 1) not find the record, and 2) find and process the wrong

record. . . . "One of the most novel uses of the check digit can be seen in the IBM 1287 optical scanner. The

writer enters his control field followed by the

check digit. If one of his characters is not clear,

the machine looks at the check digit, carries out

its arithmetic on the legible characters, and subtracts the result from the result that would give

the check digit to establish the character in doubt.

It then rebuilds this character." (Rothery. 1967,

p. 59.) 2.31 "A hash total works in the following way.

Most of our larger computers can consider alphabetic

information as data. These data are added up,

just as if they were numeric information, and a meaningless total produced. Since the high-speed

electronics are very reliable, they should produce

the same meaningless number every time the same

data fields are summed. The transfer of information

within the computer and to and from the various

input/output units can be checked by recomputing

this sum after every transmission and checking

against the previous total. . . . "Some computers have special instructions built into them to facilitate this check, whereas others

accomplish it through programming. The file designer considers the hash total as a form of built- in audit. Whenever the file is updated, the hash

totals are also updated. Whenever a tape is read,

the totals are reconstituted as an error check.

Whenever an error is found, the operation is re- peated to determine if a random error has occurred.

If the information is erroneous, an alarm is sounded

and machine repair is scheduled. If information has

been actually lost, then human assistance is usually

required to reconstitute the file to its correct content. Through a combination of hardware and pro- gramming the validity of large reference files can

be maintained even though the file is subject to repeated usage." (Patrick and Black, 1964, pp. 46-47).

2.32 "Message length — checks which involve

a comparison of the number of characters as specified for that particular type of transaction. Message

length checks can detect many errors arising from

both improper data entry and equipment or fine malfunctions." (Hillegass and Milick, 1967, p. 56). 2.33 "In general, many standard techniques

such as check digits, hash totals, and format checks

can be used to verify correct input and trans- mission. These checks are performed at the

computer site. The nature and extent of the checks

will depend on the capabilities of the computer

associated with the response unit. One effective technique is to have the unit respond with a verbal

repetition of the input data." (Melick, 1966, p. 60). 2.34 "Philco has a contract for building what is called a Spelling-Corrector ... It reads text and

matches it against the dictionary to find out whether

the words are spelled correctly." (Gibbs and MacPhail, 1964, p. 102).

"Following keypunching, the information retrieval technician processes the data using a 1401 computer. The computer performs sequence checking,

editing, autoproofing (each word of input is checked

against a master fist of correctly spelled words

376-411 O - 70 - 4
to determine accuracy— a mismatch is printed out

for human analysis since it is either a misspelled

or a new word), and checking for illegitimate characters. The data is now on tape; any necessary

correction changes or updating can be made

directly." (Magnino, 1965, p. 204).

"Prior to constructing the name file, a 'legitimate

name' list and a 'common error' name list are tabulated . . . The latter list is formed by taking character error information compiled by the instrumentation system and thresholding it so only errors with

significant probabilities remain; i.e., 'e' for 'a'. These are then substituted one character at a time

in the names of the 'legitimate name' list to create a 'common error' name list. Knowing the probability

of error and the frequency of occurrence of the

'legitimate name' permits the frequency of occur- rence for the 'common error' name to be calculated."

(Hennis, 1967, pp. 12-13).

2.35 "When a character recognition device errs

in the course of reading meaningful English words it will usually result in a letter sequence that is itself not a valid word; i.e., a 'misspelling'," (Cornew,

1968, p. 79). 2.36 "Several possibilities exist for using the

information the additional constraints provide. A

particularly obvious one is to use special purpose

dictionaries, one for physics texts, one for chemistry, one for novels, etc., with appropriate word

lists and probabilities in each. . . ." "Because of the tremendous amount of storage

which would be required by such a 'word digram'

method, an alternative might be to associate with

each word its one or more parts of speech, and make

use of conditional probabilities for the transition

from one part of speech to another." (Vossler and

Branston, 1964, p. D2.4-7).

2.37 "In determining whether or not to adopt an EDC system, the costliness and consequences of

any error must be weighed against the cost of in- stalling the error detection system. For example, in a simple telegram or teleprinter message, in which

all the information appears in word form, an error

in one or two letters usually does not prevent a reader from understanding the message. With train- ing, the human mind can become an effective error detection and correction system; it can readily

identify the letter in error and make corrections. Of

course, the more unrelated the content of the message, the more difficult it is to detect a random mistake. In a list of unrelated numbers, for example, it is almost impossible to tell if one is incorrect."

(Gentle, 1965, p. 70). 2.38 In addition to examples cited in a previous

report in this series, we note the following: "In the scheme used by McElwain and Evens,

undisturbed digrams or trigrams in the garbled

message were used to locate a fist of candidate

words each containing the digram or trigram. These

were then matched against the garbled sequence

taking into account various possible errors, such as a missing or extra dash, which might have occurred

in Morse Code transmission." (Vossler and Branston, 1964, p. D2.4-1).

"Harmon, in addition to using digram frequencies

to detect errors, made use of a confusion matrix to determine the probabilities of various letter substitutions as an aid to correcting these errors." (Vossler and Branston, 1964, pp. D2.4-1 -D2.4-2).

"An interesting program written by McElwain

and Evens was able to correct about 70% of the

garbles in a message transmitted by Morse Code,

when the received message contained garbling in 0-10% of the characters." (Vossler and Branston,

1964, p. D2.4-1).

"The design of the spoken speech output modality for the reading machine of the Cognitive

Information Processing Group already calls for a large, disc-stored dictionary . . . The possibility

of a dual use of this dictionary for both correct

spelling and correct pronunciation prompted this study." (Cornew, 1968, p. 79). "Our technique was first evaluated by a test performed on the 1000 most frequent words of

English which, by usage, comprise 78% of the

written language . . . For this, a computer pro- gram was written which first introduced into each

of these words one randomly-selected, randomlyplaced letter substitution error, then applied this technique to correct it. This resulted in the fol- lowing overall statistics 739 correct recoveries of

the original word prior to any other; 241 incorrect

recoveries in which another word appeared sooner; 20 cases where the misspelling created another

valid word." (Cornew, 1968, p. 83). "In operation, the word consisting of all first choice characters is looked up. If found, it is as- sumed correct; if not, the second choice characters

are substituted one at a time until a matching word

is found in the dictionary or until all second choice

substitutions have been tried. In the latter case

a multiple error has occurred (or the word read

correctly is not in the dictionary)." (Andrews, 1962,

p. 302).

2.39 "There are a number of different techniques for handling spelling problems having to do with names in general and names that are homonyms. Present solutions to the handling of name

files are far from perfect." (Rothman, 1966, p. 13). 2.40 "The chief problem associated with . . . large name files rests with the misspelling or misunderstanding of names at time of input and with

possible variations in spelling at the time of search.

In order to overcome such difficulties, various

coding systems have been devised to permit filing

and searching of large groups of names phonetically

as well as alphabetically ... A Remington Rand

Univac computer program capable of performing

the phonetic coding of input names has been

prepared." (Becker and Hayes, 1963, p. 143).

"A particular technique used in the MGH

[Massachusetts General Hospital] system is probably

worth mentioning; this is the technique for phonetic

indexing reported by Bolt et al. The use described

44
involves recognition of drug names that have been

typed in, more or less phonetically, by doctors or nurses; in the longer view this one aspect of a large

effort that must be expended to free the manmachine interface from the need for letter-perfect

information representation by the man. People

just don't work that way, and systems must be

developed that can tolerate normal human imprecision without disaster." (Mills, 1967, p. 243). 2.41 ". . . The object of the study is to deter- mine if we can replace garbled characters in names. The basic plan was to develop the empirical

frequency of occurrence of sets of characteres

in names and use these statistics to replace a missing character." (Carlson, 1966, p. 189).

"The specific effect on error reduction is impressive. If a scanner gives a 5% character error

rate, the trigram replacement technique can correct approximately 95% of these errors. The remaining

error is thus . . . 0.25% overall. . . . "A technique like this may. indeed, reduce the

cost of verifying the mass of data input coming from

scanners . . . [and] reduce the cost of verifying

massive data conversion coming from conventional data input devices like keyboards, remote

terminals, etc." (Carlson, 1966, p. 191.) 2.42 "The rules established for coding struc- tures are integrated in the program so that the

computer is able to take a fairly sophisticated look

at the chemist's coding and the keypunch operator's

work. It will not allow any atom to have too many or

too few bonds, nor is a

'7' bond code permissible

with atoms for which ionic bonds are not 'legal'. Improper atom and bond codes and misplaced

characters are recognized by the computer, as are various other types of errors." (Waldo and

DeBacker, 1959, p. 720). 2.43 "Extensive automatic verification of the

file data was achieved by a variety of techniques.

As an example, extracts were made of principal

lines plus the sequence number of the record:

specifically, all corporate name lines were ex- tracted and sorted; any variations on a given name

were altered to conform to the standard. Similarly,

all law firm citations were checked against each

other. All city-and-state fields are uniform. A zipcode-and-place-name abstract was made, with the

resultant file being sorted by zip code: errors were

easy to sort and correct, as with Des Moines

appearing in the Philadelphia listing." (North,

1968, p. 110).

Then there is the even more sophisticated case where ". . . An important input characteristic

is that the data is not entirely developed for proc- essing or retrieval purposes. It is thus necessary

first to standardize and develop the data before

manipulating it. Thus, to mention one descriptor,

'location', the desired machine input might be

'coordinate', 'city', and 'state', if a city is mentioned; and 'state' alone when no city is noted.

However, inputs to the system might contain a coordinate and city without mention of a state.

It is therefore necessary to develop the data and

standardize before further processing commences.

"It is then possible to process the data against the

existing file information . . . The objective of the

processing is to categorize the information with

respect to all other information within the files . . . To categorize the information, a substantial amount

of retrieval and association of data is often required

. . . Many [data] contradictions are resolvable by

the system." (Gurk and Minker, 1961, pp. 263-264).

2.44 "A number of new developments are based

on the need for serving clustered environments. A

cluster is defined as a geographic area of about three

miles in diameter. The basic concept is that within

a cluster of stations and computers, it is possible

to provide communication capabilities at low cost. Further, it is possible to provide communication

paths between clusters, as well as inputs to and

outputs from other arrangements as optional fea- tures, and still maintain economies within each

cluster. This leads to a very adaptable system. It is expected to find wide application on university

campuses, in hospitals, within industrial complexes,

etc." (Simms, 1968, p. 23). 2.45 "Among the key findings are the following: • Relative cost-effectiveness between timesharing and batch processing is very sensitive

to and varies widely with the precise manmachine conditions under which experimental

comparisons are made. • Time-sharing shows a tendency toward fewer

man-hours and more computer time for experimental tasks than batch processing. • The controversy is showing signs of narrowing

down to a competition between conversationally interactive time-sharing versus fast-turn- around batch systems. • Individual differences in user performance are generally much larger and are probably more

economically important than time-sharing/

batch-processing system differences. • Users consistently and increasingly prefer

interactive time-sharing or fast turnaround

batch over conventional batch systems. • Very little is known about individual perform- ance differences, user learning, and human

decision-making, the key elements underlying

the general behavioral dynamics of man-computer communication. • Virtually no normative data are available on

data-processing problems and tasks, nor on

empirical use of computer languages and sys- tem support facilities — the kind of data necessary to permit representative sampling of

problems, facilities and subjects for crucial

experiments that warrant generalizable re- sults." (Sackman, 1968, p. 350).

However, on at least some occasions, some clients of a multiple-access, time-shared system may be

satisfied with, or actually prefer, operation in a 45
batch or job-shop mode to extensive use of the conversational mode.

"Critics (see Patrick 1963, Emerson 1965, and

MacDonald 1965) claim that the efficiency of timesharing systems is questionable when compared to modern closed-shop methods, or with economical

small computers." (Sackman et al., 1968, p. 4). Schatzoff et al. (1967) report on experimental

comparisons of time-sharing operations (specifically,

MIT's CTSS system) with batch processing as employed on IBM's IBSYS system.

". . . One must consider the total spectrum of

tasks to which a system will be applied, and their

relative importance to the total computing load."

(Orchard-Hays, 1965, p. 239).

"... A major factor to be considered in the

design of an operating system is the expected job

mix." (Morris et al., 1967, p. 74). "In practice, a multiple system may contain both

types of operation: a group of processors fed from

a single queue, and many queues differentiated

by the type of request being serviced by the attached

processor group . . ." (Scherr, 1965, p. 17). 2.46 "Normalization is a necessary preface to the merge or integration of our data. By merge, or

integration, as I use the term here to represent the

last stage in our processes, I am referring to a complex interfiling of segments of our data — the

entries. In this 'interfiling,' we produce, for each

article or book in our file, an entry which is a composite of information from our various sources. If one of our sources omits the name of the publisher

of a book, but another gives it, the final entry will contain the publisher's name. If one source gives

the volume of a journal in which an article appears,

but not the month, and another gives the month,

but not the volume, our final entry will contain

both volume and month. And so on." (Sawin, 1965,

p. 95). "Normalize. Each individual printed source, which has been copied letter by letter, has features

of typographical format and style, some of which

are of no significance, others of which are the means by which a person consulting the work

distinguishes the several 'elements' of the item.

The family of programs for normalizing the several

files of data will insert appropriate information

separators to distinguish and identify the elements

of each item and rearrange it according to a selected

canonical style, which for the Pilot Study is one which conforms generally to that of the Modern

Language Association." (Crosby, 1965, p. 43). 2.47 "Some degree of standardized processing

and communication is at the heart of any information system, whether the system is the basis for mounting a major military effort, retrieving documents from a central library, updating the clerical and accounting records in a bank, assigning airline reservations, or maintaining a logistic inventory.

There are two reasons for this. First, all information

systems are formal schemes for handling the infor- mational aspects of a formally specified venture.

Second, the job to be done always lies embedded

within some formal organizational structure." (Bennett, 1964, p. 98). "Formal organizing protocol exists relatively

independently of an organization's purposes, origins, or methods. These established operating procedures

of an organization impose constraints upon the

available range of alternatives for individual behavior. In addition to such constraints upon the

degrees of freedon within an organization as re- strictions upon mode of dress, conduct, range of

mobility, and style of performance, there are protocol constraints upon the format, mode,

pattern, and sequence of information processing

and information flow. It is this orderly constraint

upon information processing and information

flow that we call, for simplicity, the information

system of an organization. The term 'system'

implies little more than procedural restriction and

orderliness. By 'information processing' we mean

some actual change in the nature of data or docu- ments. By 'information flow' we indicate a similar

change in the location of these data or documents.

Thus we may define an information system as simply that set of constraining specifications for the collection, storage, reduction, alteration,

transfer, and display of organizational facts,

opinions, and associated documentation which is established in order to manage, command if you

will, and control the ultimate performance of an

organization. . . . "With this in mind, it is possible to recognize

the dangers associated with prematurely standardizing the information-processing tools, the forms, the

data codes, the message layouts, the procedures

for message sequencing, the file structures, the

calculations, and especially the data-summary

forms essential for automation. Standardization

of these details of a system is relatively simple

and can be accomplished by almost anyone familiar

with the design of automatic procedures. However,

if the precise nature of the job and its organizational implications are not understood in detail,

it is not possible to know the exact influence that these standards will have on the performance of

the system." (Bennett, 1964, pp. 99, 103).

2.48 "There is a need for design verification. That is, it is necessary to have some method for ensuring that the design is under control and that the nature of the resulting system can be predicted

before the end of the design process. In commandand-control systems, the design cycle lasts from

two to five years, the design evolving from a simple

idea into complex organizations of hardware, soft- ware, computer programs, displays, human operations, training, and so forth. At all times during this cycle the design controller must be able to specify

the status of the design, the impact that changes

in the design will have on the command, and the

probability that certain components of the system

will work. Design verification is the process that gives the designer this control. The methods that
make up the design-verification process range from

analysis and simulation on paper to full-scale system testing." (Jacobs, 1964, p. 44). 2.49 "Measurement of the system was a major

area which was not initially recognized. It was

necessary to develop the tools to gather data and

introduce program changes to generate counts and

parameters of importance. Future systems designers

should give this area more attention in the design

phase to permit more efficient data collection."

(Evans, 1967, p. 83.) 2.50 "[The user] is given several control statis- tics which tell him the amount of dispersion in each

category, the amount of overlap of each category

with every other category, and the discriminating

power of the variables . . . These statistics are based on the sample of documents that he assigns

to each category . . . Various users of an identical

set of documents can thus derive their own structure

of subjects from their individual points of view."

(Williams, 1965, p. 219). 2.51 "We will probably see a trend toward the

concept of a computer as a collection of memories,

buses and processors with distributed control of

their assignments on a dynamic basis." (Clippinger,

1965, p. 209).

"Both Dr. Gilbert C. McCann of Cal. Tech and

Dr. Edward E. David, Jr., of Bell Telephone Laboratories stressed the need for hierarchies of computers interconnected in large systems to perform

the many tasks of a time-sharin'g system." (Commun.

ACM 9 , 645 (Aug. 1966).) 2.52 "Every part of the system should consist of a pool of functionally identical units (memories,

processors and so on) that can operate independently

and can be used interchangeably or simultaneously

at all times . . . "Moreover, the availability of duplicate units

would simplify the problem of queuing and the

allocation of time and space to users." (Fano and

Corbato, 1966, pp. 134-135).

"Time-sharing demands high system reliability

and maintainability, encourages redundant, modular, system design, and emphasizes high-volume

storage (both core and auxiliary) with highly parallel

system operation." (Gallenson and Weissman, 1965,

p. 14). "A properly organized multiple processor system

provides great reliability (and the prospect of con- tinuous operation) since a processor may be trivially

added to or removed from the system. A processor

undergoing repair or preventive maintenance

merely lowers the capacity of the system, rather

than rendering the system useless." (Saltzer, 1966,

p. 2). "Greater modularity of the systems will mean

easier, quicker diagnosis and replacement of faulty

parts." (Pyke, 1967, p. 162).

"To meet the requirements of flexibility of capacity and of reliability, the most natural form ... is as a modular multiprocessor system arranged so

that processors, memory modules and file storage

units may be added, removed or replaced in accord- ance with changing requirements." (Dennis and

Van Horn, 1965, p. 4). See also notes 5.83, 5.84. 2.53 "The actual execution of data movement

commands should be asynchronous with the main

processing operation. It should be an excellent use

of parallel processing capability." (Opler, 1965, p. 276).

2.54 "Work currently in progress [at Western

Data Processing Center, UCLA] includes: investi- gations of intra-job parallel processing which will attempt to produce quantititative evaluations of component utilization; the increase in complexity

of the task of programming; and the feasibility of

compilers which perform the analysis necessary to convert sequential programs into parallel-path pro- grams." (Dig. Computer Newsletter 16, No. 4, 21

(1964).)

2.55 "The motivation for encouraging the use of

parallelism in a computation is not so much to make

a particular computation run more efficiently as it is to relax constraints on the order in which parts of a computation are carried out. A multi-program

scheduling algorithm should then be able to take

advantage of this extra freedom to allocate system

resources with greater efficiency." (Dennis and Van

Horn, 1965, pp. 19-20).

2.56 Amdahl remarks that "the principal motivations for multiplicity of components functioning

in an on-line system are to provide increased

capacity or increased availability or both." (1965,

p. 38). He notes further that "by pooling, the

number of components provided need not be large

enough to accommodate peak requirements

occurring concurrently in each computer, but may

instead accommodate a peak in one occurring at the same time as an average requirement in the

other." (Amdahl, 1965, pp. 38-39).

2.57 "No large system is a static entity — it must

be capable of expansion of capacity and alteration

of function to meet new and unforeseen requirements." (Dennis and Glaser, 1965, p. 5). "Changing objectives, increased demands for use, added functions, improved algorithms and new

technologies all call for flexible evolution of the

system, both as a configuration of equipment and

as a collection of programs." (Dennis and Van Horn,

1965, p. 4). "A design problem of a slightly different character, but one that deserves considerable emphasis,

is the development of a system that is 'open-ended';

i.e., one that is capable of expansion to handle new plants or offices, higher volumes of traffic, new applications, and other difficult-to-foresee de- velopments associated with the growth of the busi- ness. The design and implementation of a data

communications system is a major investment;

proper planning at design time to provide for future

growth will safeguard this investment." (Reagan,

1966, p. 24). 2.58 "Reconfiguration is used for two prime

purposes: to remove a unit from the system for 47
service or because of malfunction, or to reconfigure

the system either because of the malfunction of one of the units or to 'partition' the system so as

to have two or more independent systems. In this

last case, partitioning would be used either to debug a new system supervisor or perhaps to aid

in the diagnostic analysis of a hardware malfunction

where more than a single system component were

needed." (Glaser et al, 1965, p. 202.)

"Often, failure of a portion of the system to provide services can entail serious consequences

to the system users. Thus severe reliability standards are placed on the system hardware. Many of

these systems must be capable of providing service

to a range in the number of users and must be able

to grow as the system finds more users. Thus, one

finds the need for modularity to meet these demands.

Finally, as these systems are used, they must be

capable of change so that they can be adapted to the ever changing and wide variety of requirements,

problems, formats, codes and other characteristics

of their users. As a result general-purpose stored

program computers should be used wherever

possible." (Cohler and Rubenstein, 1964, p. 175).

2.59 "On-fine systems are still in their early

development stage, but now that systems are beginning to work, I think that it is obvious that more attention should be paid to the fail safe

aspects of the problem." (Huskey, 1965, p. 141).

"From our experience we have concluded that system reliability . . . must provide for several

levels of failure leading to the term 'fail-soft' rather than 'fail-safe'." (Baruch, 1967, p. 147).

Related terms are "graceful degradation" and

"high availability", as follows: "The military is becoming increasingly interested

in multiprocessors organized to exhibit the property

of graceful degradation. This means that when

one of them fails, the others can recognize this and pick up the work load of the one that failed,

continuing this process until all of them have failed." (Clippinger, 1965, p. 210).

"The term 'high availability' (like its synonym

'fail safe') has now become a cliche, and lacks any

precise meaning. It connotes a system characteristic which permits recovery from all hardware

errors. Specifically, it appears to promise that

critical system and user data will not be destroyed,

that system and job restarts will be minimized and

that critical jobs can most surely be executed,

despite failing hardware. If this is so, then multiprocessing per se aids in only one of the three characteristics of high availability." (Witt, 1968, p. 699).

"The structure of a multi-computer system

planned for high availability is principally deter- mined by the permissible reconfiguration time and

the ability to fail safely or softly. The multiplicity

and modularity of system components should be

chosen to provide the most economical realization

of these requirements . . . "A multi-computer system which can perform the

full set of tasks in the presence of a single malfunction is fail-safe. Such a system requires at least one more unit of each type of system

component, with the interconnection circuitry

to permit it to replace any of its type in any configuration . . . "A multi-computer system which can perform a

satisfactory subset of its tasks in the presence of

a malfunction is fail-soft. The set of tasks which

must still be performed to provide a satisfactory

through degraded level of operation, determines

the minimum number of each component required

after a failure of one of its type." (Amdahl, 1965,

p. 39). "Systems are designed to provide either full service or graceful degradation in the face of failures that would normally cause operations to cease. A

standby computer, extra mass storage devices,

auxiliary power sources to protect against public

utility failure, and extra peripherals and communication lines are sometimes used. Manual or automatic switching of spare peripherals between

processors may also be provided." (Bonn, 1966,

p. 1865).

2.60 "A third main feature of the communication system being described is high reliability.

The emphasis here is not just on dependable hard- ware but on techniques to preserve the integrity

of the data as it moves from entry device, through

the temporary storage and data modes, over the

transmission fines and eventually to computer

tape or hard copy printer." (Hickey, 1966, p. 181.) 2.61 In addition to the examples cited in the dis- cussion of client and system protection in the pre- vious report in this series (on processing, storage,

and output requirements, Section 2.2.4), we note

the following:

"The primary objective of an evolving specialpurpose time-sharing system is to provide a real service for people who are generally not computer

programmers and furthermore depend on the system

to perform their duties. Therefore the biggest operational problem is reliability. Because the data at- tached to special-purpose system are important and

also must be maintained for a long time, reliability

is doubly crucial, since errors affecting the data base

cannot only interrupt users' current procedures but

also jeopardize past work." (Castleman, 1967, p. 17). "If the system is designed to handle both specialpurpose functions and programming development,

then why is reliability a problem? It is a problem

because in a real operating environment some new

'dangerous' programs cannot be tested on the sys- tem at the same time that service is in effect. As a

result, new software must be checked out during

offhours, with two consequences. First, the system

is not subjected to its usual daytime load during

checkout time. It is a characteristic of time-shared

programs that different 'bugs' may appear depending on the conditions of the overall system activity.

For example, the 'time-sharing bug' of a program

manipulating data incorrectly because another pro- gram processes the same data at virtually the same

48
time would be unlikely on a lightly loaded system.

Second, programmers must simulate at night their

counterparts of laymen users. Unfortunately, these

two types of people tend to use application programs

differently and to make different types of errors; so program debugging is again limited. Therefore, be- cause the same system is used for both service and

development, programs checked as rigorously as possible can still cause system failures when they

are installed during actual service hours." (Castleman, 1967, p. 17). "Protection of a disk system requires that no user be able to modify the system, purposely or inadvertently, thus preserving the integrity of the soft- ware. Also, a user must not be able to gain access

to, or modify any other user's program or data. Protection in tape systems is accomplished: (1) by

making the tape units holding the system records in- accessible to the user, (2) by making the input and

output streams one-way (e.g., the input file cannot

be backspaced), and (3) by placing a mark in the

input stream which only the system can cross. In order to accomplish this, rather elaborate schemes

have been devised both in hardware and software

to prevent the user from accomplishing certain

input-output manipulations. For example, in some

hardware, unauthorized attempts at I/O manipulation will interrupt the computer.

"In disk-based systems, comparable protection

devices must be employed. Since many different

kinds of records (e.g., system input, user scratch

area, translators, etc.) can exist in the same physical

disk file, integrity protection requires that certain

tracks, and not tape units, must be removed from

the realm of user access and control. This is usually

accomplished by partitioning schemes and central

I/O software systems similar to those used in tapebased systems. The designer must be careful to preserve flexibility while guaranteeing protection."

(Rosin, 1966, p. 242). 2.62 "Duplex computers are specified with the

spare and active computers sharing I/O devices

and key data in storage, so that the spare computer

can take over the job on demand." (Aron, 1967,

p. 54). "The second channel operates in parallel with

the main channel, and the results of the two channels are compared. Both channels must independently arrive at the same answer or operation cannot

proceed. The duplication philosophy provides for two independent access arms on the Disk Storage

Unit, two core buffers, and redundant power

supplies." (Bowers et al., 1962, p. 109).

"Considerable effort has been continuously

directed toward practical use of massive triple

modular redundancy (TMR) in which logic signals are handled in three identical channels and faults are masked by vote-taking elements distributed

throughout the system." (Avizienis, 1967, p. 735).

"He must give consideration to 1) back-up power

supplies that include the communications gear,

2) dual or split communication cables into his data

center, 3) protection of the center and its gear from

fire and other hazards, 4) insist that separate facili- ties via separate routes and used to connect locations on the MIS network, and 5) build extra capacity

into the MIS hardware system." (Dantine, 1966,

p. 409). "It is far better to have the system running at half speed 5% of the time with no 100% failures than

to have the system down 2V2% of the time."

(Dantine, 1966, p. 409).

"Whenever possible, the two systems run in parallel under the supervision of the automatic

recovery program. The operational system per- forms all required functions and monitors the

back-up system. The back-up system constantly

repeats a series of diagnostic tests on the computer,

memory and other modules available to it and

monitors the operational system. These tests are designed to maintain a high level of confidence in these modules so that should a respective counterpart in the operational system fail, the back-up

unit can be safely substituted. The back-up system

also has the capability of receiving instructions to perform tests on any of its elements and to execute

these tests while continuing to monitor the operational system to confirm that the operational

system has not hung up." (Armstrong et al., 1967,

p. 409).

2.63 "The large number of papers on vote- taking redundancy can be traced back to the

fundamental paper of Von Neuman where multiplefine redundancy was first established as a mathematical reality for the provision of arbitrarily reliable systems." (Short, 1968, p. 4). 2.64 "A computer system contains protective

redundancy if faults can be tolerated because of

the use of additional components or programs,

or the use of more time for the computational

tasks. . . . "In the massive (masking) redundancy approach

the effect of a faulty component, circuit, signal,

subsystem, or system is masked instantaneously

by permanently connected and concurrently operating replicas of the faulty element. The level at which replication occurs ranges from individual

circuit components to entire self-contained

systems." (Avizienis, 1967, p. 733-734).

2.65 "An increase in the reliability of systems

is frequently obtained in the conventional manner

by replicating the important parts several (usually

three) times, and a majority vote ... A technique

of diagnosis performed by nonbinary matrices . . . require, for the same effect, only one duplicated

part. This effect is achieved by connecting the

described circuit in a periodically changing way

to the duplicated part. If one part is disturbed the

circuit gives an alarm, localizes the failure and

simultaneously switches to the remaining part, so that a fast repair under operating conditions

(and without additional measuring instruments) is possible." (Steinbuch and Piske, 1963, p. 859).

49
2.66 "Parameters of the model are as follows: n — total number of modules in the

system

m = number of unfailed modules needed

for system survival

Pf= Probability of failure of each module some time during the mission.

This parameter thus includes both

the mission duration and the

module MTBF.

Pnd = probability of not detecting an

occurred module failure PS = probability of system survival

throughout the mission

P/= 1 — PS = probability of system failure during the mission

n/m = redundancy factor in initial sys- tem. ...

"Depending upon the attainable Pf and Pn d, the theoretical reliability of a multi-module computing system may be degraded by adding more

than a minimal amount of redundancy. For ex- ample, Pf= 0.025 ... it is more reliable to have

only one spare module rather than two or four, for a typical current-day P„d such as 0.075. Even

for a Pnd as low as 0.03 (a very difficult Pna to achieve

in a computer), the improvement obtained in system

reliability by adding a second spare unit to the

system is minor." (Wyle and Burnett, 1967, pp. 746,

748).

"The probability of system failure . . .is:

k = n „ t

k = (n-m + l) ^ n K)-K -

\ti-k

P*Al-Pf )«-*[\-{\-Pn<l) K

].

k = (n-m) R l +

fc?x (n-kl)kr f

(Wyle and Burnett, 1967, p. 746).

2.67 "One of the system design considerations is the determination of the optimum number of redundant units by means of which the required system reliability is to be reached. It will be seen that P„d as well as Pf must be considered in determining the

most economical design." (Wyle and Burnett, 1967,

p. 748).

"One of the prime requisites for a reliable, de- pendable communications data processing system

is that it employ features for insuring message pro- tection and for knowing the disposition of every

message in the system (message accountability) in case of equipment failures. The degree of message

protection and accountability will vary from application to application." (Probst, 1968, p. 21)^

"Elaborate measures are called for to guarantee

message protection. At any given moment, a switching center may be in the middle of processing

many different messages in both directions. If a malfunction occurs in any storage or processing

device, there must be enough information stored

elsewhere in the center to analyze the situation, and

to repeat whatever steps are necessary. This means

that any item of information must be stored in at least two independent places, and that the updating

of queue tables and other auxiliary data must be

carefully synchronized so that operation can continue smoothly after correction of a malfunction. If

it cannot be determined exactly where a transmission was interrupted, procedures should lean toward

pessimism. Repetition of a part of a message is less grievous than a loss of part of it." (Shafritz, 1964, p. N2.3-3).

"Reference copies are kept on magnetic tapes for protective accountability of each message. Random

requests for retransmission are met by a computer

search of the tape, withdrawal of the required messages and automatic reintroduction of the message

into the communications system." (Jacobellis, 1964,

p. N2.1-2).

"Every evening, the complete disc file inventory

is pruned and saved on tape to be reloaded the fol- lowing day. This gives a 24-hour 'rollback' capability

for catastrophic disc failures." (Schwartz and

Weissman, 1967, p. 267).

"It is necessary to provide means whereby the contents of the disc can be reinstated after they

have been damaged by system failure. The most

straightforward way of doing this is for the disc to be copied on to magnetic tape once or twice a day;

re-writing the disc then puts the clock back, but

users at least know where they are. Unfortunately,

the copying of a large disc consumes a lot of computer time, and it seems essential to develop

methods whereby files are copied on to magnetic

tape only when they are created or modified. It would be nice to be able to consider the archive

and recovery problems as independent, but reasons

of efficiency demand that an attempt should be

made to develop a satisfactory common system.

We have, unfortunately, little experience in this area as yet, and are stih groping our way." (Wilkes,

1967, p. 7). "Our requirements, therefore, were threefold:

security, retrieval, and storage. We investigated

various means by which we could meet these

requirements; and we decided on the use of microfilm, for two reasons. First, photographic copies

of records, including those on microfilm, are acceptable as legal representations of documents.

We could photograph our notebooks, store the

film in a safe place, and destroy the books or, at least, move them to a larger storage area. Second, we found on the market equipment with which

we could film the books and then, with a suitable

indexing system, obtain quick retrieval of infor- mation from that film" (Murrill, 1966, p. 52). "The file system is designed with the presumption that there will be mishaps, so that an auto- matic file backup mechanism is provided. The

backup procedures must be prepared for con- tingencies ranging from a dropped bit on a magnetic

tape to a fire in the computer room. 50
"Specifically, the following contingencies are provided for: "1. A user may discover that he has accidentally

deleted a recent file and may wish to recover

it. "2. There may be a specific system mishap

which causes a particular file to be no longer

readable for some 'inexplicable' reason.

"3. There may be a total mishap. For example,

the disk-memory read heads may irreversibly score the magnetic surfaces so that all disk- stored information is destroyed.

"The general backup mechanism is provided by

the system rather than the individual user, for the more reliable the system becomes, the more the user is unable to justify the overhead (or bother)

of trying to arrange for the unlikely contingency

of a mishap. Thus an individual user needs insur- ance, and, in fact, this is what is provided." (Corbato

and Vyssotsky, 1965, p. 193).

"Program roll-back for corrective action must be

routine or function oriented since it is impractical

from a storage requirement point of view to provide

corrective action for each instruction. The roll- back must be to a point where initial conditions

are available from sensors, prestored, or reconstitutable. Even an intermittent memory malfunction during access becomes a persistent error since it is immediately rewritten in error. Thus,

critical routines or high iteration rate real-time

routines (for example, those which perform inte- gration with respect to time) should be stored

redundantly so that in the event of malfunction

the redundantly stored routine is used to preclude

routine malfunction or error buildup with time."

(Bujnoski, 1968, p. 33). 2.68 "Restart procedures should be designed

into the system from the beginning, and the necessity for the system to spend time in copying vital information from one place to another should

be cheerfully accepted. . . . "Redundant information can be included in supervisor communication or data areas in order

to enable errors caused by system failure to be

corrected. Even a partial application of this idea

could lead to important improvements in restart

capability. A system will be judged as much as by the efficiencies of its restart procedures as by

the facilities that it provides. . . . "Making it possible for the system to be restarted

after a failure with as little loss as possible should

be the constant preoccupation of the software

designer." (Wilkes and Needham, 1968, p. 320).

"Procedures must also be prescribed for work

with the archive collection to prevent loss or contamination of the master records by tape

erasure, statistical adjustment, aggregation or

reclassification." (Glaser et al., 1967, p. 19). 2.69 "Standby equipment costs should receive some consideration, particularly in a cold war

situation: duplicate tapes, raw data or semiprocessed data. Also consider the possible costs

of transporting classified data elsewhere for computation: express, courier, messenger, Brink's

service." (Bush, 1956, p. 110).

"For companies in the middle range, the commercial underground vaults offer excellent facilities at low cost. Installations of this type are available

in a number of states, including New York, Pennsylvania, Kansas, Missouri and California. In addition

to maximum security, they provide pre-attack

clerical services and post-attack conversion

facilities. The usual storage charge ranges from

$2 to $5 a cubic foot annually, depending on whether

community or private storage is desired. . . . "The instructions should detail procedure for converting each vital record to useable form,

as well as for utilizing the converted data to per- form the desired emergency functions. The lan- guage should be as simple as possible and free of 'shop' terms, since inexperienced personnel

will probably use the instructions in the postattack." (Butler, 1962, pp. 65, 67.)

2.70 "The trend away from supporting records

is a recent development that has not yet gained

widespread acceptance. There is ample evidence,

however, that their use will decline rapidly, if the cold war gets uncomfortably hot. Except

for isolated areas in their operations, an increasing

number of companies are electing to take a cal- culated risk in safeguarding basic records but

not the supporting changes. For example, some

of the insurance companies microfilm the basic

in-force policy records annually and forego the

changes that occur between duplicating cycles.

This is a good business risk for two reasons: (1) supporting records are impractical for most emer- gency operations, and (2) a maximum one-year lag in the microfilm record would not seriously hamper

emergency operations." (Butler, 1962, p. 62.)

"Mass storage devices hold valuable records,

and backup is needed in the event of destruction

or nonreadability of a record(s). Usually the entire

file is copied periodically, and a journal of trans- actions is kept. If necessary, the file can be reconstructed from an earlier copy plus the journal to date." (Bonn, 1966, p. 1865). 2.71 "The life and stability of the [storage]

medium under environmental conditions are other

considerations to which a great deal of attention

must be paid. How long will the medium last? How stable will it be under heat and humidity

changes?" (Becker and Hayes, 1963, p. 284).

It must be noted that, in the present state of

magnetic tape technology, the average accurate

fife of tape records is a matter of a few months

only. The active master files are typically rewritten on new tapes regularly, as a part of normal up- dating and maintenance procedures. Special

precautions must be undertaken, however, to assure the same for duplicate master tapes, wherever located. "Security should also be considered in another

51
sense. Paper must be protected against fire and

flooding, magnetic tapes against exposure to electro- magnetic fields and related hazards. No special

precaution is necessary for microfilm, provided

the reels are replaced periodically in updating

cycles. Long-term storage of microfilm, however,

will require proper temperature and humidity

control in the storage area." (Butler, 1962, p. 64.)

3. Problems of System Networking

3.1 As noted in a previous report in this series: "Information processing systems are but one

facet of an evolving field of intellectual activity

called communication sciences. This is a generic

term which is applied to those areas of study

in which the interest centers on the properties

of a system or the properties of arrays of symbols

which come from their organization or structure rather than from their physical properties; that is, the study of what one M.I.T. colleague calls 'the problems of organized complexity'." (Wiesner,

1958, p. 268).

The terminology apparently originated with

Warren Weaver. Weaver (1948) noted first that the areas typically tackled in scientific research and

development efforts up to the twentieth century were largely concerned with two-variable problems of simplicity; then from about 1900 on, powerful techniques such as those of probability theory

and statistical mechanics were developed to deal with problems of disorganized complexity

(that is, those in which the number of variables

is very large, the individual behavior of each

of the many variables is erratic or unknown, but

the system as a whole has analyzable average

properties). Finally, he points to an intermediate

region "which science has as yet little explored

or conquered" (1948, p. 539), where by contrast

to those disorganized or random situations with

which the statistical techniques can cope, the

problems of organized complexity require dealing

simultaneously with a considerable number of

variables that are interrelated in accordance with

organizational factors.

3.2 "Organizational generality is an attribute

of underrated importance. The correct functioning

of on-line systems imposes requirements that have

been met ad hoc by current designs. Future system

designs must acknowledge the basic nature of the

problems and provide general approaches to their

resolution." (Dennis and Glaser, 1965, p. 5). "Diversity of needs and divisibility of computer

resources demand a much more sophisticated multiplexing strategy than the simple communication

case where all users are treated alike." (David, 1966,

p. 40).

"As we turn toward stage three, the stage characterized by the netting of geographically distrib- uted computers, we find ourselves with a significant

base of experience with special-purpose computer

networks, but with essentially no experience with

general-purpose computer networks of the kind that

will come into being when multiple-access systems

such as those at M.I.T. and the Systems Development Corporation are linked by digital transmission

channels. The difficulties involved in establishing

computer networks appear not to be difficulties of

hardware design or even of hardware availability.

Rather, they appear to be difficulties of social and

software organization, of conventions, formats,

and standards, of programming, interaction, and

communication languages. It is a situation in which

there now exist all the component hardware facilities that can be said to be required, yet in which there

do not now exist any general-purpose networks

capable of supporting stage-three interaction."

(Licklider, 1967, pp. 5-6).

"The state of affairs at the end of 1966 can be

summarized as follows. Multiaccess-system application techniques and user-oriented subsystems have

been developed to only a relatively primitive level. Far too many people, particularly those with a

scientific-application bent, still hold the short- sighted view that the real value of large, multiaccess

systems lies in their ability to simultaneously

present a powerful 'private computer' to each of

several tens or hundreds of programmers. Nearly

all of the systems actually in operation are used in

this way. Application-oriented systems that free the user of most, or all, of his concern with details of

computer-system characteristics and conventional

programming are coming much more slowly. Their

development has been inhibited by, among other

things, the temporary plateau that has been reached

in basic multiaccess system technology." (Mills,

1967, p. 247).

3.3 "The analytical tools are simply not avail- able . . ." (Baran, 1964, p. 27). "The essence of rational benefit-cost analysis is the tracing of indirect as well as direct effects of

programs and the evaluation and summing of these

effects. Typically, the methodology for tracing all but the most obvious linkages is entirely lacking or

fails to use the relevant information." (Glaser et al., 1967, p. 15). "The problem associated with providing the inter- connection of a network of processors is a major

one." (Estrin and Kleinrock, 1967, p. 92). "Solving the data base management problems of a distributed network has been beyond the state of

the art." (Dennis, 1968, p. 373).

"Although techniques for multiplex communications are well developed, we are only beginning to learn how to multiplex computers." (David, 1966,

p. 40). "The formalism of hardward/software system

52
management is just beginning to take shape. SAGE

is a landmark because it worked in spite of its immense size and complexity." (Aron, 1967, p. 50). "The system engineer presently lacks sufficient

tools to efficiently design, modify or evaluate complex information systems." (Blunt. 1965, p. 69). 3.4 "The design and analysis problems associated with large communications networks are fre- quently not solvable by analytic means and it is therefore necessary to turn to simulation techniques.

Even with networks which are not particularly large

the computational difficulties encountered when

other than very restrictive and simple models are

to be considered preclude analysis. It has become

clear that the study of network characteristics and

traffic handling procedures must progress beyond

the half-dozen switching center problem to consider

networks of dozens of nodes with hundreds or even

thousands of trunks so that those features unique to these large networks can be determined and used

in the design of communications systems. Here it is evident that simulation is the major study tool." (Weber and Gimpelson, 1964, p. 233).

"The time and costs involved make it almost

mandatory to 'prove' the 'workability' and feasibility of the potential solutions via pilot systems or by implementation in organizations or associations

which have some of the characteristics of the

national system and which would therefore serve as

a model or microcosm of the National Macrocosm."

(Ebersole, 1966, p. 34). "A report by Churchill et al., specifically recognizes the need for theoretical research in order to build an adequate foundation on which to base

systems analysis procedures. They point out that recent computer developments and particularly

large computer systems have increased the need for research and the body of data that research can

provide in such areas as data coding and file organization." (Borko, 1967, p. 37). 3.5 "The coming importance of networks of

computers creates another source of applications

for . . . multiple-queue disciplines. Computer net- work disciplines will also have to be dependent on

transmission delays of service requests and jobs

or parts of jobs»from one computer to another as well

as on the possible incompatibilities of various types

between different computers. The synthesis

and analysis of multiprocessor and multiple proc- essor network priority disciplines remains a

fertile area of research whose development awaits

broad multiprocessor application and an enlightening experience with the characteristics of these

disciplines." (Coffman and Kleinrock, 1968, p. 20). "We still are plagued by our inability to pro- gram for simultaneous action, even for the scheduling of large units in a computing system." (Corn,

1966, p. 232).

"As computer time-sharing systems have evolved

from a research activity to an operational activity,

and have increased in size and complexity, it has

become clear that significant problems occur in

controlling the use of such systems. These problems have evidenced themselves in computer

scheduling, program capability constraints, and

the allotment of auxiliary storage." (Linde and

Chaney, 1966, p. 149).

"A network has to consider with great care

the many possibilities of user access which approach more and more the vast possibilities and intri- cacies of direct human communication." (Cain

and Pizer, 1967, p. 262).

"Increased attention needs to be placed on the

problem of techniques for scheduling the many

users with their different priorities." (Bauer,

1965, p. 23). 3.6 "Much of the design effort in a messageswitching type communications system goes

into the network which links the terminals and

nodal points together. The distribution of terminals can be shown, the current message density is known, and programs exist to help lay out the

network. With most interactive systems this is not the case." (Stephenson, 1968, p. 56). 3.7 "In looking toward computer-based, computer-linked library systems, that have been

proposed as a national technical information net- work, studies of perceived needs among users

are likely to be of very little use. Instead it would seem to be more appropriate to initiate smallscale experiments designed to produce, on a limited basis, the effects of a larger-scale system

in order to determine whether such, experiments

produce the expected benefits." (Schon, 1965,

p. 34). 3.8 "Transmitting data collection systems

can assume a wide variety of equipment configurations, ranging from a single input unit with

cable-connected recorded to a farflung network

with multiple input units transmitting data to multiple recorders or computers by means of

both common-carrier facilities and direct cable

connections. Probably the most important parameter

in planning the equipment configuration of a system is the maximum number of input stations

that can be connected to a single central recording

unit." (Hillegass and Melick, 1967, pp. 50-51).

3.9 Licklider stresses the importance of "co- herence through networking" and emphasizes: "On

the average, each of n cooperative users can draw

n-1 programs from the files for each one he puts

into the public files. That fact becomes so obviously significant as n increases that I can conclude

by concluding that the most important factors in software economics are n, the number of netted

users, and c, the coefficient of contributive cooperativeness that measures the value to his colleagues

of each user's creative effort." (Licklider, 1967,

p. 13). "The circumstances which appear to call for the

establishment of physical networks (as opposed to logical networks) are generally:

"1. The existence of special data banks or special collections of information located at a 53
single institution but useful to an audience

geographically dispersed.

"2. The inadequacy of general data banks or general collections of information to meet

local needs where remote resources can be

used in a complementary fashion to fulfill the

need.

"3. The centralization of programming services,

processing capabilities or scientific resources

with a geographically dispersed need.

"4. The need for interpersonal (including inter- group) direct communication. This includes

teleconferencing and educational activities. "5. A justification on economic, security or social

grounds for distribution of responsibility

for load sharing among organizations or geo- graphical regions." (Davis, 1968, pp. 1-2). "In certain areas, such as law enforcement,

medicine, social security, and education, there is a need for joint Federal-State computer communications networks which can apply new technology to improving the management of major national pro- grams in these areas." (Johnson, 1967, p. 5). "It has been suggested that a principal advantage

to be gained from computer networks is the ability to distribute work evenly over the available installa- tions or to perform certain computations at installa- tions particularly suited to the nature of the job."

(Dennis, 1968, p. 374).

