AlllOb T7flEM3

National Bureau

of Standards

Computer Science

and Technology

„B3 NBS Special Publication 500-112

'UBLICATIONS

Selection of

Microcomputer

Systems
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards' was established by an act ot Congress on March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology

and facilitate their effective application for public benefit. To this end, the Bureau conducts

research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau's technical work is per- formed by the National Measurement Laboratory, the National Engineering Laboratory, and

the Institute for Computer Sciences and Technology.

THE NATIONAL MEASUREMENT LABORATORY provides the national system of

physical and chemical and materials measurement; coordinates the system with measurement

systems of other nations and furnishes essential services leading to accurate and uniform

physical and chemical measurement throughout the Nation's scientific community, industry,

and commerce; conducts materials research leading to improved methods of measurement,

standards, and data on the properties of materials needed by industry, commerce, educational

institutions, and Government; provides advisory and research services to other Government

agencies; develops, produces, and distributes Standard Reference Materials; and provides

calibration services. The Laboratory consists of the following centers:

Absolute Physical Quantities- — Radiation Research — Chemical Physics —

Analytical Chemistry — Materials Science

THE NATIONAL ENGINEERING LABORATORY provides technology and technical ser- vices to the public and private sectors to address national needs and to solve national problems; conducts research in engineering and applied science in support of these efforts; builds and maintains competence in the necessary disciplines required to carry out this research and technical service; develops engineering data and measurement capabilities;

provides engineering measurement traceability services; develops test methods and proposes

engineering standards and code changes; develops and proposes new engineering practices;

and develops and improves mechanisms to transfer results of its research to the ultimate user. The Laboratory consists of the following centers:

Applied Mathematics — Electronics and Electrical Engineering^ — Manufacturing

Engineering — Building Technology — Fire Research — Chemical Engineering^

THE INSTITUTE FOR COMPUTER SCIENCES AND TECHNOLOGY conducts

research and provides scientific and technical services to aid Federal agencies in the selection, acquisition, application, and use of computer technology to improve effectiveness and

economy in Government operations in accordance with Public Law 89-306 (40 U.S.C. 759), relevant Executive Orders, and other directives; carries out this mission by managing the Federal Information Processing Standards Program, developing Federal ADP standards

guidelines, and managing Federal participation in ADP voluntary standardization activities; provides scientific and technological advisory services and assistance to Federal agencies; and

provides the technical foundation for computer-related policies of.the Federal Government.

The Institute consists of the following centers:

Programming Science and Technology — Computer Systems Engineering.

'Headquarters and Laboratories at Gaithersburg, MD, unless otherwise noted; mailing address Washington, DC 20234. ^Some divisions within the center are located at Boulder, CO 80303.
Computer Science

and Technology

NBS Special Publication 500-1 1

Selection of

Microcomputer

Systems

John Barkley

Dennis Gilbert

A! Hankinson

Institute for Computer Sciences and Technology

National Bureau of Standards

Washington, DC 20234

U.S. DEPARTMENT OF COMMERCE

Malcolm Baldrige, Secretary

National Bureau of Standards

Ernest Ambler. Director

Issued March 1984
Reports on Computer Science and Technology

The National Bureau of Standards has a special responsibility within the Federal

Governnnent for computer science and technology activities. The programs of the

NBS Institute for Computer Sciences and Technology are designed to provide ADP

standards, guidelines, and technical advisory services to improve the effectiveness

of computer utilization in the Federal sector, and to perform appropriate research

and development efforts as foundation for such activities and programs. This

publication series will report these NBS efforts to the Federal computer community as

well as to interested specialists in the academic and private sectors. Those wishing

to receive notices of publications in this series should complete and return the form

at the end of this publication.

Library of Congress Catalog Card Number: 84-601010

National Bureau of Standards Special Publication 600-112

Natl. Bur. Stand. (U.S.), Spec. Publ. 500-112, 31 pages (Mar. 1984)

CODEN: XNBSAV

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON : 1984

For sale by the Superintendent of Documents. U S Government Printing Office, Wasfiington. DC 20402
Contents