"The time-sharing computer system can unite a group of investigators in a cooperative search for the solution to a common problem, or it can serve

as a community pool of knowledge and skill on which

anyone can draw according to his needs." (Fano and

Corbato, 1966, p. 129).

"Within a computer network, a user of any

cooperating installation would have access to programs running at other cooperating installations, even though the programs were written in different languages for different computers. This forms the

principal motivation for considering the implementation of a network." (Marill and Roberts, 1966, p. 426).

3.10 "The establishment of a network may lead

to a certain amount of specialization among the

cooperating installations. If a given installation, X,

by reason of special software or hardware, is particularly adept at matrix inversion, for example, one may expect that users at other installations in the network will exploit this capability by inverting

their matrices at X in preference to doing so on

their own computers." (Marill and Roberts, 1966,

p. 426).

"An interconnected network would make it possible for the top specialists in any field to in- struct anyone within the reach of a TV receiver."

(Brown et al, 1967, p. 74). 3.11 "For initial network trials the advantages

of an open system are:

a. ease of programming,

b. services for all users,

c. all operations may be publicized." (Brown

et al., 1967, p. 209).

3.12 "The operator's charges to clients must be

in fair proportion to the usage made of installation resources (processing, time, storage occupancy,

etc.). Therefore adequate records must be kept of resource use." (Dennis, 1968, p. 375).

"A principal [individual or group of individuals]

is charged for resources consumed by computations

running on his behalf. A principal is also charged

for retention in the system of a set of computing

entities called retained objects, which may be

program and data segments . . ." (Dennis and

Van Horn, 1965, p. 8). "The equitable allocation of space and time by

administrative fiat. This is probably an overwhelming problem in a network since the predicting of

communication paths and computing facilities required by any user would be quite unwieldy. . . . "Thus a more elaborate scheme seems to be

necessary — one whose rates are proportional to the value of the service. This would be modified

in a network because the rate for the same kind of service may vary among the installations." (Brown

et al., 1967, p. 212).

"Built-in accounting and analysis of system logs are used to provide a history of system performance

as well as establish a basis for charging users."

(Estrin et al., 1967, p. 645).

3.13 "Questions of technical feasibility and

economic value are not the sole determinants of the

computer utility. The development of the computer

utility may be influenced by norms, or lack of norms,

about the confidentiality of data. At the moment

there do not seem to be any clear standards of

good practice; perhaps there was less need before

technology greatly increased capabilities for handling data." (Jones, 1967, p. 555).

"It should be easy and convenient for a user to allow controlled access to any of his segments, with

different access privileges for different users." (Graham, 1968, p. 367).

3.14 "The designer must decide whether he will provide the high-speed service to all users, to provide the service that the majority request, and

leave the minority to fend for themselves, or to provide the degree of speed needed in each case, but no more. Ideally, he should know the entire

distribution of response time requirements. It is even desirable to know how the arrival of these

queries will be distributed in time throughout the

day. In attempting to meet requirements, he must

consider what is actually being retrieved in any

stated response interval. Does the user want hard

copy or will he be satisfied with citations or index

records? The engineering problems associated with

high-speed retrieval of hard copy from files can be

formidable. If a conversational, or browsing, mode

of search is used in which the searcher uses a succession of queries, do we aim to minimize his

total search time, or only to give him immediate

54
response to each single query?" (Meadow. 1967,

p. 191).

"Precedence is computed as a composite function

of:

1) the ability of the network to accept additional

traffic; 2) the 'importance' of each user and the 'utility' of his traffic; 3) the data rate of each input transmission

medium or the transducer used;

4) the tolerable delay time for delivery of the

traffic." (Baran. 1964, p. v). "Many separate low-data-rate devices time-shared

or concentrated into a single high-data-rate fink permit better averaging, as compared to a few

correspondingly-higher-data-rate users. But, as many of the high-data-rate users 'get in' and 'get out' fast, they have a short holding time. This helps

the averaging process. To be precise in this computation, a better understanding of the number of

users, their use statistics, and the network characteristics appears mandatory.

". . . The mixed requirement that, while we

wish to give priority treatment to the higherprecedence traffic of equal network loading, we

must also satisfy the goal that we preserve a minimum transmission capability for the lower-precedence traffic.' Thus, instead of a blanket rule that

all traffic of a given precedence grade will be trans- mitted before handling the next lower precedence

grade, we choose to use the time ratios of these

precedence categories to act as a preference

weighting factor." (Baran, 1964, pp. 30, 33). "An added complication may be introduced

in the form of a hierarchy of precedence classifications. This can be a very useful feature of the communications system, allowing important messages to avoid delay by by-passing a string of messages of

relatively low urgency. But it adds an extra dimension to the message queue, requiring separate list- ings for each precedence. This system can go beyond

governing of the order of transmission, and can

allow high-priority messages to interrupt others

during their transmission. In such a system,

message switching has an advantage over circuit switching, in that an interrupted message can be

automatically retransmitted as soon as possible,

with no further action by the sender. But the possibility of interruption necessitates that the entire contents of a message be retained in storage

until its last transmission is completed." (Shafritz, 1964, p. N2.3-3).

"The difference between control strength and

priority is that control strength is used for defining

interrupt classes (an interrupt class is the set of all requests with the same control strength),

while priority is used for ordering requests within

the same interrupt class." (Dahm et al., 1967,

p. 774).

3.15 "In real time data communications

oriented problems, four major system equipment

performance factors must be evaluated:

1. Real time processing capability of central

processor(s)

2. Core memory size provided in central proc- essors)

3. Bulk storage size provided

4. Limitations on real time access to bulk

storage." (Birmingham, 1964, p. 38.)

3.16 "It seems imperative that EDUCOM . . . establish certain technical standards and operation procedures which each state or regional group

must meet before they can be interconnected.

These standards should apply to digital trans- mission, telephonic communications, and tele- vision . . ." (Brown et al., 1967, p. 54). "One final thought about integration. Integration

is facilitated by the standardization of equipment,

processes, and languages. However, standardization in command-and-control systems must be

considered in the fight of the evolutionary nature

of these systerns. First, standardization should

be based upon those elements which are missionindependent; that is, the elements standardized

should be general-purpose in nature. Secondly,

the standardization of system elements should

be modular; that is, it should be possible to add

other elements to them in order to modify or increase the capabilities of the system. If system

elements are standardized at too low a level of aggregation, the system's speed of response is increased, but its flexibility is reduced. If, on the

other hand, elements are standardized at the

higher levels of aggregation, provided these are not higher than the level of the designer's problem, flexibility is increased, but there is an accompanying reduction in the system's speed of re- sponse. It is this trade-off between flexibility

and speed of response that makes the standardization problem such a difficult one." (Jacobs, 1964,

pp. 41-42). "In general the standards of distributed-control

systems are standards built around each class of

job for each level of job for each unique function of

the system. Procedures and languages need not be standardized across job levels or across functions.

Minimum standardization does not, however, imply

the complete freedom of each functional unit to select idiosyncratic communication codes or

bizarre formats. Such matters as codes, formats,

file structures, vocabularies, and message syntax

are all aspects of performance programs, and the

library of these program building blocks, from which

any information-processing job can be built, is bounded from above. Executive control over the

limits of the library establishes the boundaries of

the range of alternatives available at any organizational level. This is standardization of a sort, but it allows considerably more flexibility than the standardization generated by a rigid set of specifications

to be applied across functions and up and down the

55
hierarchy of information-processing jobs." (Bennett,

1964, p. 107).

3.17 "A built-in system for user feedback would

be essential in determining near-future needs and

current inadequacies of the network." (Brown et al., 1967, p. 216). "It was considered that it might be useful to have all users of materials feed back their evaluations, which could be analyzed statistically for consideration of the next user." (Brown et al., 1967,

p. 63). "Provisionally 'we characterize a network by: A. Remote and rapid services regarding selection, acquisition, organization, storage, re- trieval, and processing of information and

procedures in current files . . . B. Feedback to the

1. Originator or organizer of the information (hence there would be a Community

of users improving a common store of

materials and procedures).

2. Supervisor of the network services

(hence the system would be adaptive to the needs of the users)." (Brown et al., 1967, pp. 49-50). "In designing a priority handling system, we

should never permit ourselves to believe that we

have more (or less) usable communications capability than we really have. This implies network

status control feedback loops." (Baran, 1964, pp. 17-18).

3.18 "To facilitate system scaling, reliability,

and modularity, many multi-processor operating

systems are designed to treat the processors as homogeneous system resources. Hence, there is no

'supervisor' processor, each schedules and controls

itself. To prevent critical races and inconsistent

results, only one processor at a time is permitted

to alter or examine certain shared system data

bases; all other processors attempting simultaneous

access are locked-out. This phenomenon is not

strictly limited to homogeneous processor systems,

similar requirements apply to any multi-processor

scheme utilizing shared data bases." (Madnick,

1968, p. 19). 3.19 "Some general observations may be of

interest. There are indications that the cost of

operating an information system network, organized

along subject lines, varies little with change of

process allocation within the system. Whether all acquisition and input processes are carried on in a center clearing house or distributed in some logical manner among the service centers does not appear

to make a significant difference in cost. On the other

hand, centralization in the regionally organized

system becomes imperative if excess operating costs are to be avoided. In a system organized to serve

users on a project basis, there is an indication of some economy of operation being achieved by

complete decentralization." (Sayer, 1965, pp. 141-142.)

"The least expensive method of organizing a science information system network appears to be on a regional basis with the centralization of acquisition input processes being undertaken in a central

clearing house." (Sayer, 1965, p. 142.)

3.20 "In the network concept, then, the technical information centers would be finked by the

traffic routing centers. Each would become de- pendent upon the other with both responding to the

law of supply and demand, service and customer

satisfaction, and continued viability based upon

justification of existence through performance."

(Vlannes, 1965, p. 5). "Other choices in the spectrum may include that of a network of information centers in which each

community performs and contributes to the ad- vancement of knowledge in accordance with its capabilities. Of course, a network must impose a

series of constraints in order to operate, but it also allows for the flexibility that a rigidly structured

system cannot accommodate. A network also fosters a sense of competition in which each community

must ever strive to re-orient itself in order to survive

and progress in its changing environment. In

addition, each must become sensitive to the changes

in the other communities in order that it may react,

re-evaluate and adapt to the net set of goals that are inevitable." (Vlannes, 1965, p. 4.) "In order to gain control over the accountability

data, a telephone switchboard was added to the

system . . . With the formalization of the terminal

network, the concept of operation changed from a

central computer with satellite terminals to the

concept of a central terminal network with satellite computers." (O'Sullivan, 1967, p. 169). 3.21 "Many of the larger systems must also take into account the requirements for providing

machine-readable output for use in a decentralized

network of search centers. The designer must

remember that other users will place constraints on

the parent system. It must be remembered that a change to the central system has multiple effects on the various members of the decentralized net- work. Good system documentation will be essential

in providing programs to the local search centers. A

constant training requirement will also be imposed

upon the central system, and technical liaison must

be maintained with all users in the network. Effective file maintenance procedures must be developed

well in advance of implementation of the decentralized system. Changes and updatings to the central

rale will occur frequently, and an adequate mechanism must be available for insuring that these same, changes are made to all files in the field." (Austin,

1966, p. 245).

"Locating the point of minimum sufficient centralization for a system may call for a some

what atypical philosophy of system design, a philosophy not commonly held by theoreticians on the subject but often implicit in the daily design

practices of the engineers and logicians involved

in the actual specification of system details. That

56
is, a system should have standardized procedures

for only the smallest job units that can be formally

specified. These fixed subroutines can then be

combined to form larger routines suitable for performing larger segments of the overall activity.

At any point where two jobs are dissimilar, this dissimilarity can be reflected not only in different flow diagrams but also in different formats, codes,

sequencing procedures, indexing methods, displays,

and so forth. To this extent, the system is neither

tailor-made nor ready-made. It is not uneconomically designed so that every job is unique, nor is

it standard but ill-fitting because dissimilar jobs

are forced into standardization. Rather, like a made-to-measure suit, the system is built around

small standardized parts, each designed to fit a small part of the overall job. The larger portions

of the system are not standardized as total units,

but are unique configurations of standardized

smaller parts." (Bennett, 1964, p. 108).

3.22 Baran (1964) considers, for example,

"four separate techniques that can be used singly

or in combination to achieve, through automation,

'best' use of a seriously degraded and overloaded

communications plant, within the framework

of a rapidly changing organizational structure."

(p. v).

3.23 "Calulation of the average daily volume

and the peak volume of information to be handled

in the system consists of four steps:

1. Calculate the average daily volume of messages presently flowing in the system.

2. Calculate the average number of characters

in each message.

3. Calculate the average daily total transmission

time.

4. Calculate the peak volumes.

The communications designer must plan the

system to handle the peak traffic loads with acceptable delay as well as the total traffic load." (Gentle,

1965, p. 58.)

"Calculate Call Volume. The first step in cal- culating the volume of information that must

be handled by the data communications system is to determine the number of messages (called

'traffic') handled in an average day. This is done

for traffic to and from every point in the system.

The -volume is calculated by taking a sample

of several days' traffic and actually counting

the number of messages handled each day at each location. The number of days to be included

in the study is based upon the estimated number

of messages that are handled in a month. An

estimate of the monthly volume should be made,

and the following table may be used as a guide

in determining the number of days to be studied.

Number of

days to be Estimated monthly message volume studied Under 1000 20

1000 to 2000 .. 10

2000 to 5000 5 5000 to 10,000 3

10,000 and over '. 2

Ideally the working days to be studied should be

chosen at random, but if for any reason a series of

consecutive days must be selected, care should be

taken to avoid days immediately preceding or following holidays. In addition, the count must be

made at each location from which information is sent and at which information is received." (Gentle,

1965, pp. 58-59.)

"Calculate the Total Transmission Time. The

third step, after calculating the average number of

characters per message, is to determine the average

daily total transmission time. At this point a trans- mission speed must be assumed. This transmission

time can be calculated by dividing the average

number of characters per message by the assumed

speed of the system. If the average message has

2,500 characters, for example, and the assumed

transmission speed is 10 characters per second, the

average transmission time per message will be 250

seconds. To this figure, however, must be added some operating time for dialing the call, waiting for the connection to be established and, in some cases, coordinating the forthcoming transaction with the

personnel at the receiving end. Operating time

should be calculated from a study of a sample of

calls, but if this is impracticable, the system

designer may use 100 seconds as an overall average

for the operating time on each dialed-up data

communications call. . . . "The amount of' delay to be expected during the

busy hour depends upon the holding time of the

circuit at the receiving location and the total number of minutes in the busy hour during which

information will be received. Data communication

planners refer to a series of charts which indicate

the expected delay in transmissions when holding

time, circuit use, and number of circuits in the

group are known factors. The number of incoming

circuits affects the probability that a calling part

will receive a busy signal." (Gentle, 1965, pp. 63, 65). "The intervals at which messages are trans- mitted. Are these intervals fixed or random?

What are the peak rates, and at what times of

day will they occur?" (Reagan, 1966, p. 23). "To determine the proper size of a dial system

required, it is necessary to study the company's

busy hour, calculate the average message length,

determine the total number of call seconds in- volved, and then consult the hundred-call-second

(CCS) tables developed for telephone trunk loading.

On the CCS tables is a listing for the number of

trunk lines required for a given loading and grade of

service desired. If you want only one lost (busy)

57
call in every hundred, the tables will show how

many trunk lines are required. If you can tolerate 10 lost calls per hundred, the tables show that you can get by with fewer lines. In this manner,

you choose the grade of service you require to handle your particular data communications

problem." (Birmingham, 1964, p. 37). "Whenever it is necessary to have a large

number of stations communicate among a large

number of potential addresses, it is a practical

necessity to use some form of switching. There

is always a very wide variety of potential groupings

and possible network configurations. The shape

and complexity of the resulting network is very

much dependent upon the economies one wishes

to make in circuit groupings. The choice of these

groupings in turn depends upon the statistics of the expected traffic. If the traffic statistics are known very accurately, large savings in cost of selection of routes and assignment of channels can be realized." (Baran, 1964, p. 15). "Complex data communications systems that terminate many lines in a central facility usually use either a multi-line communications controller

in conjunction with general-purpose computer

or a specialized, stored-program communications

processor. These units are capable of buffering

and controlling simultaneous input/output trans- missions on many different lines. Again, a wide

variety of equipment is now available to perform

these functions. The available devices differ in the number and speed of lines they can ter- minate and in their potential for performing auxiliary or independent data processing. Examples include

the three multi-line communications controllers available for use with the general-purpose IBM

System/360 computers and the Collins Data

Central system, a computer system designed

especially for message switching applications."

(Reagan, 1966, p. 26). "Data rate alone, however, does not provide a complete measure of network loading; some

devices have a short duty cycle, such as one computer sending the contents of its core to a remote computer. While such devices place a heavy peak demand for service, they are highly

intermittent. On the other hand, a pulse-coded

telephone call places a lower peak demand load,

but ties up network capacity for a longer period

and results in heavier average loading. Therefore, we should include an expected message-duration

or holding-time factor in the network-load weighting

table." (Baran, 1964, p. 30). "It is necessary to have some idea of the types

of messages that the system will be handling so that estimates of transmission rate requirements can be

made. This calculation is intimately tied in with the

distribution of terminals from the central computer

system. It may be economically justifiable, even a

necessity, to multiplex several of the terminals

together onto one high-speed line." (Stephenson,

1968, p. 55). "It is vital to have some knowledge of the average

mix of message types and message lengths in the

system." (Stephenson, 1968, p. 55). "The results obtained from the numerical solution

of a model give a precise and comprehensive de- scription of the statistical effects of high traffic. The

value of such precise and extensive data for computer systems may not be obvious, especially since

'worst case' examples and physical reasoning can

establish much of the qualitative behavior of the

system. The two prominent facts which warrant

such analysis are the large scale of most multiconsole systems, and the critical nature of machine

response in their conception. Because multi-console systems are of such large scale, it can be worthwhile economically to thoroughly evaluate proposed

designs, seeking to achieve maximum capacity.

Such design evaluation requires a rather accurate knowledge of the traffic in the various parts of the

system. Because much of the effectiveness of a multi-console system can be rapidly dissipated by

poor response characteristics, an accurate statistical description of response is also needed. The exist- ence of a capability for rapidly solving general

queueing models makes this approach a much

needed alternative to Monte Carlo simulations or experiments in traffic studies." (Fife and Rosenberg,

1964, pp. Hl-6).

3.24 "The unequal and intermittent loading of

net-type channels in present communications results

in inefficient utilization of radio frequencies. If channels were made available to other users during

periods of idleness, more communications could

be handled within a given frequency band. A solu- tion to the problem of frequency congestion can be

found in giving each user access to a group of

channels through a system which selects an idle channel for each call and releases the channel as soon as the call is terminated. Such a system may

be called a random access system, since an idle channel is selected at random from the group each

time a user wishes to place a call. After a channel is selected, a means is needed to direct the call to the

intended group or individual without disturbing users to whom the call is not directed. This process

is called discrete addressing and is applied in the

form of tone signalling to many systems in use today.

The combination of the terms Random Access

Discrete Address describes a class of communication systems employing these principles and is frequently referred to by the acronym, 'RADA'."

(Home et al., 1967, pp. 115-116).

"Adaptive channel communication systems pro- vide efficient bandwidth utilization by allowing time

sharing of a small number of channels by a large

group of users with low duty rates. Unlike fixed

frequency netted systems, where a call to a non- busy subscriber cannot be made if his assigned

frequency is in use by another of the net members,

58
the adaptive system will allow completion of all calls provided the number of simultaneous calls is less than or equal to the number of system channels.

The adaptive system is thus similar to the telephone

system where each user has a private line, but the

number of trunks connecting the lines is less than

the number of lines." (Home et al., 1967, p. 120).

3.25 "In the distributed network routing scheme ... if the preferred path is busy, the in-transit Message Block is not stored, but rather sent out over

a less efficient, but non-busy fink. This rapid passing

around of messages without delay, even if a secon- dary route must be chosen, is called a 'hot-potato'

routing doctrine. . . . "With such a doctrine, only enough storage at each node need be provided to permit retransmitting

messages if an acknowledgement of correct receipt

is not received from the adjacent station within a prescribed time interval. Message storage capacity

is modest. . . . "A dynamically-updated routing table stored at each node indicates the best route for each Message

Block to take to reach its directed end terminal

station . . . When two messages seek the same

preferred fine, a random choice is used to select which message is sent out over the best path . . . Simulation has shown that this use of secondary

paths in lieu of storage is a surprisingly effective

doctrine, enabling transmission of about 30—50 per

cent of the peak theoretical c'apacity possible in a store-and-forward system having infinite storage

and infinite delays." (Baran, 1964, pp. 9, 12).

3.26 "If empirical data were available in the

information field we could use an input-output

matrix. On the input side the various international

and national information services should be in- cluded. Many of these services act also as users of

the input from other services, and they process it for their own purpose. Thus the output side will also contain most of the same services. The content

of the matrix should be information just as an economic matrix will contain employment, goods or

services. The economist expresses his flows in dollar values, since money is the conventional substitute. A convention measuring the information

flow of documents has to be developed." (Tell, 1966,

p. 119).

3.27 "Based upon information taken in these

[Lockheed] studies, it is quite clear that long term

information exchange requirements will include

wide band data and image transmission and that data entry points may ultimately involve more than

10,000 terminals throughout the nation." (Johnson,

1967, p. 7). "The issues of communication in the sense of the

electrical transmission of data have come to the

forefront during 1966. Most computer-system implementers and users are encountering the problems

of communication engineering for the first time.

Many have found disquieting the fact that the ele- ment of system cost arising from the necessary data- communication support of large, multiaccess sys- tems is surprisingly large — often of the same order

as that of the central computer facility." (Mills, 1967,

p. 244).

4. Input-Output, Terminal Design, and Character Sets

4.1 "The display-computer interface is a generalized requirement of all displays and provides

computer buffering for the display system. In addition, some systems may require logic level and/or

word length changes from computer to display.

These operations are also performed by the inter- face." (Mahan, 1968, p. 9). 4.2 Plans for implementation of an experimental

network for the Advanced Research Planning

Agency (ARPA) have been reported as follows: "The ARPA contractors' network is ... in the

planning stage. As one of the nodes of this network,

SDC would receive a small computer (of the PDP-8

class) as an interface message processor (IMP). All other nodes in the network would likewise have a

similar IMP. The IMP would be two-faced: one view

facing the local contractor's time-sharing system;

the other facing other node IMPs. In this fashion,

network protocol would be standardized at the

IMP, while still maintaining the flexibility of per- mitting dissimilar local time-sharing systems to be

included as nodes. An IMP will support up to two

local time-sharing systems, thereby permitting local

networking via the IMP." (System Development

Corp., 1968, p. 1-13).

4.3 "A method must be devised to develop the

storage adress of a record from a key in the record

itself. This is usually referred to as a randomizing

formula. What is implied is an arithmetical operation on a key in the record to develop from this key an

actual storage address for the record. Study is required to ascertain which technique or formula

provides a good file utilization, with the least number

of common addresses for different keys to keep over- flow records down.^ (DeParis, 1 965, pp. 30-31).

"The logical address of a data item defines the

relative position of the item within the structure of

the data base. The logical address is coded so that a unique code may be created for each item in the

data base. The logical code is a numerical repre- sentation of the nodes in the multi-list tree structure

of the data base, and is called the Item Position

Code." (Barnum, 1965, p. 50). "The technique of hash addressing by randomizing the input word was used to generate an address

for the dictionary look-up. This method results in

376-411 O - 70 - 5
the address of the first element of a chain of words in storage, each of which yielded the same random

address. An examination of the chain would pro- ceed in sequence until the word was found or until the last element of the chain was compared."

(Baker and Triest, 1966, p. 3-13).

"Every word encountered in the scan of an input

text, i.e., during the actual operation of ELIZA, is randomized by the same hashing algorithm as was

originally applied to the incoming keywords, hence

yields an integer which points to the only possible

list structure which could potentially contain that word as a keyword." (Weizenbaum, 1966, p. 38). 4.4 "The concept of on-line information control

implies the ability of such users of the system to change the performance of the system to meet their own changing needs or wishes. With adequate control, they can experiment with the display of alter- native data formats or configurations, with alternative

sequences of data retrieval, with alternative

formulae for summarizing, processing, or analyzing

data." (Bennett et al., 1965, p. 436). "Other suggestions indicate the need to reconcile data formats of

considerable variety." (Brown et al., 1967, p. 54). 4.5 "Special provisions (perhaps in the software)

may be required to prevent overlap of symbology,

as might result from adjacent aircraft tracks."

(Israel, 1967, p. 208). 4.6 "Time-shared computers need an accurate,

versatile clock to schedule programs, subroutines

or problems, and to synchronize the computers with

a desired time base. Large computer systems

usually have their own built-in clock, but smaller

units used in a time-sharing mode must be modified

by the addition of an external clock." (Electronics

38, No. 23, 194 (1965). 4.7 The question of color on output is reflected

first in the more conventional documentation or

library situation. Thus it is to be noted that "the use of color in printing is of increasing importance",

but that there are questions of whether copies in color, such as the color film versions of valuable

manuscripts supplied by the Bodleian Library or the French Bibliotheque Nationale (Gunther, 1962,

p. 8), can be preserved over extended periods of

time. (Applebaum, 1965, p. 493). 4.8 "The term 'graphical communication' pre- supposes a graphical language in which pictorial

information is transmitted between the designer and

the computer." (Lang et al., 1965, p. 1). 4.9 "M. Stafford of Westboro, Mass. . . . discussed the ways in which graphic communications systems are currently used, with emphasis

on their interface between computers and infor- mation storage centers. Some examples of their use, he noted, are to send signature samples

and information on accounts between a main

bank and its branches, to send weather maps

and technical drawings across the country, and to send pages of newspaper copy between cities." (LC Info. Bull. 25, App., 288 (1966).)

"[A] CRT display console . . . [should meet

at least] three on-line capability criteria. First,

it is directly tieable to a data processing system.

Second, it has ability to initiate messages or

control signals from a data entry keyboard or switches for transmission to the computer. Finally

it has ability to receive digital messages or control

signals." (Frank, 1965, p. 50). "Desire to display data rapidly . . . places

a premium on the efficiency of the graphical

language used at the display level." (Dertouzos,

1967, p. 203).

"The CAFE system permits definition of, or

selection from, a library of pictorial elements

(static and dynamic), formation of complex pictures

from simpler ones, and parameter control of their

individual display characteristics as well as their

synchronization into a sequence of composite

displays. Once a pictorial element is defined

by the user-editor, it is readily available by reference

to a name supplied at the time of its definition."

(Nolan and Yarbrough, 1968, p. C103).

"High-level methods for expressing scope

output and console input operations have pro- duced a great deal of display programming activity.

The obvious advantages over assembly coding

of clarity, brevity, and fewer mistakes are a strong

incentive for users. The compiler-compiler system

on TX-2 has made relatively easy the implementation and evolution of an extended highlevel language based on ALGOL. The language,

called LEAP (Language for Expressing Associative Procedures) has associative data structuring

operations, reserved procedure forms for display

or input manipulation, and real time variables

such as the clock time and tablet stylus coordinates.

Direct means for invoking the symbol recognizer's

services are even incorporated. A 'Recognize'

statement gets a symbol from the tablet just as

a 'Read' statement gets a symbol from the console

keyboard. Writing interactive programs which use

the display is straightforward, and experimentation

and modification can be rapid.

"Having LEAP available as a programming

tool has facilitated the evolutionary development

of application programs for graphical programming, data analysis, logic diagram input, and

integrated circuit mask layout. The largest effort has been on circuit mask programs. A circuit designer controls the mask layout program with

freehand figures sketched on the Sylvania tablet. The computer recognizes his rough marks as commands to create, move, group, and delete

various integrated circuit components. Once a

circuit design is complete, output tapes for each

of the mask levels required can be punched for

later use by a precision patterns making machine.

Individual variations among designers in drawing

style are accommodated easily by the trainable

recognizer." (Sutherland et al., 1969, p. 632).

"First of all, this language must be concise and

easily learned. It should permit the user to specify

60
the various features of a drawing in the natural

order in which they occur to him and in a continuous

stream rather than in segmented form in separate

statements. For publication purposes, it must give

the user direct and ultimate control of every line drawn if he so desires. Yet, where applicable, the user should be able to cause a particular version of

a whole superstructure to be generated by the sys- tem merely by specifying a few simple options.

Toward this end, the language should include the

facility to construct higher level statements from the

basic language statements. It is envisioned that a

set of such 'user defined' statements could be de- veloped by an experienced programmer for a particular application. Once defined, such statements

could then be used by non-programmers without

knowledge of their genesis. Preferably, the language

should meet the needs of users of widely varying

computer experience. At one end of the scale it should appeal to a user essentially untrained in computer programming for the simple transcription

of drawings from a rough draft. At the other end of

the scale it should satisfy a user desiring to generate

pictures controlled by algorithm at execution time.

Drawing on a conditional basis is particularly attractive for applications such as circuit drawings and

the production of musical scores. Finally, the implementation of this language should readily accom- modate minor changes in syntax dictated by user

experience. In addition, it should be designed to run

easily on a variety of computers, and hopefully on a

variety of terminal CRT systems, such as the

Stromberg Carlson 4060 or the RCA Videocomp."

(Frank, 1968, p. 179).

"For the past five years, hardware has existed

that allows a computer user to enter drawn, printed

or written information directly into a computer as

easily as writing with pencil on paper. The missing

element that would make such devices viable

entities in computer systems has been the appropriate software support. At SDC, we are developing

the necessary programs to allow a user scientist to hand-print, on-line, two-dimensional structures required in the statement and solution of his problem. These programs include an on-line, real-time

character recognition program that is independent of

both position and size of the input; editing programs

that can deal with two-dimensional entities (as

opposed to linear strings); and contextual parsing

programs that re-structure the recognized, edited

input for subsequent processing. This work is being

done within the constraints of the SDC Q-32 TimeSharing System . . . "The editing facilities are simple and straightforward, requiring a minimum of effort on the part

of the user while providing repositioning, erasure, replacement and insertion for such diverse notations

as mathematics and organic chemical structures." (Bernstein and Williams, 1968, p. C84).

4.10 "The display information is stored in a

ring-type list structure, which reflects not only the

order in which parts of the display are to be produced, but also the associations which may exist between parts of the picture. A display routine

within the executive threads its way through this ring structure transmitting the data if finds in the structure to the display generator." (Forgie, 1965,

p. 606). 4.11 "A three dimensional windowing subsystem

is available for the ACT [Adage Graphics Terminal]

in which upper and lower bounds can be placed

(in digital registers) on x, y, and z. The vector generator then blanks whenever the beam goes

beyond one of the bounds, and it also tells the

program which bound was exceeded. This device

finds use in a number of applications including

uncluttering pictures, testing the dimensions and

intersections of solids, and splitting the CRT screen up into rectangles allocated to different pictures,

which can then move beyond the 'edge' without

encroaching upon its neighbor's display space."

(Hagan et al, 1968, p. 753).

4.12 "Early graphics systems, such as the GM

DAC system and Sketchpad, were little better than

automated drafting boards. This statement is not intended in any way to belittle their efforts, but

merely to underline the fact that there was very

little that could be done with a picture once it had

been generated. Certain of Sutherland's illustrations are quite startling in their apparent sophistication,

but generally return to the use of constraints (which were satisfied using least squares fit, which is an energy constraint in engineering). In endeavoring

to ascribe meaning to pictures, later investigators were forced to use data structures in a more

sophisticated manner, and it became obvious that associations should be much more complex than the

original ring structures, etc. The CORAL language,

APL, and AL, the language described by Feldman,

are all outgrowths of the need to ascribe extra associations and meanings to a picture. Many are now

working on this problem but information in technical

literature is relatively sparse. To illustrate the

techniques being developed at the University of

Michigan, and to show the power of the associative

language, a detailed example will now be given."

(Sibley et al, 1968, p. 553).

4.13 Some other examples of experimental

capabilities in this area are as follows: "GRIN

[(GRaphical INput) language] is particularly suit- able for use in problems requiring the extensive

real-time manipulation of graphical information at the console. It takes full advantage of the incremental display structure of the scope . . . Thus,

if a display part is composed only of a sequence

of incremental words, its position on the display

scope can easily be changed by changing only the

initial absolute entry point. Also if a part is repre- sented only incrementally, it can be called up using

the display part subroutine linkage at many places on the scope face. The part has to exist in storage

only once, however." (Ninke, 1965, p. 845).

"The GRIN-2 (GRaphical INteraction) language

is a high-level graphical programming language that 61
permits the generation and manipulation of the

graphical data structure, and provides statements

for controlling real-time man-machine interaction.

The interaction portion of the language is used with

the GRAPHIC-2 graphical terminal. The rest of

the language pertains to the common data structure used by all graphical devices and terminals."

(Christenson and Pinson, 1967, p. 705).

"The PLOT operator is used to create a picture on the oscilloscope corresponding to the graphical

language statements ... It builds a list of 'con- sole commands' (plot a point, or a line, reposition

the beam etc.) known as the display file, which are interpreted by the display console hardware so producing the desired picture." (Lang et al., 1965,

p. 39). "VITAL (Variably Initialized Translator for Algorithmic Langauges), a general purpose translator for the Lincoln Laboratory TX-2 computer,

is currently being adapted for use as a graphical

control language translator." (Roberts, 1966, p. 173).

"The MAD language offers a powerful facility to programmers to tailor their compiler to fit their

application, viz., the MAD operator-definition

facility. Using this part of the MAD compiler, the

programmer (or programming staff) can extend the

compiler by introducing new operators and new

operand mode definitions into the language. In the

formulation of any graphical language, the MAD

operator-definition facility should play a large role. The syntax extensions we are describing in this paper are those which cannot be encompassed

within the operator-definition facility. The list- processing facilities described in the last section

resulted from the examination of the L6 syntax, and

the identification of these elements which were beyond the scope of the operator-definition ability.

The rest we leave for development at the MAD

programming level. "In a similar fashion, we have tried to identify

those elements of graphical language which were beyond the scope of the MAD syntax for their

possible incorporation into the compiler. The one example of a graphic language which encompasses

most of the desirable elements is the LEAP language

of Feldman and Rovner. This language is an ALGOLtype language which includes elements of set operations as well as Feldman's own method of representing graphical relations. LEAP is predicated on a

highly elaborate but efficient method of data storage

involving hash coding, but the details of the implementation do not concern us here. What does con- cern us, however, is the language syntax, insofar as

it is incompatible with a MAD representation."

(Laurance, 1968, p. 392).

"The subject of data structures has received a

great deal of attention in the past few years, especially in relation to computer-aided design. Pro- gramming systems used for creating data structures (sometimes dignified by the name 'graphical lan- guages') vary greatly in the rigidity of their repre- sentation and the types of facilities offered to the

programmer. As an example of a high-level system, we can mention the formal language LEAP, in which the programmer can easily manipulate the

logical elements of his model, and the structuring

of the information (in the form of hash-coded tables)

is performed automatically by the language system.

At the other extreme we have a language like L6

which is a macro language useful in creating

arbitrary list structures. The difference between

these two 'graphical languages' is so great that one

could easily conceive of implementing the LEAP

language using the L6 language. An excellent

review of this subject is given by Gray." (Laurance,

1968, p. 387).

"Only two other compiler-compiler systems

which cater for graphics with Computer Aided

Design in mind are known to the author. The

first of these, AED, due to Douglas T. Ross is a very long-standing and general systen of great

interest. GULP only attempts a small part of this generality; as AED has been justly called 'a system

of systems for building systems'. AED processes

graphic language using a macro-processor in a

different way from the character definition of

GULP. AED is also able to deal with context- dependent languages, and with more general

types of precedence besides including an ALGOLlike compiler and many special-purpose packages

for design; e.g., POLYFACE." (Pankhurst, 1968,

p. 416). "It is of vital importance that the language

facility for the Computer-Aided Design System

include not only flexible descriptive and pro- gramming languages in word form, but a generalized

capability for graphical communication as well. There are many aspects of design in almost any

field, for which the natural means of expression

is in terms of pictures or diagrams, and any attempt

to convey equivalent information in verbal form

would be extremely unnatural and awkward,

and would defeat the basic principle that the

designer-user be able to operate in a manner

which is natural to him." (Ross and Feldman,

1964, p. 15). 4.14 "Even within equipment classes there is a wide variation in keyboard arrangements. Though

the alphanumerics generally correspond, the

availability and location of special characters

is by no means standard. Functional controls are even more varied, and in the case of devices

using complex editing features (the alphanumeric

display device) the number, type, function, and

placement of functional controls is completely

dissimilar between manufacturers." (Auerbach

Corp., SDA, 1967, p. 2-10).

"For the inquiry/display console, the major

problem is that of determining the proper functions

to implement for the user." (Hobbs, 1966, p. 44). "Other operator input devices are available on various consoles. Alphanumeric keyboards

and function keys are used. Some function keys

use plastic overlays for additional coding. Track

62
balls and joy sticks are preferred by some users. The Rand Tablet, which provides an easy method

for graphic input, is available as an accessory

in several systems." (Machover, 1967, p. 158).

"About a half of the available buttons are left unprogrammed, so that every user can tailor the system to his own particular needs by constructing just those operators which are useful

to him at a given moment. A paper overlay is used

to mark the labels under the buttons . . . The

system provides operators which allow each

user to keep his own private programmed pushbuttons and functions in a deck of cards. The

same programmable buttons may then be utilized by different users for completely different purposes

simply by reading in a small deck of cards at the

start and punching out a new deck when someone

else wants to use the system." (Clem, 1966, p. 136).

"Registration ... is important in systems using

multiple display projectors or sources. Display

overlays are a prime example where static information is projected over the dynamic display. It is very important that the images are properly registered with respect to each other. In general,

registration accuracy should meet or exceed the

resolution of the display in order that misregistration

not be detected." (Mahan, 1968, p. 5). ". . . Better determination of the proper functions to mechanize in the display to facilitate the

human interface, including the appropriate human

factors determination of the appropriate trade-offs between manual and automatic functions." (Hobbs,

1966, p. 1882). "In addition to the standard typewriter keyboard,

the CRT set will contain 40 special function keys as well as several cursor control keys. Through the use

of plastic overlays, the meaning and purpose of the

special function keys can be changed when the

sets are used for different application modes."

(Porter and Johnson, 1966, p. 81). "Manual input to the [IBM 2250] display unit is effected by one of three devices — an alphanumeric

keyboard, a program function keyboard and a light

pen . . . The program function keyboard contains

32 keys designed to allow the operator to indicate

program interpretative functions to the computer

by means of a single key depression . . . Any

significance can be ascribed to . . . [the keys]

depending upon the requirements of the operator

and the program." ("IBM System/360", 1965, pp. 298-299).

4.15 "A system is described in this paper for developing graphical problem-oriented languages.

This topic is of great importance in computer-aided

design, but has hitherto received only sketchy

documentation, with few attempts at a comparative

study. Meanwhile displays are beginning to be used

for design, and the results of such a study are badly needed. What has held back experimentation

with computer graphics has been the difficulty of

specifying new graphic techniques using the

available programming languages." (Newman,

1968, p. 47). "The major problem is the development of

sufficiently versatile programming languages di- rected at graphic, interactive devices." (Flynn,

1966, p. 99). "Unlike conventional computer languages,

graphical languages have received little study, and

their formal properties have not been examined in depth. The lack of precise ways to formulate and

represent graphical language fundamentals impedes

the use of graphical techniques in many problem

areas." (Sutherland, 1967, p. 29). 4.16 "The types of phosphors used in current alphanumeric display terminals are of relatively low

persistence. To present a display that is suitable

for viewing and free from annoying flickering, the

display must be continually regenerated. Buffer

storage is provided within the central controller or within each display unit to store data entered locally or received from the remote computer. Logic

circuitry within the controller or display unit utilizes the buffer storage to regenerate the display, usually

30 to 40 times per second." (Reagan, 1967, p. 33). "Continual regeneration of a short persistence

CRT for flicker-free viewing demands high data

transfer rates, or considerable buffer storage; but in return for this outlay comes ready communication

by single photosensor pens and a medium for highly

dynamic displays. However, the attendant costs are

related to regeneration rates established by persist- ence of vision criteria and are disproportionate to the dynamic content of the majority of displays

where static text and diagrams prevail for seconds."

(Rose, 1965, p. 637).

"While the maximum required number of flicker- free lines varies greatly among applications, a vector construction rate of 10 microseconds per

inch for the larger component, plus a memory

access and decode time of not more than three

microseconds per vector, should satisfy the requirements for most applications. A refresh rate of 30

frames per second would display about 2,600 con- nected one-inch lines." (Chase, 1968, p. 26). 4.17 "By modulating the electron beam with

several differential selectable frequencies, one could

'color' or 'classify' various displayed points on the

CRT screen." (Haring, 1965, p. 854).

"The light pen allows good feedback in pointing

since programming can brighten what unit is being

seen, or display only the total unit being seen. The

importance of such feedback cannot be appreciated

until one works with a graphical system." (Ninke,

1965, p. 844). "In addition to selecting point locations by means

of the tracking cross, the light pen can be used in another interesting mode of operation known as the

pick function. After a figure has been drawn by the

operator, or is generated on the basis of computed

data, the operator may desire to select a particular curve, component, line of text, or other distinct element which is a part of the picture. He may do

63
this merely by pointing the light pen at the element

and pressing an 'accept' button. The light pen photomultiplier produces a pulse at the instant the

selected element is painted, which signals the computer. Since the address of the element being

painted is known by the computer, its identification can be used as directed by the program. For

example, the element may be erased, moved,

duplicated, or rotated. By proper programming,

symbols or labels on the screen can be made lightpen sensitive and can be selected by pick function.

This operation may be used to select a single option

from a list or 'menu' of alternatives presented on

the display." (Prince, 1966, p. 1699).

"After investigating several possibilities, we

concentrated on the use of intensification for highlighting parts of a display. For example, the four

boundary lines of a surface may be brightened while

the interior fines are dimmed. This technique of

varying intensification has proven to be an important

piece of feedback to the console user. We call the

preceding example 'static' intensification because

an item remains intensified throughout the current

display. Static intensification can be used meaningfully in other ways, besides highlighting. For example, user attention can be focused on suggested

choices of control words by brightening them, while

dimming the rest of the display. Shading to give a three-dimensional effect is also useful in optimizing

the user's understanding of a display. This tech- nique, however, requires enough intensity levels so

that the transition between them is continuous and

imperceptible . . . "This 'selective disabling' aids the operator in recognizing his displays as a composition of various

sets of items. In addition, he will be less confused

when trying to make a selection. Only a small subset

of items can be selected, even though other information is still displayed. Thus, the selectable items are kept in context with the rest of the display. The

combination of selective disabling and dynamic

intensification provides the means of conveying the

syntax of a graphical language to the console user." (Joyce and Cianciolo, 1967, p. 715).

4.18 "Overlays can be quickly accomplished on

standard maps by reading the maps with the computer-controlled CRT reader and combining them in memory with elements to be displayed. The results can be put out on film." (Fulton, 1963, p. 40). 4.19 Motivational factors obviously include the assurance (or lack of assurance) to the client that he

is in fact effectively online to the processing sys- tem; that he has, in effect, direct access to his own

prior program and data stores and to such other

programs or data as can be shared; and that his own data banks and programs are adequately pro- tected against unauthorized access, piracy, or inadvertent destruction.

"Evaluating the 'cost effectiveness' of graphical

I/O of various types is a particularly difficult task. The literature is noticeably lacking in any reference

to the subject. Given a particular function to implement, such as to reduce a graph to hard copy, to monitor a given equipment or program parameter, or any other straightforward operation, a cost/perform- ance comparison of alternative implementations can be made. However, to assign a widely agreed

upon numerical scale of values to human productivity or 'intellectual enhancement' is difficult, if not impossible." (Wigington, 1966, p. 88). "The art of designing man-machine systems

is still in its infancy. List selection terminals,

by placing the output burden on the data system,

are able to increase the input rate that an untrained

user can achieve. By so doing, terminal operation

is made feasible for a much broader class of users. So far this approach has proved useful in applications in which the vocabulary is limited to several

hundred words. We are just beginning to develop

the automatic formatting procedures that will expedite the design of the next generation of

matrices. The potentials of information systems

that adapt to the user's response patterns are yet

to be realized. To the retriever, this approach

offers the ability to control the quality of the

data at the time that they are entered without, we hope, placing an undue burden on the enterers . . . Although we have been heartened by

our limited successes in facilitating man-machine

communication, we have at the same time been

humbled and challenged by our ignorance of how

a dialogue should be structured, how we should | mold the machine to fit the man. It is perhaps

in this area that the next advances will be made."

(Uber et al., 1968, p. 225).

4.20 "In order for computer-aided design

to achieve its full potential in the coming years,

significant hardware advances are called for in several areas. More natural means for communicating with the computer are desirable. Although

many clever techniques have been developed

for using the light pen, it is still not completely

satisfactory. Also, the need is sometimes expressed

for large, high-resolution 'drawing board' displays."

(Prince, 1966, p. 1706).

"A variety of light pen configurations are avail- able ranging from a simple penholder type to a gun type. Some pens are relatively heavy while

others are lightweight. Some use a very flexible cable and others use a rather stiff cable or coil cord. Aiming circles are provided with some light pens so

that the operator knows where the sensitive area of

i the light pen is pointed. Activating switches

for the light pen include mechanical shutters on the pen, electrical switches on the pen, knee ( switches and foot pedal switches." (Machover, | 1967, p. 158). 4.21 "Another difficulty of the lite pen . . . is that its broad end which contacts the scope

face obliterates that portion of the screen where

the lite pen is acting. One means of overcoming

this difficulty might be to display the points drawn

by the pen to one side of the area actually sensed."

(Loomis, 1960, p. 9).
4.22 "Display maintenance has been provided

by the large computer or by a data channel off the

large computer. The high transfer rates needed for such an organization have dictated that the consoles

be very close, if not physically adjacent, to the supporting computer or channel." (Ninke, 1965, p. 839).

". . . Display maintenance is independent of control computer intervention. Thus, once started

by the control computer, the display continuously

refreshes itself with a direct jump word at the end

of the display picture providing the link back to the

start." (Ninke, 1965, p. 842).

"To avoid flicker and to update picture information, each point of the display must be repeated at least every 1/50 second. Although high-speed

repetition is within the capability of light-deflection

methods, rapid repetitive presentation is unnecessary if the display screen has good persistence."

(Soref and McMahon, 1965, p. 60). "Memory for a vector display file requires about

4K words of storage per user." (Roberts, 1965,

p. 217). 4.23 "Operable flat oscilloscopes have been

constructed and have proved to afford excellent

resolution." (Licklider, 1965, p. 96). 4.24 For example, "the most difficult aspects of

the keyboard to experiment with are the key

pressure required and the reaction and travel of the

keys at the moment the signal is transmitted."

(Boyd, 1965, p. 157).

"The keyboard design would be based on principles of motion study. Each key would be shaped

and positioned for maximum accessibility by the

shortest route, with compensations made for dis- tances traveled, varying strength in different

fingers, and other factors." ("The (R)evolution in Book Composition . . . IV", 1964, p. 69). "The keyboard must be kept fairly small, at least within the span of an operator's hands. In

effect, this does mean a single alphabet keyboard

whose condition is controlled by function buttons."

(Boyd, 1965, p. 157).

". . . Various criteria such as weight of key

depression, key travel, key spacing, layout, and

whether or not you want hard copy." (Boyd, 1965,

p. 153).

"One possible result of this type of analysis could

be a bowl-shaped keyboard, with keys on the sides

and rear banked up from the horizontal . . . This

would enable the fingers to reach outlying keys by

moving in a straight fine, rather than in an arc or in two moves, over and down. Another feature would

be larger keys on the outskirts, to reduce the need

for accuracy in moving fingers long distance."

("The (R)evolution in Book Composition . . . IV",

1964, p. 69.)

"Kroemer (1965) . . . arranged the keys in two

separate but symmetrical groups, one for each hand.

Each group consists of three curved rows of five keys. The form of the curve corresponds to that of

the fingers and the possible movements of the

individual fingers. The two space bars for the

thumbs are curved as well, which enables the

thumbs to strike them from any hand position. The

keyboard position is no longer horizontal since tests disclosed that an angle of 30°-45' to the horizontal

gives the most comfortable position to the hands and

arms." (Van Geffen, 1967, p. 6). Hobbs points out further that "new types of keyboards are being developed that do not involve

mechanically moving parts and that may permit more design freedom from the human factors standpoint. These include pneumatic, optic, and piezoelectric techniques." (Hobbs, 1966, p. 38). 4.25 Mills, in a review of 1966 developments,

concludes that "work directed toward solving this interface problem has appeared to be poorly

focused. Only a few attempts to specify an improved

general-purpose terminal were reported, and even

fewer reports of actual hardware development and

prototype testing were discovered." (Mills, 1967,

p. 245).

Further, "it will require major research and

engineering efforts to implement the several functions with the required degrees of convenience,

legibility, reliability, and economy. Industry has

not devoted as much effort to development of devices and techniques for on-fine man-computer

interaction as it has to development of other classes

of computer hardware and software." (Licklider,

1965, p. 66). 4.26 "Specific to the time-sharing field there is a need for the development of adequate consoles,

especially graphical input-output consoles. There

are conflicting requirements for low cost and for many built-in features that minimize the load on the

central computer. An adequate graphical console

may require built-in hardware equivalent to that required in a fairly sophisticated computer. This is an area in which analogue as well as digital tech- niques may be important. It is an area in which the new component technologies may make significant

contributions." (Rosen, 1968, p. 1447).

"Design efforts are directed towards realizing a console that uses a cathode-ray tube (CRT) display

with approximately 1,800 alphanumeric-character

capacity. The data-communication between central

computer and console will initially be 200 characters

per second with provisions for higher data rates. Several character sets should be possible in addition

to the English alphabet. User communications are entered by means of a typewriter keyboard, and

special function buttons which designate frequently

encountered commands. The user's message is displayed on the CRT prior to the transmission to the time-shared computer, and editing of displayed

commands is possible. As the user's conversation

with the catalog system progresses, certain data

supplied by the computer may be stored locally for future reference, edited as required, and eventually

printed in hard-copy form." (Haring, 1968, p. 37). 4.27 "On the hardware side the picture seems to be much brighter, at least in terms of providing

65
color-display systems of greater color fidelity and

reliability." (Rosa, 1965, p. 413).

4.28 "Color is deemed a necessary feature be- cause it can reduce errors and increase the assimilation of displayed information." (Mahan, 1968, p. 34). 4.29 "To produce a stereographic display

the computer calculates the projected video

images of an object, viewed from two separate

points. The resulting video maps are stored on

separate refresh bands of the rotating memory.

The two output signals are connected to separate

color guns of a color television monitor, thus

creating a superimposed image on the screen. Optical separation is achieved by viewing the

image through color filters. "The display is interactive and can be viewed

by a large group of people at the same time."

(Ophir et al., 1969, abstract, p. 309).

4.30 "Unsolved problems . . . that derive

from the graphic themselves include flicker, ease of use, coupling of programs to do substantive

computations, the language of discourse, and

the desirability of halftone capability." (Swanson,

1967, pp. 38-39).

"Although the display field has progressed

rapidly during the past five years, significant

future progress is still required to provide the

types of displays necessary to achieve the essential

close man-machine interaction at a price that

will permit their widespread use. Several major

needs and problems facing the display field have

been discussed here, including the need for:

(1) better methods of implementing large-screen

displays which can provide dynamic real- time operation with both alphanumeric

and graphical data

(2) flat panel visual transducers for both large- screen and console displays that:

(a) can be addressed digitally

(b) provide storage inherent to the display

panel

(c) are compatible with batch-fabricated

electronics and magnetics

(3) better determination of the proper functions

to mechanize in the display to facilitate the human interface, including the appropriate human factors determination of the

appropriate trade-offs between manual and

automatic functions

(4) more effective software both to facilitate the programming of display functions and to provide for the efficient computer generation

and control of operations such as the rotation

and translation of drawings and the interro- gation of large data bases

(5) lower cost for all categories of displays, but

particularly for low performance remote

display consoles.

Developments or improvements needed in specific

display technologies (e.g., the need for higher

power or ultra-violet lasers) have also been cited."

(Hobbs, 1966, p. 1882). 4.31 "There are . . . areas which I believe de- serve priority attention. The first is the development

of a small, cheap, convenient desk-top terminal

set such as the duffer unit." (Mooers, 1959, p. 38). "Whereas fast time sharing divides the cost

of the computer itself among many users, there is no comparable way to distribute the cost of users' input and output equipment. Therefore the problems

of console design and development are critical. Teletype equipment is inexpensive and reliable,

but the character ensemble is small, and this seems likely to limit the applicability of teletype

seriously. Electric typewriters are more expensive

and less reliable, but they provide a reasonably

large set of characters (enough, for example, to handle ALGOL with only a few two-stroke characters), and they may be adequate for the input and

output requirements of the majority of users. If they are not, then almost surely the next requirement is a drawing board or 'doodle pad' onto which

both the operator and the computer can write and

make graphs and diagrams. These functions are now instrumented with oscilloscopes; what is needed is a less expensive means." (Licklider,

1964, pp. 124-125).

"Displays are good, but, in the generalized form

needed, they tend to be expensive. This means a reduction in physical accessibility, since one does

not put a $50,000 or $100,000 box in every office. Displays which are both low-cost and adequate

do not exist." (Mills, 1966, p. 197).

4.32 "William N. Locke (MIT) reported briefly on INTREX ... an MIT Lab is trying to develop a

better console because the small consoles are not now very satisfactory." (LC Info. Bull. 25,

90 (2/10/66).)

"Effective testing of user interaction with the

augmented catalog requires a remote computer

console optimally suited to the task. Currently

available consoles, however, exhibit serious

shortcomings as regards catalog experimentation.

Impact-printing teletypewriters operating at ten

to fifteen characters per second, for example, are

clearly too slow for rapid scanning of large quantities of bibliographic data. The cathode-ray-tube

(CRT) alphanumeric display terminals now offered

by several manufacturers do allow for more rapid,

quiet display of computer-stored data. However,

they, too, lack features essential to effective user

interaction with the augmented catalog. For

instance, there is generally a lack of flexibility in operating modes, in formats (e.g., no superscripts

and subscripts) and a severe limitation on the size of the character set. On the other hand, the CRT

graphic display terminals that are currently available can be programmed to circumvent these deficiencies

but are very expensive as regards original cost, communications requirements, and utilization of

computer time." (Haring, 1968, pp. 35-36).

66
4.33 "How much is the end user willing to pay

for his terminal? What does he expect for it? What

could he do without? The terminal's requirements

are obviously going to vary with the application

program." (Stotz, 1968, p. 16). "The need for graphical displays at a large number of terminals remote to the utility places a severe

constraint on the allowable cost per display unit."

(Dertouzos, 1967, p. 203).

Typically, the R&D requirement is noted for

". . . lower cost for all categories of displays, but

particularly for low performance remote display

consoles." (Hobbs, 1966, p. 1882).

4.34 "In the multiple-access system environment, point-by-point generation of the display by

the main computer results in the imposition of intolerable loads on the processor. The task of

simply regenerating a fixed picture, involving no new information, can occupy a major part of

processor capacity." (Mills, 1965, p. 239).

"Also, if such high speed consoles are to be used

remotely, local display maintenance is essential. Thus, a picture need be transmitted only once, maybe over low-cost low-speed fines." (Ninke,

1965, p. 840).

"There is an increasing trend toward using small

satellite computers for local servicing of the

immediate demands of the display and the human

operators while communicating with a large timeshared computer for complex computations."

(Wigington, 1966. p. 88). "Many modern computers have a memory configuration which can be used to refresh the display

without interrupting other computations. Where

this is not possible, a buffer memory is available

within a display. Commercial terminals use core memories, delay fines, and drums. With the

availability of low cost, high-speed, general purpose,

digital computers, it becomes feasible to consider

including a digital computer in the CRT graphic

terminal. BR, DEC, and IDI offer terminals in which the digital computer is an integral part of

the display and provides functions of storage,

plus some of the hardware mode control features."

(Machover, 1967, p. 153).

"There is growing awareness that display buffers should, in fact, be small general purpose computers,

which opens up a whole new spectrum of possibilities in properly assigning tasks within the

overall system." (Ward, 1967, p. 49). "The concepts of list processing have proven to be desirable in the manipulation of display data. Second, the hardware and software design of MAGIC . . . provides sufficient local processing

abilities to significantly remove the burden of dis- play data processing from the C.P.U. to which it is to be interfaced." (Rippy et al., 1965, p. 829).

"The display material memory is an Ampex RVQ

core unit with 4096 36-bit words and a 5 microsecond cycle time. This storage capacity represents

about eight large pictures, i.e., those which take

about 1/30-th of a second to display." (Ninke,

1965, p. 841).

"The remote operation of displays is facilitated

if local storage is provided at the display for re- freshing the picture. Thus only changes need be

transmitted from the central computer, and the

data transmission requirements are greatly re- duced. Also, some computing capability can be

placed at the display so that change of scale,

translation, rotation, and other modest computations can be done locally. In this regard, M.I.T. and others are experimenting with satellite computers which can continuously refresh several

displays and perform simple calculations for them,

but which call upon a larger computer for extended

computation." (Prince, 1966, p. 1706).

4.35 "The Control Edit Console consists of

two dark trace storage tubes and associated

equipment for control and operation. The dark

trace storage tube, and its associated equipment,

is a device which will store and display a single

frame of video scan for a relatively long period of

time (up to several days). It has excellent resolution

of up to 500 or more fine pairs per inch . . . Through manual control it is possible to erase and

edit portions of the display. By using two DTS

tubes, it will be possible to duplicate the graphic

portions of the original document on the second

tube. The display on the first tube will, of course,

retain the original document for reference pur- poses. The selective transfer is accomplished by

XY coordinate sliding markers, or by tracing area boundaries with electrostatic or infrared pencil

directly on the screen . . ." (Buck et al., 1961,

p. VI-21).

4.36 "Bunker-Ramo communications devices

lend themselves particularly well to engineering

applications. The results of the computations

requested by the engineer may be displayed in a meaningful format he is accustomed to seeing —

such as a Nyquist plot, or families of plots, for any

number of variables." (Dig. Comp. Newsletter 16,

No. 4, 37 (1964).)

4.37 "No matter what logic is applied to the

management of the data base inside the machine,

the surface appearance of the data base must be

under the user's on-fine control. He should be able

to set up the file display, the object and property

names, the formats of these files, including sequence

and arrangement of data as he desires. He should

be able to generate, store and revise the structure

of his displays, on-line . . ." (Bennett et al., 1965, p. 436).

For these reasons, it is suggested that "display

equipment manufacturers [should] improve and

provide software packages that allow:

a. One, two, or three variable-width column page

formats with justification routines and masking

provisions for inserting graphics.

b. Variable character spacing to improve text density,

67
c. Variable line spacing to allow text with or without superscripting and subscripting, and

d. Utilization of the software packages on additional general purpose digital computer

systems." (Burger, 1964, p. 12). 4.38 For example: "To qualify as standard, a terminal device must operate on-line, use a voice

grade channel, provide a visual display, at a rate taxing the reading and scanning speed of the

proficient user." (DeParis, 1965, p. 49). "A reasonable goal is that the console should

sell for under $15,000, that it should have a cathode

ray tube or something equivalent, that it should

allow for some buffering of information, and that

it should have a flexible and adaptable keyboard

structure and status information display." (Bauer,

1965, p. 23). "Certainly the design of the user's terminal is important; but far too much emphasis seems to have been placed on high style and novelties to the detriment of dependability and economy."

(Adams, 1965, p. 486).

"This terminal equipment should be small. It should be easy to use, since this is to be the main

channel of intercommunication between the

human worker and the machine system. . . . "The terminal equipment should provide a typewriter-style keyboard for input, and it should

have an alpha-numeric printing device for printing

its output. Its output should be printed on paper,

either on a paper sheet or on a paper 'ticker tape'

with a gummed back. Thus the output can be

assembled and edited by scissors and pasting."

(Mooers, 1959, p. 10). "If any of these qualities [good resolution, no

flicker, upper and lower case] are badly deficient,

the reading becomes so difficult that the type of

person required to understand and edit complex

information will refuse to use the display." (Buckland, 1963, p. 179).

"To allow a user, however, to do real-time composing, editing, or other manipulation of graphical

information with a fight pen or other graphical

device, the sum of access time and transmission

delay must be only a few milliseconds." (Ninke,

1965, p. 840).

"It would seem that an automated system, to be completely satisfactory, has to respond within

a few seconds and should present output results

at roughly a normal reading rate." (Drew et al., 1966, p. 6). "The display should have controllable per- sistence . . . and should be free of flicker." (Licklider, 1965, p. 94). "Upper and lower case alphabetics should be

provided; two symbols should be able to be plotted

at the same position on the screen (for underline,

circumflex, etc.); and superscripts and subscripts

should be possible. Both the computer and the user should be able to set Tabs and their settings

should show at a glance." (Stotz, 1968, p. 17).

4.39 "We should like to have: a color dis- play ... if possible, or, if not, a black-on-white

display . . . with at least eight gradations of brightness . . . and a resolution exceeding

400 ... or 200 ... or, at any rate, 100 . . . lines per inch." (Licklider, 1965, p. 94). While eight levels of gray scale may be adequate

for many user-oriented remote terminal inputoutput units (and more is sometimes available), far more is required for sophisticated pictorial

data processing.

Ledley's FIDAC (Film Input to Digital Automatic

Computer) currently provides only eight gray

levels for a 700X500 input spot raster. (Ledley

et al., 1966, p. 79). "Digital Electronics Inc. L-SCAN rapidly converts visual data, such as drawings and objects,

into digital format for computer analysis and

record storage. It uses a vidicon tube pick-up and

records on IBM compatible magnetic tape. The

unit can discriminate 64 shades of gray and has

a field of view divided into 40,000 segments."

(Data Proc. Mag. 7, 50 (Feb. 1965).) "Interest is developing in extensions of the dis- play technique to include color and grey scale.

It seemed likely from the earliest experiments that the use of phosphors inside the cells could be used

in multi-color displays. The later observation of

ultra-violet radiation in the cells led to the idea

that this radiation could excite phosphors deposited on the outside of the outer glass panels, and that the effect should be enhanced if the panels were made of quartz or some other material with good

U V transmission characteristics." (Arora et al., 1967, p. 11). "The practical application of such displays as chromatron photochromic dyes, coupled with such

reproduction means as thermoplastic recording or smoke printing will usher in an era of true electronic

printing in all the flexibility we have come to expect

in printed communication." (Herbert Ohlman,

panel discussion of Markus, 1962, p. 25). Further, "the National Aeronautics and Space

Administration has awarded the Philco Corp.,

two contracts to develop an experimental color

television display system for possible use in the

mission control center of the Manned Spacecraft

Center in Houston." (Electronics 38, No. 18,

40 (1965).)

4.40 "Most experienced users want 'terse' modes of expression to the computer and full, unabbreviated (and fast) responses from the

computer." (Licklider, 1965, p. 182). "It should be possible, in a 'debreviation' mode,

to type 'clr' on the keyboard and have 'The Council on Library Resources, Inc.' appear on the display."

(Licklider, 1965, p. 100).

"Several types of keyboarding shortcuts have

been developed; for example, computer programs

automatically provide italicized and capitalized

characters in chemical names, and the computer

68
also expands useful abbreviations." (Davenport,

1968, p. 37). 4.41 "Each element of the display should be

selectively erasable by the computer program,

and also directly or indirectly by the operator."

(Licklider, 1965, p. 94). 4.42 "DOCUS, developed by Informatics for the multicomputer complex at Rome Air Development Center, provides a display-oriented man- machine system with some built-in data

management functions and a capability to assign

functions to control keys at the display and define an execute compound functions based on earlier defined tasks." (Minker and Sable, 1967, p. 137).

Other examples viewed generally with favor in the literature include the following:

(1) "Placing control functions on the scope face

has two advantages. First, only those controls

which should be present at a particular stage

of a problem are displayed. If a light button

labeled 'MOVE' is one of those present, a user knows that he can move picture parts

around. Similarly, if only light buttons in the form of PNP and NPN transistor symbols

are displayed, a user knows he must select a particular type of transistor at that time.

Thus, in effect, a user is steered through a problem. Second, during most operations

there is only one center of attention, the scope

face, on which a user' need concentrate. This allows faster and smoother work on

a problem." (Ninke, 1965, p. 845).

(2) "STATPAC, a program for scientific data

analysis, allows an experimenter to apply

various statistical operations and mathematical transformations to data simply by

fight-penning a desired operation chosen

from a fist of operations displayed on the

scope." (Baker, 1965, p. 431).

(3) "This [SDC Variable Display] program is intended to assist in the design of tabular

displays. It permits a user to sort, delete,

insert and exchange rows and columns of

information presented in matrix form on a

display console. Actions can be taken by

both light-pen and teletype input." (Schwartz

et al., 1965, p. 30).

(4) "These programs . . . [may lead the operator]

by providing information on the next step,

by informing him which next console steps

are permissible, or by signaling him when

a console step has been initiated which is not permissible." (Bauer, 1965, p. 22).

4.43 "The major limiting factor in further improvement in light-pen speed is in the phosphor

screen itself, which must be of a persistent type in order to reduce display flicker. . . . "We have developed a system to detect the

electron beam causing the screen fight rather than

the fight itself ... [as a] new approach to increasing the speed of the CRT display system for man-machine communication. . . . "From experimental evidence we conclude that

it is possible to make a system to detect when and

where the electron beam of a CRT strikes the screen, thus essentially eliminating the bandwidthlimiting effects of the CRT phosphor and making

a high-speed man-machine communications

system possible." (Haring, 1965, pp. 848, 854).

"Current development work on CRT's is con- centrated heavily in the search for new phosphors

to provide increased brightness and longer fife." (Mahan, 1968, p. 19). "Both electroflors [liquid phase materials that fluoresce or change color when small electric currents are passed] and piezoelectric displays

show promise, but are hardly beyond the feasibility state of development. Current research spending

is not very heavy for these displays so few results are expected in the near future." (Mahan, 1968.

p. 28). 4.44 "The use of analog predictive circuitry

should be explored as a possible means of improving

tracking performance. The simple noise filter in the present experimental circuit serves to provide

velocity prediction in the sense that the voltage on the filter capacitor is the average of past error

voltages. If an error signal should fail to be de- veloped over several cycles, the voltage on this capacitor would provide tracking continuity."

(Stratton, 1966, p. 61). "The merit of the analog technique lies in the

small processing time required to determine the

position of the moving pen. Decreasing the track- ing interval allows more time to be utilized for dis- play—a particularly important consideration when

many consoles share the same display channel."

(Stratton, 1966, p. 58). 4.45 ". . . The computer may be operated in a multisequenced fashion . ... One sequence may

be used to calculate a file of point coordinates for display and a higher priority sequence may be used

to display these points. In this manner, the high

priority display sequence insures that points are displayed as often as possible so that the picture

does not flicker objectionably as a result of the

computation of new points usurping display time."

(Loomis, 1960, p. 2). 4.46 "Research and development work on

several display technologies offer promise for improved real-time large screen displays by the

early 1970's. These include.

Photochromic displays with cathode-ray-tube or

laser image generation

Thermoplastic and photoplastic light valves

with cathode-ray-tube or laser-image generation

Crossed-grid electroluminescent displays with

integrated storage

Laser inscribing systems

Solid-state light valves

Opto-magnetic displays

69
Electro-chemical displays

Injection electroluminescence matrix displays."

(Hobbs, 1966, p. 42). 4.47 "Large-screen displays are used where

it is necessary for a group of people to view the same

information simultaneously. Because of the cost involved in implementing large-screen displays,

their use has been confined largely to military sys- tems. The high cost plus the lack of really adequate

technologies for presenting dynamic information on a large screen have seriously restricted the use

of group displays. Significant technological improvements are necessary to permit satisfactory group

displays at a reasonable price before their utiliza- tion will become widespread in the commercial

world. Most group displays that have been installed

to date involved projection systems of one type or another with the display generated in one device

and then projected onto a screen. However, work

is underway on several technologies that will permit

the generation of the visual image in the screen

itself. Some of these are considered later in the

discussion of display technologies. Most of the

research and development on the visual trans- ducer portion of display systems is devoted to techniques applicable to large-screen displays

because of the lack of suitable means for implementing displays of this type at present. The CRT

enjoys a dominant position in console displays,

but there is no equivalent dominant technology for large-screen displays." (Hobbs, 1966, pp. 1871—

1872).

"While large scale display techniques have ad- vanced considerably in the past few years, there is

still much room for improvement. Their capability

to handle dynamic data needs considerable expansion. Cost which is now high must be lowered and

reliability needs improvements. . . . "Toward this end, considerable research is now

underway to improve existing techniques. New

films which do not need wet chemicals are being ex- plored along with novel methods of processing

conventional films. Considerable effort is under way

to improve the performance of the light valve

technology. Also, new and better techniques are being developed to convert digital data to the analog

form necessary for the exploitation of TV type

devices." (Kesselman, 1967, p. 167).

4.48 "When data phones are used in the communication link, experience with existing display

systems indicates that several data phones are required to handle many user consoles from a

single buffer/controller. Data phones now available

for switched telephone networks provide approximately 2000 bits per second of data, but within the near future this rate may be approximately doubled,

according to information received from the tele- phone company. Since one CRT frame contains

approximately 20,000 bits, at least ten seconds is required to transmit a complete single frame.

Fortunately, the majority of the messages between

the user and the time-shared computer will be on

the order of one line of text requiring only one-third

of a second. However, since a single user might

wish to request up to five frames at a time, a maximum of 50 seconds might be required to serve a

single user. In order to avoid prolonged delays in service to other users who may be awaiting service

at that instant, one 2000-bps data phone must be

dedicated to a small number of consoles, or the

servicing of the consoles must be interlaced, or combinations of these two must be employed. At

the present time, our thinking runs toward use of one data phone for every three consoles, and inter- lacing the service to provide response time of less than 30 seconds under worst-case conditions. Since,

in actual practice, users most frequently will be

sending and receiving much less than a complete

frame and furthermore, since the probability that several users will be communicating data simultaneously is very small, as regards the communications delays, the service would typically be less than a second." (Haring, 1968, pp. 38-39).

"The video buffer contains the necessary elec- tronics for head selection, writing, and sync mixing.

Each head is in a read (or display) mode except

when writing, and a single write driver serves all the heads." (Terlet, 1967, p. 172).

Roberts suggests that "it is possible ... to time-share one vector-curve generator for several

display units if the generator is fast enough to eliminate excessive flicker. Each display then

receives the common deflection signals, but is only intensified when the segments being drawn are intended for that unit. This technique allows the

generator cost to be shared by up to four displays

at present speeds." (1965, p. 217). "In order to reduce the cost of individual consoles,

it is advantageous to cluster consoles around a local station which includes data storage and processing

that is common to all clustered consoles. Initial investigations indicate that it should be possible

to design economical console systems which cluster

about ten consoles at distances of a thousand feet from a local station. Thus, the consoles could be

placed in several different rooms of a single building.

Interconnections between the consoles and the

station are made with coaxial cables, while the

connection between the station and the time-shared

computer utility are made by common carrier. In the

future, a high-speed photographic printer will be

located in the vicinity of the console to produce hard

copy on command from any of the consoles."

(Haring, 1968, p. 258).

4.49 "Human factors, habit patterns, etc., have

to be considered with respect to both operation of

the terminal and designing new procedures."

(Duffy and Timberlake, 1966, p. 273).

"We have planned a survey of man-machine

relationships, both at present and with contemplated

systems, from two points of view: (1) man-machine

relationships from the standpoint of human engineering principles, and (2) the relationships from

70
the standpoint of the attitudes of the people who

will be operating the system." (Sharp and McNulty,

1964, p. 2). "Heretofore not much has been said about the

mechanical design features of the consoles. A great

deal of design effort is being applied to the human

engineering aspects of the consoles since it is imperative that the user's initial contact with the

consoles, the only part of the Intrex experimental

library which the average user sees, be a pleasant

one. The objectives here are to retain sufficient

flexibility in the initial consoles to permit effective user evaluation of various features and options

while at the same time to maintain a finished look

to the consoles." (Haring, 1968, pp. 263-264).

"Human errors and the education of human

beings are, therefore, two systems design factors

which must receive significant attention. The sys- tems designer must understand the chief motivations of the terminal operators. Wherever possible,

he must design into the system factors which will lead to operator satisfaction as a result of successful

operation of a terminal. Operator education, both

at the start and on a continuing basis, must also be

carefully planned. This is particularly true for sys- tems which may expect a significant turn-over in terminal operators within a relatively short period

(e.g., 6 months to a year) after the initial implementation of the system. Operator education must be

recognized as a continuing system function.

Wherever possible, means for providing education

or guidance for operators should be designed into the terminal device or the system as a whole.

"The efficiency of the terminals and the system,

and the degree of intrusion introduced by the system

into the regular jobs or occupations of the terminal

operators, also must be considered. Many people

in the organization will assume a second role as a

result of the information system. In addition to their regular job, they will now also be expected to act as a recorder of data. As a result, human factors

will be extremely important in the design of ter- minal devices. This will insure that the data recording operation is as simple and straightforward as

possible, and requires a minimum effort from the

terminal operator." (Pedler, 1969, p. 30). 4.50 " 'Interface', with its connotation of a mere surface, a plane of separation between the man and the machine, focuses attention on the caps

of the typewriter keys, the screen of the cathode-ray

tube, and the console fight that wink and flicker,

but not on the human operator's repertory of skilled reactions and not on the input-output programs of

the computer. The crucial regions for research and

development seem to lie on both sides of the literal interface." (Licklider, 1965, p. 92). 4.51 "The 'process' keys would be used to

institute queries to specific portions of the auto- mated catalog and to respond to the next steps

suggested by the automated system. At least a 120-character or symbol set would be desirable, in contrast with the 64 characters typically available

now. This means that effort will have to be placed on new or improved and certainly more economical means of character generation." (King, 1963, p. 19). "Several basic hypotheses resulted from the

study program and have been used in the formulation of the initial design concepts. First, it is ad- vantageous to handle many routine operations at the console in order to minimize communication

between the console and the time-shared computer.

This approach reduces the demands on the central

computer and should result in more rapid access

to the central machine when required. It further

reduces the cost of transmitting information from

the time-shared computer to the console, an important consideration in any large operational system.

Second, careful attention should be given to the

size and content of the console alphabet, the ability to produce superscripts and subscripts, and to the

human engineering aspects of the console in order

to ensure favorable user reaction to the console and

to the overall system. Third, it must be possible for the uninitated user to become familiar with the

operation of the console and the catalog system

rapidly and easily. Finally, the design of the console

should be such that it can be economically repro- duced. This feature is a necessary prerequisite to the wide-scale user of computer-based library

systems." (Haring, 1968, pp. 257-258).

4.52 "Careful planning of systems outputs may

permit the complete specification of all files to be

maintained and the input entering such files. Let

us examine input first. The systems designer must

be concerned with content. All needed data to be

printed in reports must first be entered into the

computer. In addition to this substantive data, the

designer must also consider any necessary control

data which must be part of the input to the computer. For example, if the system is to use sophisticated photocomposition equipment with an ex- panded character set, then typographic symbols

must be included in the computer input. For ex- ample, upper and lower case indicators must be

entered, variations in sizes of type to be used on the

composer, indications of which characters are to be

printed in bold face, which are to be printed in

italics, etc. . . . "The character set to be employed in a system

is an obvious important factor in systems design.

The designer must consider how sophisticated a

character set is required. He must decide whether

on the basis of the user's requirements upper and

lower case characters are needed, whether different

sizes of type would be useful in preparing publications, whether the Latin alphabet is adequate or whether Cyrillic characters must be provided. He

must also determine the requirements for special

characters such as diacritical marks required for certain foreign languages or subscripts and superscripts needed for chemical notations." (Austin,

1966, pp. 243-244, 245).

4.53 "In a comprehensive chemical data

processing system there is a real need to input

71
and output conventional molecular or empirical

formulae, various nomenclatures, structure formula

diagrams, and considerable generic information

and data. To accomplish the output function,

the system analyst was, until recently, limited

in his choice of output hardware. This restraint

led to the use of numerous and often cumbersome

coding techniques and printing conventions

which must very often be learned by the chemists

themselves." (Burger, 1964, p. 1). "Examples of elaborate code conventions adopted

for keypunching of text include reports by Nugent

(1959) and by Ray (1962), both of which point out some of the requirements and some of the difficulties encountered with respect to providing a manual

for the keypunching of natural language texts. An even more sophisticated encoding-transliteration

scheme is detailed by Newman, Knowlton and Swanson (1960) as necessary for the keypuching of patent

disclosures in which a very wide variety of boldface,

normal, italic faces and of special symbol insertions

must be provided for. . . . "Flexible selection from amongst a large variety

of available characters and symbols may thus

be provided for, but at the high expense of multiple

initial keystroking, multiple code-sequence processing and redundant storage requirements for each

'actual' character eventually to be reproduced.

For example, with respect to the early Barnett experiments using Photon, it is claimed that the

proportion of control and precedence coding

to actual character-selection identifications could run as high as 75 percent of the total input. While

possibilities for re-design of keyboards and for multiple-output from a single key depression

may alleviate this problem somewhat, the difficulties of precedence coding to achieve larger and more

versatile character sets remain a major problem

area." (Stevens and Little, 1967, p. 75). "As an output device . . . the painfully slow

printing rate [of the teletypewriter] impedes

all but the dullest of men. Its limited symbol

set, and its rigid format for placing characters on a page, makes its display of information very

minimal. Graphs come out as x's on a page, giving

only the coarsest possible feel for the information.

Mathematical expressions must be coded in such a complicated shorthand that only the pro- gram's author can interpret it without a guidebook." (Stotz, 1968, p. 13). 4.54 ". . . Special provision for 64 program

keyboard overlays, each of which, when inserted,

changes both the labels and the functions associated

with the keyboard buttons. A newly inserted overlay

links the buttons with different sets of computer

programs and so completely reorients the use of

the console." (Dig. Comp. Newsletter 16, No. 4,

35-36 (1964).)

4.55 Thus: "The greatest promise for future

development seems to be in increasing input flexi- bility of user terminals . . . We are beginning to

see the use of parallel-key devices, based on the

stenotype principle . . ." (Ohlman, 1963, p. 194). "If a data file is extremely redundant (such as a natural-language text) then the stenotyping technique cuts the number of keystrokes required by as much as two-thirds." (Partick and Black, 1964,

p. 43). "The automatic conversion of stenotyping is being actively pursued with the aim of reducing the

cost of file conversion." (King, 1963, p. 9). ". . . The central problem of keyboard design

is to get a large selection of codes from a limited,

properly spaced, simple-to-operate arrangement of keys." ("The (R)evolution in Book Composition . . . IV," 1964, p. 68). "It may be that we shall have to wait for more

fundamental research to clear the way for a chord

typewriter, played more like a piano." (Duncan,

1966, p. 264). "If it turns out, as seems likely, that very large

ensembles of characters are desirable in man- computer interaction with the body of knowledge,

then it will become much more important that it is now to be able to specify the desired character by

pressing a pattern of keys on a small keyboard. That

is a much better solution than pressing a single key

on a keyboard with several thousand keys." (Licklider, 1965, p. 100).

4.56 The case of chemical information is even more demanding: "It is difficult to devise an

algorithm that allows the sorting process to ignore

characters that should be ignored in traditional

alphabetization of chemicals. For instance, 1,3- dimethyl is alphabetized under M, dimethylaminopropyl under D, and l,3-bis(dimethylaminopropyl)

under B. Using a flexible listing order that can be

specified for the index solves the ordering problem

in this system; editorial work is, of course, a con- sequence. The advantage of flexibility in the face

of a difficult problem was considered sufficient justification for this effort." (Tinker, 1968, p. 324).

4.57 Problems of character-set repertoire are

particularly acute in the areas of primary publication

of scientific and technical texts, bibliographies

(e.g., in the Besterman World Bibliography of

Bibliographies, 1950 different pieces of Monotype

characters were used) (Shaw, 1962, p. 268) and in library card catalogs.

Ohringer comments: "There will be many

formulas and special mathematical symbols inter- spersed with the text. The type fonts used tend to vary greatly, including many Greek letters in addition to many styles and sizes of Roman alphabet.

The page arrangement also contains too much

variation for present-day optical character readers."

(1964, p. 311).

4.58 "A character set for instruction must often

include a far larger number of characters and

symbols than is needed for other applications. For

example, teaching a foreign language may require

that two different alphabets be displayed at once.

In mathematics, a display must often include ex- 72
ponents. subscripts, and fraction lines, as well as alphanumeric characters and mathematical

symbols.*' (Terlet, 1967, pp. 169-170).

"'Primarily because of the complex chemical

names, chemical information pubhshing demands

the use of the Roman and Greek alphabets, upper

and lower case letters, several type fonts (italics, boldface, small capital letters), and superior and

inferior positions. In all, nearly 1500 symbols are used in CA issues." (Davenport, 1968, p. 37). 4.59 "The data contained in the augmented

catalog are basically alphanumeric. Of particular

consequence to both the display console design and

the entire computer-based library is the large

number of alphanumeric symbols that is required.

The set of 128 USASCII standard symbols is in- sufficient, and thus must be augmented. Further- more, provisions for superscripts, subscripts and

underlines must be included to properly display to users in forms with which they are familiar such

items as chemical formulas and mathematical

equations." (Haring, 1968. p. 36). 4.60 "Filing rules pose a particularly complex

problem to the designer of an information system.

Unfortunately, the machine has not been built which will sort according to such filing rules as those laid down by the American Library Association. The system designer must choose between

an attempt to program these rules into the computer

or to employ special control codes on input to per- mit the citations to be sorted according to the fifing rules rather than the normal collating sequence of

the computer." (Austin. 1966, p. 244). 4.61 "The earlier work of Opler and Baird in drawing chemical structure diagrams on a computer

controlled CRT gave much promise for the future

applicability of such devices. . . . "Use of 2-case print mechanisms on high-speed

computer printers for the display of extended chemical character sets has been under joint development

by IBM and Chemical Abstracts . . ." (Burger.

1964, p. 2). "The use of photocomposition equipment to reproduce structural chemical formulas from coded

tape is of special interest in the publication of the

output of chemists and chemical engineers, but the

proposed work would have application to almost

all other branches of science where publication of material requiring spatial delineation is necessary."

(Kuney, 1963, p. 249).

"Using as a starting point the characters developed by workers at American Cyanamid for the

typing of chemical structures, we proposed a font of 50 lines and angles with which we could construct

the needed bonds and rings.

"Machine setting of chemical structures was

suggested as one of the potentials of the photocomposition work we started in 1958. The development of the chemical typewriter by Jacobus and

Feldman at Walter Reed and computerized typesetting techniques by Barnett and others stimulated

the development of a test matrix disc for the

Photon." (Kuney and Lazorchak, 1964, p. 303).

"With the cooperation of the workers at Walter

Reed, we are planning to encode structures using

the Army chemical typewriter and process this input via computer to get a tape which will operate

the Photon for the setting of chemical structures." (Kuney and Lazorchak. 1964, p. 305).

4.62 "The ultimate challenge to calligraphy for computers is the imitation of brush strokes in Chinese and Japanese characters. An investigation

has been made to determine the feasibility of

digit alization of the Japanese characters. The

results . . . have been used for the preparation of an abstract of a Naval Weapons Laboratory report

in Japanese as well as in French and German."

(Hershey, 1967, p. 15). 4.63 "An application of the GDP, dubbed

'Type-A-Circuit', has been developed by L. Mailloux

and his colleagues. A contrived alphabet or char- acter set may be assembled into a pattern to create

a mask for printed circuit etching. Horizontal,

vertical, and diagonal segments, bends, mounting

pads, and sockets or transistors and several types

of integrated circuits have been made a part of this character set . . . "The processing program also contains plugboard prongs which are superimposed over the

image generated by the Type-A-Circuit specifications. In use, the designer prepares the string of

'letters' which specify the elements of the Type-ACircuit character set in juxtaposition with one

another, thus forming leads, bends, pads, and

sockets. This specification is prepared with the

aid of a rough sketch drawn on a specially prepared

form. The graphical output consists of a finished

negative which may be used directly for photoetching of a copper clad board. The time required

to prepare artwork for etched circuit boards has

been greatly reduced with the Type-A-Circuit

system." (Potter and Axelrod, 1968, p. 4).

5. Programming Problems and Languages and Processor Design Considerations

5.1 "The most important need is for a design

philosophy that aims at the design of total information processing systems, and that will eliminate

the mostly artificial distinction between hardware

systems and software systems. We need a continuing development of the trend toward combined hardware-software programming." (Rosen.

1968, p. 1446).

"Since, ultimately, the only computer system

of any significance to the outside world is the

system composed of hardware plus software, one cannot claim to have truly designed a computer
system without having designed both . . . 'Inte- grated Hardware/Software Design' requires

not only a knowledge of hardware design and

program design, but a thorough understanding

of the total relationships between hardware and

software in a working system. Effective hardware/

software design means consideration of the many

potential tradeoffs between capability resident

in the machine configuration and capability resident

in the supporting software." (Constantine, 1968,

p. 50). 5.2 For example, at the [ACM-SUNY Conf.], "Dr. McCann talked about the need for 'Language

Escalation'" (Commun. ACM 9, 645 (1966)),

while Perlis (1965), Clippinger (1965), and Burkhardt (1965), among others, discuss the general

problems of hierarchies of language.

5.3 "Very large programs, roughly defined, are those that (1) demand many times the available

primary storage for retention of code and immanent data, and (2) are sufficiently complex

structurally to require more than ten coders

for implementation." (Steel, 1965, p. 231).

"For the hypothetical air traffic control system

used as an example, approximately forty volumes

of several hundred pages each would be necessary

to specify the program subsystems fully. In addition

to detailing the many functions that must be

performed by the several programs, limits on

environmental behavior and transfer functions

between the environment and the communication

network must be described . . . The amount

of interrelated, precise and not easily obtainable

data required is staggering." (Steel, 1965, p. 233).

"The point upon which the mind should focus in the foregoing description of current large-scale

programming procedures is that many people work

a long time to prepare a computer to do quickly

what it would take many people a long time to do. The number of people involved in a large programming task is very great, and the time it takes to prepare the program successfully is very long. For

example, the programming of the entire Semi-Automatic Ground Environment system took roughly a thousand man-years, and the average output for the entire staff was between one and ten 'debugged'

and final machine instructions per day. Despite the

fact that almost any programmer can write a valid

subroutine of ten instructions in ten minutes, the

figure for the Semi-Automatic Ground Environment

system does not indicate that anyone was lazy or

inept. It represents the extreme difficulty of very- large-scale programming and the essential incoher- ence, insofar as complex and highly interactive

procedures are concerned, of large, hierarchical

staffs of people." (Licklider, 1964, p. 121).

5.4 How can very large, very complex, problems

be effectively segmented for programmer attack?

"For the practical application of programming

languages to large problems, efficient segmentation

features are desirable so that parts of problems can

be handled independently." (Burkhardt, 1965, p. 5). "Automatic segmenting of code is a critical and

difficult problem. To be efficient, a program should

not loop from segment to segment and further, all code not normally executed should be separate

from the main flow of the program. Since program

segments will be retrieved on demand, this reduces

the program accesses." (Perry, 1965, p. 247).

"Since running programs will have access to only

a portion of the memory, frequent 'page turning' will be necessary as the program goes through its major

operating pieces. Segmenting of the program can

be very difficult if it must be done manually by the

programmer. Assemblers or compilers with auto- matic segmentation or semi-automatic segmentation

are needed." (Bauer, 1965, p. 23). 5.5 "We must now master, organize, systematize

and document a whole new body of technical experience—that pertaining to programming systems."

(Brooks, 1965, p. 88). "When a programmer is asked to change a record

format, for example, in an unfamiliar program, or when a systems analyst must estimate the time

required for such a change, difficulties may arise which are out of proportion to the routine nature of

the problem . . . "Inadequate documentation may be regarded as one of the most serious problems confronting computer users." (Fisher, 1966, p. 26). "One major concern is the program library. There

are many needs here. One is an indexing system to permit users to retrieve a program from among the

many. Another is adequate documentation of library

programs. Documentation must specify what the

program will do and under what conditions. Still another need is a linking mechanism: That is, a means for passing data from one library program to another without manual intervention so that

library programs can become segments of composite, larger programs. These requirements make

it difficult today to provide a convenient library of

computer processes even in a single computer, not

to mention the problems raised by machine-tomachine incompatibility. Today it is difficult to stand on the shoulders of previous programmers."

(David, 1966, p. 2). "The importance of a library to provide a repository for programs was recognized early, but full exploitation has been impeded by poor program

documentation, lack of interest on the part of pro- grammers, and language problems. Many program

libraries now consist of programs in languages either

dead or destined for an early demise. Limitations

result from the dearth of program 'readers' and the

serious practical difficulties in translation between

machine languages." (Barton, 1963, p. 170). 5.6 "One of the most significant elements in the

orderly, rapid assimilation of multiaccess system

technology is adequate and appropriate documentation. 'Appropriate' is the operative word here, since

the historical norms for system and program docu74
mentation are probably inappropriate for the future. The time is rapidly approaching when 'professional'

programmers will be among the least numerous and

least significant system users." (Mills, 1967, p. 227).

5.7 "However, there is another means of reducing programming cost — making use of program

development already done by others. At present this

is difficult to do because of poor documentation and

maintenance of programs by their authors. The

primary reason for this sad state of affairs is the

absence of any clear incentive for program authors

to provide good documentation and to tailor their

programs to the demands of prospective users

rather than their own private whims." (Dennis,

1968. p. 376).

5.8 "The importance of documentation in the

management of large programming developments

is generally accepted. A number of groups have

found a formal system of documentation the

most effective management tool at their disposal. In its most advanced implementation, such a system of documentation is on-line to a time

sharing system available to all participating members of the system programming project.

"Difficulties often are related to the programmer's resistance to documentation which may

be due to several reasons: • Lack of tangible evidence of benefit to his own activity. • The inaccessibility of his colleagues' documentation because of sheer quantity, lack

of organization and common format and out

of date status. • Rejection of standards, imposed for reasons he does not appreciate. • Belief (often confirmed) that he can get

along without, and in fact feel at his creative

'best' when free to improvise.

"Putting a documentation system on-line appears

to have overcome this resistance in a manner

acceptable to the programmer. • The system itself can help him by rejecting

certain types of inconsistencies. • He has instant access to the latest version

of his colleagues' work. • Standards have been translated into for- matting conventions with which he is familiar. • He understands that the system must safe- guard itself and his programs from unauthorized change. Thus, he more readily accepts

the need for authorization to change and

implement." (Kay, 1969, p. 431)..

5.9 "The greatest difficulty in programming

still concerns the language to be used and the

fact that any given program is relatively non- interchangeable on another machine unless it has been rather wastefully written in, say ALGOL

or FORTRAN." (Duncan, 1967, p. x). Machine language translation programs are therefore of interest, since they allow programs written for

one machine to be run on another and they provide

a bootstrap for changeovers from one equipment

system to another. Examples of such programs

are Control Data's computer-aided translation

system to transfer 7090 programs into their own

3600 Compass language (Wilson and Moss, 1965)

and a system developed to reprogram Philco

2000 codes into IBM 7094 language (Olsen, 1965).

5.10 For example, "Any software system would

become increasingly useful if it could be adapted

to a variety of I/O configurations." (Salton, 1966,

p. 209). "If the performance of input/output functions

requires specialized coding in the master control

program of a system, then altering the set of peripherals or changing its i\o functions requires modifications of the master control programs, leading to the . . . problem of coping with evolution."

(Dennis and Glaser, 1965, p. 9). "If systems design can be automated, i.e., programmed for a computer, ultimately the configuration can be selected by systematically designing the systems for a variety of configurations and

selecting the configuration which will run these

applications at lowest cost." (Greenberger, 1965,

p. 278). 5.11 "Several apparently mutually exclusive

features of programming languages all have their advantages . . . How are we to resolve these

issues?" (Raphael, 1966, p. 71). 5.12 "Walter F. Bauer, president of Informatics

Incorporated, . . . predicted that in ten years all computer systems will be online systems and that 90 percent of all work on computers will involve

online interaction." (Commun. ACM 9, No. 8, 645

(Aug. 1966).)

5.13 "Multiprogramming: That operation of a

(serial) processor which permits the execution of a number of programs in such a way that none of the

programs need be completed before another is started or continued." (Collila, 1966, p. 51.)

"A subfield of multiprogramming is concerned

with the problems of computer system organization

which arise specifically because of the multiplicity

of input-output devices which interface with the

system. The problems in this area are referred to as problems of multiaccessing." (Wegner, 1967, p. 135.)

"The requirements for console languages will pose a formidable problem for facility designers of

the future." (Wagner and Granholm, 1965, p. 287).

"The whole system is multi-programmed, there

being a number of object programs in core at once. Undoubtedly, we shall see such systems in operation

and undoubtedly they will work. In the present state of knowledge, however, the construction of a supervisor for such a system is an immense task, and

when constructed it has severe run-time overheads."

(Wilkes and Needham, 1968, p. 315).

5.14 Brooks says further, "the new systems con- cepts of today and tomorrow are most keenly

programming systems concepts: efficient time-sharing, fail-softly multiprocessing, effective mass

376-411 O - 70 - 6
information retrieval, algorithms for storage allocation, nationwide real-time Teleprocessing systems."