CHAPTER 1 INTRODUCTION

CHAPTER 2 THE RECOMMENDED SELECTION PROCESS

2.1 IDENTIFY REQUIREMENTS 2-2

2.2 IDENTIFY AND EVALUATE ALTERNATIVE SOURCES FOR

APPLICATION SOFTWARE 2-M

2.3 IDENTIFY AND EVALUATE ALTERNATIVE SOURCES FOR

OPERATING SYSTEM SOFTWARE AND HARDWARE 2-6

2.4 IDENTIFY AND EVALUATE ALTERNATIVE SOURCES FOR

SYSTEM SUPPORT 2-7

CHAPTER 3 TECHNICAL CONSIDERATIONS

3.1 WHEN SHOULD MICROCOMPUTER SYSTEMS BE CONSIDERED AS

ALTERNATIVES AND/OR ADJUNCTS TO CENTRAL

FACILITIES? 3-1

3.2 HOW SHOULD MICROCOMPUTER SYSTEMS BE CONFIGURED TO

ENHANCE THE SHARING OF DATA AND THE SHARING OF

EXPENSIVE PERIPHERALS? 3-3

3.2.1 Intra-System Data And Resource Sharing 3-3

3.2.2 Inter-systems Data And Resource Sharing .... 3-^

3.3 HOW SHOULD APPLICATIONS SOFTWARE BE ACQUIRED IN

ORDER TO MINIMIZE DEVELOPMENT AND MAINTENANCE

COSTS? 3-6

3.4 HOW SHOULD THIS TECHNOLOGY BE "PACKAGED" TO MEET

THE NEEDS OF END-USERS? 3-7

3.5 HOW SHOULD SYSTEMS BE ACQUIRED TO FACILITATE

ORDERLY MIGRATION TO NEW TECHNOLOGY? 3-8

APPENDIX CHARACTERISTICS OF MICROCOMPUTER SYSTEMS

A.I INTRODUCTION A-1

A. 2 ADMINISTRATIVE/MANAGEMENT APPLICATIONS A-3

A. 3 COMMUNICATIONS A-5
EXECUTIVE SUMMARY

This document assists end-users in evaluating the utility of

microcomputer systems. For those end-users who have determined a need for a microcomputer, this document provides assistance in

choosing a system which will satisfy their requirements. While the

document is oriented toward the end-user, ADP professionals should

find the material useful. Similarly, while the document focuses on

administrative/management applications, the concepts are suitable to

other application environments.

The methodology advanced in this guide recommends that primary

consideration be given to user application requirements and

commercially available software. Emphasis is placed on finding the

appropriate tool to address specific needs rather than first

acquiring a tool and then searching for a problem that it solves.

The recommended sequence consists of:

1. identifying requirements

2. identifying and evaluating alternative sources for application

software

3. identifying and evaluating alternative sources for system

software and hardware

4. identifying and evaluating alternative sources of support

The issues that need to be addressed include: a) the

relationship of micro-based systems to central facilities, b) the

configuration of systems to facilitate the sharing of resources, c)

the acquisition of application software in a way that minimizes

development and maintenance costs, d) the "packaging" of the

technology for non- technical users, and e) the acquisition of systems

in a way that eases migration to new technology.

The Appendix provides an additional basis for understanding

microcomputer system selection. The types of

administrative/management applications available are presented, and

the features associated with data communications are discussed.

This document is introductory to a more comprehensive treatment

of the subject of selecting microcomputer systems that is in

preparation and will be available late in FY 1984. Information about

that guidance document and other NBS microcomputer-related products

and actvities can be obtained from the authors at:

NBS/ICST

B266 Technology Bldg

Washington, DC 20234

(301) 921-3485
CHAPTER 1 INTRODUCTION

This document is primarily intended to assist end-users who are

faced with the tasks of evaluating the applicability of microcomputer

systems technology to their needs, and selecting a system to meet

those needs. Although the document focuses on end-users, the material

should also be of use to computer professionals who are selecting

microcomputer systems for use by an organization. While the

information presented here is generally applicable across the full

range of microcomputer applications, a primary focus is on issues

which arise in an administrative/management environment. Our

experience is that the use of microcomputers for

administrative/management applications has the largest potential

payoff for Federal agencies.

This document is limited in scope. A more comprehensive

treatment of the subject is presently underway. While the material

was specifically designed to help Federal agencies make better

informed decisions in the selection of microcomputer systems,

information presented may be useful for private organizations, and

state and local government organizations.

The ready availability and adaptability of microcomputer systems,

which are compact enough to easily fit on a desk or in a briefcase,

will change the expectations, and the habits of users of information

systems. The microcomputer system has advanced to the point where

individuals can make effective use of information systems technology

without being highly trained specialists in the technology. In

addition, these systems are beginning to mimic capabilities of large

mainframe computers of only a few years ago. It has been

characteristic of the past that enhanced computational resources

usually lead to attempts to take on new problems, as opposed to just

solving a larger volume of the old problems.