(1965, p. 90). 5.15 "Most individuals accustomed to scientific computation or commercial data processing fail to appreciate the magnitude of the programming effort required for real-time control system implementation." (Steel, 1965, p. 231). "Dr. Saul Rosen of Purdue University mentioned several fallacies of current time-sharing

systems of which the most important is the belief

that manufacturers who have great difficulty pro- ducing relatively simple software systems will somehow be better able to produce the very complex systems required for time sharing." (Commun.

ACM 9, No. 8, 645 (Aug. 1966).)

5.16 "Typical functions of such executive sys- tems include: priority scheduling, interrupt handling, error recovery, communications switching

and the important and relevant area of cataloging,

accessing and manipulating information and pro- gram files." (Weissman, 1967, p. 30). 5.17 "Today's fastest machine cannot be loaded

down and will be idle most of the time unless it is coupled to a large number of high speed channels

and peripheral units ... In order to distribute

input-output requests in a balanced flow, it must

also be controlled by a complex monitor that chooses

wisely among the jobs in its job queue." (Clippinger,

1965, p. 207). "In some systems, more than one single program

is processed with simultaneity . . . Inefficiency

often results because the mix of individual pro- grams, each written for sole occupancy of a computer, is unlikely to demand equal loading of each

parallel element." (Opler, 1965, p. 306).

"System overhead includes scheduling and the

continuous processing of console input. These

functions are almost uniformly distributed, degrading the processor's execution rate by almost a constant." (Scherr, 1965, p. 14). "The executive is usually multipurpose. It must

be designed with a balance between the conflicting

requirements of (1) continuous flow or batch processing, and (2) control for a demand processor in case

time-sharing consoles should be attached. In addition, it usually has facilities for on-line control — in particular for communications switching." (Wagner

and Granholm, 1965, p. 287).

"The utility programs provide three basic functions: the movement of data within the system

required by time sharing or pooled procedure, the

controlling of the printout of information on a pooled

basis, and the controlling of accesses to auxiliary

memory." (Bauer, 1965, p. 22). "From the system designers' point of view, in time-sharing systems the most important thing is the supervisory program. Gallenson & Weissman

pursue this subject in considerable detail and highlight other features such as 'memory protection,

error checking circuitry for hardware, software and

operator error checks, an interrupt system . . . reli- able logical modules [and] dynamic relocation

mechanism' as being essential for time-sharing."

(Davis, 1966, p. 225).

"From a programmer's point of view, one of the

most important features of the second generation

of computers is the way it is possible to exploit

their automatic interruption facilities to provide

control programs and operating systems. A typical I computer will have stored in it, more or less per- manently, a control program (which may be called

the 'Director', 'Master', 'Supervisor', 'Executive',

etc.) whose functions are usually to arrange the

loading and unloading of independent 'object' pro- grams (the programs which actually do the work)

and keep a record of the sequence of jobs they

perform, to allocate input-output devices to these

programs, and to enable the computer's operators

to exercise the necessary control over its operation.

It may also provide facilities for performing various

kinds of input-output operation. The control

program may be able to arrange for several object

programs to be stored in the computer at once, and

to 'time-share' the use of the instruction-sequencing

unit of the computer between all these programs. . . . "The relationship between a control program

and the object programs it controls in many ways

resembles that between a deity and mere mortals —

the analogy extends to the permanence, privileges,

independence and 'infallability' of control programs.

Perhaps because of this, a misconception seems

to have grown up about the extent of their activities. Although in a computer equipped with one instruction-sequencing unit the control program only

'comes to life' following an interruption of the

object program, and effectively expires when the

latter is resumed, it seems to be half-believed

that, all the time the object program is active,

the control program is leading some kind of independent existence; like an all-seeing presence,

keeping a close watch on all the activities of the

object program. This myth probably springs

from experience of the behaviour of the control

program when the object program is caught obeying

an illegal instruction: but in fact this occurrence

is detected by hardware, not by the control program \ itself." (Wetherfield, 1966, p. 161).

"Built-in accounting and analysis of system

logs are used to provide a history of system per- formance as well as establish a basis for charging

users." (Estrin et al., 1967, p. 645).

5.18 "A very significant development in soft- ware and one which must be given serious attention

by the facility system designer, is the relatively new concept of Data Base Management." (Wagner

and Granholm, 1965, p. 287).

"The layout and structuring of files to facilitate the efficient use of a common data base for a wide range of purposes requires careful analyses

of the applications, the devices which store the

files, and the file organization and processing.

The criteria for efficiency are, as usual, maximum

76
throughput and minimum requirement for storage

space. Ease of programming, program size, and

running time are also important considerations."

(Bonn, 1966, p. 1866).

"The most widespread information retrieval systems are those for data base file management,

which process records organized into fields, each

containing a type of data in the record." (Hayes,

1968, p. 23). "Data Management Problems. It is interesting

to review a few of the problems raised by G. H. Dobbs at the summary session of the first symposium on data management systems mentioned

above. One of these was the diverse terminology

and points of view, which make it difficult to extract any basic principles. Another was lack of concern

to input quality control. Still another was lack of

appreciation for the real-life data base problems

as the user sees them. At the second symposium,

two years later, Galentine described the relative lack of progress as 'apalling.' Dobbs, at this sec- ond session, identified several specific technical

areas needing further development — among these,

the ability to allow an unsophisticated user to describe data structures, capability to change data

and file organization, ability to share files among

simultaneous users with adequate file security

'lockout' procedures, and the need for more flexible report formatting." (Climerrson, 1966, p. 128). 5.19 One example of a developmental system

claiming to incorporate these features is the Catalog

Input/Output System at RAND Corporation. More

specifically: "Computer applications in linguistics,

library science, and social science are creating a need for very large, intricately structured, and in some cases tentatively organized files of data. The

catalog — a generalized format for data structures —

is designed to meet that need . . . The computer

programs will:

a) Facilitate partitioning, rearranging, and converting data from any source in preparation

for writing the catalog.

b) Format and convert data for printing on one

of a variety of printers.

c) Sort the data elements within a catalog and

merge data from two or more separate catalogs.

d) Restructure a file by rearranging the order

of classes of data — catalog transformations.

e) Address nodes in the structure, retrieve data

from the structure, and add to or delete from

the structure — file maintenance." (Kay et al., 1966, pp. 1-2).

5.20 "In recent years there has been a rapid

growth in the use of so-called 'formatted file sys- tems'. These systems are general-purpose data

storage, maintenance and retrieval systems de- signed to provide the user with a maximum amount

of flexibility. They feature the use of a single set of

programs to handle a variety of demands on a group

of large files. Each file may possess a different

format, but all records within a file must be identical

in format. New files may be created or old files changed to meet new requirements. Data can be

added to files, or changes can be made to correct

errors in existing files." (Baker and Triest, 1966,

p. 5-1).

"The Formatted File System (FFS) developed for the Defense Intelligence Agency is a generalpurpose data management system for the IBM 1410

which is coupled to the 1410/7010 Operating Sys- tem. It is oriented to a set of users (technicians) who

can maintain an intimate knowledge of the structure

of their files and the query language to access them.

It employs both tapes and disc to define, maintain,

and query a set of independent files. A table of contents and cross index can be defined and maintained on tape or disc. An FFS file must have a unique key field group in each record. A single level of embedded files (periodic sets) is permitted in the

record. Except for the last field of a record, all fields are fixed in length. The query language permits

general logical conditions and relations and provides

several geographical and statistical operators. FFS is one of the few general-purpose data management

systems which are operational." (Minker and Sable,

1967, p. 148).

"The users of non-numeric systems had requirements for very long alphanumeric records. Some

of the records were formatted as were unit records

but the fields were not all of predetermined length.

To cope with this, the formatted file concept was

developed. It had the ability to handle records of

variable length by referring to a data definition which described the permissible record contents,

context, and internal structure. The data definition

could be carried within each record but was more

normally separated into a data definition table to eliminate redundant entries. The formatted file could handle variable length records but could not

interpret completely free form text. Special techniques were developed to handle free text which, in general, relied on the usual delimiters in the text, such as periods and commas, to identify the end of

each structural unit. Free text then could be

interpreted by scanning it as though the computer

were reading it from left to right." (Aron, 1968, p. 7). 5.21 "Univac's B—O or Flow-Matic, which was

running in 1956, was probably the first true Data- Processing compiler. It introduced the idea of

file descriptions, consisting of detailed record and

item descriptions, separate from the description of

program procedures. It also introduced the idea of

using the English language as a programming

language." (Rosen, 1964, p. 8). 5.22 "General Electric has announced GECOS

III (General Comprehensive Operating Supervisor

III), an advanced operating system for large-scale

computers. GECOS III integrates requirements for on-line batch, remote batch, and time-sharing into one system using a common data base. The 'heart' of the GECOS III is a centralized file system of

hierarchical, tree-structured design which provides
multiprocessor access to a common data base, full

file protection, and access control." (Commun.

ACM 11, 71 (Jan. 1968).)

5.23 "The Integrated Data Store (IDS), developed by Bachman of the General Electric Company,

is a data processing programming system that relies on linkage of all types for its retrieval and mainte- nance strategies. Through extensions to the COBOL

language and compiler, IDS permits the programmer

to use mass random-access storage as an extension

of memory." (Minker and Sable, 1967, p. 126).

"The IDS file structure allows a linked-list structure in which the last item on every list

is linked back to the parent item that started the

list. Thus, it is possible to return to the parent

item without a recursive list of return points. In IDS, each record is an element in a finked

list. A file of records may be subordinated to a master record by linking it to the first member

of the subordinate file and chaining from that

point, through each record in the subordinate

file, through the last one, and back to the master

record. There is no inherent limit in IDS to the

number of records that may exist in a chain or

to the number of detailed chains that may be

linked to a given record with a single master

record. There is also no inherent limit to the

depth of nesting that is permitted; i.e., a record

in a chain that is subordinate to a given record

may, in turn, have subordinate record chains."

(Minker and Sable, 1967, pp. 126-127).

"The G.E. Integrated Data Store is an example

of a linked file organization. Master and detail items are organized in a series of linked chains

to form records. Each chain at least one master

item and one or more detail items. Each item

contains linking or chaining information which

contains the addresses of the next item and the

previous item in the chain. An item may belong

to several chains, and linking information to

all chains is included in the record." (Bonn, 1966,

p. 1867).

5.24 "Franks describes the SDC Time-Shared

Data Management System (TDMS), whose design

draws upon ADAM and the earlier LUCID. TDMS

employs an interesting data structure involving

only a single appearance of each item of data

with appropriately organized pointers to represent

order, multiple instances, etc. This is a muchdiscussed idea that has needed exploration in a large system. TDMS, like too many similar

systems, lacks means by which the system can

'learn' frequently traversed paths through the

data, a mechanism that would permit subsequent

identical or similar searches to be handled more

efficiently." (Mills, 1967, p. 240).

"Williams & Bartram have developed a report

generator as part of the TDMS. The object of

this program is to give a nonprogrammer the

ability, while he is on-line with the system, to access a large file of data for the purpose of describing and generating a report. Another work

in this area is by Roberts." (Minker and Sable,

1967, p. 137).

"The file organization of TDMS is an inverted

tree structure with self-defining entries. This

organization has made it possible for TDMS to meet its goal of providing rapid responses to unpredictable queries in a time-shared environment. Although this organization requires more

on-line, random-access storage than most other

file organizations, the benefits obtained far out- weigh this storage cost." (Bleier and Vorhaus,

1968, p. F97).

5.25 "IBM has developed a Generalized Infor- mation System based on experience gained with

military file applications. Because of IBM's intention

to provide this system as part of its applications

library for the System/360 series, this system un- doubtedly will be examined quite closely by a variety

of potential users. The system has two basic

modules: one for defining, maintaining, and retriev- ing files of 'formatted' data, and one for text processing and concordance-type retrieval." (Climenson,

1966, p. 126).

"The text-processing module of GIS includes

three basic files: (1) a dictionary ordered on key

word, each record containing: pointers to synonyms

and equivalents, key word frequency data, and a pointer to (2) the inverted file, which can contain a

variable number of document numbers indexed by

the given key word. Finally, (3) the master file can

contain bibliographic data and all words stored for that document. Given the document number, the

bibliographic data, and key words from the document, the system can automatically generate the

above files." (Climenson, 1966, p. 127).

5.26 "GRED, the Generalized Random Extract Device developed at Thiokol Chemical Corporation

and described by Heiner & Leishman, is written

in COBOL. Files within the system follow the

COBOL restrictions of fixed-record size and fixedfield length size for each field; the files are also restricted to tape. File definitions are provided at run time by the user, who specifies the file and

record description. A file definition library option

is provided and can be maintained by input request.

The system, developed for the IBM 7010 computer,

has the ability to sort and output data, and is useful for small files." (Minker and Sable, 1967,

p. 147).

5.27 "At a second symposium held in September

1965, a benchmark problem was used to organize

the discussion of specific systems. The problem

involved a management data base — that is, an organization table and personnel files. Five systems were

given the same file data and asked to create the

file(s) and perform several kinds of operations on it. The five systems were: COLINGO of MITRE Corporation, the Mark III File Management System of

Informatics, Inc., the on-line data management

system by Bolt, Beranek, and Newman, Inc., the

BEST System of National Cash Register, and the

78
'Integrated Data Store' of General Electric."

(Climenson, 1966, p. 125). 5.28 "This work has led to the definition of FILER (File Information Language Executive

Routine), the formalization of a calculus of operations with specific relevance to problems of file organization." (Hughes Dynamics, 1964, p. 1.3). 5.29 "Apart from languages at the implementation or procedural level, a number of user-oriented

systems employ list-structured data as a basic

mechanism. Bernstein & Slojkowski describe a system called Program Management System (PMS),

which stores data in a two-level file structure. Associated with each file is a file name, a list of pointers

to its subfiles, and a list of pointers to other files." (Minker and Sable, 1967, p. 126).

5.30 "The long-range objectives are:

"1. To define some of the characteristics of large

files, and to develop the structure for a large

file of heterogeneous scientific and technical

information including chemical structure representations, with particular attention to the necessity for:

a. Manipulating information which is in some cases formatted and in others

completely amorphous.

b. Making provision for inclusion of certain kinds of information when it exists,

and for later filling -of gaps when the

information is not available at the time

of file initiation.

c. Creating a multi-level file of information

so that provision may be made for the

inclusion of general information, as well as the addition of various levels of

specificity as required by the user, either

simply because the additional levels of

specificity exist and might be useful at a

later date or because there is a user requirement for that degree of specificity.

d. Examining the inter-structuring of files that are part of the larger files but which

may be geographically separated.

"2. To provide fist-processing capability in the

file structure in order to:

a. Maintain flexibility in the file. b. Provide for an efficient means of

updating.

c. Permit additions to files, both in classes existing already in the system

and in the entry of new classes of

information.

d. Free the system from the constraints

of fixed-length and formatted files.

e. Permit aggregations of data from files that are geographically separated.

"3. To investigate the techniques of file manipulation in order to provide systems of subfiles, special files, desirable redundancy

in exchange for multiple access to information, and the necessary keying or crossreferencing facility required for such a system of multi-level, multi-subject files. This work must take into account also the

planning and development of several kinds

of computer programs which are required

for file maintenance . . . "4. To determine the kind of organization

of information which will most readily

permit questioning of the file by different

groups of questioners who have varied (and

varying) requirements for the kinds of infor- mation contained in the file, and who have,

furthermore, requirements for different

degrees of specificity in the information

they are seeking." (Anderson et al., 1966,

pp. 2-4). 5.31 "Fossum & Kaskey examine different

kinds of file organization and investigate the

potential of a 'list ordered file' for economizing on the work-load on a computer when carrying

out a search. The data base used is the terms

assigned to a number of DDC documents, using

the DDC thesaurus. The relevance of this study

for this chapter is the analysis of word associations,

and the objective of the analysis is, in effect, to permit a certain amount of precoordination of

terms, in order to reduce the amount of processing

necessary in the retrieval operation. The means

to achieving this objective is the determination

of the mutual exclusiveness of terms. Unlike the

rigorous intellectual marshalling of terms in facet analysis, the procedure here is to determine

mutual exclusiveness on the basis of whether or not terms appear together in the indexing of

individual documents. The attempt to develop

an economic list-organized file, the specific purpose

of the work reported here, is abortive, but the

technique of handling terms in this way remains

an intriguing possibility as a machine aid to the

generation of schedules for faceted classification schemes." (Sharp, 1967, p. 102).

5.32 "The fundamental importance of data

structures may be illustrated by considering the

problem of designing a single language that would

be the preferred language either for a purely arith- metic job or for a job in symbol manipulation.

Attempts to produce such a language have been

disappointing. The difficulty is that the data struc- tures required for efficient implementation in the

two cases are entirely different. Perhaps we should

recognize this difficulty as a fundamental one, and

abandon the quest for an omnibus language which

will be all things to all men." (Wilkes, 1968, p. 5). 5.33 "Historically primary preoccupation with

three classes of data structures (real-complex

scalars and arrays, alphanumeric strings and files, and symbolic lists) have led to three major language

developments; exemplified — but not exhaustively

defined -by ALGOL, COBOL, and LISP, respectively. A major concern of procedural language

designers is the reconcilization of these diverse

79
data types and their transformations with one

language." (Pedis, 1965, p. 189).

"Studies in artificial intelligence call for powerful

list-processing techniques, and involve such operations as the placing of items on lists, the searching

of lists for items according to specified keys, and

so on. Languages in which such operations can be

easily specified are indicated. The pioneer language

in this regard was IPL developed by Newell, Simon

and Shaw." (Wilkes, 1964, p. F 1-3).

5.34 "Early list processing languages were

invented in order to carry out specific projects of a non-numerical nature. The sequence of languages

called IPL . . . Started out in order to provide

satisfactory methods of organizing information for work in theorem proving and problem solving, a

field in which the amount of storage needed is very

variable and unpredictable, and in which the struc- ture of the fists carries important information.

LISP . . . was developed partly for the use of a

project called the 'Advice Taker' which was in- tended to operate in a complex way on English state- ments about situations. A language called FLPL . . . which was embedded in FORTRAN was produced

to write programs for proving theorems in geometry. COMIT . . . was devised for language re- search." (Foster, 1967, p. 3). 5.35 "Furthermore, since a list is itself an

ordered set of items which may themselves be lists, there is no limit to the complexity of the structures

that can be built up except the total memory space

available. Also, there is no restriction to the number

of lists on which an item can appear." (Hormann,

1960, p. 14). "List structures have, as their fundamental

property, the substitution rule that allows any

symbol in a fist to be substituted by a fist structure. The natural control procedure for such rules is recu[r]sion: the use of rules whose definition contains calls on itself." (Perlis, 1965, p. 189).

5.36 "List structures allow dynamic storage

allocation for units of data larger than can be stored

in a single computer word. Normally blocks of con- secutive storage cells are allocated for data sets prior to program execution based on estimates of

the maximum size of these sets. If the sizes of data

sets are variable or unknown, wasteful amounts of

storage must be assigned to guard against program

failure caused by overflow at some block of assigned

storage. Faced with this problem, Newell, Shaw,

and Simon organized information in memory into an

associative list structure format." (Fuller, 1963, p. 5). "Since the order relation among items is deter- mined only by links, this relation can be changed

simply by changing the links without moving the

items physically, thus allowing simple and quick

changes of organization of memory content. Processes such as insertion and deletion of items in a list become very simple." (Hormann, 1960, p. 13). 5.37 For example, "list processing is relatively new; none of the forms for the components of list

languages has as yet been established as 'standard' even in an informal sense." (Raphael, 1966, p. 67). "The concept of list processing, or chaining, has

been used as a technique for the manipulation of

logical data strings for many years and has been

formalized as a language for handling data in computer storage. List processing has also been utilized with limited success for the control of data in direct- access storage devices. In general, when list struc- tures are used for external data control, only a subset of the possible data structures is implemented,

and the logical and physical relationships are approached as a single entity. Thus, the many ventures into this area are highly individualized, result- ing in duplication and incompatibility." (Henry,

1969, p. 2). 5.38 "List processing is a convenient mode of

description for many of the more interesting and

provocative areas of computer application, but the

available languages — such as IPL—V, COMIT,

LISP, SIMSCRIPT — require a level of programmer

sophistication that makes them almost prohibitive

for normal classroom use." (Conway et al., 1965,

p. 215).

5.39 "While the list processing languages . . . make it possible to handle reasonably complicated

data structures, the programmer is nevertheless

faced with a number of difficult problems as soon

as he attempts to use such languages in practice . . .

it becomes necessary to fit the given data structures

into what often turns out to be an unnatural for- mat ... At the very least, this type of data

organization wastes a great deal of storage space . . . Furthermore, the inefficient space allocation also results in extremely slow execution times for the

object programs." (Salton, 1966, p. 205).

"The user of list-processing languages is fre- quently plagued by the lack of memory space. Sophisticated means of 'garbage collection' have

become important to circumvent memory space

limitations; however, they constitute mostly a

palliative that seldom satisfies the user's appetite

for extra space." (Cohen, 1967, p. 82). "In their relation to machines the list processing

languages are burdensome, first because the data

structures involved may be represented only

through explicit links, and second because the

free growth and cancellation of structures re- quires a troublesome administration of the storage."

(Naur, 1965, p. 197).

"Powerful software schemes (e.g., the list processing languages) have been developed to deal with the problem of treating scattered data

as a contiguous string, but they pay a very heavy

price in memory overhead (in some schemes over

three-fourths of the available memory is required to handle the addressing mechanisms) and in the

processing time required to perform the address

arithmetic.

"An alternative solution is proposed here which

involves the addition of a small Associative Memory

80
(AM) to the addressing machinery of the computer

(or peripheral direct pccess storage device). As

will be shown, this hardware modification will permit scattered data to appear contiguous, with

only a token overhead cost in memory and processing time." (Fischler and Reiter, 1969, p. 381). 5.40 "The process of item deletion involves

the elimination of an existing item in the file. This task is complicated by the fact that after deletion, linkage information must be modified

if the system is to operate properly. This can

be accomplished in two ways. In the first case

the item can be physically deleted and each list associated with the item can be searched and

the associated fink deleted. Alternatively, the

specified item can be flagged in the control section.

Then during retrieval flagged items are ignored."

(Prywes, 1965, p. 20). "There are several penalties paid for obtaining

the flexibility of a memory organized into a fist structure. One of these is the requirement for additional memory bits to store appropriate finking

addresses. A far more serious penalty is the time

required to retrieve symbols from lists and for operations required to add symbols to lists, reorder

lists, delete symbols from lists, erase lists, transfer

lists to and from bulk storage, and manipulate

push-down registers. These tasks are taken out

of the hands of the programmer by various list- processing languages, but they 'still must be per- formed by the machine." (Fuller, 1963, p. 12). 5.41 "Most fist-processing languages have

suffered from their inability to deal directly with

complex data structure and/or from their inability

to perform the complete range of programming

language operations upon the data list structures." (Lawson, 1967, p. 358). 5.42 ". . . In many cases, especially among the

list-oriented languages, they simply have not geared

themselves to the large amounts of data and data

processing required in this special field." (Simmons,

1966, p. 214).

"The reason list processing has yet to acquire

universal popularity in non-numeric data processing

is that, while these mechanics are easy in the list processing language, they can be very time-consuming when performed by a computer, so much so

that the economics of use of present-day list processing languages in most information retrieval applications is questionable. Because of the saving

in programming time that is possible, however, we

may anticipate future hardware and software developments that will enable these methods to be made

practical." (Meadow, 1967, pp. 200-201.)

"This suggests that a conventional linked fist structure is inadequate for representing map (or picture) structure. Alternative forms might be an

associative memory or a more general linked ele- ment structure." (Pfaltz et al., 1968, p. 369). 5.43 "It must be said also that numeric information is often awkward to store in terms of list structures, and arithmetic procedures may be corre- spondingly difficult to perform." (Salton, 1966,

p. 208).

"The well-known list structure languages such as LISP were not designed for graphics and are not very efficient or easy to use for such multidimensional problems. They are well suited for processing

strings of text but break down when two-way associations between list elements are the rule rather

than the exception." (Roberts, 1965, p. 212).

5.44 "The list processing section of the compiler

should make it possible to handle variable length

data structures, in such a way that each data item

may be associated with a variable number of list pointers, as specified by a special parameter."

(Salton, 1966, p. 209).

5.45 "It might ... be useful to think about a general graph and tree manipulator, capable of

performing most of the common transformations on

abstract graphs and trees." (Salton, 1966, p. 209).

"The value of a generalized file processing system

is directly related to the variety of file structures it can accommodate. With most existing systems, the user is limited to structures having the form of

hierarchies or trees. For many problems, such

structures are either not adequate or not efficient; instead, these problems require structures of the

form of graphs, of which the tree is a special case. Examples of problems of this type are network and

scheduling problems, computer graphic problems,

and information retrieval problems." (McGee, 1968,

p. F68).

"Most complex data structures can be adequately represented as directed graphs. A directed

graph is defined informally as a set of labeled points

or nodes, and a set of directed line segments or

arcs connecting pairs of nodes. An arc running from

node x to node y denotes that the entities repre- sented by x and y are related in some way, e.g., x is superior to y, or x precedes y. If x and y bear

multiple relationships to each other, they may be

connected by multiple arcs, each arc being labeled

with the relation being represented." (McGee, 1968,

p. F68).

5.46 "Since Rover has more features that are common to IPLs than any other language, it may

be said to be a member of the IPL family. Some

additional features are present in Rover which

attempt to provide a more powerful tool for syn- thesizing complex processes. . . . "The original design of IPL memory structure has only DLs [down links] which, by themselves can form lists and achieve a great flexibility. We

are introducing ULs [up finks] here in order to give

greater flexibility and to overcome some of the

difficulties encountered by having only DLs. . . ." "Since the order relation among items is deter- mined only by finks, this relation can be changed

simply by changing the links without moving the

items physically, thus allowing simple and quick

changes of organization of memory content.

81
Processes such as insertion and deletion of items in a list become very simple. . . . "Another disadvantage is the loss of ability to compute addresses. Since the order relation is introduced to a set of items only by extending

'adjacency' defined by links, the 'table look-up'

feature is lost. "A part of the seemingly lost feature is regained,

and furthermore, an added feature is gained by

introducing 'side links' which are extension of ULs

and DLs. . . . "The first item on a list . . . uses its UL to store the name of the list [the location of the cell that

contains the name of the first item on the list]. The last item of a fist contains the name of the first item as its DL as well as the 'end bit' description.

"This internal convention gives a list the effect of being a ring; having reached to the end item, the

processor has an access to the first item as well as the name of the list without backtracking." (Hormann, 1960, pp. 2, 13, 15-16, 21).

5.47 "The Association-Storing Processor (ASP)

consists of a language designed to simplify the

programming of non-arithmetic problems, to- gether with a number of radically new machine

organizations designed to implement this language.

These machine organizations are capable of highspeed parallel processing, and take advantage

of the low cost of memory and logic offered by

large scale integration (LSI).

"The ASP concept has been developed specifically for applications having one or more of the

following characteristics:

(1) The data bases are complex in organization

and may vary dynamically in both organization and content.

(2) The associated processes involve complex

combinations of simple retrieval operations.

(3) The problem definitions themselves may

change, often dramatically, during the life of

the system." (Savitt et al., 1967, p. 87). 5.48 "Sketchpad's topological file uses a

special ring structure that permits storage structure rearrangement with a minimum of searching . . . The use of redundant interconnecting blocks in its

list structure gives it the appearance of being

ordered more like a tree. This allows fast forward

and backward searches for subgroups. The structure used insures that at most two steps must betaken

to find either the header block or the previous

element." (Coggan, 1967, p. 6). 5.49 "If some connection is deleted, it is not

sufficient to just remove the line from the display

file. That line represents an association between

two elements and may constrain the movement

of the elements, the distance between them and

their deletion, as well as their external properties

(e.g., electrical, program flow, etc.). Thus, each

line or other picture element must be attached

to an undetermined number of graphical elements

and constraints in such a way as to facilitate the

processing of these associations." (Roberts, 1965,

p. 211).

"A block of elements collects many ties together

and thus allows the multi-dimensional associations required for graphical data structures . . . A block is formed from a sequence of registers

of any length and contains a blockhead identifier

at the top, a group of ring elements and any number

of data registers . . . Blocks are used to represent

items or entities and the rings form associations

between blocks." (Roberts, 1965, pp. 212-213).

"There are two operators for moving around

classes, one to go through all members of a class (arrows leaving this item), and one to find all the

classes an item belongs to (arrows pointing at this item)." (Roberts, 1965, p. 214).

"Before a new free block is added to the free

lists, the block just after it in memory is examined

and if it is free also, then the two blocks are merged

into one larger free block. This merging technique

makes the allocation of variable length blocks

almost as efficient as the allocation of fixed length

blocks." (Roberts, 1965, p. 213).

5.50 "In the current DEACON work, data is organized into ring structures. These structures are

similar in many respects to the plex structures defined by Ross and used by Sutherland in Sketchpad, and are an extension of the notion of list structure." (Thompson, 1966, pp. 354-355).

5.51 "SLIP was the first embedding of a fist- processing capability within a higher level language

and has a formative ring structure. The idea of

rings was crystallized by Sutherland and Roberts

and used with data systems designed primarily for graphics and computer-aided design. Roberts has

also developed a language to refer to rings (Class

Oriented Ring Associative Language: CORAL).

In such languages, the associations are built into the structure by allowing blocks of information to be threaded by rings which carry the associations

between the blocks of data. This is illustrated

. . ., where 'JOHN's' 'parent of ring goes through

'NLB C and 'NUB A', which in turn reference

'Edith' and 'Arnold' respectively. Thus John is the parent of both Edith and Arnold. A similar structure has been implemented with PL/1 by Dodd.

The duality of certain relationships, such as: 'de- fined by' and 'defines' or 'to the left of and 'to the

right of, etc., led to the need for a connector block,

here illustrated by the three NUBS. In essence, the

NUB represents a two-way switch for transferring out of one ring and into another. The subroutines

or macros pass along the ring until they arrive at a NUB. They 'switch' it, and pass into the other ring,

passing along the second ring (and others as found)

picking up information until they return to the

original NUB and re-enter the first ring. This allows answers to questions such as 'Who is the mother of

Arnold?' as well as 'Who is the son of Mary?' One

of the major disadvantages of these structures occurs on adding a new, not previously anticipated,
association. The operation either is impossible,

requiring a complete re-compilation, or else clumsy,

patching on additional blocks . . . and requiring

sophisticated garbage collectors. A recent survey

by Gray describes these and similar structures." (Ash and Sibley, 1968, p. 145). 5.52 "An interesting variation on the basic list processing technique was described by Cheydleur

in 1963. In this technique, a datum is stored just once in memory, but provision is made for many

pointers both to and away from a given element.

Data redundancy of normal list processing is eliminated at the expense of addressing redundancy.

The address bookkeeping becomes quite complex,

but it is interesting to note that Cheydleur's concept

is applicable to cells of varying sizes. He suggests

methods for partitioning strings of symbols so that there is a reasonable distribution of pointers throughout the store. That is, if it can be predicted that the co-occurrence of individual letters or words will be

of high frequency, these co-occurrences would be

stored in the same cell. Since the storage space

taken by pointers competes with data storage

requirements, methods for balancing cell size and

pointer distribution are quite important." (Climenson, 1966, p. 114). 5.53 "Ring structures are adequate for storing

a wide range of richly interrelated data that is pertinent to such functions as intelligence analysis,

management planning, and decision making. Typical of these functions are resource allocation problems, in which the pertinent data is an inventory of

the resources, their characteristics, and their inter- relations. This type of data is specifiable in ring

structures." (Craig et al., 1966, p. 366).

5.54 "APL was conceived at the General Motors

Research Laboratories to satisfy the need for con- venient data association and data handling tech- niques in a high-level language. Standing for ASSOCIATIVE PROGRAMMING LANGUAGE, it is designed to be embedded in PL/1 as an aid to the user dealing with data structures in which associations are expressed." (Dodd, 1966, p. 677). 5.55 "The principal tool used by this system is the Associative Structure Package (ASP7) implemented by W. A. Newman for the PDP7. It is used

to build data structures whose associative properties are expressed using rings, where a ring is a

series of addresses in words so that the first points

to the next, and so on until the last points back to the first. The first pointer is specially marked and

is called a ringstart. The ringstart may point to

itself; i.e., the ring may be null." (Pankhurst, 1968,

p. 410).

5.56 "On-line interaction introduces into the

language picture the possibility of 'conversation'.

This possibility, together with the need to bring online languages abreast of conventional programming

languages, opens an inviting field to research and

development." (Licklider, 1965, p. 124).

We note also the following: "On-line Programming Systems put the raw power of a computer at

the immediate disposal of a human user. Evidence

of today's great interest in on-line programming

systems is that more and more of them are being

used." (Sutherland, 1965, p. 9). "The on-line nature of time-sharing permits direct

man-machine communication in languages that are beginning to approach natural language, at a pace

approaching normal human conversation, and in some applications, at graded difficulty levels appropriate to the skill and experience of the user." (Sackman, 1968, p. 1). "To improve all our on-line systems, we need more and better languages of communication

between the man and the machine which are

'natural' in the sense that they are easy to use and

fit the task. Why can't I write mathematical equations which look like mathematical equations and

have the machine accept, compile and perform

them? Why can't I describe network problems to the computer by means of the picture showing the

network? Why can't I, in filter design, place poles

and zeros on the complex plane? The answer in each case is: I can in principle, but not in practice.

As yet, the techniques which let me do these things are not widely used." (Sutherland, 1965, pp. 11-12).

5.57 "Overhead computation can be thought of

as degrading the effective operating rate of the

processor as seen by the user." (Scherr, 1965, p. 28). 5.58 Examples include, but are not limited to, the following: "With each computation there is associated a set of information to which it requires

a high density (in time) of effective reference.

The membership of this working set of information varies dynamically during the course of the

computation." (Dennis and Van Horn, 1965, p. 11). "Various problem areas make different demands

for data structures and for syntax. The argument

is not to restrict specialization to transliteration.

It is to avoid unnecessary diversity and to achieve

necessary diversity by specializing in the various

directions at as high a point on the scale as possible

and thus by handling the bulk of the languageimplementation process in a uniform way with

common facilities." (Licklider, 1965, p. 181).

"Most writers of papers on on-line applications

of time-shared systems are universal in their agree- ment on the importance of interactive languages.

They also seem to concur that such languages will differ substantially from the programming languages now in existence, such as FORTRAN, ALGOL, and

IPL-V. The difference is primarily due to the new

kinds of operations made possible by the remote

console through which communication between man and computer takes place." (Davis, 1966,

p. 229). "In programming as well as in hardware design

and system organization, time sharing calls for new

departures. Perhaps the most significant is the one referred to by the term 're-entrant programs'.

When many computer programs are currently

active, it is likely that several of them are doing

83
essentially the same thing at the same time. Whenever that is the case, efficiency in use of memory

space would be gained if the several programs

shared a common subprogram." (Licklider, 1965,

p. 26).

5.59 "In artificial intelligence problems, this process [code, run & see, code] must often be

prolonged beyond the debugging phase. It is important for the programmer to experiment

with the working program, making alterations

and seeing the effects of the changes. Only in this way can he evaluate it or extend it to cover more

general cases." (Teitelman, 1966, p. 2). "This appears to be the best way to use a truly

interactive man-machine facility — i.e., not as a device for rapidly debugging a code representing

a fully thought out solution to a problem, but

rather as an aid for the exploration of problem

solving strategies." (Weizenbaum, 1966, p. 42). "If computers are to render frequent and intensive service to many people engaged in creative

endeavors (i.e., working on new problems, not merely resolving old ones), an effective compromise

between programming and ad hoc programming is required." (Licklider, 1965, p. 181).

5.60 "Programs very likely to contain errors must be run but must not be permitted to interfere

with the execution of other concurrent computations. Moreover, it is an extremely difficult task to determine when a program is completely free of

errors. Thus, in a large operational computer

system in which evolution of function is required,

it is unlikely that the large amount of programming

involved is at any time completely free from errors, and the possibility of system collapse through soft- ware failure is perpetually present. It is becoming

clear that protection mechanisms are essential to any multiprogrammed computer system to reduce

the chance of such failure producing catastrophic

shutdown of a system." (Dennis, 1965, p. 590). 5.61 "The functional language makes no refer- ence to the specific subject matter of the problem . . . The program must be organized to separate

its general problem-solving procedures from the

application of these to a specific task." (Newell and

Simon, 1959, p. 22). "There has been a shift away from a concern

with difficulty and toward a concern with generality. This means both a concern that the problem

solver accept a general language for the problem

statement, and that the internal representation be

very general." (Newell, 1965, p. 17). 5.62 For example, "Multilang is a problemoriented language that translates the user's state- ment of the problem into requests for relevant

programs and data in the system's memory. The

language was designed specifically to assist in problem-solving and, in so doing, to 'accumulate knowledge'. For example, it may not recognize the term

'eligible voter', but it can be told that an eligible voter is a thing that is 'human', 'age over 21' and

either 'born in the U.S.' or 'naturalized'. If these

terms have been previously defined, the computer

can find an answer to the question; additionally,

the next time it is asked about eligible voters, it will know what is meant." (Carr and Prywes, 1965,

pp. 88-89).

5.63 "Each user, and each user's program, must

be restricted so that he and it can never access

(read, write, or execute) unauthorized portions of

the high-speed store, or of the auxiliary store. This

is necessary (1) for privacy reasons, (2) to prevent a defective program from damaging the supervisor

or another user's program, and (3) to make the

operation of a defective program independent of the

state of the rest in store." (Samuel, 1965, p. 10). 5.64 "The TRAC (Text Reckoning And Compiling) language system is a user language for control

of the computer and storage parts of a reactive

typewriter system." (Mooers, 1966, p. 215).

"A solution to this problem is to use a machineindependent computer language, designed to operate with a reactive typewriter, to operate the

local computer. With this method, the computer

acts in place of the human controller to gain access

to remote computer systems. This approach is possible only with an extremely versatile language,

such as the TRAC language. ... It is relatively

easy to describe in TRAC the set of actions which

must be taken in order to make the remote computer

perform and bring forth the desired files." (Fox

et al., 1966, p. 161).

5.65 "The basic property of symbolic languages

is that they can make use in a text of a set of local symbols, whose meaning and form must be declared

within the text (as in ALGOL) or is to be deduced

by the context (as simple variables in FORTRAN)."

(Caracciolo di Forino, 1965, p. 227). However, "it

is . . . regrettable from the standpoint of the

emerging real-time systems that languages like COBOL are so heavily oriented toward processing

of sequential tape file data." (Head, 1963, p. 40). 5.66 Some other recent examples include

LECOM, L6

, LISP II, CORAL, and TREET, characterized briefly as follows: "The compiler language, called LECOM, is a version of COMIT, and is especially designed for small (8K) computers. The microcategorization

program was written in LECOM, and assigns an

appropriate syntactic category to each word of an

input sentence." (Reed and Hillman, 1966, p. 1). "Bell Telephone Laboratories' Low-Level Linked

List Language (L6

, pronounced 'L-six') contains

many of the facilities which underlie such fist processors as IPL, LISP, COMIT and SNOBOL,

but it permits the user to get much closer to machine

code in order to write faster-running programs, to use storage more efficiently and to build a wider

variety of linked data structures." (Knowlton, 1966,

p. 616).

"L6 ... is presently being used for a variety

of purposes, including information retrieval, simu84
lation of digital circuits, and automatic drawing of flowcharts and other graphical output." (Knowlton.

1966. p. 617).

"The most important features of Lsix which

distinguish it from other list processors such as IPL. LISP, COMIT and SNOBOL are the availability of several sizes of storage blocks and a flexible means of specifying within them fields containing

data or pointers to other blocks. Data structures

are built by appropriating blocks of various sizes,

defining fields (simultaneously in all blocks) and

filling these fields with data and pointers to other

blocks. Available blocks are of lengths 2

n machine

words where n is an integer in the range 0—7. The

user may define up to 36 fields in blocks, which

have as names single letters or digits. Thus the D

field may be defined as bits 5 through 17 of the

first word of any block. Any field which is long

enough to store an address may contain a pointer

to another block. The contents of a field are inter- preted according to the context in which they are used." (Housden, 1969. p. 15). "LISP 2 is a new programming language designed

for use in problems that require manipulation of

highly complex data structures as well as lengthy

arithmetic operations. Presently implemented

on the AN/FSQ-32Y computer at the System

Development Corporation ... A particularly

important part of the program library is a group

of programs for bootstrapping LISP 2 onto a new machine. (Bootstrapping is the standard

method for creating a LISP 2 system on a new

machine). The bootstrapping capability is suffici- ently powerful so that the new machine requires no

resident programs other than the standard monitor

system and a binary loader." (Abrahams et al., 1966. pp. 661-662).

"This fist structure processing system and

language being developed at Lincoln is called

CORAL (Class Oriented Ring Association Language). The language consists of a set of operators

for building, modifying, and manipulating a list structure as well as a set of algebraic and conditional forms." (Roberts, 1965, p. 212).

"TREET is a general-purpose list processing

system written for the IBM 7030 computer at the MITRE Corporation. All programs in TREET

are coded as functions. A function normally has

a unique value (which may be an arbitrarily complex

list structure), a unique name, and operates with

zero or more arguments." (Bennett et al., 1965,

pp. 452-453).

5.67 "The growing importance of the family

concept accentuates the need for levels of soft- ware. These levels of software will be geared to configuration size instead of family member.

In other words, the determining factor will be the

amount of memory and the number of peripheral

units associated . . ." (Clippinger, 1965, p. 210).

"The advantages of high-level programming

languages . . . [include] higher machine independence for transition to other computers, and

otherwise for compatibility with hardware . . . [and] better documentation (compatibility among

programs and different programmers)." (Burkhardt, 1965, p. 4). "The user needs to employ data structures and

processes that he defined in the past, or that were

defined by colleagues, and he needs to refresh his understanding of those objects. The language must

therefore have associated with it a metalanguage

and a retrieval system. If there is more than one working language, the metalanguage should be

common to all the languages of the system." (Licklider, 1965, p. 185).

"The over-all language will be a system because

all the sublanguages will fall within the scope of one

metalanguage. Knowing one sublanguage will make

it easier to learn another. Some sublanguages will be subsets of others." (Licklider, 1965, p. 126).

5.68 "The most immediate need is for a general

compiling system capable of implementing a variety of higher-level languages, including in particular, string manipulations, fist processing facilities, and complete arithmetic capabilities." (Salton,

1966, p. 208).

5.69 Licklider, 1965, p. 119.

"It will be absolutely necessary, if an effective procognitive system is ever to be achieved, to have

excellent languages with which to control processing

and application of the body of knowledge. There

must be at least one (and preferably there should be

only one) general, procedure-oriented language for use by specialists. There must be a large number of

convenient, compatible field-oriented languages for the substantive users." (Licklider, 1965, p. 67). 5.70 "There is, in fact, an applied scientific lag in the study of computer programmers and

computer programming — a widening and critical lag that threatens the industry and the profession

with the great waste that inevitably accompanies

the absence of systematic and established methods

and findings and their substitution by anecdotal

opinion, vested interests, and provincialism."

(Sackman et al., 1968, p. 3). "Work on programming languages will continue

to provide a basis for studies on languages in general, on the concept of grammar, on the relation

between actions, objects and words, on the essence

of imperative and declarative sentences, etc. Unfortunately we do not know yet how to achieve a

definition of programming languages that covers both their syntactic and pragmatic aspects. To this goal a first step may be the thorough study of special

languages, such as programming languages for machine tools, and simulation languages." (Caracciolo di Forino, 1965, p. 6). 5.71 "As Levien & Maron point out, and Bobrow

analyzes in detail, natural language is much too

syntactically complex and semantically ambiguous

to be efficient for man-machine communication. An

alternative is to develop formalized languages with

85
a simplified syntax and vocabulary. Examination of

several query languages, for example, COLINGO

and GIS, reveals a general (and natural) depend- ence on, and adaptation of, the rules of formal

logic. However, even with English words for logical

operations, relations, and object names, formal

query languages have been a less-than-ideal solution

to the man-machine communication problem. Except for the simplest queries, punctuating a nested

Boolean logical statement can be tricky and can

lead to errors. Furthermore, syntactic problems

aside, a common difficulty arises when the user does not know the legal names of the data for which

he is searching or the structural relationships among

the data items in the data base, which may make

one formulation of his query very difficult and ex- pensive to answer whereas a slightly altered one may be simple to answer." (Minker and Sable,

1967, p. 136).

"The possibility of user-guided natural-language

programming offers a promise of bridging the man- machine communication gap that is today's greatest

obstacle to wider enjoyment of the services of the

computer." (Halpern, 1966, p. 649).

"Such a language would be largely built by the users themselves, the processor being designed to

facilitate the admission of new functions and notation of any time. The user of such a system would

begin by studying not a manual of a programming

language, but a comparatively few pages outlining

what the computer must be told about the location

and format of data, the options it offers in output

media and format, the functions already available

in the system, and the way in which further functions and notation may be introduced. He would

then describe the procedure he desired in terms

natural to himself." (Halpern, 1967, p. 143).

5.72 "Further investigation is required in searching and maintaining relationships represented by

graph structures, as in 'fact retrieval' systems.

Problems in which parts of the graph exist in one

store while other parts are in another store must

be investigated, particularly when one breaks a

link in the graphs. The coding of data and of rela- tions also needs much work." (Minker and Sable,

1967, p. 151).

5.73 "This program package has been used in the analysis of several multivariate data bases,

including sociological questionnaires, projective

test responses, and a sociopolitical study of Colombia. It is anticipated that the program will also prove

useful in pattern recognition, concept learning,

medical diagnosis, and so on." (Press and Rogers,

1967, p. 39). 5.74 "The execution of programs at different

installations whose total auxiliary storage capacities

are made up of different amounts of random access

storage media with different access characteristics can be facilitated by the organization of the auxiliary

storage devices into a multilevel storage hierarchy

and the application of level changing." (Morenoff

and McLean, 1967, p. 1).

5.75 "A systems problem that has received

considerable attention is how to determine which

data should be in computer memory and which

should be in the various members of the mass

storage hierarchy." (Bonn, 1966, p. 1865).

"The key requirement in multiprogramming sys- tems is that information structures be represented

in a hardware-independent form until the moment

of execution, rather than being converted to a hardware-dependent form at load time. This requirement leads directly to the concept of hardwareindependent virtual address spaces, and to the

concept of virtual processors which are linked to physical computer resources through address

mapping tables." (Wegner, 1967, p. 135).

5.76 "With respect to the central processing

unit, the major compromise of future needs with

present economy is the limitation on addressing

capacity." (Brooks, 1965, p. 90). "Other major problems of large capacity memories are related to the tremendous amount of elec- tronic circuitry required for addressing and sensing." (Kohn, 1965, p. 132). 5.77 For example, "the problem of assigning

locations in name space for procedures that may be

referenced by several system functions and may

perhaps share references to other procedures, is not widely recognized and leads to severe complications when implementation is attempted in the context of conventional memory addressing."

(Dennis and Glaser, 1965, p. 6). 5.78 "A particularly troublesome phenomenon,

thrashing, may seriously interfere with the perform- ance of paged memory systems, reducing computing giants (Multics, IBM System 360, and others

not necessarily excepted) to computing dwarfs.

The term thrashing denotes excessive overhead and

severe performance degradation or collapse caused

by too much paging. Thrashing inevitably turns a shortage of memory space into a surplus of processor

time." (Denning, 1968, p. 915).

5.79 ". . . Global weather prediction. Here a three-dimensional grid covering the entire world

must be stepped along through relatively short

periods of simulated time to produce a forecast in a reasonable amount of time. This type of problem

with its demand for increased speed in processing

large arrays of data illustrates the applicability of a computer designed specifically for array processing."

(Senzig and Smith, 1965, p. 117).

"Most engineering data is best represented in the

computer in array form. To achieve optimum capability and remove the restrictions presently asso- ciated with normal FORTRAN DIMENSIONed

array storage, arrays should be dynamically allo- cated. Dynamic allocation of data achieves the

following:

"1. Arrays are allocated space at execution

time rather than at compilation time. They

are only allocated the amount of space

needed for the problem being solved. The

86
size of the array (i.e., the amount of space

used) may be changed at any time during

program execution. If an array is not used

during the execution of a particular problem,

then no space will be allocated.

"2. Arrays are automatically shifted between

primary and secondary storage to optimize

the use of primary memory.

"Dynamic memory allocation is a necessary

requirement for an engineering computer system

capable of solving different problems with different

data size requirements. A dynamic command

structured language requires a dynamic internal

data structure. The result of dynamic memory

allocation is that the size of a problem that can

be solved is virtually unlimited since secondary

storage becomes a logical extension of primary

storage." (Roos, 1965, p. 426).

5.80 "Any language which lacks provision

for performing necessary operations, such as bit editing for telemetered data, forces the user to write segments in assembly language. This destroys

the machine independence of the program and

complicates the checkout." (Clippinger, 1965,

p. 207). 5.81 "Thus one must consider not only whether

the logical possibilities of a new device are ignored

when one is restricted to a binary logic, but also whether one is sufficiently using the signals when

only one of the parameters characterizing that

signal is used." (Ring et al., 1965, p. 33). 5.82 "For a variety of reasons, not the least of which is maturing of integrated circuits with

their low cost and high density, central processors

are becoming more complex in their organization."

(Clippinger, 1965, p. 209).

5.83 "No large system is a static entity —

it must be capable of expansion of capacity and

alteration of function to meet new and unforeseen

requirements." (Dennis and Glaser, 1965, p. 5). "Changing objectives, increased demands for use, added functions, improved algorithms and new technologies all call for flexible evolution

of the system, both as a configuration of equipment

and as a collection of programs." (Dennis and

Van Horn, 1965, p. 4). "By pooling, the number of components pro- vided need not be large enough to accommodate

peak requirements occurring concurrently in each computer, but may instead accommodate

a peak in one occurring at the same time as an

average requirement in the other." (Amdahl,

1965, pp. 38-39).

5.84 "The use of modular configurations of

components and the distributed executive principle . . . insures there are multiple components

of each system resource." (Dennis and Glaser, 1965,

p. 14). "Computers must be designed which allow the

incremental addition of modular components, the use by many processors of high speed random

access memory, and the use by many processors of

peripheral and input/output equipment. This

implies that high speed switching devices not now

incorporated in conventional computers be developed and integrated with systems." (Bauer, 1965,

p. 23). See also note 2.52. 5.85 "The actual execution of data movement

commands should be asychronous with the main

processing operation. It should be an excellent use

of parallel processing capability." (Opler, 1965,

p. 276).

5.86 "Work currently in progress [at Western

Data Processing Center, UCLA] includes: investi- gations of intra-job parallel processing which will attempt to produce quantitative evaluations of

component utilization; the increase in complexity

of the task of programming; and the feasibility of

compilers which perform the analysis necessary

to convert sequential programs into parallel path

programs." (Digital Computer Newsletter 16,

No. 4, 21 (1964)).

5.87 "The motivation for encouraging the use

of parallelism in a computation is not so much to make a particular computation run more efficiently as it is to relax constraints on the order in which

parts of a computation are carried out. A multiprogram scheduling algorithm should then be able

to take advantage of this extra freedom to allocate system resources with greater efficiency." (Dennis

and Van Horn, 1965, pp. 19-20).

5.88 "The parallel processing capability of an

associative processor is well suited to the tasks of abstracting pattern properties and of pattern

classification by linear threshold techniques."

(Fuller and Bird, 1965, p. 112).

5.89 "The idea of DO TOGETHER was first mentioned (1959) by Mme. Jeanne Poyen in dis- cussing the AP 3 compiler for the BULL Gamma 60

computer." (Opler, 1965, p. 307).

5.90 "To date, there have been relatively few

attempts made to program problems for parallel

processing. It is not known how efficient, for ex- ample, one can make a compiler to handle the

parallel processing of mathematical problems. Fur- thermore, it is not known how one breaks down

problems, such as mathematical differential equations, such that parts can be processed independently

and then recombined. These tasks are quite

formidable, but they must be undertaken to establish whether the future development lies in the area

of parallel processing or not." (Fernbach, 1965,

p. 82). 5.91 For example, in machine-aided simulations of nonsense syllable learning processes, Daly et al. comment: "Presuming that, for the

parallel logic machine, the nonsense syllables were presented on an optical retina in a fixed

point fixed position set-up, there would be a re- quirement for recognizing (26f or about 104 dif- ferent patterns. If three sequential classification decisions were performed on the three letters
of the nonsense word only 3(26) or 78 different

patterns would be involved. "In the above simple example converting from

purely parallel logic to partially sequential processing reduced the machine complexity by two order(s)

of magnitude. The trend is typical and may involve

much larger numbers in a more complicated problem. Using both parallel and sequential logic as design tools the designer is able to trade-off time

versus size and so has an extra degree of freedom

in developing his system." (Daly et al., 1962, pp. 23-24).

5.92 ". . . The SOLOMON concept proposed

by Slotnick at Westinghouse. Here it is planned

that as many as a thousand independent simple

processors be made to operate in parallel under

an instruction from a network sequencer." (Fernbach, 1965, p. 82). "Both the Solomon and Holland machines belong

to a growing class of so-called 'iterative machines'.

These machines are structured with many identical,

and often interacting, elements.

"The Solomon machine resulted from the

study of a number of problems whose solution

procedures call for similar operations over many

pieces of data. The Solomon system contains,

essentially, a memory unit, an instruction unit,

and an array of execution units. Each individual

execution unit works on a small part of a large

problem. All of the execution units are identical, so that all can operate simultaneously under

control of the single instruction unit. "Holland, on the other hand, has proposed

a fully distributed network of processors. Each

processor has its own local control, local storage,

local processing ability, and local ability to control

pathfinding to other processors in the network.

Since all processors are capable of independent

operation, the topology leads to the concept of

'programs floating in a sea of hardware'." (Hudson,

1968, p. 42). "The SOLOMON (Simultaneous Operation

Linked Ordinal MOdulator Network), a parallel

network computer, is a new system involving

the interconnections and programming, under

the supervision of a central control unit, of many

identical processing elements (as few or as many

as a given problem requires), in an arrangement

that can simulate directly the problem being

solved." (Slotnick et al, 1962, p. 97). "Three features of the computer are:

(1) The structure of the computer is a 2-dimensional modular (or iterative) network so that,

if it were constructed, efficient use could be

made of the high element density and 'template' techniques now being considered in research on microminiature elements.

(2) Sub-programs can be spatially organized and

can act simultaneously, thus facilitating the

simulation or direct control of 'highly-parallel'

systems with many points or parts interacting

simultaneously (e.g., magneto-hydrodynamic

problems or pattern recognition).

(3) The computer's structure and behavior can, with simple generalizations, be formulated in a way that provides a formal basis for theoretical

study of automata with changing structure

(cf. the relation between Turing machines

and computable numbers)." (Holland, 1959,

p. 108).

5.93 ". . . The development of the Illiac III computer, which incorporates a 'pattern articulation

unit' (PAU) specifically designed for performing

local operations in parallel, on pictures or similar

arrays." (Pfaltz et al., 1968, p. 354).

"One of the modules of the proposed ILLIAC III will be designed as a list processor for interpreting

the list structure representation of bubble chamber

photographs." (Wigington, 1963, p. 707).

5.94 "I use this term ['firmware'] to designate

microprograms resident in the computer's control

memory, which specializes the logical design for a

special purpose, e.g., the emulation of another

computer. I project a tremendous expansion of

firmware — obviously at the expense of hardware

but also at the expense of software. . . . "Once the production of microprogrammed computers was commenced, a further area of hardwaresoftware interaction was opened via microprogramming. For example, more than one set of microprograms can be supplied with one computer. A

second set might provide for execution of the order

set of a different computer — perhaps one of the

second generation. Additional microprogram sets might take over certain functions of software

systems as simulators, compilers and control pro- grams. Provided that the microsteps remain a small

fraction of a main memory access cycle, microprogramming is certain to influence future software

design." (Opler, 1966, p. 1759).

"Incompatibility between logic and memory

speeds . . . has also led to the introduction of

microprogramming, in which instruction execution

is controlled by a read-only memory. The fast access time of this memory allows full use of the

speed capabilities offered by the fast logic." (Pyke,

1967,p.l61).

"A microprogrammed control section utilizes a macroinstruction to address the first word of

a series of microinstructions contained in an

internal, comparatively fast, control memory.

These microinstructions are then decoded much

as normal instructions are in wired-in control

machines . . ." (Briley, 1965, p. 93). "The microprogrammed controller concept

has been used to implement the IBM 2841 Storage

Control Unit, by means of which random access

storage devices may be connected to a System/360

central processor. Because of its microprogram

implementation, the 2841 can accommodate

an unusually wide variety of devices, including

88
two kinds of disk storage drive, a data cell drive,

and a drum." (McGee and Petersen, 1965, p. 78). "In microprogram control, the functions of the

controller [for source experimental data auto- mation] are vested in a microprogram which

is stored in a control memory. The microprogram

is made up of microinstructions which are fetched

in sequence from memory and executed. The

microinstructions control a very general type of

hardware configuration, so that merely by changing

the microprogram, the functions available in the

controller can be made to range between wide

limits." (McGee and Petersen, 1965, p. 78). 5.95 "The computer science community has

not recognized (let alone faced up to) the problem

of anticipating and dealing with very large individual

differences in performing tasks involving mancomputer communications for the general public."

(Sackman, et al., 1968, pp. 9-10). 5.96 "The dynamic nature of multiprogram

on-line computation should have a strong influence on memory organization." (Lock, 1965, p. 471).

"The tradeoffs in speed, cost, logic complexity,

and technology are inherent to the design of systems and are not separable in spite of the good

intentions of the semiconductor manufacturers

or the abstract logicians." (Howe, 1965, p. 506).

5.97 "I cannot emphasize too strongly the

interdependence of hardware and software (the statements of procedures, implementation of

which in a given equipment configuration constitutes

the processing capability)." (Schultz, 1967, p. 20).

6. Advanced Hardware Developments

6.1 "It will be necessary to scan the photochromic plane very quickly and accurately, with an

extremely fine pinpoint of light. Lockheed Electronics has been exploring a method of rapidly

deflecting a laser beam, nonmechanically, in two

dimensions. The technique is based on refraction

of the beam by acoustic energy." (Reich and

Dorion, 1965, p. 573). 6.2 "Laser holography is finding some practical

applications. Technical Operations, Inc., of Burlington, Mass., says it has delivered what is believed to be the first operational holography equipment to Otis Air Force Base in Massachusetts, where it will be used to photograph fog in three dimensions."

(Electronics 38, No. 20, 25 (1965).) 6.3 "A work horse of unsuspected power was

harnessed in 1960 when the first operating laser was

demonstrated at Hughes Research Laboratories."

("The Lavish Laser", 1966, p. 15). "The first device to be successfully operated was

a pulsed ruby laser." (Baker and Rugari, 1966, p. 37). Further reference is to Maiman, 1960.

6.4 "Gas lasers are the most monochromatic,

fluorescent crystal lasers are the most powerful,

while semiconductor lasers are the smallest, the

most efficient and can be directly modulated."

(Gordon, 1965, p. 61). 6.5 This area of technological development has

already received such a responsive interest, in general, that Lowry-Cocroft Abstracts, Evanston,

Illinois, provides a punched card abstracts service

in the field of laser developments.

6.6 "The development of the laser as a practical,

continuous, coherent light source has created a new

display technology, that of the laser-beam display.

This type display can be considered to be analogous

to well-known electron-beam type displays, e.g., the

cathode ray tube and the liquid-light valve. The

primary difference is that the electron beam is constrained to a vacuum environment and requires

a special screen for the emission or control of light

while a laser beam can operate in air and be the source of light directly. . . . "The major significance of the laser in a display

system is that all of the energy is usable since the

apparent source of this fight is a diffraction-limited

point-dipole radiator. Conventional light sources such as tungsten filament or a mercury arc are quite

wasteful since light is emitted into a 360-degree

solid angle from a relatively large area. When these

light sources are used to illuminate the limited aper- ture of a practical optical system, only a small frac- tion of the emitted fight is used." (Baker and Rugari,

1966, p. 37). 6.7 "Since the polarization of the light can be

electro-optically switched in nanoseconds, the

inherent speed of the electro-optic effect does not

limit the rate of data projection. However, in practice the rate is limited by dissipation in the deflection

elements and by the stored-energy requirements of

the associated circuitry. Therefore the voltage across the half- wave plate and the loss tangent of the

dielectric are important parameters." (Soref and

McMahon, 1965, p. 59). 6.8 "Coherent light from lasers will provide a

revolutionary increase in the volume of communication that can be sent over a single pathway."

(McMains, 1966, p. 28). "In communications the laser can far surpass conventional facilities. Operating on frequencies many

times higher than radio, it can carry many times as much information. In fact, one laser beam could

carry thousands of TV signals at once. Experiments now under way with lasers enclosed in large pipes

indicate their wide employment for mass communications for the future." ("The Lavish Laser",

1966, p. 16). "As man goes farther away from the earth in space exploration, laser communication will become

more important, because the problems of power

supply and background noise besetting conventional

microwaves at distances beyond the moon will be

89
minimized. In an example of speed comparison,

eight hours were required to transmit the pictures

from Mars, but a laser beam could carry even televi- sion images across the same distance in a few

minutes." ("The Lavish Laser", 1966, p. 16). "The laser— with its extremely narrow beam due

to its short wavelength, notwithstanding its high

quantum and background noise — offers the possibility of surpassing RF techniques in its ability to satisfy deep-space requirements." (Brookner et al., 1967, p. 75). In terms of immediate practicality, however,

experiments in the use of laser techniques for data

transmission have been limited to very short dis- tances. For example, "television signals have been

transmitted on laser beams for distances of the order

of a mile in clear weather . . ." (Gordon, 1965, p. 60), and "the Lincoln Laboratory developed an

optical communications system based on an array

of multiple semiconductor lasers that propagates

pulses through a 1.8-mile path in most weather

conditions." (Swanson, 1967, p. 38). Goettel therefore concludes that "years of con- tinued research remain before an economical laser- transmission system becomes a reality." (Goettel,

1966, p. 193). 6.9 "Scientists from the Honeywell Research

Center in Minneapolis say that optical techniques

provide a means for increasing information storage

density above the levels obtainable with current technology. A memory element under development

will permit over two million bits of information to be

stored on a surface the size of a dime. The information can be read at the rate of 100 million bits per

second using a low power— 1 milliwatt — laser." (Bus. Automation 13, No. 12, 69 (Dec. 1967).)

6.10 "The laser will transform Raman spectroscopy from a time-consuming tool of limited useful- ness to an important analytical technique; for example, the hour-long exposures of Raman spectra on photographic plates are eliminated. Raman spec- troscopy with gas-laser beams should have widespread application in analytical chemistry and solid- state physics." (Bloembergen, 1967, p. 85). "The microscopic electrified fluid streams studied occur at high speed, and are virtually impossible to record with a conventional optical microscope or imaging system. In order to overcome the workingdistance and depth-of-field limitations of the classical microscope, a two-step imaging process

(holographic photomicroscopy) of high resolution was developed and applied to the study of the

electrostatic charging process. In this technique, one first records the optical interference pattern of

the 'scene', and then uses this record to reconstruct

the original scene. The reconstructed scene can be

leisurely examined with conventional optical

systems of limited object volume . . . "The practical consequences of pulsed laser holographic photomicroscopy go beyond the re- quirements of the present application. Reasonable

projection would indicate application to scientific

studies that involve moving unpredictable phe- nomena of either uncertain or changing location.

Physical applications include terminal and inflight ballistics, aerosol-size distributions, cloud

physics, studies of sprays, and combustion and

rocket-exhaust studies, among others." (Stephens,

1967, p. 26). "Recently at Boulder, Colo., Michael McClintock

of the NBS Institute for Basic Standards used an

argon laser as a source to obtain and analyze the

Raman and Rayleigh spectra in several transparent

liquids . . . His mathematical evaluation of the

experimental data related scattered light spectra to viscosity, to molecular rotation and vibration, and to certain molecular concentrations in mixtures of two

unassociated liquids. Analysis of the Raman

spectrum also provided new data on molecular

coupling . . . "In general, the beam from an argon ion laser was

first passed through a dispersing prism to eliminate

all but the 4880-angstrom radiation. The fight was

then examined from various angles by a spectrometer. Photomultiplier tubes served to increase the

intensity of the spectral lines so that they could be

recorded." ("Laser Applied to Molecular Kinetics

Studies", 1968, p. 242). 6.11 "A very special hologram, called a spatial

filter, has the capability of comparing two patterns

and producing a signal which is a function of the cor- relation or similarity of the patterns. Experimentally,

it has been found that complicated, natural objects

with irregular patterns can be recognized with

greater confidence than can man-made objects

which tend to be geometrically symmetrical.

Fingerprints, because of their randomness, appear

to be ideal objects for the spatial filtering method

of recognition . . . "The spatial filtering method of fingerprint recognition has several advantages over other methods

of recognition.

"Recognition is instantaneous, limited only by

the mechanical pattern input mechanism.

"Partial prints can be recognized. As long as the

information which is available does correlate,

recognition will take place even though one of the

two patterns being compared is incomplete. This

property is especially advantageous when you

are attempting to correlate partial latent prints

with complete recorded prints." (Horvath et al., 1967, pp. 485, 488).

6.12 "A laser image processing scanner (LIPS),

able for the first time to quantize high resolution

photographs for computer manipulation, has been

developed by CBS Laboratories . . . and accepted

by the Air Force . . . LIPS can simultaneously

digitize a developed high-resolution photograph

from a negative and produce a much more detailed

negative from the computer image adjacent to the original on the same drum. This makes it much

easier for a photo interpreter to recognize important

details . . . 90
"The Air Force system uses a commercial

helium-neon gas laser to produce black and white

images . . . However, color photos could be

produced by substituting an argon ion laser system . . . "Elements of LIPS include a laser light source focused on a five microns spot size on the negative

being digitized in turn feeding into a linearly

scanning microdensitometer and a computer buffer

storage.

"On reconstruction of the higher quality negative on the same drum, the same laser is employed in combination with an optical modulator in duplicate

scanning . . ." (Electronic News 14, No. 714,

38 (June 23, 1969).)

"When the Air Force permitted CBS Labs to talk about its high-resolution laser-scanning system

(part of Compass Link) used to transmit reconnais- sance photos from Vietnam to the Pentagon in minutes [Electronics, April 14, p. 56], CBS officials were optimistic about the possibility of broader

applications. A step in that direction has been

taken with the modification of the laser scanner

so that it can convert high-resolution photos for handling by a computer.

"Called LIPS-laser image processing scanner —

the system digitizes the image, then feeds the

signal through a buffer to an IBM 360/40 computer.

The computer processes the picture to emphasize

fine details or improve the contrast. The reconstructed image is then read out of the computer

onto photographic film. Thus, LIPS enables the

photo interpreter to manipulate his picture to bring out any desired detail with a high degree

of resolution.

"Routine work. In operation, the interpreter

tells the computer what areas he wants emphasized. For example, he could call for a routine

that would bring out high-frequency detail. If the

finished picture were unsatisfactory he could go

to a routine that not only would emphasize highfrequency detail, but also would suppress or clean

up large areas of black.

"LIPS uses a sequential scan to attain a resolution of 100 fines per millimeter. It can digitize, or record from digital data, a 1.8-centimeter-square

area in 15 minutes; that's at least twice as fast as conventional scanners such as those used on the

Ranger moon probes.

"CBS says the advantages of LIPS — high

resolution and geometric fidelity, high-speed readwrite rates, and operation in standard room lighting- can be used by map makers, meteorologists, or news organizations." (Electronics 42, No. 13, 46

(June 23, 1969)). 6.13 "Laser photographs, called holograms,

are true three-dimensional representations, and

the process of holography not only provides a means

for lensless microscopy but may make possible

microscopic systems at wavelengths where lenses

are not now available." ("The Lavish Laser",

1966, p. 15). "The original idea of holography and specifically,

spatial filtering dates back to 1886 when Ernst Abbe suggested their existence. However, it re- mained for Dennis Gabor to show in 1951 that a hologram, which has little recognizable information

could be 'reconstructed' to a normal recognizable

image. Various other workers showed his analysis

to be correct. Spatial filtering was investigated at about the same time by Marechal and others

primarily as a means of improving photographic

images. These pioneers demonstrated that the

concepts of holography and spatial filtering would

work, but they were handicapped by the lack of a strong source of coherent light. The advent of

the laser in 1960 as a source of essentially a single

wavelength of light excited new interest in the field of holography. Scientists at General Electric demonstrated the feasibility of using a two-beam

holographic spatial filter as a means for recognizing patterns. A. Vander Lugt, at the University of

Michigan, also investigated methods by which two- beam spatial filters could be produced." (Horvath

et al., 1967, p. 485).

"Laser beams will be used to print the catalogs

and newspapers of the future using a new technique

developed by Radio Corporation of America.

Announcement of the development of the technique

that can eliminate the need to print in signatures was made last month by the company. The method

uses the intense light produced by the laser to fuse

powdered ink spread over the paper to reproduce

the original. Excess ink is removed by vacuum. "The image comes from a photograph of the material to be printed — half-tones, line drawing or newspaper page — on a transparency. The image

is transferred with the aid of a laser beam to a hologram or lensless photograph which serves as

a permanent plate. A separate hologram is used

for each page. "Dr. Kenneth H. Fishbeck, a technical advisor

at the David Sarnoff Research Center, Princeton,

N.J., and holder of the patent, said publishers will be able to eliminate signatures since the new

process reproduces pages in sequence, from title to index. He claims publishers could almost print on demand." (SPIE Glass 5, No. 1, 12 (June 1969)).

6.14 "Dillon et al. have proposed and operated

a limited-population memory using a ferramagnetic

garnet and driven by a laser beam." (Kump and

Chang, 1966, p. 255; see also Dillon et al., 1964).

6.15 Reimann reports that: "The neuristor

laser computer, conceived at RCA, is an 'all- optical' computer in which all information and

control signals are in the form of optical energy . . . "A theoretical study of the neuristor concept

in form of Fiberglas lasers concluded that the

fundamental requirements of a neuristor line could, at least in principle, be met with lasers . . . "The main result of the laser neuristor feasibility

I

376-411 O - 70 - 7
study was the conclusion that lasers are capable

of satisfying all the requirements for digital devices.

It was shown that, in addition to the neuristor-type

logic, lasers in form of resonators and amplifiers can have input-output characteristics that resemble

those of conventional logic circuits such as gates

or flipflops." (Reimann, 1965, pp. 250-251).

"Fiber-optic elements, with appropriate concentrations of active emissive ions and passive

absorptive ions, are the basic components of this system. The computer is powered by being in a continuous fight environment that provides a constant pump power for maintaining an inverted

population of the emissive ions. Among the potentially attractive features of such a system are the

freedom from power-supply connections for indi- vidual circuits, the possibility of transmission of

signals without actual connections between certain

locations, and a promise of high-speed operation."

(Reimann and Kosonocky, 1965, p. 182).

6.16 "The feasibility of machining resistive and

capacitive components directly on thin film metallized substrates with a laser has been demonstrated.

Tantalum films can be shaped into resistor geo- metries and trimmed to tolerance by removing

metal. These films also can be oxidized to value

using the laser beam as the heat source. Resistors can be made with tolerances in value of less than

±0.1 per cent. . . . "Pattern generation by laser machining has

been demonstrated on various thin films as well

as on electroplated films. Vaporized lines as fine as 0.25 mil are readily attainable in thin films, as are 0.4 mil lines in plated films. Much narrower

lines may be obtained under particularly well- controlled conditions. Uniform lines as fine as 1 micron have been scribed in thin films on suffi- ciently flat substrates. These films have been

removed with minimum effect to the substrate

surface." (Cohen et aL, 1968, p. 403).

"Semiconductor laser digital devices offer an improvement in information processing rates of one to two orders of magnitude over that expected

from high-speed integrated transistor circuits. Data processing rates of 10 to 100 gigabits per

second may be possible using semiconductor lasers. However, the technology for fabricating low-power

laser circuits is still undeveloped and low-temperature operation may be required." (Kosonocky and

Comely, 1968, p. 1). "Laser digital devices may be used for generalpurpose logic circuits in very much the same way

that transistors are now used, except that all of the processing is done with optical rather than

electric signals." (Reimann and Kosonocky, 1965,

p. 183).

"Semiconductor current-injection lasers are most

attractive for digital devices because of their small

size, high pumping efficiency, and high speed of

operation." (Reimann and Kosonocky, 1965, p. 194).

"The utility of a laser as a tool for fabricating thin

film circuits results primarily from the spectral

purity and degree of collimation of the laser light.

These characteristics allow the beam to be focused

to a very fine and intense spot. The high heat

flux which occurs when the light is absorbed by

the target material, and the sharp definition and

localized nature of the working region allow heating,

melting, or vaporizing minute amounts of material,

with minimum effect to adjacent material or components." (Cohen et al., 1968, p. 386).

6.17 See Hobbs, 1966, p. 42. 6.18 "A new laser data storage/retrieval system

that provides a 1000-time increase in packing

density over conventional mag tape, an error rate of 1 X 10 8 or better, permanent (nonerasable)

storage, a transfer rate of 4 megabits/sec, and

instantaneous read-while-write verification has

been developed by Precision Instrument Co.,

Palo Alto, Calif. "A working demonstrator of the 'Unicon' system

uses a 1-watt argon gas laser, which makes a hole

in the metallic coating of a mylar-base tape wrapped

around a drum. The current system, using 5-micron

holes, offers a packing density of 13 million bits/sq.

in."Readout is accomplished by reducing the

laser power; beam reflection or non-reflection in- dicates nonholes or holes. The tape being used on

the current system offers storage equivalent to 10 2400-ft. reels of 800 bpi tape. The system can

serve on- and off-line, and is capable of recording

analog, FM or video data, all of which require

high speed." (Datamation 14, No. 4, 17 (Apr. 1968)).

6.19 "By early 1968, Precision Instrument

Co. had developed a massive-scale laser recorder/

reader storage system, but the first order for the

device was not received until this year. Ed Gray,

the chief engineer on the UNICON (Unidensity

Coherent Light Recorder/Reproducer) Laser Mass

Memory System, said that convincing the first potential customers that they should acquire a $500K to $1 million memory system was not easy, especially when you had to 'tell someone that you were not going to store data with magnetics like God intended.' Now that the first order has been

placed, by Pan American Petroleum Corp. of

Tulsa, Oklahoma, Mr. Gray feels that the systems

will move a little faster in the marketplace.

"The $740K system placed with Pan American

is to be installed with all requisite software about

March of 1970. Four other potential customers,

including some government agencies and a private

credit-reporting firm, are also expected to place

orders." (Datamation 15, No. 3, 116 (Mar. 1969).)

6.20 "The National Archives and Records

Service has begun a cost-effectiveness study of archival storage systems in an effort to shrink its mag tape library, which contains one million plus

reels. The study, due for completion next month,

is using the capabilities of Precision Instruments' Unicon device as a model. The Unicon employs a 92
laser-etched aluminum strip with a 30-year shelf

life." (Datamation 14, No. 10, 171 (Oct. 1968)). 6.21 "Honeywell scientists are investigating

a method that uses a laser for mass storage and

retrieval of information in computer memory.

Although emphasizing that development is still in the research stage and may be several years away from practical application, the researchers

believe the discovery is a possible key to inexpensive mass storage of data for the enormous

computer networks envisioned for the 1970's." (Commun. ACM 11, 66 (Jan. 1968)). 6.22 "The system . . . uses a modulated laser beam to inscribe data onto photosensitive discs . . . Each disc contains 3, 100 tracks with a capacity

of 67,207 bits per track, including error corrections

bits. The storage unit holds 2, 600 discs, stored on edge, in four [or eight] trays . . . two auxiliary

disc banks can be added to achieve the maximum

memory capacity ... of 150 billion characters.

The reader reaches any piece of information on

the 3, 100 tracks (per disc) within 15 milli- seconds . . ." (Business Automation 12, No. 6,

84 (1965)).

A CW helium-neon laser is used to "achieve

real-time writing of information on the system's

photosensitive memory discs." (Connolly, 1965,

p. 4). 6.23 "A method for producing erasable holo- grams may enable an optical memory to store 100

million bits in a film one inch square. "The memory could be read out, erased and

reused repeatedly, according to Dr. William

Webster, vice president in charge of RCA Laboratories. "Information can be written into the magnetic

film in 10 billionths of a second, and erased in 20 millionths of a second. Laser light split into two beams, one going directly to the film and the

other going to the information bit pattern, interferes

constructively to produce heat and consequently

a realignment of atoms. "Where the two beams interfere destructively,

nothing happens." (Data Proc. Mag. p. 21 (Sept.

1969)). 6.24 In the IBM-laser system developed for Army Electronics Command and installed at Fort Monmouth, it is noted that: "Through employment of a deflection technique, the shaft of light can be focused on 131,072 distinct points within

a space smaller than a match head. ... To

provide a readout in printed form, the laser beam

can scan through a mask inscribed with the alphabet and other symbols and — through the action

of light-bending (deflection) crystals — turn out the

final product on photo-sensitive paper." (Commun.

ACM 9, 467 (1966)).

"At International Business Machines Corp. . . . one method, devised for the Army Electronics

Command, Fort Monmouth, N.J., makes use of

a high-speed switching arrangement with electronically controlled crystals.

"Such a system could be used with a matrix

containing alphabetical or other symbols. The

laser would be used as a print-out device, pro- jecting the various symbols onto a recording

medium.

"The Air Force Systems Command at WrightPatterson AFB is interested in IBM's work on a variable frequency laser which might be used in conjunction with a color-sensitive computer.

This type of setup is said to have a potential capacity

of a hundred million bits per square inch of photographic material." (Serchuk, 1967, p. 34). 6.25 "Instead of recording a bit as a hole in a card, it is recorded on the file as a grating pattern

of a certain spacing ... A number of different grating patterns with different spacings can be

superposed and when light passes through, each

grating bends the light its characteristic amount,

with the result that the pattern decodes itself . . . The new system allows for larger areas on the film

to be used and lessens dust sensitivity and the

possibility of dirt and scratch hazards." (Commun.

ACM 9, No. 6, 467 (June 1966).)

6.26 "Recently Longuet-Higgins modeled a temporal analogue of the property of holograms

that allows a complete image to be constructed

from only a portion of the hologram. In the present

paper a more general analogue is discussed and

two two-step transformations that imitate the

recording-reconstruction sequence in holography

are presented. The first transformation models

the recall of an entire sequence from a fragment

while the second is more like human memory in that it provides recall of only the part of the se- quence that follows the keying fragment." (Gabor,

1969, abstract, p. 156).

6.27 "A new recording mechanism . . . consists of the switching of magnetization under the

influence of a stress resulting from a heat gradient

introduced by a very narrow light or electron beam.

The mechanism is assumed to be magnetostriction

with a rotation of the anisotrophy. The model pre- sented and the criteria for recording are supported,

at least in part, by experimental observations."

(Kump and Chang, 1966, p. 259).

6.28 "In attempts to provide computers with

previously unavailable amounts of archival (readonly) storage, various techniques involving optical

and film technology have been employed to utilize the high information capacity of film (approximately

106 bits/in. 2

) and the high resolution and precision

of lasers and electron beams. The trillion-bit IBM 1350 storage device, an offshoot of the

'Cypress' system, . . . uses 35 mmX70 mm silver halide film 'chips.'

"A total of 4.5 million bits are prerecorded on each chip by an electron beam. For readout, a

plastic cell containing 32 film chips is transported

to a selector, which picks the proper chip from

among the 32; average access time to any of the

1012 bits is 6 seconds. After a chip is positioned,

information is read using a flying-spot CRT scanner. 93
Two IBM 1350 units are scheduled for mid-1967

delivery to the Atomic Energy Commission at Livermore and at Berkely for use with bubble

chamber data. Other techniques of reading and

writing with electron beams are explained by

Herbert." (Van Dam and Michener, 1967, p. 205).

6.29 "Results of basic theoretical studies con- ducted at the NCR research laboratories have

indicated that CW lasers of relatively low power

should be capable of permitting very high resolution real-time thermal recording on a variety of

materials in the form of thin films on suitable

substrates. Subsequent laboratory studies have

shown that such thermal recording is indeed

possible. This recording technique has been termed

heat-mode recording." (Carlson and Ives, 1968,

p. 1). "The recording medium is coated on a 5- by

7-inch glass plate, a quarter of an inch thick. The

plate carrier mechanism is capable of stepping in the horizontal and vertical directions to form

matrices of up to 5,000 images at an overall reduction of 150 to 1." (Carlson and Ives, 1968, p. 5). "The results of the studies described in this paper have established laser heat-mode recording

as a very high resolution real-time recording

process capable of using a wide variety of thin

film recording media. The best results were obtained with images which are compatible with

microscope-type optics. The signals are in elec- tronic form prior to recording and can receive

extensive processing before the recording process

occurs. In fact, the recordings can be completely

generated from electronic input. For example,

Figure 6 shows a section of a heat-mode microimage

with electronically generated characters, produced

by the Engineering Department in our Division.

The overall image is compatible with the 150-to-l PCMI system (less than 3 mm field), and consists

of 73 lines of characters, 128 characters per line. Although this image was recorded in 1.6 seconds,

faster recordings are anticipated. A description

of this work will be published in the near future."

(Carlson and Ives, 1968, p. 7). 6.30 "Another scheme for storing digital in- formation optically is the UNICON system, under

development at Precision Instrument Company.

This system uses a laser to write 0.7-microndiameter holes in the pigment of a film. Information

is organized in records of at most a million bits; each record is in a 4-micron track extending about a meter along the film. Individual tracks are slanted

slightly so that they extend diagonally across the

film. (The amount of slant and the width of the

film determine the length of the records.) Each

record is identified by information stored next

to the beginning of that record, in an additional

track at the edge of the film. Readout of a particular

record involves scanning the identifier track for the proper code and then scanning the track with a

laser weaker than that used for writing. It is pre- dicted, on the basis of an experimental working

model, that one UNICON device with 35 mm film could store a trillion bits on 528 feet of film, with an average access time to a record of 13 seconds."

(Van Dam and Michener, 1967, p. 205). (See also note 6.14). 6.31 "Considerable experimentation in modulation and transmission is needed before optical

communication by laser can be said to be really

useful except in very specialized cases." (Bloom,

1966, p. 1274).

6.32 "At first sight a laser communication

system with its extremely wide information carrying

capacity would appear to be a natural choice for an interplanetary communication system. However, among other things, the acquisition and

tracking problems are considered to be so severe

that such a system is not thought to be realistic at the present time. This may be indicative of an in- formation technology utilization gap." (Asendorf,

1968, p. 224).

6.33 "In general, earthbound laser-ranging

systems are limited by local atmospheric conditions.

A typical value of range routinely measured is 20 km or less." (Vollmer, 1967, p. 68). "Earthbound applications of coherent optical

radiation for communications appear to be severely

limited for two reasons. The first, and most significant, is the effect of atmospheric turbulence on the

coherence of the radiation. The second is the effect of small vibrations on the coherent detection

efficiency and signal-to-noise ratio. This can be

minimized by careful design, but the first factor is beyond the designer's control. Although coherent

optical detection has been demonstrated over some useful paths, the vulnerability of the link to atmospheric variations makes practical application somewhat doubtful." (Cooper, 1966, p. 88). 6.34 "Is the enormous increase in bandwidth

offered by light as a carrier frequency in communications needed? For transmission in space the acquisition and aiming of the light beams pose formidable

problems. In the atmosphere, rain, smog, fog,

haze, snow, etc., make fight a poor competitor of

microwaves. Can a system of enclosed tubes with

controlled atmosphere and light repeater stations

be built on a technologically sound and economically feasible basis?" (Bloembergen, 1967, p. 86). 6.35 "Information Acquisition, Sensing, and

Input", Sect. 3.1.1. Some additional references

are as follows: "Since the first laser was demonstrated in 1960,

considerable interest has developed in its possibilities for use in communication systems. The

basic sources of this interest are the coherent

nature of the radiation obtained as compared with

all previously known extended sources of optical

radiation, and the laser's short wavelength. This

latter characteristic provides the potential ability to achieve bandwidths, or information capacities,

that are orders of magnitude greater than anything

obtained heretofore. A more realistic advantage,

in terms of presently available information sources, 94
results from the combination of high coherence and

short wavelength. It is the ability to generate a

highly collimated beam (limited by diffraction phenomena), which leads to the ability to achieve

communications over great distances. Of equal

importance is the fact that with a coherent signal,

coherent detection of the information can be

obtained with greatly improved immunity to natural

incoherent noise sources such as the sun." (Cooper,

1966, p. 83). "The first enthusiastic suggestions that laser technology potentially provides many orders of

magnitude more communication capability than

RF technology, and that it might, therefore, offer the only solution to the problem of general wideband

communications with deep-space probes, needs

to be more carefully assessed." (Dimeff et al., 1967, p. 104).

"For deep-space, wide-band communication . . . another factor may be . . . important — namely, the

size of the transmitting aperture. A very large

aperture, as would undoubtedly be required by a microwave channel, is likely to prove an obstruction

to the sensors of the aircraft and will, therefore,

reduce the time available for collecting information

or transmitting it. In this respect, the laser has an

important advantage over microwave." (Brookner

et al., 1967, p. 75). "Several optical links which use GaAs injection

lasers as transmitters have been constructed. One

of them has been demonstrated to be capable

of transmitting 24 voice channels over 13 km."

(Nathan, 1966, p. 1287).

6.36 "If we classify our communication requirements on the basis of range, we find that lasers can

be helpful at the range extremities — that is, for distances less than about 15 km and for those

greater than 80 million km." (Vollmer, 1967, p. 66). 6.37 "An electronic system that transmits

military reconnaissance pictures from Saigon to Washington in minutes via satellite may soon

enable news media to dispatch extremely highquality photographs and type around the world

for instant reproduction.

"Potential benefits are also foreseen for medicine,

earth resources surveys and industry.

"The high-performance system was developed

for the U.S. Air Force Electronics Systems Divisions

by CBS Laboratories, a division of Columbia

Broadcasting System, Inc. It combines electro- optical and photographic techniques to relay highl resolution aerial photographs of ground activity

in Vietnam to the President and Pentagon officials. Pictures seen by the President are many times

sharper than the best pictures shown on home

television sets. "Within minutes after photographs have been

taken in Vietnam, they are readout by the system's

electronic scanning device and converted to video signals. The signals are then fed to a communication link, which relays them over the U.S. Defense Satellite Network to Washington. A

similar receiving and recording station there reconstructs the photographs to their original form

for immediate inspection." (Spie Glass 5, No. 2,

9 (Aug. 1969).)

"According to Air Force officials, pictures pro- duced by the CBS Laboratories Image Scanning

and Recording System contain the highest resolution ever reported in the transmission of aerial reconnaissance photographs. High-altitude photographs processed by the system show such detailed

information as identification numbers of ships in port, planes on runways and troop movements . . . "In operation, the lightweight system uses a precisely controlled laser beam to scan rapidly across photographic film. The laser converts each picture

frame to an electronic video signal. The signal is then fed to a transmitting device for satellite relay,

said John Manniello, CBS Laboratories Vice

President for Government Operations, who con- ceived the system application. Once the signals contact the satellite, they are flashed to a receiving

station in Washington within seconds, he added.

"The receiving station — which has related photoscanning, recording and developing equipment —

reconstructs the video signal to the original film image and produces high-quality photographic

prints.

"Because of the laser-scanning technique in- volved, no photographic resolution is lost between

recording and transmission from the original

film taken in Vietnam." (Spie Glass 5, No. 2, 9

(Aug. 1969).)

6.38 "Superficially, it appears attractive to have

fast switching, high storage density, direct visual

display. Such developments would depend heavily on the availability of cheap, small, high-quality

semiconductor lasers. If these were available, the

entire organization of computers using them would

probably be different." (Bloembergen, 1967, p. 86). 6.39 "The power and efficiency available from

lasers at the desired wave lengths (particularly

ultraviolet) must be improved, and adequate laser deflection techniques must be developed before

laser displays will be feasible for widespread use." (Hobbs, 1966, p. 1882).

"Since lasers don't require vacuums, there is a significant convenience relative to electron

beams. But there is a severe penalty compared to electron beams due to problems in deflecting,

modulating, and focusing." (Gross, 1967, pp. 7-8).

"Lasers offer great promise for future implementation of display systems — particularly large- screen displays. The ability of a laser to deliver

highly concentrated fight energy in a coherent beam

of very small spot size is well known. Several dif- ferent approaches to laser displays are being in- vestigated. Since they all require some means for deflecting and modulating the laser beam, considerable development efforts are being expended

on deflection techniques. Digital deflection of

lasers by crystals has been satisfactorily demonstrated for 256 positions in each direction, but at
least 1024 positions in each direction are needed

for a practical large-screen display system." (Hobbs,

1966, p. 1881).

"The laser is an efficient light source, and its output can be focussed to small sizes and high

power densities. There is confidence that laboratory means for modulating lasers and deflecting their

beams will be found practical." (Bonn, 1966, p. 1869).

"More rapid progress would be made in utilizing laser recording if better means of deflecting laser beams at the desirable speeds and resolutions

existed or were clearly foreseeable." (Smith, 1966,

p. 1297).

"An experimental device that can switch the

position of a light beam more than a thousand

times faster than the blink of an eye could become

an important part of computer memories of the

future. The device, a digital light deflector, was

developed at the IBM Systems Development

Div. laboratory in San Jose, Calif. "The experimental deflector changes the location

of a beam in 35 millionths of a second by a unique

method of moving a glass plate in and out of contact with a prism.

"High-speed deflectors of this type are potentially useful in future optical memories to randomly

position a laser beam for data recording and reading.

Such beam addressable memories are expected

to be many times faster than present magnetic

storage methods because of the relative speed

of relocating a light beam in comparison to moving

a bulky recording head." (Computers & Automation

18, No. 5, 68 (May 1969).)

6.40 "Another attractive approach is the use of

a laser beam to write directly on a large luminescent

screen. This is somewhat equivalent to an 'outdoor'

cathode-ray tube in which the laser beam replaces

the electron beam and the luminescent screen

replaces the phosphor face plate of the tube.

It offers advantages over a CRT in that a vacuum

is not required and a large-screen image can be

generated directly. One feasibility system has been

developed using a 50 milliwatt neon-helium gas

laser, a KDP crystal modulator, a piezoelectric

crystal driven horizontal deflecting mirror, and a galvanometer driven vertical deflecting mirror to provide a television rastor scan image projected onto a 40 inch screen. Brightness of 50 foot-lamberts, contrast ratio of 100 to 1 (dark environment),

resolution of 1,000 to 2,000 lines, and update time

of 33 milliseconds are anticipated for direct view

laser systems." (Hobbs, 1966, p. 1882). 6.41 "Electron-beam devices, including those

which use photographic emulsions and thermoplastic films, operate in a vacuum, which is a nuisance." (Bonn, 1966, p. 1869).

6.42 "By definition, phototropy is the photochemical phenomenon of changing some physical

property (color) on exposure to electromagnetic

radiation (light) and returning to its original (colorless) state after removal of the activating source

and under a de-activation condition and/or at a

later time." ("Investigation of Inorganic Phototropic Materials . . .", 1962, p. 1). "The property of certain dyes and other chemical

compounds to exhibit a reversible change in their absorption spectrum upon irradiation with specific

wavelengths of fight has been termed phototropism,

or photochromism. The emphasis in this definition

is on reversibility, because, upon removal of the

activating radiation the systems must revert to their original states to be considered photochromic."

(Reich and Dorion, 1965, p. 567).

"By definition, photochromic compounds exhibit

reversible spectral absorption effects — color

changes, resulting from exposure to radiant energy

in the visible, or near visible, portions of the

spectrum. For example, one class of photochromic

materials consists of light-sensitive organic dyes.

NCR photochromic coatings consist of a molecular

dispersion of these dyes in a suitable coating

material. Photochromic coatings are similar to photographic emulsions in appearance and with

respect to certain other properties. Coatings can

be made to retain two-dimensional patterns or images which are optically transferred to their surface." (Hanlon et al., 1965, p. 7). "Photochromic film, a reusable UV sensitive

recording media has progressed to the point

where prototype equipment is being designed."

(Kesselman, 1967, p. 167).

6.43 "Photochromic coatings exhibit excellent

resolution capabilities. In addition, both positiveto-negative and direct-positive transfers are possible . . . The coatings are completely grain-free,

have low gamma (excellent gray scale characteristics), and exhibit inherently high resolution . . . Further, because the coatings are reversible, the

information stored can be optically erased and

rewritten repeatedly." (Hanlon et al., 1965, p. 7). "Photochromism may be defined as a change in color of a material with radiation (usually near

ultraviolet) and the subsequent return to the

original color after storage in the dark. Reversible

photochromism is a special case of this phenomenon

in which a material can be reversibly switched by

radiation between two colored states. Photochromic

compounds may be valuable for protection from

radiation; reversibly photochromic materials are

potentially valuable for data storage and display

applications." (Abstract, talk on photochromic

materials for data storage and display, by U. L. Hart and R. V. Andes, UNIVAC Defense Systems

Division, at an ONR Data Processing Seminar,

May 4, 1966, See also Hart, 1966).

6.44 "Most of the systems so far reported are only partially, or with difficulty, reversible, or are subject to fatigue — a change in behavior either

with use or with time in storage." (Smith, 1966,

p. 40). "Organic photochromic materials fatigue with use." (Bonn, 1966, p. 1869).

6.45 "Photochromic films permit the storage

96
of images containing a wide contrast of gray

scale because they are inherently low gamma and

grain-free." (Tauber and Myers, 1962, p. 409).

6.46 "It is recorded that Alexander the Great

discovered a substance, whose composition has

been lost in the obscurity of antiquity, that would

darken when sunlight shone upon it. He dipped a narrow strip torn from the edge of his tunic into a solution of the material and wore this strip

wrapped about his left wrist. Many of his soldiers

did the same. By observing the changes of color

during the day, they could tell the approximate

hour. This became known as Alexander's rag

time-band. (I am sorry that I cannot identify, and

hence cannot give proper credit to the author of

this delightful footnote to history.)" (Smith, 1966,

p. 39). 6.47 "1. Photochromic films provide very high

resolution with no grain.

"2. Photochromic films permit the storage

of images containing a wide contrast

of gray scale because they are in- herently low gamma and grain-free.

"3. Photochromic films provide immediate

visibility of the image upon exposure.

No development process is required.

"4. Photochromic films provide both

erasing and rewriting functions.

This permits the powerful processes

editing, updating, inspection, and

error correction to be incorporated

into systems.

"5. The PCMI process incorporates the

ability to effect a bulk-transfer read-out

of micro-images at the 200:1 reduction

level by contact printing.

"6. Use of high-resolution silver halide

films provides both permanency for the storage of micro-images and eco- nomical dissemination of duplicates.

"7. The very high density of 200:1 microimages offers the possibility of using some form of manual retrieval tech- niques for many applications. This

eliminates the normal requirement in systems of this size for expensive and

complex random access hardware."

(Tauber and Myers, 1962, p. 266). In the photochromic micro-image (PCMI) microform process developed by the National Cash

Register Company there have been achieved

"linear reductions from 100-to-l to greater than

200-to-l, representing area reductions from 10,000-

to-1 to greater than 40,000-to-l, [which] have been

successfully demonstrated by using a variety of image formats, such as printed materials, photographs, drawings, and even fingerprints." (Hanlon

et al., 1965, p. 1), "NCR has developed a number of research

prototype readers for viewing PCMI transpar- ences . . . [including] a miniaturized microimage

reader . . . which was designed specifically for possible use aboard a manned space vehicle. The

reader would have a self-contained, fixed reference

file of up to 50,000 pages of information, such as navigational charts, planetary and space data,

and checkout, maintenance, and emergency

procedures." (Hanlon et al., 1965, p. 13). "Current design emphasis by NCR has been

toward the development of low cost PCMI readers

for commercial applications." (Hanlon et al., 1965, p. 19). 6.48 "The information glut threatening to swamp

the engineer and the scientist is being eased by a

British organization called Technical Information on Microfilm. The medium of the 'message' is the

National Cash Register Company's PCMI process. This makes possible the storage of over 3000 printed

pages of information on a single 4-by-6-inch trans- parency. The system used by TIM enables the

engineer to locate the data he wants in a matter

of seconds. He simply selects the proper trans- parency and immediately locates the appropriate

page images with an NCR reader which displays

the selected pages on an illuminated viewing screen. TIM points out that one of the most valuable sources

of information to engineers and scientists is manufacturers' literature. The problem has been that

this is produced in an extraordinary variety of

forms. These are difficult to catalogue comprehensively and they also create an enormous bulk. The NCR-developed PCMI technology involves

a photochromic coating which produces an image

that is virtually grain-free. The process permits

a microscopic-size reduction which is not practical

with conventional microfilm processes. NCR is producing the transparencies for TIM in its Dayton,

Ohio processing center from 35-millimeter microfilm supplied by the British firm. All data is updated

every six months." (bema News Bull., Dec. 9, 1968,

P. 8). 6.49 "Information stored on photochromic

coatings is semipermanent . . . This is a result of the reversible nature of the photochromic coating.

The life of the photochromic micro-image is de- pendent upon the ambient temperature of the coating. At room temperature, image life is measured

in hours, but as the temperature is lowered, life can be extended very rapidly to months, and even

years." (Hanlon et al., 1965, p. 8). 6.50 "The temperature-dependent decay of

image life obviously prohibits the use of photochromic micro-images in their original form for archival storage. To overcome this problem, means

have been developed for contact-printing the photochromic micro-images to a high-resolution

photographic emulsion, thereby producing

permanent micro-images." (Hanlon et al., 1965,

pp. 8-9).

"The entire contents of the photochromic microimage plate are then transferred (as micro-images)

in one step, by contact-printing onto a high-resolution silver halide plate . . . Micro-image dissemi97
nation (duplicate) films are prepared in a similar

manner, using the silver masters to contact-print onto high-resolution silver halide film." (Hanlon

et al., 1965, p. 9). 6.51 Further, "a more realistic assessment . . . so that spillover, halation, and registration restric- tions would not be impossibly severe, still results

in a contiguous bit density of 107cm2 ." (Reich and

Dorion, 1965, p. 572).

6.52 "Transparent silicate glass containing

silver halide particles darkens when exposed to visible light, and is restored to its original trans- parency when the fight source is removed. These

glasses have been suggested for self-erasing memory

displays, readout displays for air traffic controls,

and optical transmission systems. . . . "Photochromic glass appears to be unique among

other similar materials because of its non-fatiguing

characteristics. No significant changes in photochromic behavior have resulted from cycling o JO

samples with an artificial 3600A black light source up to 30,000 cycles. There were also no apparent

solarization effects causing changes in darkening

or fading rates after accelerated UV exposure

equivalent to 20,000 hours of noon-day sunshine."

(Justice and Leibold, 1965, p. 28). "Another potentially important application of

photochromic materials is in the display of infor- mation. Data can be recorded in photochromic

glass in two ways: by darkening the glass with short- wavelength light in the desired pattern; or by uni- formly darkening the glass and bleaching it, in the

desired pattern, with longer wavelength light."

(Smith, 1966, p. 45). 6.53 "To produce a display, patterns of varying

optical density are written on photochromic film with a deflected ultraviolet light beam. The film so exposed forms the 'object' in a projection system.

Visible light is projected through the film onto a screen. This display has mechanical simplicity,

controllable persistence, and a brightness comparable to conventional film-projection displays."

(Soref and McMahon, 1965, p. 62). 6.54 "For dynamic applications such as target

tracking, this technique not only permits a real- time target track, but also provides target track

history in the form of a trace with 'intensity'

decreasing with time. The time period covered by

the visible target track history is a function of the photochromic material. At the present time,

the speed of photochromic materials limits the

character generation rate to less than 100 characters

per second. Successful development of faster photochromic materials will provide an attractive

electro-optical dynamic large-screen display with no mechanically moving parts." (Hobbs, 1966,

p. 1879).

6.55 "One of the technological trends which

will give us mass memories at a viable price is photochromic microimagery. Photochromic tech- niques—by which as many as 2,000,000 words

can be stored on a film transparency only 4 inches

by 6 inches — can now be used to store a pattern

of bits instead of images of pictorial or alphabetical

information. Photochromic high-resolution films coupled with proper light sources and optical

systems can provide the storage of millions of bits to the square inch. A micro-holographic indexing

system used with such storage devices may revolutionise data storage and retrieval." ("R and D for Tomorrow's Computers," 1969, p. 53). 6.56 "The breadth of the sensitivity characteristics of the photochromic films in conjunction

with the width of the spectral characteristics of the

available phosphors present a potential systems

designer with a choice of a number of component

parts . . . Future improvements in CRT-photochromic film display systems are dependent upon

the capabilities of each of the components. The

basic parameters which enter into the cathode

ray tube efficiency are the fiber optic plate and

phosphor. An increase in the fiber optic efficiency

is doubtful except through the use of higher numerical aperture fibers. Increasing the numerical

aperture has the disadvantage of requiring a higher

degree of control on the film-CRT gap. An improvement in basic phosphor efficiency is difficult to foresee although several military agencies are now or will be sponsoring programs to achieve

this goal.

"An advance of the state-of-the-art of phosphor

technology should be possible by a factor of 4,

but probably not beyond. By careful optimization

of the phosphor deposition with respect to particular

applications some improvement is possible. At

the same time an increase in the efficiency of the

photochromic film by a factor of 2 is theoretically

possible. Of more importance to the system de- signer is the understanding and optimization of writing and rewriting rates as they affect phosphor

efficiency and life and in the matching of the CRT

with the photochromic film." (Dorion et al., 1966,

p. 58). 6.57 "Wavefront reconstruction was invented

by Gabor and expounded by him in a series of

classic papers [1948-1951]." (Armstrong, 1965,

p. 171).

"The wavefront reconstruction method of image

formation was first announced by Gabor in 1948."

6.58 Stroke gives a derivation of the term: "Hence, the name 'hologram' from the Greek

roots for 'whole' and 'writing'." (Stroke, 1965, p. 54). And also defines it: "A hologram is therefore an

interference pattern between a reference wave

and the waves scattered by the object being re- corded." (Stroke, 1965, p. 53). 6.59 See also the following:

"Arbitrary objects . . . are illuminated by

parallel laser light. In the general case, the light

reflected by these objects will be diffuse and the

reflected wavefronts will proceed to interfere in the photosensitive medium where the interference

pattern can be recorded. After the photosensitive

medium has been exposed and processed it is 98
called the hologram, which may be defined as the

recorded interference of two or more coherent

wavefronts. When the hologram is illuminated by

one of the original wavefronts used to form it, the

remaining wavefronts are reconstructed . . . Observation of these reconstructed wavefronts is nearly equivalent to observing the objects from

which they were originally derived." (Collier, 1966,

p. 67). "An optical hologram is a two-dimensional photographic plate which preserves information about

the wavefront of coherent light which is diffracted

from an object and is incident upon the plate. A

properly illuminated hologram yields a three- dimensional wavefront identical to that from the

original object, and thus the observed image is an exact reconstruction of the object. The observed

image has all of the usual optical properties as- sociated with real three-dimensional objects;

e.g., parallax and perspective." (Lesem et al., 1967, p. 41). 6.60 "Holography is the science of producing

images by wavefront reconstruction. In general no lenses are involved. The reconstructed image

may be either magnified or demagnified compared

to the object. Three-dimensional objects can be

reconstructed as three-dimensional images."

(Armstrong, 1965, p. 171). 6.61 "Are Holograms Already Outdated?

Holography is one of the most exciting developments

of today's technology. Holograms make use of a high-energy laser beam to store or display three- dimensional images for such applications as readonly storage; packing densities and device speeds

are extremely impressive. However, at today's

pace of innovation, holography may be outmoded

before it approaches being practical. One of the

latest competitors for 3-D display, storage, and wave

conversion applications is the kinoform, a new wavefront reconstruction device which also projects a 3-D image, but requires one-fourth of the computer

time to generate and creates images roughly three

times as bright.

"A computer program is used to produce a coded

description of light being scattered from a particular

object. The resultant computations are used to produce a 32-grey-level plot which is photoreduced

and bleached. Then, when subjected to even a very small fight source, such as the girl's earring

in the photo above, the 3-D image is formed. A

kinoform image can be produced of any object which

can be computer-described. Examples might in- clude proposed buildings, auto designs, relief maps, or two-dimensional alphanumeric data."

(Datamation 15, No. 5, 131 (May 1969)). 6.62 "The kinoform is a new, computer-generated, wavefront reconstruction device which, like the hologram, provides the display of a three- dimensional image. In contrast, however, the

illuminated kinoform yields a single diffraction order and, ideally, all the incident light is used

to reconstruct this one image. Similarly, all the

spatial frequency content or bandwidth of the

device is available for the single image. Computationally, kinoform construction is faster than

hologram construction because reference beam

and image separation calculations are unnecessary.

"A kinoform operates only on the phase of an

incident wave, being based on the assumption that only the phase information in a scattered wavefront is required for the construction of an image

of the scattering object. The amplitude of the

wavefront in the kinoform plane is assumed constant. The kinoform may therefore be thought of

as a complex lens which transforms the known

wavefront incident on it into the wavefront needed

to form the desired image. Although it was first conceived as an optical focusing element, the

kinoform can be used as a focusing element for any physical waveform, e.g., ultrasound or microwaves." (Lesem et al., 1969, p. 150).

6.63 "A new hologram made at Bell Telephone

Laboratories now allows the viewer to see a 3D

image rotate through a full 360 degrees as he moves

his head from side to side ... To make a flat hologram with a 360-degree view, vertical strips of the photographic plate are exposed sequentially

from left to right across the plate. A narrow slit in a mask in front of the plate allows only one

strip to be exposed at a time, each strip becoming

a complete hologram of one view of the object."

(Data Proc. Mag. 10, No. 4, 16 (Apr. 1968)).

6.64 "Holography provides an alternative

description of pictures, which might be more

amenable to bandwidth compression. To investigate

this possibility, it is desirable to measure various

statistics of the hologram, and to try various operations on it to see what their effects would be on

the reconstructed pictures. . . . Holography and

other coherent optical processing . . . techniques

have made possible relatively simple ways of obtaining the Fourier transforms of two-dimensional

functions and operating on them in the frequency

domain." (Quarterly Progress Report No. 81,

Research Laboratory for Electronics, M.I.T.,

199 (1966)).

6.65 "Gabor and others have proposed the use

of the wavefront reconstruction method to produce

a highly magnified image, using either a change in wavelength between recording of the hologram and

its reconstruction, or by using diverging light for one or both steps of the process. The two-beam

process is readily amenable to such magnification . . ." (Leith et al., 1965, p. 155).

6.66 "Color reconstructions should be attainable

from black and white holograms if suitable temporal

coherence conditions are ensured." (Stroke, 1965,

p. 60). "Holography is another field for which the laser has opened many possibilities. Perhaps it will find useful applications in pattern recognition and

in storage of three-dimensional information as a Fourier transform. . . . 99
"Three-dimensional displays of airfield ap- proaches in the cockpit of a jet finer with the correct viewing angle from the position of the aircraft would be a more interesting application [of laser- holographic recordings]." (Bloembergen, 1967,

p. 86). "We read about images having three-dimensional

properties, magnification obtained by reconstruct- ing with a wavelength greater than that used in forming the hologram, diffuse holograms which, even when broken, produce whole images, multicolor images obtaining from emulsions which

normally produce only black and whites." (Collier,

1966, p. 67). "The recording of surface deformations in engineering components demonstrated here shows

how these techniques may be applied at low cost and in a short time. For teaching purposes it has

been shown that interference holography of the

distortions of a rajor blade can be demonstrated

adequately to a large group of people in only a few minutes." (Bennett and Gates, 1969, p. 1235).

"With practical applications for holograms still in the few-and-far-between stage, the Office of

Naval Research and IBM believe they have a holo- graphic application that is both practical and

unique: in a head-up, all-weather landing system.

"The system — now at the laboratory model

stage — employs a hologram of an aircraft carrier. The hologram is picked up by an infrared vidicon

and projected on a crt cockpit display . . . "The achievement is one of application in which

a two-dimensional representation with the so- called six degrees of freedom encountered in a carrier landing, and full ranging capability, is produced without employing a computer. The

demonstration model simulates an approach window

two miles wide and a half-mile high and offers a 3.5-degree glide slope. The six degrees (glide-slope

deviation, localized deviation, depression angle,

bearing angle, roll, and slant angle) are achieved

mechanically, electronically, and optically. For

example, roll is achieved as the vidicon itself is rolled; glide-slope deviation is simulated by manipulating the hologram. In the model, the generated

image allows a view which includes magnification

of the holographic image of the carrier up to 16-to-l and permits views including one below

the deck of the carrier." (Electronics 42, No.

13, 46 (June 23, 1969).)

"General Electric has also examined the hologram

for potential in character recognition. One method

suggested by GE is to create a spatial filter using

a hologram. This filter can be used to detect, or recognize, specific shapes from among a random

assortment. "This general scheme is the basis for a personnel

identification system being developed by National

Cash Register Co., Dayton, Ohio.

"According to NCR, two of the most important

aspects of identification are signatures and photographs. In the NCR system, a hologram containing

signatures and numbers randomly located is placed

in the optical path of a laser. "If matching occurs when a signature card is inserted into a receiving device, the system locates

the picture [which] is projected for comparison."

(Serchuk, 1967, p. 34). 6.67 "The wavefront reconstruction method

offers the possibility of extending the highly de- veloped imagery methods of visible-light optics

to regions of the electromagnetic spectrum where

high-quality imagery has not yet been achieved . . ." (Leith et al., 1965, p. 157).

6.68 "A Megabit digital memory using an array

of holograms has been investigated by Bell Laboratory scientists. The memory is semipermanent,

with information being stored in the form of an

array of holograms, each hologram containing a page of information. A page is read ... by

deflecting a laser beam to the desired element of

the array, so as to obtain reconstruction of the

image stored in the element — the digital information—on a read-out plane which is common to all elements of the array. Photosensitive semiconductors arrayed on the read-out plane then sense

the stored information . . . "In the Bell Labs experimental system, the fight source is a continuous-wave helium-neon laser operating in the lowest order transverse mode.

Two-dimensional deflection is accomplished by

cascaded water-cell deflectors, using Bragg dif- fraction from ultrasonic waves in water, and

capable of deflecting the beam to any of 300

addresses in less than 15/u,sec . . . "The present system comprises 6 k bits per page,

and a 16 X 16 matrix of pages, for a total capacity

of 1.5 M bits access time is 20 /xsec. Total optical

insertion loss is 75 db, resulting in 70 k photons

impinging on each bit detector . . . and Bell Labs scientists project that, by straightforward

extensions of the present system, 25 M bits with an

access time of 7 yitsec is a feasible system. This

system would have 65 X 65 matrix of 6 k bit pages, a

faster deflection system, and a reduced insertion

loss of 65 db, resulting in 0.5 M photons per bit

at the detectors.

"Ultimately, it is predicted that a memory can

be built having greater than 100 million bits of

storage, with an access time in the one microsecond

range." (Modern Data Systems 1, No. 2, 66 (Apr.

1968).)

"Bell Labs has already constructed a 'bread- board' hologram memory system . . . that may

eventually be able to display any one of 100 million

units of information upon one millionth of a second's

notice.

"It is based on using a number of closely spaced

holograms on a single photographic plate. Bell Labs had in mind switching operations as one fundamental application . . . "This memory system works by directing a laser 100
beam to one 'page' (location of a hologram) in an

array. Initial goals are to make each hologram

about a millimeter in diameter and to space them

rather closely in a pattern of 100 rows by 100 rows. Each hologram will store, encoded in the form of an interference pattern, another 100 by 100 matrix.

This will be coded in dots or blanks to represent

information. The reconstructed hologram will be aligned precisely with an array of phototransistors (also under development at Bell Labs),

which will 'report' to the electronic device which

of the dots are present and which are absent. This

roll call is the message." (Photo Methods for Industry 12, No. 3, 61-62 (Mar. 1969)).

6.69 "Carson Laboratories, Bristol, Conn.,

for example is working on the development of

potassium bromide and similar crystals as holo- graphic materials.

"The 1 laser is used to bleach the crystal in accordance with the holographic interference

patterns. Such a memory device is said to have a capacity of 1 million bits per square half-inch of

material." (Serchuk, 1967, p. 34). 6.70 "An experimental optical memory system

that could lead to computer storage devices a thousand times faster than today's disk and drum

storage units was reported ... by three Inter- national Business Machines Corporation engineers. "In the experimental system, blocks of infor- mation are accessed by a laser beam in just ten- millionths of a second. More than 100 million bits of computer information could be stored on a nine

square inch holographic plate . . . "The experimental memory system uses a laser beam to project blocks of information contained on

the hologram onto a light-sensitive detector. The

detector then converts the projected hologram into electronic signals which can be processed by a computer.

"In a feasibility model, assembled at IBM's

Poughkeepsie, N.Y., Systems Development Divi- sion Laboratory, size, direction, and focus of the

laser beam are determined by a series of lenses. The beam is positioned on the hologram by a

crystal digital light deflector. By controlling the

polarization of the light from the laser the deflector

is used to select any block of information stored on

a single plate.

"The hologram splits the laser beam into two

separate rays: one non-functional and the other a

first-order diffraction pattern which carries the

holographic information. This first-order diffraction pattern is then focused on a light-sensitive detector

array, which converts the optical information to electronic signals. The signals, representing data, are then sent to the computer's central processing

unit at high speeds." (bema News Bull. 5, Nov.

18, 1968). 6.71 "An advantage of storing information in the form of a hologram rather than as a single real image is that the loss of data due to dust and

film defects is minimized, since a single bit is

stored not on a microscopic spot on the film but as

part of an optical interference pattern which is contained in the entire hologram." (Modern Data

Systems 1, No. 2, 66 (Apr. 1968).)

"A bad spot in a photographic image will not

spoil all bits of information completely; the Fourier

transform of such a plate will still give a good

image." (Bloembergen, 1967, p. 86). "Since information from any one bit of the object

is spread out over the whole hologram, it is stored

there in a redundant form, and scratches or tears

of the hologram make only a minor deterioration

in the overall reconstructed image. In particular, no single bit is greatly marred by such damage to the hologram." (Smith, 1966, p. 1298).

"Leith reports that diffused illumination holo- grams have an immunity to dust and scratches

and that particles have little effect in producing

erroneous signals as in previous photographic

memories." (Chapman and Fisher, 1967, p. 372).

"Since light from the point source is spread over

the entire hologram's surface (thus ensuring inter- ference patterns over the entire film surface),

any part of the hologram will reproduce the same

image as any other part of the hologram. It can be seen that the only effect of dust and scratches

is to reduce the active area of the hologram."

(Vilkomerson et al., 1968, p. 1199).

"Generally, the light projected into an image by

a hologram is not associated with any specific

point of the hologram, thus, if the hologram becomes

marred by dust or scratches there is little degradation of any one point in the image. Dust and film imperfections can be a severe problem in non- holographic storage, because errors arise from the

degradation of specific bits." (Gamblin, 1968,

pp. 1-2).

6.72 Further, "the results of this study have

indicated that holographic techniques are particularly suited to satisfy the functional requirements

of read-only memory . . . Holography offers solu- tions to two key problems associated with the

requirement for a single removable media storing

up to 160,000 bits. First, the unique redundance

inherent in holograms constructed with diffused

illumination eliminates the loss of data due to such

environmental effects as dust and scratches.

Second, the potential freedom from registration

effects which can be achieved by proper selection

of construction techniques allows the manual

insertion and removal of media with high bit packing densities and does not add a requirement

for complicated mechanical positioning or complex

electrical interconnection in the read unit." (Chapman and Fisher, 1967, p. 379).

6.73 "One can construct computer techniques

which would take an acoustic hologram (the wavefront from a scattered sound wave) and transform

it into an optical hologram, thereby allowing us

to construct the three-dimensional image of the

scatterer of the sound waves." (Lesem et al., 1967, p. 41). 101
6.74 "In a paper presented at the International

Symposium on Modern Optics, researchers at the

IBM Scientific Centre at Houston, Texas, de- scribed how they have programmed a computer—

an IBM System/360 Model 50 — to calculate the

interference patterns that would be created if light waves were actually reflected from a real

object. Neither the real object nor actual light waves

are required to produce holograms with the computer technique. While the initial IBM computer

hologram experiments have been restricted to two-dimensional objects for research simplicity,

the authors said further work is expected to make

possible digital holograms which can be recon- constructed into 3-D pictures. An engineer could

then get a 3-D view of a bridge or car body design

without actually building the physical object or even drawing it by hand." (The Computer Bull. 11, No. 2, 159 (Sept. 1967)).

"More recently, firms have experimented

with computer-generated holograms for unique

data display. NASA's Electronics Research Center

in Boston, Mass., is said to be investigating making

real-time holograms for such applications as air- port display to approaching aircraft. "A team at IBM's Houston Scientific Research

Center has programmed a System/360 Model 50

to create hologram by calculating the necessary

interference patterns.

"Thus it may soon be possible to use the computer

to create a mathematical model of a device and

then translate equations into a three-dimensional

hologram of the mathematical model." (Serchuk,

1967, p. 34). 6.75 "Holograms of three dimensional images

have been constructed with a computer and re- constructed optically. Digital holograms have been

generated by simulating, with a computer, the wave

fronts emanating from optical elements, taking into account their geometrical relationship. We have

studied in particular the effects of various types of

diffuse illumination. Economical calculations of

high resolution images have been accomplished

using the fast finite Fourier transform algorithm to evaluate the integrals in Kirchoff diffraction

theory. We have obtained high resolution three

dimensional images with all the holographic properties such as parallax, perspective and redundancy." (Hirsh et al., 1968, abstract, p. H 104).

"Kinoforms serve for all of the applications of

computer-generated holograms, e.g., three-dimensional display, wave conversion, read-only storage,

etc. However, kinoforms give a more practical,

computationally faster display construction that yields more economical use of the reconstructing

energy and that yields only the desired image.

"The principal computational advantage of kinoforms as compared with digital holograms is embodied in the fact that all of the spatial frequency

content of the device is used in the formation of the

real image; none is required for the separation of

the real and conjugate images. There is then at

least a factor of four reduction in the computer

time needed to calculate the wavefront pattern

necessary for equivalent image quality. Corre- spondingly there is a reduction in plotting time

for the kinoform.

"A further economy is achieved in that no cal- culations involving a reference beam are necessary.

Finally, in the cases of one- and two-dimensional

objects only real-number additions are required, once the basic transform is calculated, to determine

the wavefront phase for plotting. The corresponding

quantity to be plotted for digital holograms is the

wavefront intensity which requires multiplication

of complex numbers." (Lesem et al., 1969, p. 155).

6.76 "A[n] . . . important reason for synthesizing holograms is to create optical wavefronts

from objects that do not physically exist. A need to form such a wavefront from a numerically described

object occurs whenever the results of a three- dimensional investigation, for example, the analysis

of an x-ray diffractogram must be displayed in three dimensions." (Brown and Lohmann, 1969,

p. 160).

"Scientists, stock brokers, architects, statisti- cians and many others who use computers may

soon have a practical, fast, and inexpensive way

of converting memory data into three-dimensional

pictures and graphs.

"With a process devised at Bell Telephone

Laboratories, it takes only a few seconds of computer time to turn equations, formulas, statistical data and other information into a form suitable

for the making of holograms. Viewed under ordinary

light, the holograms produce three-dimensional

pictures that can display a full 360-degree view of

the object shown.

"Holography, which has been called 'lensless photography,' records a subject through the

interference of two laser beams on a photographic

plate. One beam is aimed directly at the plate,

and the other reaches the plate after being trans- mitted through, or reflected by, the subject being

'photographed.' "In the BTL method, the original subject exists only as a group of numbers or coordinate points

in three dimensions, for example, in the computer's memory. The hologram is made in two steps.

First, the computer is programmed to construct

a series of two-dimensional pictures, or projections,

each showing the 3-D data from a precisely defined

unique angle. A microfilm plotter, connected to the computer, produces a microfilm frame for each

picture. "In the second step, a holographic transparency

is made. The frames of the microfilm are used as subjects to make very small holograms (1 to 3 mm

across), which are positioned sequentially on a holographic medium."

"Thus, a composite hologram is made up of a

series of small holograms, each of which is formed

with a two-dimensional image. But the composite

image appears three-dimensional, and shows a 102
360-degree view of the object. With this type of

hologram — also invented at BTL — the viewer can

see the object rotating through a full cycle by simply

moving his head from side to side in front of the

hologram." (Computer Design 8, No. 6, 28 (June

1969).)

6.77 "By the use of photographic recording

techniques a very high information density can be

achieved to which rapid random access can be made

by appropriate electronic and optical techniques.

If, therefore, there are any classes of information

which must be read frequently, but are not changed

for at least a week, then such a storage technique

would be appropriate. This is evidently the case

for all system programmes including compilers and

monitor programs . . ." (Scarrott, 1965, p. 141).

"Photographic media are quite inexpensive, are capable of extremely high bit densities, and exhibit an inherent write-once, read-only storage capability.

The optical read-out techniques, which are used,

are nondestructive." (Chapman and Fisher, 1967,

p. 372).

6.78 "To get an order of magnitude idea of

the memory capacity, we will consider a memory

plane of 2 in. square . . . There will be approximately 645 subarrays [individually accessible].

Consider that only one-half the memory plane is composed of active film. The memory would then

contain almost 13 million bits." (Reich and Dorion,

1965, p. 579).

6.79 "The inherent power of optical processing can be exploited without suffering the speed limita- tions usually associated with static spatial filters. The method consists of using an electron beamaddressed electro-optic light valve (EOLV) as the

spatial filter. Thus the filter need no longer be a

fixed transparency, but can instead be a dynamic

device whose orientation is controlled electronically

rather than mechanically. This opens the method

of optical processing to the domain of real time and

presents exciting possibilities for its use in a variety

of applications." (Wieder et al., 1969, p. 169).

6.80 "In optical transmission lines, the wavelength of the signals will be shorter than any of

the circuit dimensions; therefore, one could elimi- nate, for example, all the reactive effects in the

interconnections." (Reimann, 1965, p. 247).

"High-speed electronic computer circuitry is becoming interconnection limited. The reactance

associated with the mounting and interconnections

of the devices, rather than the response of the active

components, is becoming the main factor limiting

the speed of operation of the circuits. "A possible approach to computer development

that might circumvent interconnection limitations

is the use of optical digital devices rather than

electronic devices as active components." (Reimann,

1965, p. 247).

"One factor of growing significance, as circuit

size is reduced, is the increasing amount of surface area consumed by areas devoted to interconnections

and pads for interconnections. There have been

marginal improvements over the past few years, but no startling improvements have been made

in comparison to reductions in the basic device

geometry.

"The consumption of real estate may be reduced

by interconnecting the logic circuits with the narrow lines allowed by the masking technology,

thus reducing to a minimum the area requirements

for external lead pads. At this point, the semiconductor manufacturer relaxes and says in effect

to the computer designer: Reduce your logic to a few standard configurations, and I will reduce

costs by a large factor. Hence, we have a search for magic standard logic functions." (Howe, 1965,

p. 507).

"Interconnections are already our problem for designing and building systems, and applying

Large Scale Integration (LSI) to digital systems

will inevitably force the realization that interconnections will be more important in determining

performance than all other hardware factors. This

is because the problems of physical size and bulk,

DC Shift over long cables, reflections and stub

lengths, crosstalk and RFI, and skin effect degradation are making computer systems interconnection

limited." (Shah and Konnerth, 1968, p. 1). 6.81 "One example of these more exploratory

attempts is the optically addressed memory with

microsecond nondestructive read cycle and much

longer write cycles. Chang, Dillon and Gianola

propose such a changeable memory employing

gadolinium iron garnets as storing elements."

(Kohn, 1965, p. 133).

6.82 "Maintaining low power supply and dis- tribution impedances in the presence of nanosecond

noise pulses is an increasingly difficult problem . . . As more circuits are placed on a chip, decoupling

of power supply noise will be required on or in close proximity to the chip." (Henle and Hill,

1966, p. 1858).

6.83 "Integrated circuitry has been widely

held to be the most significant advance in computer technology since the development of the

transistor in the mid-fifties . . . Semiconductor

integrated circuits are microminiature circuits with the active and passive microcomponents on

or in active substrate terminals. In thin-film inte- grated circuitry, terminals, interconnections, re- sistors and capacitors are formed by depositing a

thin film of various materials on an insulating

substrate. Microsize active components are then

inserted separately to complete the circuit. Micromodules are tiny ceramic wafers made from semiconductive and insulative materials. These then

function either as transistors, resistors, capacitors,

or other basic components." ("The Impact . . .", 1965, p. 9). 6.84 "Integrated circuit technology will bring

revolutionary changes in the size, cost, and

reliability of logical components. Lesser improvements will be realized in circuit speed. . . . "Advances in integrated circuit logic components

103
and memories . . . will provide significant reductions in cost since the implementation of flexible character recognition equipment involves complex

logical functions." (Hobbs, 1966, p. 37). "Of course, the cost of electronics associated

with peripherals will be drastically reduced by

LSI. But the promise of LSI is greater than that. Functions that are now handled by mechanical

parts will be performed by electronics. More logic

will be built into terminals, and I/O devices such

as graphic displays, in which the major cost is circuits, will come into more general use." (Hudson,

1968, p. 47). "This speed power performance requires only

modest advances from today's arrays. The board

module size is convenient for small memory

applications and indicates the method whereby

LSI memories will establish the production volume

and the impetus for main frame memory applications. The LSI memory being produced for the Air

Force by Texas Instruments Incorporated falls into

this category." (Dunn, 1967, p. 598).

"The Air Force contract [with Texas Instruments]

has as a specific goal the achievement of at least a

tenfold increase in reliability through LSI tech- nology as compared with present-day integrated

circuits." (Petritz, 1967, p. 85). "Impetus for continued development in microelectronics has stemmed from changing motivations.

Major emphasis was originally placed on size re- duction. Later, reliability was a primary objective.

Today, development of new materials and processes

point toward effort to reduce cost as well as to further increase reliability and to decrease weight,

cube, and power." (Walter et al., 1968, p. 49). "This [LSI] technology promises major impact

in many areas of electronics. A few of these are:

1. Lower cost data processing systems.

2. Higher reliability processing systems.

3. More powerful processing systems.

4. Incorporation of software into hardware,

with subsequent simplification of hardware."

(Petritz, 1966, p. 84). "Computer systems built with integrated cir- cuits have higher reliability than discrete-component machines. This improved reliability is due to two factors: (1) the silicon chip has a higher relia- bility than the sum of the discrete components it replaces, and (2) the high density packaging

significantly reduces the number of pluggable contracts in the system." (Henle and Hill, 1966, p. 1854).

6.85 "One of the most interesting and significant

paradoxes of the new technology is the apparent

reconciliation of a desire to achieve high speed

and low cost. The parameters which yield high

speed, i.e., low parasitics, small device geometry,

also yield lowest ultimate production cost in silicon integrated circuits." (Howe, 1965, p. 506).

6.86 "Some examples of functional expansion we would naturally consider are as follows. In the

central processor LSI might 'be used to carry out more micro-operations per instruction; address more operands per instruction; control more

levels of look-ahead; and provide both repetition

and more variety in the types of functions to be

executed. In system control, LSI might provide

greater system availability through error detection,

error correction, instruction retry, reconfiguration

to bypass faulty units, and fault diagnosis; more

sophisticated interrupt facilities; more levels of

memory protection; and concurrent access to independent memory units within more complex pro- gram constraints. In system memory, LSI might

provide additional fast local memory for operands

and addresses; improved address transformation

capability; content-addressable memory; and

special fast program status tables. In system

input-output, LSI might provide more channels;

improved interlacing of concurrent input-output

operations with automatic memory protection

features; and more sophisticated pre- and postprocessing of data and instructions to relieve the

central processor of these tasks." (Smith and Notz,

1967, p. 88). "LSI has an inherent functional advantage over magnetics in associative applications, namely

that fast bit-parallel searches can be achieved.

The main drawback of magnetic associative memories, even in those applications which require

relatively simple match-logic per word, is that imperfect cancellation of analog sense signals and

other noise effects give rise to a low signal-to-noise

ratio and thereby limit the technology to essentially

bit-serial operation. Thus, the more nearly binary

signals available from semiconductor associative

devices seem to provide a unique advantage over magnetics which is not strongly evident in comparisons of the two technologies over other categories

of memory." (Conway and Spandorfer, 1968,

p. 842).

"Content Addressable Memories: As the semiconductor manufacturer learns to produce more

and more components on a single silicon chip,

reasonably sized content-addressable memories

may become feasible. Memories of this type,

available on a large scale, should permit significant

changes in the machine language of the computer,

and possibly provide simplification in the design

of such software as operating systems and compilers." (Graham, 1969, p. 104).

6.87 "Revolutionary advances, if they come,

must come by the exploitation of the high degree

of parallelism that the use of integrated circuits

will make possible." (Wilkes, 1968, p. 7). "One area in which I feel that we must pin our hopes on a high degree of parallelism is that of

pattern recognition in two dimensions. Present-day

computers are woefully inefficient in this area." (Wilkes, 1968, p. 7). 6.88 "The recent advance from discrete transistor circuits to integrated circuits is about to be

104
overshadowed by an even greater jump to LSI

circuitry. This new jump will result in 100-gate and

then 1000-gate circuit modules which are little larger in size or higher in cost than the present

four-gate integrated circuit modules." (Savitt et al., 1967, p. 87). 6.89 "Discrete components have given way to integrated circuits based on conventional etched

circuit boards. This fabrication technique is in turn giving way to large scale integration (LSI),

in which sheets of logic elements are produced as

a unit." (Pyke, 1967, p. 161).

"The initial results suggest the possibility of

fabricating, in one step, a complete integrated

circuit with all the passive elements. Such a process

would start with a metallized substrate and would

use a programmable laser and work stage. Complete laser fabrication of hybrid circuits will require

a process in which a metal film is removed selectively, exposing a different film. For example such

a process may be necessary in order to remove the

conductor and expose the resistor film. "In the present tantalum-chrome-gold technology

such a selective removal of the gold presents substantial difficulties because the reflectivity of the

gold is much greater than that of the tantalum

nitride. It is quite probable, however, that some

combination of films will be found for which the

upper film can be removed from the resistor without

damaging it." (Cohen et al., 1968, p. 402).

6.90 "Integrated circuits (more importantly,

large scale integration (LSI) which involves numerous integrated circuits tied together on the same chip) offer the best promise from the standpoint of size, reliability and cost [for scratch-pad

memories]." (Gross, 1967, p. 5). 6.91 "Of all the potential applications of largescale integration, new memory techniques are the most startling. Ferrite core memories have

just about reached their limit in terms of access speeds required for internal scratchpads. Magneticthin films, while fast enough, are too costly. Studies

show that because of LSI, semiconductor memories

are less costly than any other approach for speeds

from 25 to 200 nanoseconds and for capacities up

to 20,000 bits— just the range required by scratchpads." (Hudson, 1968, p. 41). 6.92 "In addition to being used for circuitry,

LSI techniques apply to the construction of

memories, since some of the new memory elements

mentioned above can be fabricated using the

micro-construction techniques. The possibility also comes to mind of fabricating both the comparison circuitry and the memory cells of a content- addressable memory into a single unit. Thus the

development of large-scale integration holds

considerable promise for improving computer

hardware." (Van Dam and Michener, 1967, p. 210).

6.93 "In view of the economy that should

accompany widespread use of LSI, it may become

less expensive to use LSI logic elements as main

memory elements, at least for some portion of

primary storage. Even today some systems have

scratchpad memories constructed of machine

logic elements, so that the fast processor logic

is not held back by the slower memory capability."

(Pyke, 1967, p. 161).

6.94 "LSI memories show considerable potential

in the range of several hundred nanoseconds down

to several tens of nanoseconds. In contrast with

logic, LSI memory is ideally suited to exploit

the advantages and liabilities of large chips:

partitioning is straightforward and flexible, a high circuit density can be obtained with a manageable number of input-output pads, and the major

economic barriers of part numbers and volume

which confront LSI logic are considerably lower.

Small-scale memory cell chips have already

superseded film memories in the fast scratchpad

arena; the depth of penetration into the mainframe is the major unresolved question." (Conway

and Spandorfer, 1968, p. 837).

6.95 "As technological advances are made,

the planar technology permits us to pack more

and more bits on a single substrate thus reducing

the interconnection problem and simplifying

the total memory packaging job. This integration

will reflect in the long run on product cost and

product reliability." (Simkins, 1967, p. 594).

6.96 "The new technology has a number of problems whose solution can be facilitated by

arranging the circuitry on these arrays in a 'cellular' form — that is, in a two-dimensional iterative pattern with mainly local intercell connections —

that offers such advantages as extra-high packing

density, ease of fabrication, simplified testing

and diagnosis, ease of circuit and logical design,

the possibility of bypassing faulty cells, and particularly an unusually high flexibility in function

and performance." (Kautz et al., 1968, p. 443).

6.97 "LSI offers improvements in cost and

reliability over discrete circuits and older integrated

circuits. Improvement in reliability is due to the

reduction of both the size and the number of necessary connections. Reductions in cost are due largely to lower-cost batch-fabrication tech- niques. One problem in fabrication is the increased

repercussion of a single production defect, necessitating the discarding of an entire integrated component if defective instead of merely a single

transistor or diode. This problem is attacked

by a technique called discretionary wiring; a computer tests for defective cells in a redundantly

constructed integrated array and selects, for the

good cells, an interconnection pattern that yields

the proper function." (Van Dam and Michener,

1967, p. 210).

"Since packaging and interconnections are major factors in the cost of an integrated circuit,

the cost potentials . . . can be achieved only by

batch fabricating large arrays of interconnected

circuits in a single package. This raises many

difficult and conflicting questions, such as packag105
ing design, maintenance philosophy, flexibility

and functional logic segmentation." (Hobbs, 1966,

p. 39). "The rapid and widespread use of integrated

circuit logic devices by computer designers,

coupled with further improvements in semiconductor technology has raised the question

of the impact of Large Scale Integration (LSI) on computer equipment. It is generally agreed

that this is a very complex problem. The use

of Large Scale Arrays for logic require solutions

to the problems such as forming interconnections,

debugging logic networks, specifying and testing

multistate arrays, and attempting to standardize

arrays so that reasonable production runs and

low per unit design costs can be obtained." (Petschauer, 1967, pp. 598-599).

"The advent of large-scale integration and its resultant economy has made it clear that a complete

re-evaluation of what makes a good computer

organization is imperative. Methods of machine

organization that provide highly repetitive logical

subsystems are needed. As noted previously,

certain portions of present computers (such as successive stages in the adder of a parallel machine)

are repetitive; but others (such as the control

unit) tend to have unique nonrepetitive logical

configurations." (Hudson, 1968, p. 42). 6.98 "Graceful performance degradation through

use of majority voting logic.

"LSI will allow a single logical element to be

replaced by several logical elements in a manner

such that the elements can be used to determine

the state or condition of a situation. The state or condition of the situation indicated by a majority

of the elements can be accepted as valid — hence,

majority voting logic." (Walter et al., 1968, p. 52.)

"Because of low cost modules, pennies and less per logic function, maintenance will be simplified

and maintenance cost will be reduced by using

throw-away modules. By 'wiring' the spares in,

fabricated on the same LSI wafer that they are

sparing, it becomes practical to self-repair a computer. This is accomplished by including

diagnostic logic (coupled with programs) to effect the self-repair. Such a self-healing computer

system, using electronic surgery, need only be

manually maintained when its spare parts bank

becomes exhausted. Some advantages of self- repair are: • Increased system reliability • Continuous operation (system always avail- able) • Long term (years) remote system operation

without manual repair • Considerable reduction in maintenance

costs." (Joseph, 1968, p. 152).

6.99 See, for example, Rajchman (1965) and

Van Dam and Michener as follows: "However, new memory elements, such as plated wires,

planar thin films, monolithic ferrites, and inte- grated circuits, are becoming competitive. One

advantage of these new elements is that a memory

array made with them can be batch-fabricated

in one step, leading to simpler, lower-cost pro- duction (the production of core memories requires

making the magnetic cores and then stringing

the cores together to make a memory). Another

advantage appears to be in memory speed. The new memory elements have taken over the fields of high-speed registers and temporary 'scratch- pad' memories. Integrated circuitry . . . will probably replace the planar magnetic thin-film currently used for high-speed registers; however,

the planar film will be extended to intermediatesized stores (lO^lO6 bits)." (Van Dam and Michener, 1967, p. 207).

6.100 "Today most common types [of core memories] have about a million bits and cycle

times of about one microsecond, with bigger

and faster types available. Capacity and speed

have been constantly increasing and cost constantly decreasing." (Rajchman, 1965, p. 123).

"The ferrite core memory with 106 bits and

1/u, sec cycle time is the present standard for main

memories on the computer market. Larger memories up to 20. 10 6 bits at 10^i sec cycle time have

already been announced." (Kohn, 1965, p. 131).

"Ferrite cores dominated the main memory

technology throughout the second generation.

Most, although not all, of the third generation

machines thus far announced have core memories."

(Nisenoff, 1966, p. 1825).

6.101 "The NCR 315 RMC (Rod Memory

Computer) has about the fastest main memory

cycle time of any commercial computer yet de- livered— 800 nanoseconds. The unique thin-film memory is fabricated from hairlike berrylliumcopper wires plated with a magnetic coating. In the Rich's system the 315 RMC processes data

from over 100 NCR optical print cash registers . . ." (Data Proc. Mag. 7, No. 11, 12 (1965)).

A later version of NCR's rod-memory computer,

the 315-502, adds multiprogramming capability

at an 800 nanosecond cycle time. (Datamation 12,

No. 11, 95 (Nov. 1966)).

"NCR's new thin-film, short-rod memory repre- sents one of the most significant technical in- novations in the Century series . . . The rods

are made by depositing a thin metallic film and

then a protective coating on 5-mil copper wire.

This process yields a plated wire 0.006 inch in diameter, which is then cut into 0.110-inch lengths

to form the 'bit rods'. The basic memory plane

is formed by inserting the bit rods into solenoid

coils wound on a plastic frame. Then the entire

plane is sealed between two sheets of plastic.

Automated processes are used to plate the wire, cut the rods, wind the solenoid coils, insert the

rods into the solenoids, and seal the planes. The

result is a high-performance memory at an unusually low bit cost." (Hillegass, 1968, p. 47). 6.102 For example, "laminate-diode memories

106
of millions of bits operating in less than one microsecond seem possible in the near future." (Rajch- man. 1965, p. 125).

"The cryotrons, the memory structure, and all connections are constructed by a single integrated

technique. Thin films of tin, lead and silicon monoxide are evaporated through appropriate

masks to obtain the desired pattern of fines. The masks are made by photoforming techniques

and permit simple fabrication of any desired

intricate patterns. . . . "The superconductive-continuous sheet-cryotronaddressed approach to large capacity memory

offers all the qualities, in its principle of operation and its construction, to support ambitions

of integration on a grand scale as yet not attempted

by any other technology. No experimental or

theoretical result negates the promise . . . There

is, however, a serious difficulty: The variation of

the thresholds of switching between elements in the memory plane." (Rajchman, 1965, p. 127).

6.103 "A planar magnetic thin film memory

has been designed and built by Texas Instruments

using all integrated circuits for electronics achieving a cycle time faster than 500 ns, and an access

time of 250 ns. The memory is organized as 1024

words by 72 bits in order to balance the costs of

the word drive circuits against the sense-digit

circuits. The inherent advantage of this particular

organization is that the computer can achieve

speed advantage not only because of a fast repetition rate, but also because four 18 bit words are accessed simultaneously. (Comparable core memory

designs are ordinarily organized 4096 words

of 18 bits each.) The outlook is for higher speed

(faster than 150 ns) memories in similar organizations to be developed in planar magnetic films. The cost of these memories will be competitive

with 2-1/2 D core memories of the same capacity

but the organization and speed can be considered

to offer at least a 4 : 1 improvement in multiple

word accessing and a 3 : 1 improvement in speed. As

a result of this, more computers will be designed to take advantage of the long word either by extending the word length of the computer itself or by

ordering instructions and data in such a manner

that sequential addressing will be required a large

percentage of the time." (Simpson, 1968, pp. 1222-1223).

6.104 "If the high-speed memory is to operate

at a cycle time in the 100-nanosecond region, the

class of storage elements that can be used is some- what limited. Storage elements capable of switching

speeds compatible with 100-nanosecond cycle

times include (a) thin magnetic films of several

types, (b) some forms of laminated ferrites, (c) tunnel diodes, and (d) semiconductor flip-flop type

devices." (Shively, 1965, p. 637).

6.105 For example, "most forms of thin films and laminated exhibit adequately fast switching

times, but the drive current requirements are large

and the readout signals small." (Shively, 1965,

p. 637).

"The thin film transistor is barely emerging

from the laboratory and it may require several years before it becomes a serious contender for integrated-all-transistor-random-access-memories of

large capacities." (Rajchman, 1965, p. 126). "The development of higher-speed conventional

memory devices, of cores and thin films, has

slowed, and progress with such devices in breaking

the hundred nanosecond barrier will probably

take some time." (Pyke, 1967, p. 161).

"Thin films appeared to be more hopeful and are

certainly an area where extensive research is being

carried out. The main problems still appear to be

those of production, especially the problem of

achieving reproduceabifity from one film to an- other." (Fleet, 1965, p. 29). "The development of Cryogenic memories has

reached the point where planes storing several

thousand bits can be fabricated with high yield.

However, there are still many problems, such as interconnections, cost, data rate, etc., to be solved

before considering a mass store large enough to justify the overhead of cryostat and dewar."

(Bonn, 1966, p. 1869).

"Key problems in the fabrication of large monolithic memories are reliability (what to do if a bit

fails) and the volatility of the monolithic cell (if the power goes off, the information is lost)." (Henle

and Hill, 1966, p. 1859).

6.106 Kohn points out, for example, that "at present, such optically addressed memories seem

to be capable of storing 105. . . 106 bits/sq in. to have about 0.1 fx sec read access time, and one

cell can be written in 100 /jl sec. Very high voltages

for the light switches are required. This appears

to be quite unfavorable from a technical point of

view; however, an intensive materials research

may overcome the weakness of electrooptic effects and lead to more realistic devices." (Kohn, 1965,

p. 133).

6.107 "In the subsystems of a large computer,

one serious problem is ground plane noise — spurious

signals generated by large currents flowing in cir- cuits which have a common ground . . . Another

noise nuisance arises when signals have to be

coupled from two subsytems which are operating

at two widely different voltages. Lumped together,

such difficulties are known as the 'interface problem'." (Merryman, 1965, p. 52). 6.108 "Superconductive cryogenic techniques,

which were advocated for quick, on-line storage,

will probably not become operational because of

the high costs of refrigeration." (Van Dam and

Michener, 1967, p. 207).

6.109 "The projected 'break-even' capacity,

including refrigeration cost, for a cryoelectric

memory is approximately 107 bits." (Sass et al., 1967, p. 92). "The cryoelectronic memory is made up of

107

376-411 O - 70 - 8
strip lines, which, though interconnected from

plane to plane, display low characteristic impedance

and high propagation velocity, and require modest

peripheral electronics. Therefore, propagation

velocity is the only real limit to memory cycle time.

Typical cycle time for the 10 8 -bit AB system . . . is approximately 1 /as." (Sass et al., 1967, p. 97). 6.110 "The use of small special purpose memories has become prevalent in recent years. The

Honeywell H-800 employed a small core memory

to permit multiprocessing as far back as 1960."

(Nisenoff, 1966, p. 1826).

6.111 "Much interest has recently been shown

in the computer art in incorporating a low-cost,

mechanically changeable, read-only store in the

control section of a central processing unit. Flexibility of organization and compatibility with other

systems can be built into a computer that has a readily changeable read-only store. The printed

card capacitor Read-only store is one of three

technologies selected for the ROS function in System/360." (Haskell, 1966, p. 142).

"The Read Only Store (ROS) memory is a pre- wired set of micro-instructions generally set up

for each specific application. This means that the

specifications of the computer may be tailored to

suit the specific application of the user. Thus in an application where square root or some other

special function must be performed rapidly or repeatedly, such a sequence of operations may

be hard wired into the ROS." (Dreyer, 1968, p. 40). "Micro-steps, the basic instructions of a stored

logic computer, permit the programmer to control

the operation of all registers at a more basic level than is possible in the conventional computer.

Sequences of micro-steps (each of which requires

only 400 nsec to perform) are stored in the ROS

as 'micro-routines' which are executed much as a conventional subroutine. However, unlike the

unalterable commands of the conventional computer, stored micro-routines may be designed by

the programmer to form the most efficient combination of basic computer logical operations for a given application. The speed increase available

by use of a ROS does not come from faster computing circuits, but from operating instructions

built into the hardware for more efficient ordering

of gates, flipflops, registers et al. Thus at the

outset of each application, tradeoff studies must

be made to determine to what extent software may

be replaced by hardware through use of the ROS."

(Dreyer, 1968, p. 41). "The implementation of read-only memories as the control element in a computer has significance

for maintainability and emulation. Instruction de- coders and controls present a difficult problem to the designer. These elements contain no repetitive

patterns like those in data paths and arithmetic

units. In addition, they have many external connections. A read-only memory can be used to pro- vide these same control signals. It would contain

a long fist — hundreds or thousands — of microinstructions. Each program microinstruction from the main

memory addresses a sequence of microinstructions

in the read-only memory. Each microinstruction in the sequence describes the state of the entire

machine during its next cycle. The read-only

memory divides easily into segments, since its only external connections are the words address

inputs and control signal outputs. LSI read-only

memories are being offered by several manufacturers." (Hudson, 1968, p. 42). "If a read only-memory (ROM) module were

used to store subroutines, the relative-efficiency

of the code would be much less important. ROM

modules cost less than one-fifth as much as comparable amounts of main core storage. Use of

ROM to 'can' bread and butter subroutines in lowcost hardware provides an effective solution to a

particular problem. The main or read/write memory,

thus liberated, can be used to provide feasible

flexibility for the main program and to incorporate

inevitable, unforeseen, jobs that arise during the

development and operating life of a computer

system. . . . "One of the most significant aspects of fourth

generation computers will be the use of read-only

memories. Tradeoffs of hardware for software

and/or speed, and/or reliability, will significantly

affect computer organization. Advantages to be

gained through the use of ROM include (1) increased

speed, output signal level and reliability, (2) de- creased read-cycle time, operating power, size,

weight, and cost, and (3) nonvolatility." (Walter

et al., 1968, pp. 51, 54). "The 'read-only' function includes the storage

of indirect accessing schemes, the implementation

of logic functions, the storage of microprogrammed

instructions, and related applications." (Chapman

and Fisher, 1967, p. 371).

"The attractions of a good read-only storage

include not only extremely reliable nondestructive

readout, but also lower cost." (Pick et al., 1964,

p. 27). "Special hardware functions implemented in the

read-only memory of the 70/46 supplement the

[address] translation memory. They are used as additional privileged instructions. Among the capabilities they provide are the ability to load or un- load all or selected parts of translation memory

and to scan translation memory in such a way that only the entries of those pages that have been

accessed are stored into main memory." (Oppenheimer and Weizer, 1968, p. 313).

6.112 "A MYRA memory element is a MYRi

Aperture ferrite disk which, when accessed, pro- duces sequential trains of logic-level pulses upon

64 or more otherwise isolated wires ... A picoprogrammed system, then, consists essentially of an arithmetic section and a modified MYRA

memory. A macroinstruction merely addresses an element in the MYRA memory; when the element

is accessed, it produces the gating signals which

cause the arithmetic unit to perform the desired

108
functions. In addition, it provides gating pulses

which fetch the operand (if needed), increment the

control counter, and fetch the next instruction."

(Briley. 1965, p. 94). •'Picoprogramming is realized by the use of the

_\IYRi — Aperture (MYRA) element, a multiaperture

ferrite device which is the basic building block

of the instruction mode. Each instruction module

is a complete entity and is fabricated on a conventional printed wiring card that can be inserted

in a conventional PC connector. Incorporation of a new instruction in the computer or alteration of an

existing one is accomplished by the addition or

substitution of the appropriate instruction module

card." (Valassis. 1967, p. 611).

6.113 "With this GaAs diode array system a very fast, medium capacity, read-only memory with

changeable contents becomes realizable. Since

many of the existing third generation computers

contain microinstructions in read-only stores of

about the same capacity as that indicated for the

diode-accessed holographic memory, it would seem

that the existing read-only memories could be

replaced by this type of holographic memory;

such a system could be an order of magnitude

faster and allow for increased flexibility of CPU

configuration by easy change of the microinstruction repertoire." (Vilkomerson et al., 1968, p. 1198).

6.14 In general, these terms are interchangable.

Some typical definitions are as'follows: "Basically an associative memory involves sufficient logical

capability to permit all memory locations to be

searched essentially simultaneously — i.e., within some specified memory cycle time . . . Searches

may be made on the basis of equality, greater-thanor-equal-to, less-than-or-equal-to, between limits,

and in some cases more complex criteria." (Hobbs.

1966, p. 41). "An associative memory which permits the

specification of any arbitrary bit pattern as the

basis for the extraction of the record within which

this pattern appears is called a fully associative

memory." (McDermid and Petersen, 1961, p. 59). "The content-addressable memory (CAM) was

initially proposed by Slade as a cryogenic device . . . For this type of memory, word cells are accessed

by the character of stored data rather than by

physical location of the word cell. The character

of data is evaluated in parallel throughout the

memory. A common addressing characteristic is equality of stored data and some externally pre- sented key. Memories of this type have also been

called associative since a part of the cell contents may be used to call other cells in an 'associative' chain." (Fuller, 1963, p. 2). "An associative memory is a storage device that permits retrieval of a record stored within by

referring to the contents or description rather than

the relative address within the memory." (Prywes,

1965, p. 3). "The distinguishing feature of an associative

memory is that it has no explicit addresses. Any

reference to information stored in an associative

memory is made by specifying the contents of a part of a cell. All cells in the memory which meet

the specification are referred to by the statement." (Feldman, 1965, p. 1). "We have described here an iterative cell which

can be used as a content addressable memory

from which an entry may be retrieved by knowing

part of its contents." (Gaines and Lee, 1965, p. 74). "Memory systems which retrieve information on the basis of a given characteristic rather than

by physical location . . . are called 'content- addressed', 'catalog', or 'associative'. In these

types of memory systems, an interrogation word

. . . is presented to the memory and a parallel

search of all words within the memory is conducted.

Those stored words which have a prescribed rela- tionship (e.g., equal to, nearest to, greater than,

etc.) to the interrogation word are tagged. Subsequently, the multiple tagged words or responses

are retrieved by some interrogation routine."

(Miller, 1964, p. 614).

"Associative Memories. An associative memory

is a collection of storage cells that are accessed

simultaneously on the basis of content rather than

location. The ability to associate with circuit logic

those cells with similar contents achieves a hard- ware implementation of an associatively linked

or indexed file. Sufficient quantitative results have

not yet been developed to establish conclusively

the merits of the hardware implementation as against software associative systems. A comprehensive study of hardware associative memory

systems given by Hanlon should be read by those

interested in this growing technology." (Minker and

Sable, 1967, p. 129.)

6.115 "It is extremely unlikely that large fast associative stores will become practicable in the near future . . . We cannot expect associative

stores to contribute to a solution of our problems

other than in very small sizes to carry out special

tasks, e.g., the page register addresses in Atlas."

(Scarrott, 1965, pp. 137-138).

"The concept of the content-addressable memory

has been a popular one for study in recent years, but relatively few real systems have used content- addressable memories successfully. This has been

partly for economic reasons — the cost of early

designs of content-addressable memories has

been very high — and partly because it is a difficult problem to embed a content-addressable memory

into a processing system to increase system effec- tiveness for a large class of problems." (Stone,

1968, p. 949).

"Considerations of cost make it impossible for the

associative memory to contain many registers, and

the number that has been adopted in current de- signs is eight. Unless the associative memory has

very recently been cleared, it will be necessary to suppress an item of information in order to make

109
room for a new one; the obvious thing is to suppress

the item that has been there for the longest period of time, but other algorithms slightly cheaper to implement have also been proposed. It is claimed on the

basis of simulations that eight associative registers

enable the full procedure of three memory cycles to be shortcircuited on 90% of occasions." (Wilkes,

1967, p. 4). "In the past, associative or content addressable

memories of any significant size have been impractical for widespread use. Relatively small associative

memories have been built with various technologies,

such as multiaperture ferrite cores, cryotrons, and

various thin-film techniques. The logical flexibility

of microelectronics now makes at least scratchpadsize associative memories practical." (Hudson, 1968,

p. 42). 6.116 "By a slave memory I mean one which

automatically accumulates to itself words that come

from a slower main memory and keeps them avail- able for subsequent use without it being necessary

for the penalty of main memory access to be in- curred again. Since the slave memory can only be a fraction of the size of the main memory, words

cannot be preserved in it indefinitely, and there

must be wired into the system an algorithm by which

they are progressively overwritten. In favorable

circumstances, however, a good proportion of the

words will survive long enough to be used on subsequent occasions and a distinct gain of speed

results. The actual gain depends on the statistics of

the particular situation. "Slave memories have recently come into promi- nence as a way of reducing instruction access time

in an otherwise conventional computer. A small,

very-high-speed memory of, say, 32 words, accumulates instructions as they are taken out of the main

memory. Since instructions often occur in small

loops a quite appreciable speeding up can be

obtained. . . . "A number of base registers could be provided

and the fast core memory divided into sections, each

serving as a slave to a separate program block in the main memory. Such a provision would, in principle, enable short programs belonging to a number

of users to remain in the fast memory while some

other user was active, being displaced only when

the space they occupied was required for some other

purpose." (Wilkes, 1965, pp. 270-271).

6.117 "The B8500 scratchpads are implemented

by magnetic thin film techniques developed and

organized into linear-select memory arrays ... To

realize the high speed access requirement of 45

nanoseconds, the reading function is nondestructive,

eliminating the need for a restoring write cycle when

data are to be retained unchanged. . . . "Insertion of new data into the local memories

(writing) can be accomplished within the 100- nanosecond clock period of the computer module."

(Gluck, 1965, p. 663).

"4 52-bit words can be requested from a memory

module and received at a computer module in a

total of 1.0 microsecond, or an average of 250

nanoseconds per word." (Gluck, 1965, p. 662).

"The rationale behind the inclusion of local scratchpad memories in the B8500 computer

module encompasses . . . the need for buffering

of four-fetches of instructions and data in advance

of their use, i.e., lookahead. Also important are

its uses as storage for intermediate results, as an economical implementation for registers and

counters, and for the extension of the push-down

stack." (Gluck, 1965, p. 663).

6.118 "A specific application for a CAM is encountered when assembling or compiling pro- grams where it is common to refer to variables,

locations and other items in terms of a symbol.

The value or information associated with each

symbol must be stored somewhere in memory

and a table must be made to relate each symbol

to its value. As an example, the symbol ABLKR

may be assigned the value 5076. The computer

may take this information and store the value

5076 at location 1000 for example. Then the first entry in the symbol table will relate the symbol

ABLKR to the location 1000 where the value of

ABLKR is stored. As more symbols are defined,

this symbol table will grow in length." (Rux, 1967,

p. 10). 6.119 "Tied in with scratchpad No. 2 is a small

28-word associative memory (19 bits per word)

whose use enhances the utilization of the scratchpad

memory by providing content addressing as well

as the conventional binary coded word addressing

capability." (Gluck, 1965, p. 663).

6.120 "Each cell of the memory receives signals

from a set of pattern lines and command lines in

parallel, and the commands are executed simultaneously in each cell. One of the commands orders

each cell to match its contents against the pattern

lines. Each cell in which a match occurs sets its match flip-flop and also generates an output

signal . . ." (Gaines and Lee, 1965, p. 72). These investigators describe some of the differ- ences between their proposed system and others,

in part as follows: "The memory we describe here

is a logical and practical outgrowth of the content addressable distributed logic memory of Lee and

Paull. However, there are several significant

differences: the inclusion of a 'match' flip-flop and

a 'control' flip-flop in each cell of the memory, the

addition of a 'mark' line to activate many cells simultaneously, and the control of the propagation

of the marking signal. As a consequence of these,

the memory has some novel capabilities, among

which are the ability to simultaneously shift the contents of a large group of cells, thus opening or closing a gap in the memory, and the ability to simultaneously mark strings of interest in separate

parts of the memory.

"By properly manipulating the cell states, simple

programs for correcting errors involving missing

or extraneous letters, multiple mispellings, etc.,
can be devised. Furthermore, by using the marking

capabilities of the memory, error correction

during retrieval can be accomplished on a selected

subset of strings which may be located at widely

separated parts of the cell memory." (Gaines and

Lee, 1965, p. 75). 6.121 This Sylvania development involves the use of automatically preprocessed plastic sheets

to affect the performance and logic behavior of a solenoid-transformer array. "The interrogation, which may consist of a number of descriptors, each containing many bits of information, causes an appropriate group of solenoids to be driven . . . The solenoids interact

simultaneously with all enclosed loops on all the

data planes, resulting in a simultaneous voltage on the output of each data plane that is the cross- correlation between the driven input solenoids and

each individual data plane. The output of each

plane is connected to its own detector-driver which

tests the output in comparison with all the other

data plane outputs to find that output containing

the best correlation. Alternatively, the detectordriver can be set to test for some pre-determined

threshold." (Pick and Brick, 1963, p. 245).

Brick and Pick (1964) describe "the application

of the solenoid array principle to the problem of word recognition, code recognition, and (in a limited

sense), associative memory. The proposed device,

based entirely on existing experience with a large

character recognition cross correlator, is capable

of recognizing one of 24,000 individual English

words up to 16 letters long. The simultaneous

correlation and selection is made in less than

3 /usee. The selection can be made either on a perfect-match or a best-match basis." (Brick and

Pick, 1964, p. 57). "This form of semipermanent memory offers many advantages to computer and memory users. Among these are: a) ease of contents preparation,

involving automated punching of inexpensive

standardized cards; b) reliability, as a result of

few electrical connections, loose mechanical

tolerances, and passive components; c) low cost, since the cards are not magnetic and need only a continuous conducting path; and d) high speed,

with estimated cycle time below 1 /x,sec." (Pick

et al., 1964, p. 35). 6.122 "A number of associative memory stacks

of 120 resistor cards have been constructed, each

stack storing 7200 bits, with each card storing one word of 60 bits length." (Lewin et al., 1965,

p. 432).

"This paper describes a fixed memory consisting

of one or more stacks of paper or plastic cards,

each of which contains an interconnected array

of printed or silk-screened film resistors. Each

card is compatible with conventional key punches,

and information is inserted by the punching of a pattern of holes, each of which breaks an appropriate electrical connection. All punched cards

in a stack are cheaply and reliably interconnected

using a new batch interconnection technique which

resembles an injection molding process, using

molten low-temperature solder. The circuit which

results is a resistor matrix where the information

stored is in the form of a connection pattern. The

matrix may be operated as a content-addressable

or associative memory, so that the entire array can be searched in parallel, and any word or words

stored answering a given description can be

retrieved in microseconds." (Lewin et al., 1965,

p. 428).

6.123 "The study by Dugan was restricted to considering an existing computer environment and

the Goodyear Associative Processor (GAP), a 2048-word associative memory with related logic

and instructions. A benchmark problem was

studied in which the data base exceeded the size of GAP and was stored on disc. The disc-stored

data required transfers to the associative processor

or the conventional core for further operations.

The study concluded that the effectiveness of a small associative processor, such as GAP, for formatted file problems depended upon the inter- face of the associative processor with the computer

system, the logic of the associative processor, and

the load/unload characteristics of the memory

associated with the problem. The authors showed

that embedding the associative processor within

the core memory provided the best system. It also provided a facility for performing arithmetic

operations on data, which is ordinarily difficult for an associative processor. The study did not show any major advantages in using a system with an associative processor similar to GAP over one without an associative processor. . . . "Gall utilized the same computer environment as Dugan but investigated a dictionary lookup phase

of an automatic abstracting problem. He concludes

that incorporating associative memories that do

not have the capacity to store the entire data base

requires excessive data transfer and cannot compete

with conventional systems that employ a pseudorandom mapping of a word onto a storage location

and, therefore, can locate a word by content. Randomized addressing is another software

simulation of but one of the facilities provided by

an associative processor, namely, the so-called 'exact-match' function.'' (Minker and Sable, 1967,

pp. 130-131).

6.124 The Librascope Associative Parallel Processor was developed for use in the extraction

of pattern properties and for automatic classifica- tion patterns. It is noted in particular that "the

parallel search function of associative memories

requires that comparison logic be provided at each

memory word cell. The APP, by moderate additions

to this logic, allows the contents of many cells, selected on the basis of their initial content, to be modified simultaneously through a 'multiwrite'

operation." (Fuller and Bird, 1965, p. 108).

Ill
Swanson comments as follows: "Fuller, Bird,

and Worthy recently described two machines:

an associative parallel processor programmed to abstract properties from visual and other patterns

and classify the patterns from the properties; and

an associative file processor for rapid parallel

search of large complex data bases." (1967, p. 38). 6.125 "The ASP machine organization . . . [has as its dominant element] the context-addressed

memory . . . [which] stores both ASP data and

programs, and . . . provides the capability to identify, in parallel, unknown items (and link

labels) by specifying the context of relations in which the unknowns appear .... [It] consists of

a square array of identical storage cells which are interconnected both globally and locally. Each cell contains both memory and logic circuitry. The

memory circuitry stores either an item, link label, or a relation, plus tag bits. The main purpose of

the logic circuitry is to perform the comparison

operations which are required to implement global

searches of the array and local inter-cell communication." (Savitt et al., 1967, p. 95). See also note 5.47. 6.126 "In the earliest associative memories

all bits of all the words of the memory were simultaneously compared with a search word; this is called word-parallel search. For such word-parallel

search, the memory has to be of the nondestructivereadout (NDRO) type." (Chu, 1965, p. 600).

"Instead of word-parallel search, bit-parallel

search has been developed because of its simpler

design and because word-parallel search is of less importance in more complex searches. Bit-parallel

search (or bit-sequential search) searches one

corresponding bit of all words at one time. For a word of 64 bits, a maximum of 64 bit-parallel

searches is made in succession; thus, bit-parallel

search pays a price in speed . . . [but] the price

is a limited one. In a bit-parallel-search associative

memory, nondestructive readout property of

memory elements is not necessarily required. This

paper describes the organization of a destructivereadout associative memory which can be implemented by a special, very high-speed, magneticcore memory using conventional technology."

(Chu, 1965, p. 600).

"Because parallel-search logic is implemented

for only one long-word, implementation of several

varieties of search logic is practical. In addition

to a bit-comparison logic, other logical operations

(such as NAND, NOR, AND, OR) can be implemented relatively simply and less expensively."

(Chu, 1965, p. 600).

"For these operations [bit count and bit count

and store], each bit of the memory short-word may

represent an attribute (a property or a characteristic), and the count of attributes is a useful argu- ment for searching closeness in attributes." (Chu,

1965, p. 605).

6.127 "Circulating memories offer an enormous

savings in quantities of logic necessary for a CAM

since one set of comparison logic can be used to compare the key register with many memory locations. The comparison logic need only monitor the

memory's contents as it passes through the circulat- ing system. . . . "The principle disadvantage of a circulating

CAM is speed. At least one circulation time of the

memory is required to interrogate the entire

memory. In the case of a magnetic drum system,

this time would be measured in milliseconds which

is much too slow for many applications. However,

with the use of glass delay lines, information can

be stored at very high rates, 20 MHZ and higher,

and short circulation times can store large amounts

of data. For example, a 100 microsecond delay

line at 20 MHZ can store 2,000 bits of information.

Thus 32 delay lines could store 2,000 words of 32

bits each and this memory could be searched in 100 usee." (Rux, 1967, p. 2). 6.128 "A goal in designing and interfacing the

associative mapping device into the System/360,

Model 40, was to introduce no time degradation in the critical main memory address path. We have

accomplished this goal by designing the hardware

to perform this address translation function in 220 ns. This interrogate time through the associative

memory is approximately 50 ns and the remaining

time is spent in wire delay and conventional logic,

such as the encode circuit which was designed

using the 30-ns IBM SLT family. . . . "The technology used to implement the associative mapping device is the IBM SLT technology.

Four special circuits were designed for the associative memory array. They are the associative memory

cell used for storing one bit of information, the bit driver, the word driver, and the common sense

amplifier used for sensing a mismatch signal in the word direction or a binary 'one' signal in the

bit direction." (Lindquist, et al., 1966, p. 1777).

"The mapping device which provides the dynamic

storage allocation function in the time-shared system

is a 64-word, 16 bit per word, associative memory."

(Lindquist et al., 1966, p. 1776).

". . . The Univac 128-word by 36 bit-per-word,

600-nsec scratch pad memory." (Pugh et al., 1967,

p. 169).

"The memory . . . utilizes a plated-wire (Rod)

memory device operating in a 512-word 36 bit per

word memory system. The DRO mode is employed

and operation at a 100-nanosecond read-write cycle

time is achieved." (Kaufman et al., 1966, p. 293).

"The memory is word-organized with a capacity

of 64 words each 24 bits long. Cycle time is approximately 250 nanoseconds. Such memories are

suitable for use as 'scratchpads' operating within

the central processor or input-output control

systems of a computer." (Bialer et al., 1965, p. 109).

"All of the memory circuits — approximately 180

chips — plus 1,536 bits of thin-film magnetic storage

and the thin-film interconnection wiring are on a

112
glass substrate measuring 3 by 4-1/2 by 1/10 inches.

The circuits occupy about half the substrate area. The extremely small physical size of the memory,

the shorter signal paths, the elimination of redundant connections, which packaged circuits would

have required, all contribute to an improvement in system speed. . . . "The 64-word memory has a cycle time of about

250 nanoseconds . . . Plans are to build a 256-word

memory that is equally fast and expectations are

that eventually 50-nanosecond memories can be

built with similar design and fabrication methods

[i.e., ultrasonic face-down bonding for interconnection of integrated circuit chips with thin-films]."

(Bialer et al., 1965, pp. 102-103).

6.129 "The sonic film memory represents a novel approach to the storage of digital information.

Thin magnetic films and scanning strain waves are combined to realize a memory in which information

is stored serially. The remanent property of magnetic films is used for nonvolatile storage. The effect of strain waves on magnetic films is used to obtain

serial accessing. This effect is also used to derive a nondestructive read signal for interrogation."

(Weinstein et al., 1966, p. 333).

6.130 "The new [tunnel diode] memory system

contains 64 words of 48 bits each, and test results from a partiallv-populated cross-sectional model

indicate a complete READ/RESTORE or a CLEAR/

WRITE cycle time of less than 25 nanoseconds."

(Crawford et al, 1965, p. 627).

6.131 "The basic cell employs a thick magnetic

film as the high-speed sensing element to sense the

information which is stored as a pattern of magnets

on a card. Since the magnet card is separate from

the array, the latter can be permanently laminated

or sealed and the information can be changed very

simply and reliably. The advantages of this system

stem from a combination of several important fea- tures, namely card changeability, high speed, wide

mechanical and electrical tolerances, and a linear

drive-sense relationship which results in a wide

range of operating levels. "Circuit costs can be minimized by using low-level

drivers, giving an additional increase in speed with

only a minor increase in sense circuitry . . . For

a memory containing four arrays of 256 words and

288 bits per word, an access and cycle time of 19

and 45 ns respectively was achieved . . ." (Matick

et al., 1966, p. 341.)

6.132 These investigators suggest further that "the number of bits of storage can be increased in several ways. A modular approach can be used by

connecting 64 X 8 memories in parallel or the memory boards can be redesigned to accept the larger

number of bits. The modular approach is particularly applicable to the distribution of small memories

of various sizes throughout a large computer. It is possible to construct a 64 X 32 memory using either

of the above approaches with a cycle time of approximately 20 nanoseconds." (Catt et al., 1966, p. 330).

6.133 "It has been demonstrated that 1000-bit

NiFe film DRO memories with cycle times of

60 nsec and access times of about 30 nsec can be

built using existing components. Experience with

this model indicates that the design can be extended

to allow a significant increase of capacity in a memory having this same cycle time and access

time; however, it is felt that to achieve a marked

increase in speed will require radical departures

from the conventional circuit and array techniques

that were employed in the model described here."

(Anacker et al, 1966, p. 50). "IBM has developed a bipolar monolithic IC

buffer memory for use on the 360/85 that is faster than any they have previously introduced. Access

time to the entire contents of the 2K by 72-bit memory is 40 nsec. The buffer memory is con- structed of half-inch square building blocks composed of two silicon chips and their leads and

insulation. Each of the chips measures less than an eighth of a square inch and contains 664 components (transistors, diodes, and resistors). Each

chip provides 64 distinct but interconnected

storage cells. The components involved are so minute that 53,000 can fit into a one square inch

area. "The significance of the microminiaturization is of course little related to 'how many of what fit where.' What IBM gains from this construction is a circuit speed — demonstrated on some experimental chips — that is as fast as 750 picoseconds

(trillionths of a second).

"The speed of the buffer memory (which at one

time was to be called a 'cache', but that term has

apparently been dropped) is not down to the

750 pisec figure, but a 7 n sec/chip read and a

12 n sec/chip write speed isn't bad." (Datamation

15, No. 4, 193 (Apr. 1969).)

6.134 "Electronic Memories, Inc., demonstrated

its NANOMEMORY 650 .. . capacity of 16,384

words of up to 84 bits, and an access time of

300 nsec." (Commun. ACM 9, No. 6, 468 (June

1966).)

6.135 "The ICM-40, a one ix sec cycle time,

500 nsec access time, core memory, available with

capacities from 4K X 6 bits to 16K X 84 bits has

been announced by Computer Control Company,

Inc." (Commun. ACM 9, 316 (1966).)

6.136 "International Business Machines Corp.

has developed an experimental thin-film computer

memory that has a 120-nanosecond cycle time, a

589, 824-bit capacity and fits in a frame 68 by 42

by 7 inches — including the electronic circuits for driving and sensing." (Electronics 39, No. 3, 41

(1966).

6.137 "The memory has a capacity of 8192

words, 72 bits per word, and has a cycle time of

110 nanoseconds and an access time of 67 nanoseconds. The storage devices are miniature ferrite cores, 0.0075 by 0.0123 by 0.0029 inches, and

are operated in a two-core-per-bit destructive read- out mode. A planar array geometry with cores 113
resting on a single ground plane is used to control

drive line parameters. Device switching speed and

bit line recovery are treated as special problems."

(Werner et al., 1967, abstract, p. 153).

6.138 "It seems a certainty that plated wire

memories will become a very important member

in the hierarchy of storage systems to be used in the computers of tomorrow." (McCallister and

Chong, 1966, p. 313).

"Both UNIVAC 9200/9300 Systems utilize a new

plated-wire memory for internal storage featuring

a non-destructive read-out mode and monolithic

circuitry." (Commun. ACM 9, 650 (1966).)

6.139 "Capacity of this memory is 4096 68-

bit words (278, 528 bits, to be exact) and it operates

with a cycle time of 200 nanoseconds and an access time of 160 nanoseconds. It is a word-organized,

random-access memory. The memory element is composed of a pair of planar thin films coupled

together and read out destructively." (Meddaugh

and Pearson, 1966, p. 281).

6.140 "The operation of this half-microsecondcycle memory module represents a significant

achievement in a program of magnetic thin-film development for computer storage which was

begun at these laboratories in 1955. Large numbers

of substrates were processed and tested, and

memory plane assembly and test are now routine

operations.

"Memory frames which contain 20 substrates

(15,360 bits) can be assembled without great

difficulty . . . "A shorter memory cycle can be made possible

by reducing the total sense delay, and by the elimination of the bit recover pulse. The pulse trans- formers will be replaced by active solid-state devices. A reduction of 150 nsec — 50 nsec from a shorter sense delay and 100 nsec from elimination

of the bit recover pulse — make a cycle time of 350 nsec, or 3-Mc operation, possible." (Bittman,

1964, p. 105).

"Fabrication, assembly, and operation of these

half-microsecond memories has proven that large

numbers of reliable film substrates are producible

and that the completed memories can compete

in both speed and price with the high-speed 2-1/2

D-type core memories. The future for planar films looks very bright — both larger and faster memories

are in the design stage. These memories will combine the economic advantages of batch fabrication

with the fast switching properties of thin-films."

(Jones and Bittmann, 1967, p. 352).

6.141 "Extensive memory research aimed at implementing the inherent 1-ns switching capabilities of thin magnetic films within a system

environment has resulted in a cross-sectional

147000-bit capacity film memory model with a nondestructive-READ-cycle time of 20 ns, an

access time of 30 ns, and a WRITE-READ time

interval of 65 ns. The shortest time interval between

addressing of two different word lines is 20 ns."

Seitzer, 1967, p. 172).

6.142 "A single layer composite magnetic film

is operated in a rotational destructive-read-out

mode with two access wires. Each bit is composed

of two 2X6 mil intersections of the word and

digit lines with a density of 12,500 bits/in. Magnetic film structures which provide flux closure

in the hard, easy, or both directions were con- sidered by rejected when adequate margins were

obtained with the single layer. Although the open

structure has fabrication advantages, the closed

structures remain of interest for future work."

(Raffel et al., 1968, pp. 259-260).

"The access time of the memory from change

of address to information output from the buffer

flip-flops is about 450 nsec. The largest contribution

to this delay is the transient on the sense-line due

to group-switch voltage transitions. The circuit- limited cycle time for read-write or clear-write is 600 nsec. Recovery from the digit-pulse transient

limits the total cycle time to l/usec with the digit

transient overlapping the group-switch transient."

(Raffel et al, 1968, p. 261).

6.143 "The chains are made from copper

strips which have been plated with a Ni-Fe film and are used to carry word current. The bit/sense

signals are carried in wires which pass through

the holes in the 'links' of the chain. The memory

element thus formed will operate in a rotational

switching mode and can be used for a word-organized memory." (Geldermans et al., 1967, abstract,

p. 291).

6.144 "It has been shown that high-speed

chain memories can be built in very high-density

arrays with minimum electromagnetic interactions.

The bit/sense wires can be treated as homogeneous

transmission lines with relatively high characteristic impedence (100 fi) and good signal-to-noise

ratios. The word lines are high-impedence strip lines whose inductance is mainly determined by

the nonlinear magnetic film. This makes evaluation more difficult, but implies favorable properties

for the design of very long lines. "Based on the analysis of recently plated chains

with smaller dimensions and better films, the characteristics of various possible chain memories have

been extrapolated. Straightforward design philosophy, using transistor selection can be applied for a 0.3Xl06 -bit NDRO memory, a 106 -bit, 100-nsec

DRO memory, and a 38xl06 -bit 500-nsec DRO

memory.

"These performance predictions reflect the merits

of a film device with complete flux closure and highquality oriented films as exhibited in the chain

device; they appear quite attractive for their size,

speed, and circuitry requirements. Chains imply a simple semi-batch process and combine fast rota- tional switching properties of oriented films with

the larger signal capability of cores." (Abbas et al., 1967, p. 311).

114
1.145 Further, "the memory under development has a capacity of 108 bits. This capacity is achieved by stacking 107 -bit modules into one

unit . . . Each module has its own set of driving

circuits and sense amplifiers. This arrangement

leads to a fast, random-access memory, readily

realizable mechanically; it is justified from the

viewpoint of modularity and cost because the elec- tronic circuits are shared by a large number of bits. All modules share one set of auxiliary circuits,

which include the address decoders, timing cir- cuits, information registers, and power supply . . . "The plated wire used is a nondestructive readout (NDRO) element with equal word currents for reading and writing. This property makes it unnecessary to have rewrite circuitry for each stored bit." (Chong et al., 1967, p. 363).

6.146 "Much attention is currently focused on

the development of block-oriented random-access

memories. One prospect is the magnetosonic

delay-line memory which employs magnetic stor- age and block-access by semiconductor electronics

(to cause the propagation of a sonic wave in the

selected line). Nondestructive read-out is derived on

the digit fines in sequence by the propagation sonic wave, and write-in is carried out by the coincidence

of digit currents and the propagating wave. Another

prospect is the opto-electric read-only memory,

where the stored information on high resolution

photographic plate is block-selected by optical

means, employing light-beam deflection or an array

of light-emitting elements. The optical readout (of all the bits in the block in parallel) is converted to electric signal by an array of photosensitive ele- ments. Holographic techniques are proposed for the implementation of the high-density photographic

processing. The practicality of these block-oriented

systems are too early to be realistically appraised."

(Lo, 1968, p. 1465).

6.147 For example: "A new mass core memory

which offers data access time of 1.5 microseconds

and capacity of up to 20 million bits has been placed

on the market as a standard product by Ampex

Corporation. The RM, which is suitable for use with

most large scale computers and data processing

systems now in production or use, will be available

for delivery early in 1968." (Data Proc. Mag. 10,

No. 1, 58 (Jan. 1968).)

"A randornly-addressable, low cost magnetic mass core memory system with a storage capacity

of 0.5 megabytes at a cost of 1 to 2 cents per bit is now available from Ferroxcube's Systems Division.

The new memory offers the optimal compromise

between cost, bit transfer rate and capacity. It has

a full cycle time of 2.5 /as and is capable of operation

in ambients to 105° F. The memory system can be

organized in word capacities of from 9 to 144 bits

(in multiples of 9) pfer 524-K byte module. Any

number of modules can be connected for series oi parallel operation to build systems of almost infinite storage capacities. A total of 4.7 million cores are

used in the unique 2-1/2 D selection organization,

which incorporates an extra wire for sensing the

interrogated bits. The total package with all electronics and power supplies measures 72" X 25" X 28"." (Computer Design 7, No. 6, 70 (June 1968).)

"A new, duplex version of the Potter RAM, a magnetic tape random access memory. The new

unit has the same performance characteristics as

its predecessor, 50.2 million bits of information

packed at 1,000 bp; and an average access speed

of less than 90 milliseconds." (Commun. ACM 8,

343-344 (1965).)

"Available in storage capacities up to 32 million

bits (1,024,000 words of 32 bits), a new magnetic

core memory has a cycle time of less than 4 microseconds. Dependent upon quantity and capacity,

the price will be as low as 1-1/2 cents per bit. The

Model CM-300 is said to offer true random access

at speeds and capacities not previously available

in static storage devices. As such, this memory is expected to forge a place in the hierarchy of bulk

storage peripherals permitting greater programming

flexibility and increased computer throughput. A

2-wire, 2-1/2D magnetics organization and field proven circuitry are utilized to assure high reliability

and wide operating margins. All circuits in the

system have been subjected to verifiable worst case

design. Modular design permits exceptional flexi- bility in selecting memory interface, ease of maintenance and low logistic support cost. Lockheed

Electronics Company, Los Angeles, Cal." (Modern

Data Systems 1, No. 2, 74 (Apr. 1968).)

"The LIBRAFILE 4800 is one of a series of large

capacity, high-speed head-per-track disc file memories developed by the Systems Division of

Librascope Group. It has a capacity in excess of 400

million data bits, with an average access time of

35 milliseconds. Additional memory modules may be

added to increase storage and the head-per-track

design permits bit parallel data transfers to meet

interface and speed requirements." (Computer

Design 7, No. 6, 22 (June 1968).)

"Laboratory developments completed prior to the initiation of the program described here demonstrated that tape speeds well in excess of 1000

inches per second (ips) and packing densities of one million bits per square inch, with high data

reliability, were feasible. Using these developments

as a basis, a large memory system could therefore

be designed. A prototype 'small' system with a total storage capacity of 10 n bits has been built and

tested. The following is a description of such a system and its major components.

TBM system description: "The TBM (terabit

memory, i.e., 10 12 bit memory) random access memory uses magnetic tape as a basic storage

medium. Random access is provided by using tape

search speeds of 1000 ips (compared to approximately 300 ips used on conventional transports)

and by using packing densities of 700,000 bits per

square inch (compared to approximately 14,000

115
bits/in. for standard computer tape transports).

Data recording is done in the transverse mode (to the direction of tape motion) using rotating heads,

the technique used for video recording. A redundant

recording scheme permits the achievement of error

rates of two errors in 1010 information bits. The

salient features of the tape transport, permitting

this high search speed, and of the recording mode

and associated data channels, permitting this high

packing density, will be considered in detail follow- ing the system description." (Damron et al., 1968,

pp. 1381-1382).

"The NCR 353-5 Card Random Access Memory

(CRAM) File provides high-speed random or sequential processing of data for NCR 315 computer

systems. The data recording is done on magnetic

cards 3.65" x 14", each containing 144 recording

tracks. Each track has a storage capacity of 1,500

6-bit alphanumeric characters. The removable

cartridge houses 384 magnetic cards, providing a

total storage capacity of 82,944,000 6-bit alphanumeric characters.

"Any card from a cartridge can be dropped to read/write position within 125 milliseconds, providing throughput of 5 cards per second. Data is transferred to the processor at the rate of 50,000

alphanumeric characters per second.

"Up to sixteen CRAM Handlers may be connected

to the processor. This provides an online file capacity of over 1,327,104,000 alphanumeric char- acters (over 1,990,656,000 digits)." (Management

Report: MASS RANDOM ACCESS FILES from

NCR, nd., p. 1). 6.147a "Enthusiasts of Bell Telephone Labs'

recently-patented single-wall domain magnetic

memory claim it may some day obsolete the disk. By controlling the magnetic domains, millions of

bits can be stored in a diameter less than a micron.

The action can actually be seen through a microscope, according to one source. "Developed by William Schockley, Andrew

Bobeck, and H. E. Scoville, the memory works on

the spin moments between electrons and the

nucleus in a magnetoplumbite material containing

rare earth orthoferrites." (Data Proc. Mag. 11,

No. 8, 19 (Aug. 1969).)

6.148 "Magnetic recording bit and track densities, each an order of magnitude higher than those now used, have been demonstrated in the laboratory. Twenty thousand bits per inch and one thousand tracks per inch have been reported. The practi- cal application of these experiments requires

considerable development of magnetic heads,

recording media, and track location techniques."

(Bonn, 1966, p. 1868).

"Ferroxcube Corporation has announced the

development of a monocrystalline ferrite material

for use in magnetic recording heads. The new material, with its increased wear resistant characteristics, is expected to find wide use in video and high

density tape-recording applications where recording

head wear is a significant problem. Recording heads

made of a new material are expected to increase the

head life in these applications by a factor of 10

times or more thereby reducing the service costs of users. "The practical process for growing single-crystal

manganese-zinc ferrite has been developed by

using a technique similar to that used in producing

synthetic gem stones. This material is not the conventionally designated 'monocrystalline' ferrite,

which, though composed of large-size crystals, is actually polycrystalline.

"The single-crystal ferrite, as the name implies,

is a single, completely homogeneous crystal, with no grain boundaries to permit crystal puhout which

is frequently responsible for the familiar crumbling

or wear of the contact face and gap edges. The

superior mechanical properties of this new ferrite are further enhanced by proprietary glass-bonding,

or metal-bonding processes. Heads fabricated from

single-crystal ferrite and bonded by this means pre- sent a monolithic contact surface of extremely high

density and very low porosity in which the magnetic

gap can be controlled to within ± 5 microinches or

less and original sharp edges and machined profiles preserved intact through thousands of hours of

operation.

"Characteristics include an initial permeability

(uo) of 2250 ±250 at 100 kHz, 350 ±50 at 5 MHz."

(Comp. Design 8, No. 1, 30 (Jan. 1969)).

6.149 "There are severe problems in locating

and tracking information stored at very high

density. Servo-techniques (also being pursued for higher track density in magnetic recording) based

upon track-seeking principles are essential for beam

scanning approaches." (Hoagland, 1967, p. 259).

6.150 "Adapting videotape recording methods to computer systems may increase the capacity of

bulk, random access computer memories a thousandfold. According to Dr. William A. Gross, Ampex

vice president, an experimental system now in the

lab stores 50 billion bits on single 10- by 1/2-inch

reels of magnetic tape, or about 1000 times the

capacity of reels currently in use. Information can be accessed and transferred in less than 10 seconds.

"A finished memory based on these developments

would enable a user to place all of his digital rec- ords on line, ready for random access. This would

eliminate shelf storage and delays when a disk

pack must be located and placed in the system.

"This videotape recorder increases recording

density by using four recording and playback heads

mounted on a small metal disk that rotates perpendicularly across the moving tape. This rotary head

increases tape-to-head speed by six times that of the fastest fized-head device and enables the recording of tv pictures or, when applied to coded data,

increases the density." (Data Proc. Mag. 11, No. 2, 14 (Feb. 1969).)

6.151 "A light sensitive recording process called Photocharge, uses a photoelectric potential of

material in the film to produce images. It was

invented by Dr. Joseph Gaynor and Gordon Sewell

116
[G. E. Advanced Technology Labs.]. Its main

advantage lies in the fact that no external electrical charges or fields are required, as in conventional

electrophotographic processes. "Light and heat alone produce a completely

developed picture which consists of minute defor- mations on the surface of the film. "Recorded images can be erased by reheating

the film. It is then ready to receive and record

another picture. . . . "Since the material is limited in the range of

light to which it is sensitive and requires brighter

light than conventional film, Dr. Gaynor anticipates

that early applications probably will be directed

toward memories for graphic and pictorial information and high resolution, inexpensive image repro- duction." (Bus. Automation 12, No. 7, 50 (1965).)

6.152 "A technological development prerequisite

to the widespread exploitation of large, multiaccess

data-base systems is the large, low-cost, fast random-access mass store. Kuehler & Kerby

describe an IBM. 'Photo-Digital' storage device,

which is a step in this direction. The article gives no cost information, which makes evaluation

difficult, and the long random-access delay is a handicap; the other properties of the device are nevertheless rather exciting. Briefly, a modest

configuration can store 10 12 bits of data, accepting

them at a rate of about 0.2 megabits per second and

sequentially reading them at a rate of about 1 megabit per second. Random access requires a maximum 3-second delay for acquisition of the

proper 'cartridge.' A cartridge is roughly equivalent

in capacity to a reel of magnetic tape; the reading

rate after acquisition is also roughly equivalent to that of a high-performance tape drive. It would

require nearly two months of continuous writing at the maximum rate to fill a 10 12-bit configuration."

(Mills, 1967, p. 226).

Recent IBM papers describe error detection and

correction and data recovery techniques for this system. For example: "In a high-density photodigital storage system, contamination and other

defects can easily obliterate a group of data bits. To

operate successfully in spite of this problem in the

IBM Photo-Digital Storage System ... a powerful

error-correction code is used . . . "The problem of effectively implementing a code

of this complexity has been solved by a number of

innovations. Most important is the use of hardware

for encoding, calculation of the power sums, and

error detection, while using a control processor, on

a time-sharing basis, for error correction. Another

important feature is that single-character error correction is tried first; if this is not sufficient,

further correction activities can be tried. Other

important features are use of a 'trial and recheck'

method of error correction, selection of a symmetric

code polynomial, use of a table of logarithms for multiplication and division in a Galois field of 64

elements, et cetera." (Oldham et al., 1968, p, 422).

"The chance for error in a line of data read by

the world's largest computer storage system is only 0.000075 percent. This statistic is based on test data in 'Error Detection and Correction in a PhotoDigital Memory System,' an article in the November

issue of the 'IBM Journal of Research and Development.' The journal article describes the trillion- bit system's error-correction techniques and shows

how the system can correct errors rapidly enough

for real-time operation. The Photo-Digital Storage

System was built by the International Business

Machines Corporation under a special contract

for the U.S. Atomic Energy Commission. The AEC

contract specified the allowable error rate as no more than one 300-bit line with uncorrected errors

in 2,700,000 lines read. The system has demonstrated a much better average of one line with un- corrected errors in 13,500,000 lines read. Constructed by the IBM Systems Development Laboratory, San Jose, Calif., the system functions in a network of computers at the Lawrence Radiation

Laboratory in Livermore, Calif. A second PhotoDigital System, using the same error-correction

techniques and having approximately one-third

the storage capacity of the first, has been installed

at the Lawrence Radiation Laboratory in Berkeley,

Calif." (bema News Bull., Dec. 16, 1968, p. 6). "The theory of error detection and correction

codes is finding its way into practice. With these

codes, machines can reconstruct data that have

been destroyed. The first practical implementation

of a powerful and complex code was achieved in the trillion-bit IBM Photo-Digital Storage System,

which uses a Reed-Solomon code for correcting up

to 5 error characters in a line of 50 data characters.

"With a correction facility able to correct bursts

of errors in a line, a recorded bit need not be larger

than the average flaws in the recording medium.

In this system flaws cannot be eliminated by pre- testing the medium, because the recording is permanent on silver halide photographic film. However, since the film has high resolution, there is a

tradeoff between the cost of the correction facility

and the cost savings of high-density recording."

(Griffith, 1969, p. 456).

6.153 "The principle of the UNICON Computer

Mass Memory is derived from the UNICON

Coherent Light Data Processing System to create and detect (record and reproduce) information

elements in two dimensions by means of signalmodulated coherent laser radiation. . . . "Continuous readout of the UNICON system

utilizes a lightguide surrounding the imaging circle of the rotating objective, carrying the laser radiation

transmitted through the unidensity film to a central

photomultiplier. Hence, any coherently illuminated

information bit is photoelectrically detected within

few nanoseconds. . . . "Width of the information-carrying area of the

16 mm Unidensity film is 8 mm. Information packing

density is 6.45 X 108 bits per square inch. Rate of

information processing is in the megabits-persecond range. Total capacity of one UNICON

117
memory system is 88 X 109 bits for a 16 mm Unidensity film reel of 100 feet." (Becker, 1966, pp. 711-712).

"The Laser Recording Unit designed and developed by Precision Instrument Company provides

a means for reliably and permanently recording and

reproducing digital data. "The Laser Recording Unit uses a new type of

permanent recording process which employs a laser to vaporize minute holes in the metallic surface

of the recording medium. In this manner digital

information is recorded in parallel data tracks along

the length of a recording medium strip. The tracks

are spaced on the order of five to ten microns (micrometers), center-to-center; each track is composed

of bit cells three to five microns in size. For re- cording or reproducing sequential tracks of digital

data, the maximum transfer rate of the Laser Recording Unit is approximately four million bits per

second, with an average unrecoverable error rate

of one in 108 to 109 bits, depending on the data

density selected. "The Laser Recording Unit includes a programmable Recorder Control Subsystem which can be

designed to provide a hardware and software inter- face compatible with a specified computer system.

"The major benefits offered by the Laser Recording Unit as a mass digital-data storage unit are summarized below:

(1) Permanent Storage: Data do not degrade

over a period of time of the order of years.

(2) Compact Storage: Data are stored at a density approximately 250 times greater

than that of digital magnetic tape.

(3) Unlimited Readout: Data can be repeatedly

readout for long periods of time without

reduction in quality or damage to the record.

(4) Recording Verification: Essentially error- free data records result from the simultaneous

read-while-write verification capability that

is unique to the laser hole-vaporization

method of permanent recording.

(5) Low Error Rates: The average unrecoverable

error rate is approximately one in 108 to 109

bits.

(6) Economical Data Storage: Recording of large

quantities of data on the Laser Recording

Unit and permanent storage of the data in PI Record Strips significantly decreases the

cost-per-bit of recording and storage imposed

by existing methods." (McFarland and

Hashiguchi, 1968, p. 1369).

See also notes 6.18, 6.19, 6.20. 6.154 "A Photo-Optical Random Access Mass

Memory (FM 390) with multibillion bit capacity,

announced by Foto-Mem, Inc., can be used to replace or supplement magnetic tape, disk or drum units. Used separately or combined into one

system, the FM 390 uses a Photo-Data Card (PDCtm

) for data storage. Advantages over magnetic storage

are in cost and space saving. A typical Foto-Data

Celltm with 100 PDC's stores 3 billion bits of information, allowing a typical installation to hold

several trillion bits of data on fine." (Data Proc. Mag. 1 1 , No. 8, 73 (Aug. 1969)).

6.155 "Thin dielectric films which exhibit

sustained electronic bombardment induced conductivity (SEBIC) appear to satisfy the control

layer requirements for high sensitivity and storage.

"Thin films of cadmium sulfide which exhibit

SEBIC were first developed by the Hughes Research

Laboratories. . . . "SEBIC layers can store information in the

form of two dimensional conductivity modulations

with almost photographic resolution. In addition,

they can be excited with brief pulses of high

energy electron beams, and they are reusable

because they can be erased almost instantaneously.

In a sense, they may be thought of as a form of real time photographic film — the principal remaining

problem concerns the readout of information."

(Lehrer and Ketchpel, 1966, p. 533).

6.156 "This program is devoted to the preparation and investigation of novel kinds of data storage

elements of about micron size, and high-density

regular arrays thereof, to be addressed with an elec- tron beam of diameter comparable to the element

size. Such storage mosaics are formed by developing and adapting appropriate thin-film deposition

and micromachining techniques. The latter is based on the use of an electron beam probe to expose an electron-sensitive resist. A storage

capacity of about 108 bits is believed to be realizable

and accessible with an electron beam, without

mechanical movement of the storage surface. Currently we are investigating two kinds of elements.

The first one is an electrically isolated microcapacitor ... at the bottom of a hole in a metaldielectric-metal film sandwich. The other consists

of an isolated washer or ring of metal embedded in the dielectric of a multilayer metal and dielectric

film sandwich. Ultimately, elements 1/4/u. in di- ameter or smaller, spaced approximately 1/2/a center to center, are expected to be feasible, repre- senting ultimate packing densities up to 4 X

108/cm2 ." (Rogers and Kelly, 1967, p. 1). 6.157 "The selection of materials and thick- nesses for the recording media and substrates is based on obtaining maximum sensitivity to a minimum power density in the recording spot, while

maintaining adequate contrast for the readout means selected and stability to the anticipated

environment. This basis for selection implies that an increase in the absorption efficiency of the

medium is useful only if it leads to a more sensitive

media and/or improved contrast. Excellent record

ing have been achieved at high rates with coatings

having less than 20 percent absorption at the laser wavelength. Additional coating and substrate considerations are: adequate adhesion to one another,

abrasion resistance, permanency, cost, etc., and

special considerations, e.g., the use of a mica substrate to help obtain certain unique properties in the

118
thin films of MnBi which are used for Curie point

magnetic recording." (Carlson and Ives, 1968, p. 1). 6.158 "The results of the studies described in

this paper have established laser heat-mode recording as a very high resolution real-time recording

process capable of using a wide variety of thin

film recording media. The best results were ob- tained with images which are compatible with

microscope-type optics. The signals are in elec- tronic form prior to recording and can receive ex- tensive processing before the recording process

occurs. In fact, the recordings can be completely

generated from electronic input." (Carlson and

Ives, 1968, p. 7). 6.159 "Instead of recording a bit as a hole in a

card, it is recorded on the file as a grating pattern

of a certain spacing ... A number of different grating patterns with different spacings can be

superposed and when fight passes through, each

grating bends the light its characteristic amount,

with the result that the pattern decodes itself . . . The new system allows for larger areas on the film

to be used and lessens dust sensitivity and the possibility of dirt and scratch hazards." (Commun.

ACM 9, No. 6, 467 (June 1966)).

6.160 "Both black-and-white and color video

recordings have recently been made on magnetic

film plated discs. . . . "Permanent memory systems employing silver- halide film exposed by electron'or laser beams. It

is possible to record a higher density with beams.

Readout at an acceptable error rate is the major

problem." (Gross, 1967, p. 5). "A recently conceived memory which uses

optical readout. Instead of recording bits as pulses,

bits are recorded as frequencies. An electron beam,

intensity modulated with the appropriate fre- quencies, strikes the electron sensitive silver-halide

film moving transverse to the direction of tape motion . . ." (Gross, 1967, p. 8). "For recording analog information Ampex has

focussed efforts on silver-halide film . . .[which] can be made sensitive to either electron or laser beams . . . packing density is an order of magnitude

greater than the most dense magnetic recording."

(Gross, 1967, p. 6). "Recent work at Ampex indicates that the

Kerr magneto-optic effect is likely to be practical

for reading digital information. Recording on a

reflective plated tape for magneto-optic repro- ducing can be done by local heating with a laser or electron beam." [Erasable, potential density

1 X 108 ]." (Gross. 1967, p. 8). 6.161 "At first glance, machining with electron

beams, or adding ions, appear to be suitable for recording digital information. However, problems in obtaining sufficient linearity in the transfer function (the dynamic range and signal-to-noise limits),

and accurately positioning the electron beam for reading make it impossible to read out the potential

recording density with acceptable error rates.

The reduced packing density necessary for acceptable error rates cause these approaches to suffer by comparison with magnetic recording." (Gross,

1967, p. 6).

6.162 "The advantages of electron beams over

light are a thousandfold increase in energy density,

easy control of intensity and position, and a substantial increase in resolution. To offset these

advantages, there are the complications of a demountable vacuum system." (Thornley et al., 1964, p. 36).

6.163 ". . . Some [media] like thermoplastics,

involve nearly reversible changes, and the noise content therefore rises with use." (Gross, 1967,

p. 2). 6.164 "The standing-wave read-only memory

is based on the Lippmann process . . . [in which]

a panchromatic photographic emulsion is placed

in contact with a metallic mirror . . . Sufficiently

coherent light passes normally through the emulsion, reflects from the mirror, and returns through

the emulsion. This sets up standing waves with a node at the metallic mirror surface. Developable

silver ions form in the regions of the antinodes

of the standing wave ... If several anharmonic waves are used to expose the same region of the

emulsion, each will set up a separate layer struc- ture . . . Conceivably, n color sources spaced

appropriately over the band of sensitivity could

provide n information bits, one per color, at each

location". (Fleisher et al., 1965, p. 1). Advantage would then be taken of ". . . the

Bragg effect, which causes the reflected light to

shift to shorter wavelength as the angle of incidence

increases . . . With this method, a monochromatic

light source, say of violet color, could read out the

violet bit at normal incidence and the red bit at the

appropriate angle from normal. Hence, a single

monochromatic source, such as a laser, could be

used to read out all bits . . ." (Fleisher et al., 1965,

p. 2). Further, "random word selection requires a summation of various injection lasers ... or the use of

a white light source in which all colors are present.

This source is then deflected to the selected

location by the electro-optical deflector. The output

from the memory plane is then separated into the

various colors by means of a prism or other dis- persive medium for a parallel bit readout". (Fleisher

et al., 1965, p. 19). 6.165 "A feature of the SWROM [standing-wave

read-only memory] which appears to be unique is its capability of storing both digital and video

(analog) information. This feature, combined with

the capability of the memory for simultaneous,

multibit readout with minimal cross talk, will give

the SWROM an even wider range of application."

(Fleisher et al., 1965, p. 25). 6.166 "Parallel word selection . . . could be

119
accomplished by fiber-optic light splitting. It could is that of the bit or series of bits to be selected. This

also be accomplished by flooding the area to be type of word selection would be useful for associaread out with monochromatic light whose frequency tive word selection." (Fleisher et al., 1965, p. 21).

7. Debugging, On-Line Diagnosis, Instrumentation, and Problems of Simulation

7.1 "The quantity and quality of debugging

must be faced up to in facility design. This is perhaps the area which has been given more lip

service and less attention than any other." (Wagner

and Granholm, 1965, p. 284).

"Software checkout still remains an unstructured

art and leaves a lot to be desired for the production

of perfect code." (Weissman, 1967, p. 31). "Debugging, regardless of the language used, is one of the most time consuming elements in the

software process." (Rich, 1968, p. 34). "It has been suggested that . . . we are now

entering an era in which computer use is 'debugginglimited'." (Evans and Darley, 1966, p. 49). 7.2 "As computing systems increase in size and

complexity, it becomes both more important and more difficult to determine precisely what is happening within a computer. The two sorts of

performance measurements which are readily

available are not very useful; they are the microtiming information provided by the manufacturer

(.4 microseconds/floating add) and the macro-timing

information provided by the user ("why does it take three days to get my job back?"). The relation- ship, if any, between them is obscured by the

intricate bulk of the operating system; if it is a multi-programming or time-sharing system, the

obscurity is compounded.

"The tools available to the average installation

for penetrating this maze are few and inadequate.

Simulation is not particularly helpful: the information which is lacking is the very information necessary for the construction of an accurate model.

Trace routines interfere excessively with the operation of the system, distorting storage requirements

as well as relative timing information. Hardware

monitors are not generally available, and though a wondrous future is foreseen for certain of them,

they have yet to demonstrate their capabilities in an operational environment; furthermore, they are

certain to be too costly for permanent installation,

and perhaps too cumbersome for temporary use. The peripheral processor of the Control Data 6000

series computers, however, provides some installa- tions with an easily utilized, programmable hard- ware monitor for temporary use at no extra cost." (Stevens, 1968, p. C34).

"Without instrumentation, the user is swimming

against the tide of history. It is commonly thought

that a good programmer naturally achieves at least 80% of the maximum potential efficiency for a program. But while systems have increased greatly

in size and complexity, the average expertise of programmers has decreased. In fact, it is axiomatic

that virtually any program can be speeded up 25 to 50% without significant redesign! Unless monitored

and measured, a program's efficiency may easily

be as low as 25%. What is worse, multiprogramming,

multiprocessing, real time, and other present-day

methods have created such a jumble of interactions

and interferences that without instrumentation it would be impossible to know where effort applied

for change would yield the best return. One tries to mine the highgrade ore first, while it still exists."

(Bemer and Ellison, 1968, p. C40).

7.3 For example, "another practical problem,

which is now beginning to loom very large indeed

and offers little prospect of a satisfactory solution,

is that of checking the correctness of a large pro- gram." (Gill, 1965, p. 203).

"With the introduction of time-sharing systems,

the conventional tools have become almost worthless. This has forced a reappraisal of debugging

procedures. It has become apparent that a new type

of debugging tool is needed to handle the special

problems created by a time-sharing system. These

special problems result from the dynamic character

of a time-sharing system — a system in which the

program environment is continually changing, a system in which a user is unaware of the actions of

other users, a system in which program segments

are rolled in and out of storage locations, and a system in which one copy of code can be shared by

many users. To debug in this dynamic environment,

the programmer needs a debugging support sys- tem—a set of debugging programs that operate

largely independently from the operating system

they service. . . . "What is needed for time-sharing is a debugging

support system that meets the following requirements: • The system should permit a system pro- grammer at a user terminal to debug system

programs associated with his task. When

used in this manner, the support system should

operate in a time-sliced mode. • When used to debug a separate task, the support system should provide the facility to modify a system program in relation to that task, without affecting the program as executed

in relation to other tasks. • When a system program bug cannot be lo- cated and repaired from a user terminal, the

support system should permit a skilled sys- tem programmer at a central location to sus- pend time-sharing activity until the error is located and repaired. The support system

should then permit time-sharing activity to be

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resumed as though there had been no inter- ruption. The support system should permit a system programmer to monitor the progress of

any task from a remote terminal or from the

user's terminal. • The support system should contain the facility to remain dormant until activated by a specified condition. When activated by the condition, the system should be able to gather

specified data automatically and then permit

processing to continue. • In its dormant state, the support system should

not impact the performance of the parent timesharing system. • The support system should use a minimum of main storage and reside primarily on highspeed external storage. • The support system should be completely

independent of the time-sharing system (that

is, it must use none of the facilities of the

parent system), and it must be simple enough

to eliminate any requirement for a support

system of its own. "An effort is currently under way to produce a time-sharing support system that meets these re- quirements." (Bernstein and Owens, 1968, pp. 7, 9). "There has been far too little concern on the part

of the hardware system designers with the problems of debugging of complex programs. Hardware

aids to program debugging would be among the most

important hardware aids to software production.

On-line debugging is essential. It should be possible

to monitor the performance of software on a cathode

ray tube console, without interfering with the per- formance of the software. It should be possible to examine areas of peripheral storage as well as areas

of core storage." (Rosen, 1968, p. 1448).

Further, "the error reporting rate from a program

system of several million instructions is sufficient to occupy a staff larger than most computing installa- tions possess." (Steel, 1965, p. 233). 7.4 "By online debugging we mean program

debugging by a programmer in direct communication with a computer (through, typically, a typewriter or teletype), making changes, testing his program, making further changes, etc., all with a reasonably short response time from the computer,

until a satisfactory result is achieved." (Evans and

Darley, 1965, p: 321).

7.5 "Another area of contact between hardware

and debugging is involved with trapping . . . The

user may ask for a trap on any combination of a number of conditions, such as a store into a specified

register, execution of an instruction at a specified

location, or execution of any skip or jump instruction. The debugging program handles the interrupt

and reports the relevant information to the user." (Evans and Darley, 1966, p. 44).

It is to be noted that although these authors,

as of 1966, were concerned that "very little data seems to exist on the relative efficiency of on-line

program debugging versus debugging in a batchprocessing mode." (Evans and Darley, 1966, p. 48), by 1968 Sackman et al., could report "on the

basis of the concrete results of these experiments,

the online conditions resulted in substantially

and, by and large, significantly better performance

for debug man hours than the offline conditions."

(Sackman et al., 1968, p. 8). 7.6 "We have, in general, merely copied the

on-line assembly-language debugging aids, rather

than design totally new facilities for higher-level

languages. We have neither created new graphical

formats in which to present the debugging infor- mation, nor provided a reasonable means by which

users can specify the processing required on any

available debugging data. "These features have been largely ignored be- cause of the difficulty of their implementation.

The debugging systems for higher-level languages

are much more complex than those for assembly

code. They must locate the symbol table, find the beginning and end of source-level statements,

and determine some way to extract the dynamic

information — needed for debugging— about the

program's behavior, which is now hidden in a sequence of machine instructions rather than

being the obvious result of one machine instruction.

Is it any wonder that, after all this effort merely

to create a minimal environment in which to per- form on-line higher-level language debugging,

little energy remained for creating new debugging

aids that would probably require an increased

dynamic information-gathering capability.

"EXDAMS (Extendable Debugging And Monitoring System) is an attempt to break this impasse

by providing a single environment in which the users can easily add new on-line debugging aids

to the system one-at-a-time without further modifying the source-level compilers, EXDAMS, or their programs to be debugged. It is hoped that EXDAMS

will encourage the creation of new methods of debugging by reducing the cost of an attempt

sufficiently to make experimentation practical.

At the same time, it is similarly hoped that EXDAMS will stimulate interest in the closely related

but largely neglected problem of monitoring a program by providing new ways of processing

the program's behavioral information and presenting it to the user. Or, as a famous philosopher once almost said, 'Give me a suitable debugging

environment and a tool-building facility powerful

(and simple) enough, and I will debug the world'."

(Balzer, 1969, p. 567). 7.7 "Diagnostics have been almost nonexistent

as a part of operating software and very weak as a part of maintenance software. As a result needless

time is spent determining the cause of malfunctions;

whether they exist in the program, the hardware,

the subsets, the facilities or the terminals." (Dantine, 1966, pp. 405-406).

7.8 "Another advantage of computer simulation

is that it may enable a system's manager to shrink

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the anticipated real world life of his system into a

relatively short span of simulation time. This capability can provide the manager with a means of

examining next week's (month's, year's) production

problems this week; thus he can begin to antici- pate the points where the operations will require

modification. Moreover, he can examine alternative courses of action, prior to their being implemented

in the system, to determine which decision is most

effective. For example, the manager can increase

the processing load in the simulation to determine

where the saturation points are. Once these have

been determined, he can hold these overloading

states constant and vary the other variables (e.g., number of service units, types of devices, methods

of operations) to determine how best to increase the

system's capacity." (Blunt et al., 1967, p. 76). Mazzarese (1965) describes the Air Force Cambridge DX— 1 system with a "dual computer con- cept" that permits investigators to change computer

logic and configuration in one machine without

interference to programs which run on its inter- connected mate, especially for study of real time

data filtering operations.

7.9 "A technique for servicing time-shared

computers without shutting them down has been

developed by Jesse T. Quatse, manager of engineering development in the Computation Center at the Carnegie Institute of Technology. The tech- nique is called STROBES, an acronym for sharedtime repair of big electronic systems. It includes a

test program to exercise the computer, and modified test gear to detect faults in the system." (Electronics 38, No. 18, 26 (1965)).

7.10 "Diagnostic engineering begins in the initial phases of system design. A maintenance strategy

is defined and the system is designed to include

features necessary to meet the requirements of this strategy. Special features, known as 'diagnostic

handles', are needed for testing the system auto- matically, and for providing adequate error isola- tion." (Dent, 1967, p. 100).

"An instantaneous alarm followed by a quick and

correct diagnosis in a self-controlling system will limit down-time in many cases to the mere time of

repair. Instruments for error detection are unnecessary." (Steinbuch and Piske, 1963, p. 859). 7.11 Further, "when a digital system is par- titioned under certain restrictions into subsystems

it is possible to achieve self-diagnosis of the system

through the mutual diagnosis of its subsystems."

(Forbes et al., 1965, p. 1074).

"A diagnostic subsystem is that portion of a digital

system capable of effectively diagnosing another

portion of the digital system. It has been shown that

at least two mutually exclusive diagnostic subsystems are needed in self-diagnosable systems."

(Forbes et al., 1965, p. 1081). 7.12 "Systems are used to test themselves by

generation of diagnostic programs using predefined data sets and by explicit controls permitting

degradation of the environment." (Estrin et al., 1967, p. 645).

"The 'Nightwatchman' experiments are directed

toward the maintenance problem. Attempts will be

made to structure a maintenance concept that will allow for the remote-automatic-checkout of all the

computers in the network from a single point. The

concept is an extension of the 'FALT' principle

mentioned previously. Diagnostic programs will be

sent over the lines, during off-use time, to check

components, aggregates of components, complete

modules, and the entire system. The 'Sentinel'

station of the network will be responsible for the

gathering of statistical data concerning the data,

the queries, the traffic, and the overall operations."

(Hoffman, 1965, pp. 98-100.)

"The Sentinel is the very heart of the experimental network. It is charged with the gathering

of the information needed for long range planning,

the formulation of data automation requirements,

and the structuring of prototype systems. In addition to the gathering of statistical data, the

sentinel will be the control center for the network,

generating priority, policy, and operational details. The responsibility for the observance of security

and proprietary procedures will rest with the

sentinel station." (Hoffman, 1965, p. 100.)

"This data was taken by a program written to run

as part of the CTSS Supervisory Program. The

data-taking program was entered each time the

Scheduling Algorithm was entered and thus was

able to determine the exact time of user state changes." (Scherr, 1965, pp. 27-28).

"Data taken over the summer of 1964 by T. Hastings . . . indicates that the average program

accesses (i.e., reads or writes) approximately 1500

disk words per interaction." (Scherr, 1965, p. 29). "We can and will develop instrumentation which

will be automatically inserted at compile time. A

user easily will be able to get a plot of the various

running times of his program . . ." Sutherland also refers to a Stanford University

program which "plots the depth of a problem tree versus time was used to trace the operation of a Kalah-playing program." (Sutherland, 1965, pp. 12-13).

7.13 "The techniques of fault detection fall into two major categories:

1. Concurrent diagnosis by the application of

error-detecting codes and special monitoring

circuits. Detection occurs while the system

is being used.

2. Periodic diagnosis using diagnostic hardware

and/or programs. Use of the system is inter- rupted for diagnosis." (Avizienis, 1967, p. 734).

"The four principal techniques of correction are:

1. Correction of errors by the use of error- correcting codes and associated special

purpose hardware and/or software (including

recomputation).

122
2. Replacement of the faulty element or system

by a stand-by spare.

3. Replacement as above, with subsequent maintenance of the replaced part and its return

to the stand-by state.

4. Reorganization of the system into a different

fault-free configuration which can continue

the specified task." (Avizienis, 1967, p. 734).

"The STAR (Self-resting and .Repairing) computer, scheduled to begin experimental operation

at the Jet Propulsion Laboratory of the California

Institute of Technology this fall, is expected to be

one of the first computers with fully automatic self- repair as one of its normal operating functions . . . There are three 'recovery' functions of the STAR

computer: (1) detection of faults; (2) recognition of

temporary malfunctions and of permanent failures; and (3) module replacement by power switching.

The occurrence of a fault is detected by applying an error-detecting code to all instructions and numbers within the computer. Temporary malfunctions

are corrected by repeating a part of the program. If the fault persists, the faulty module is replaced."

(Avizienis, 1968, p. 13). 7.14 "Diagnostic routines can check the operating of a computer for the following possible malfunctions: a single continuous malfunction, several

continuous malfunctions, and intermittent malfunctions. When the test routine finds an error it can transfer program control to an appropriate malfunction isolation subroutine. This type of diagnostic

technique is standard and has been well used by the

computer industry for large package replacement."

(Jacoby, 1959, p. 7-1).

"Needless to say, in order for any malfunction

to be isolated by an automatic program, it is necessary for a minimum amount of equipment to function adequately. One of the functions of this minimum equipment includes the ability to sequence

from one instruction to another, and to be able to interpret (correctly) and execute at least one transfer of control instruction so that logical choices can

be made. The control functions of a computer can

be defined as Boolean algebraic expressions of the

instantaneous state of the computer. If we state that a line, or path, common to two control state- ments contains those components that are acti- vated when either of the statements is true, this fine

is either a factor of both statements or a factor of

terms of both statements. Similarly, if we consider

circuit elements activated by one but not both of two ways to accomplish the same control function, we have a picture of two terms in the algebraic statement for the control function separated by

the connector OR.

"A Boolean term will appear as a circuit which

must be active for any statement, of which it is a

factor, to be true. Hence the location of circuit malfunctions may be considered from the point of

view of isolating the minimal Boolean term in- volved." (Jacoby, 1959, p. 7-1).

7.15 "A program testing method based on the

monitoring of object-program instruction addresses

(as opposed to a method dependent on, e.g., the occurrence of particular types of instruction, or the use of particular data addresses) would appear

to be the most suitable, because the instruction

address is the basic variable of this monitoring

technique. Monitoring could be made 'selective' by specifying instruction addresses at which it is to start and stop: to start it at an arbitrary instruction address it is only necessary to replace the

instruction located there by the first unconditional

interrupt inserted, and similarly when monitoring

is to stop and restart later. . . . "Another use in this field would be to include in the Monitor facilities for simulating any instruction,

and to supply it with details of particular instructions

suspected of malfunctioning. The Monitor could

then stop any program just before one of these

instructions was to be obeyed, simulate it, allow

the program to execute the same instruction in the normal way, and then compare the results obtained by the normal action and by simulation."

(Wetherfield, 1966, p. 165).

"Of course, having achieved the aim of being

able to trace in advance the exact course of the

object program's instructions, the Monitor is then

able to simulate their actions to any desired degree,

and it is here that the power of the technique can be

exploited. The contents of the store, registers, etc., before the execution of any instruction can be in- spected by the Monitor if it temporarily replaces

that instruction by an unconditional interrupt."

(Wetherfield, 1966, p. 162).

"The monitoring operation can go wrong for any

of the following three reasons.

"(1) In the first case one of the planted unconditional interrupt instructions actually overwrites

the instruction at which the object program is going

to resume (the one at which monitoring started).

This would effectively bring things to a standstill since the situation will recur indefinitely. If the rules above have been followed, this situation can only

arise when a branching instruction includes itself among its possible destinations, i.e., there is a potential loop stop in the object program. In order to cope with this situation, if it could occur, it may be

necessary for the Monitor to simulate the action

of the branch instruction completely and make the

object program bypass it. The loop stop might still occur, but it would be foreseen.

"(2) The second possible reason for a failure of

the monitoring operation occurs if one of the planted

instructions overwrites part of the data of the object

program, thus affecting the latter's behaviour. This

'data' might be a genuine instruction which is examined, as well as obeyed, by the object program.

Alternatively it might be genuine data which

happens to be stored in a position which is, by

accident or design, a 'redundant' destination of a branching instruction. Both of these dangers can be

anticipated by the Monitor, at the cost of a more

123

376-411 O - 70 - 9
detailed examination of instructions (to find out which store references by the object program

involve a replaced instruction location) and more

frequent interrupts.

"The situation savours of 'trick' programming. It is apparent that the monitoring process will be

simplified if there is some guarantee that these

oddities are absent from object programs." (Wetherfield, 1966, pp. 162-163).

7.16 "MAID (Monroe Automatic Internal

Diagnosis) is a program that tells a machine how

to measure its circuitry and test performance

on sample problems — computer hypochondria,"

(Whiteman, 1966, p. 67). 7.17 "I have used a program which interprets

the program under test and makes a plot of the

memory address of the instruction being executed

versus time. Such a plot shows the time the program

spends doing its various jobs. In one case, it showed

me an error which caused a loss of time in a program

which nevertheless gave correct answers. . . . "Think of the thousands of dollars saved by

tightening up that one most-used program loop.

Instrumentation can identify which loop is the

most used." (Sutherland, 1965, pp. 12-13). 7.18 "On-Line Instrumentation will bring us

better understanding of the interplay of the pro- grams and data within the computer. Simple devices

and programs to keep track, on-line, of what the

computer does will bring us better understanding

of what our information reprocessing systems

are actually doing." (Sutherland, 1965, p. 9). 7.19 "The process of building a pilot system

configuration and then evaluating it, modifying it, and improving it is very costly both in time and

money. Another approach is possible. Before he

builds the system, the designer should be able

to test his concepts on a simulation model of a document retrieval system. One such model for simulating information storage and retrieval systems was designed by Blunt and his co-workers

at HRB-Singer, Inc., under a contract with the

Office of Naval Research. In this model, the

input parameters for the simulation reflects the

configuration of the system, the work schedule of the

system, the work schedule of the personnel,

equipment availability, the likelihood and effect of errors in processing and the location and availability of the system user. Simulation output pro- vides a study of system response time (both delay

time and processing time), equipment and personnel

work and idle time and the location and size of

the data queues. The systems designer can thus vary

the inputs, use the model to simulate the inter- actions among personnel, equipment, and data at each step of the information processing cycle,

and then determine the effect on the system re- sponse time." (Borko, 1967, p. 55). 7.20 "Simulation is a tool for investigation and,

like any tool, is limited to its inherent potential.

Moreover, the realization of this potential is dependent upon economics, the craftsmanship of the

designer and the ingenuity of the user. Digital

simulation can expedite the analysis of a complex

system under various stimuli if the aggregate can

be divided into elements whose performance can be

suitably described. If the smallest elements into which we can divide a system are themselves un- predictable (even in a probabilistic sense) digital

simulation is not feasible. (Conway, et al., 1959,

p. 94). This feasibility test uncovers an important

limitation in today's simulation technology with

respect to information systems. In many respects some of the more important man-information-system

interactions cannot now be described in a formal manner; hence, cannot be characterized for

digital simulation. For example, one can calculate

the speed and costs of processing an inquiry, but

cannot predict if the output will satisfy the user or estimate its impact on his operations.

"This limitation, therefore, (1) restricts simulation

applications to examining the more mechanical

aspects of data processing, or (2) forces the design

engineer to adopt some simplifying assumptions

concerning the effects of man's influence on the

system. An example of the first point is a data

flow simulation examining the rate of data proc- essing without regard to the quality of the types

and mixes of equipment and personnel. This capability for examining the resultant effects in varying

parameters of the system enable the design engineer

to explore more alternatives in less time and at less cost than ever before; e.g., he can develop cost- capability curves for different possible system

configurations under both present and anticipated

processing needs. Neglecting this aspect of systems

analysis has sometimes led to the implementation

of a system saturated by later requirements and

confronted by an unnecessary high cost for modification or replacement." (Blunt et al., 1967, pp. 75-76).

"To use simulation techniques in evaluating

different computer systems, one must be able to specify formally the expected job mix and constraints under which the simulated system must

operate, e.g., operating time per week. Equally important, one must carefully select a set of characteristics on which the competing systems will be

judged. For different installations the most important characteristics may well be different. Each

system under consideration is modelled, simulation runs are executed, and the results are compared on

the selected characteristics.

"Unfortunately, the ideal case seldom occurs. Often the available information about the computer

system's expected job mix is very limited. Further- more, it is a well-known fact that an installation's job mix itself may be strongly influenced both

qualitatively and quantitatively by the proposed

changes in the system. For example, many of the

difficulties with early time-sharing systems can be

attributed to the changes in user practices caused

by the introduction of the system. When statistics on job mix are available, they are often expressed in averages. Yet, it may be most important to simulate

124
a system's performance under extreme conditions.

Finally, it is often difficult to show that a simulation

is valid — that is. that it actually does simulate the

system in question." (Huesmann and Goldberg,

1967, p. 150). 7.21 "The field of information retrieval has been

marked by a paucity of mathematical models, and

the basis of present operational computer retrieval svstems is essentially heuristic in design." (Baker,

1965, p. 150).

"The semantic and linguistic aspects of infor- mation retrieval systems also lend themselves

poorly to the rigidity of models and model tech- niques, for which claims often lack empirical

support." (Blunt. 1965, p. 105). 7.22 "There are structures which can easily

be defined but which present-day mathematics

cannot handle because of the limitations of presentday theory." (Hayes, 1963, p. 284).

"Markov models cannot, in general, be used

to represent processes where other than random

queuing is used." (Scherr, 1965, p. 32). "Clearly, we need some mathematical models

permitting the derivation of methods which will accomplish the desired results and for which

criteria of effectiveness can be determined. Such

models do not appear often in the literature." (Bryant, 1964, p. 504).

"First, it will be necessary to construct mathematical models of systems in which content, structure, communication, and decision variables all appear. For example, several cost variables are usually included in a typical operations research

model. These are either taken as uncontrollable

or as controllable only by manipulating such other

variables as quantity purchased or produced, time

of purchase or production, number and type of

facilities, and allocation of jobs to these facilities. These costs, however, are always dependent on human performance, but the relevant variables

dealing with personnel, structure, and communication seldom appear in such models. To a large extent this is due to the lack of operational defini- tions of many of these variables and, consequently,

to the absence of suitable measures in terms of

which they can be characterized." (Ackoff, 1961,

p. 38). "Mathematical analysis of complex systems

is very often impossible; experimentation with

actual or pilot systems is costly and time consuming, and the relevant variables are not always

subject to control. . . . "Simulation problems are characterized by being

mathematically intractable and having resisted

solution by analytic methods. The problems

usually involve many variables, many parameters,

functions which are not well-behaved mathematically, and random variables. Thus, simulation is a technique of last resort." (Teichroew and

Lubin, 1966, p. 724).

"The complex systems generally encountered

in the real world do not lend themselves to neat mathematical formulations and in most cases

the operations analyst is forced to reduce the

problem to simpler terms to make it tractable."

(Clapp, 1967, p. 5). "Admittedly the degree to which identifiable factors can be measured — compared to the in- fluence of unidentifiable factors — does help deter- mine whether or not an approach can be scientific.

It acts as a limit on the area where scientfic methods

can be applied. Precision in model building is relating to the difficulty of the problem and the

state of human knowledge concerning specific

techniques and their application." (Kozmetsky

and Kircher, 1956, p. 137). 7.23 "There is no guarantee that a model

such as latent class analysis, factor analysis, or anything else borrowed from another field will meet the needs of its new context; however this should not dissuade one from investigating such

plausible models." (Baker, 1965, p. 150).

"Models must be used but must never be believed.

As T. C. Chamberlain said, 'science is the holding

of multiple working hypotheses'." (Tukey and Wilk,

1966, p. 697). 7.24 "System simulation or modeling was subsequently proposed as a substitute for deriving test problems and is still generally accepted as such even

though its use introduced the new difficulty of deter- mining and building meaningful models." (Davis,

1965, p. 82). "The biggest problem in simulation modeling, as

in all model building, is to retain all 'essential' detail and remove the nonessential features."

(Scherr, 1965, p. 109).

"The fundamental problem in simulation of digital

networks is that of economically constructing a mathematical model capable of faithfully replicating

the real network's behavior in regard to simulation

objectives." (Larsen and Mano, 1965, p. 308). 7.25 "At this time, there exists no specialpurpose simulation programming language specifically for use with models of digital computer

systems. The general-purposes languages, such as SIMSCRIPT, GPSS, etc., all have faults which

render them unsuitable for this type of work."

(Scherr, 1965, p. 43). "The invention of an adequate simulation

language promises to be the crowbar needed to bring the programming of operating systems to the level of sophistication of algebraic or commercial

programming languages." (Perlis, 1965, p. 192). "The technique of input simulation . . . can be

very expensive. The programs necessary to create the simulated inputs are far from trivial and may

well constitute a second system larger than the

operational system." (Steel, 1965, p. 232). 7.26 "Those programs which require the simulated computer system and job mix to be specified

in algebraic or assembly languages have proved

useful; but as general computer systems simulation

tools, they require too much difficult recording to be
completely satisfactory. One way to improve upon

this situation has been to use languages specifically

designed to simulate systems. Teichroew and Lubin

in a recent review have listed more than twenty

languages, among them GPSS, SIMSCRIPT, SOL,

and CSL. These simulation languages allow the

modeller to specify the computer configuration

and job mix in a more convenient manner."

(Huesmann, and Goldberg, 1967, p. 152).

7.27 "One of the more exotic applications of

digital computers is to simulate a digital computer

on another entirely different type of computer. Using

a simulation program, application programs de- veloped for the first computer, the source computer,

may be executed on a second computer, the object

computer.

"Simulation obviously provides many advantages

in situations where a computer is replaced by a

different computer, for which the applications have

not yet been programmed. Simulation techniques

enable an installation to continue solving problems

using existing programs after the new computer

has been installed and the old one removed' . . . "Another situation in which simulation is advantageous is during the development of a new computer. Once specifications for the new computer

have been established, programming of applications

for the computer can proceed in parallel with hard- ware developments. The use of a simulator in this situation enables the users to debug their applications before the hardware is actually available."

(Trimble, 1965, p. 18). "One of the most successful applications of the recent microprogramming technology is in the

simulation of computers on computers.

"The microprogram control and the set of

microprogram routines are in effect a simulation

program that simulates the programmer's instruction set on a computer whose instruction set is the set of elementary operations. It may be equally

possible to simulate computers with other pro- grammer instruction sets in terms of the same set of elementary operations. This, slightly oversimplified perhaps, is the idea of hardware assisted

simulation that is now usually called emulation."

(Rosen, 1968, p. 1444).

"As a result of simulation's ability to deal with

many details, it is a good tool for studying extensive

and complicated computer systems. With simulation, one may assess the interaction of several subsystems, the performances of which are modified

by internal feedback loops among the subsystems.

For instance, in a teleprocessing system where pro- grams are being read from drum storage and held

temporarily in main storage, the number of messages in the processing unit depends upon the drum

response time, which depends upon the drum access

rate, which, in turn, depends upon the number of

messages in main storage. In this case, only a system-wide simulation that includes communication lines, processing unit, and I/O subsystems will determine the impact of varying program priorities

on main-storage usage. Studies of this nature can become very time consuming unless parameter

selections and variations are carefully limited. It

is no small problem to determine which are the

major variations that affect the system. In this aspect, simulation is not as convenient as algorithmic methods with which many variations can

be tabulated quickly and cheaply." (Seaman, 1966,

p. 177).

7.28 "The [SIMSCRIPT] notation is an aug- mented version of FORTRAN, which is acceptable:

but this organization does not take advantage of the

modularity of digital systems.

"SIMSCRIPT is an event-based language. That

is, the simulation is described, event by event, with

small programs, one per event. Each event program

(or sub-program) must specify the times for the events following it. Conditional scheduling of an

event is extremely difficult." (Scherr, 1965, p. 43). 7.29 Ewards points out that ". . . the preparation of so-called scenarios, or sequences of events

to occur as inputs to the simulation, is a major

problem, perhaps the most important one, in the

design of simulations, especially simulations of

information-processing systems." (Edwards, 1965,

p. 152).

7.30 "Parallel processes can be rendered

sequential, for simulation purpose; difficulties then

arise when the processes influence each other,

leading perhaps to incompatibilities barring a simultaneous development. Difficulties of this type

cannot be avoided, as a matter of principle, and the

system is thus not deterministic; the only way out would be to restore determinism through recourse to appropriate priority rules. This approach is justified

only if it reflects priorities actually inherent in the

system." (Caracciolo di Forino, 1965, p. 18). 7.31 "As a programming language, apart from

simulation, SIMULA has extensive list processing

facilities and introduces an extended co-routine

concept in a high-level language." (Dahl and

Nygaard, 1966, p. 671). 7.32 "The LOMUSS model of the Lockheed

UNIVAC on-line, time-sharing, remote terminal

system simulated two critical periods . . . and

provided information upon which the design of the

1108 system configuration was based. An effort is continuing which will monitor the level and characteristics of the workload, equipment utilization,

turnaround time, etc., for further model validation."

(Hutchinson and Maguire, 1965, pp. 166-167).

"A digital computer is being used to simulate the

logic, determine parts values, compute subunit

loading, write wiring fists, design logic boards, print

checkout charts and maintenance charts. Simulating

the logic and computing the loading of subunits

gives assurance that a computer design will function

properly before the fabrication starts. After the logic

equations are simulated, it is a matter of hours until

all fabrication information and checkout information

is available. Examples are given of the use of these

126
techniques on the design and fabrication of a large

scale military computer." (Malbrain, 1959, p. 4-1).

"The new EDP Machine Logic and Control

Simulator, LOCS, is designed to facilitate the simulation of data processing systems and logic on the

IBM 7090 Data Processing System . . . The inputs

of LOCS consist of a description of the machine to be simulated, coded in LOCS language, and a set of

test programs coded in either the procedure lan- guage of the test problems (e.g., FORTRAN) or in the instruction language of the simulated machine . . . The outputs of LOCS consist of the per- formance statistics, computation results, and

diagnostic data which are relevant to both the test programs and the design of the simulated machine."

(Zucker, 1965, pp. 403-404)

.

7.33 "... A system of software and hardware

which simulates, with a few exceptions, a multiple

set of IBM System/360 computing systems (hard- ware and software) that are simultaneously available

to many users." (Lindquist et al., 1966, p. 1775).

7.34 "Another simulation program designed to simulate multiprocessor systems is being developed

by R. Goldstein at Lawrence Radiation Laboratory.

Written in SIMTRAN, this program is specifically

designed to simulate the OCTOPUS computer

system at LRL which includes an IBM 7030

STRETCH, two IBM 7094's, twp CDC 6600's, one CDC 3600, two PDP 6's, an IBM 1401, and various

I/O devices. A parameterized input table specifies

the general multiprocessing configuration, the data

transmission rates, memory sizes and buffer sizes. Any other hardware variations and operating system

characteristics are introduced with SIMTRAN

routines. As output the program produces figures on

actual memory utilization, graphs of memory access

time, graphs of overhead, graphs of response time,

and graphs of several other relevant variables."

(Huesmann and Goldberg, 1967, p. 153). 7.35 "One of the more exotic applications of

digital computers is to simulate a digital computer

on another entirely different type of computer. Using

a simulation program, application programs devel- oped for the first computer, the source computer,

may be executed on a second computer, the object

computer." (Trimble, 1965, p. 18).

7.36 "The flexibility of a digital computer enables one to try out complicated picture processing

schemes with a relatively small amount of effort. To facilitate this simulation, a digital picture scanner and cathode-ray tube display was constructed.

Pictures were scanned with this system, the signal was recorded on a computer magnetic tape, and this tape was used as input to a program that simulated

a picture-transmitting system." (Huang and Tretiak,

1965, pp. 45-46).

"Computer simulation of a letter generator using

the above grammar is a comparatively straightforward programming task. Such a program, making

use of COMPAX, has been written for CDC 3600

system at the Tata Institute of Fundamental

Research, Bombay." (Narasimhan, 1966, p. 171).

At IBM, there has been developed a computer

program for image-forming systems simulation

(IMSIM/1), so that the photo-optical design engineer can study performance before such systems are

actually built (Paris, 1966).

7.37 "The first model developed matches

CTSS . . . Next, a simple, first-come, first-served round-robin scheduling procedure will be substituted. Then, a model which incorporates multiprogramming techniques with the CTSS hardware

configuration will be developed. Finally, a simple

continuous-time Markov model will be used to repre- sent both single-processor and multiple-processor

time-shared systems. . . . "The primary result obtained is that it is possible

to successfully model users of interactive computer

systems and systems themselves with a good degree

of accuracy using relatively simple models." (Scherr,

1965, p. 31). "The final model to be simulated will represent a system in which swapping and processor operation

are overlapped. While a program is being run by

the processor, the program which was running

previously is dumped and the next program to run

is loaded. Since loading and dumping cannot occur

simultaneously, there must be room in the core memory for at least two complete user programs —

the program being dumped or loaded. Should two

programs intended to run in sequence not fit together

in the core memory, the processor must be stopped

to complete the swapping." (Scherr, 1965, pp. 40-41).

Other examples of experiments in computer

simulation of multiple access and time-shared

systems include the following: "The development of the simulation program now provides a first-comefirst-serve queue unloading strategy. Continuing

effort, however, will provide for optional strategies,

e.g., selecting the data unit with the shortest servic- ing time, consideration of what flow will minimize

idle time at the central processor etc." (Blunt, 1965,

p. 15). "Project MAC is using a display to show the

dynamic activity of jobs within its scheduling

algorithm. Watching this display, one can see jobs

moving to higher and lower priority queues as time

passes." (Sutherland, 1965, p. 13). 7.38 "A great advance also is the wide application of digital computers for the simulation of

recognizing and adaptive systems. Digital simulation extraordinarily facilitates and accelerates

conducting experiments in this realm by permitting

extremely effective experimental investigations

without expenditure of materials and with little time spent." (Kovalevsky, 1965, p. 42).

127
"Third, computer simulation may serve as a heuristic in the search for models. The effort of

getting a computer to perform a given task may lead

to illuminating psychological hypotheses, even if no behavioral evidence has been taken into account.

Moreover, a program which solves problems is by

that sole virtue a candidate for a model and deserves

the psychologists' attention. After all, proving

theorems or recognizing patterns was until recently

uniquely human or animal." (Frijda, 1967, p. 59).

128
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143

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