The discussion above would lead one to expect the evolution of a whole new set of applications that were unthought of prior to the

advent of microcomputer systems; and indeed, a new class of

"spreadsheet" processing applications has already emerged.

Spreadsheet processors allow end-users to develop, inexpensively and

quickly, specialized display tables representing budgets, taxes, and

other computational models. A key characteristic of these models is

that changes in table values are almost instantly propagated to all
INTRODUCTION Page 1-2

other dependent values. The concept underlying the spreadsheet

processor is simple, but was not realized until microcomputer systems

provided the low cost, fast response, and high bandwidth environment

to make implementation feasible.

The spreadsheet application is just one of a growing list of

applications that bring computing power within reach of end-users.

This ready access to computing power offers the potential for both

large and small organizations to significantly improve the

productivity of their workforce as well as the quality of the products

and services being provided.

There appears to be a tremendous amount of pressure on both

individuals and organizations to get on the "microcomputer systems

bandwagon" without fully exploring the issues involved. Inexperience

in the use of this new technology increases the risks that

organizational goals will not be adequately considered, and that

selection decisions will be made by people who are not equipped by

either training or experience to make such decisions. Mass media

marketing tends to paint an overly optimistic picture of the

capabilities of microcomputer systems and tends to obscure the issues

that should be considered when making a system selection decision.

Chapter II of this document describes the process that we

recommend for selecting a microcomputer system. Chapter III

highlights some significant technical considerations associated with

selecting a microcomputer system. The Appendix provides a more

detailed technical discussion of microcomputer systems capabilities

and applications.
CHAPTER 2

THE RECOMMENDED SELECTION PROCESS

A number of factors combine to make the process for the selection

of microcomputers different from that of mainframes. Microcomputers

will typically have associated with them:

o a shorter life cycle

o a lower unit cost

0 a lower perceived risk

o a greater need for matching and integrating system components

by the user

o a greater interest in individual computing by the user

o a greater overall control and responsibility on the part of

the user for individual computing

Some factors contributing to these differences include:

o fast moving technology

o increased market place competition

o a low system cost

0 evolving requirements, particularly for first time users

o difficulty and expense of modifying application software

o significant media coverage of microcomputers, the technology

and the market place

Traditionally, the selection of mainframes has been associated

with a focus on hardware. In contrast, the methodology advanced in

this guide recommends deemphasizing hardware and giving primary

consideration to user application requirements and commercially

available software. Emphasis is placed on finding the appropriate
THE RECOMMENDED SELECTION PROCESS Page 2-2

tool to address a specific need rather than first acquiring a tool and

then searching for a problem that it solves. The recommended sequence

consists of:

1. identifying requirements

2. identifying and evaluating alternative sources for

application software

3. identifying and evaluating alternative sources for system

software and hardware

4. identifying and evaluating alternative sources of support

It should be noted that while the steps are discussed as a series

of sequential activities, in fact the process is more complicated and

dynamic. Each step has implicit in it the task of insuring that the

decisions made or alternatives identified up to that point are

consistent and do not overly constrain the final choices. For

example, the choice of a particular application package may dictate a specific operating system which decreases rather than increases the

system's flexibility for expansion or enhancement. In such a case it

may be advisable to reevaluate and modify requirements so as to still

accomplish objectives, but yet remove the undesired constraints on

future actions. In that light, the steps of the recommended selection

process are discussed below.

2.1 IDENTIFY REQUIREMENTS

Clearly, the process of requirements identification does not take

place in a vacuum. Although we would like to initially state what we

want independent of available resources, in actuality that is not

exactly the case. In fact, we begin to frame such concepts in terms

of what currently exists or the expectation we have of what will be

available shortly. Some sources of information about the capabilities

of available software and hardware include:

o microcomputer and information systems periodicals, journals

and newspapers

0 vendor literature

0 electronic bulletin boards

o technology forecasts

0 local computer stores

(See NBS Special Publication 500-102, Microcomputers: A Review of

Federal Agency Experiences, page 7, for a description of the Institute

for Computer Sciences and Technology (ICST) Microcomputer Electronic

Information Exchange which contains pointers to other sources of
THE RECOMMENDED SELECTION PROCESS Page 2-3

related information.)

One step in identifying requirements is to recognize the generic

class of applications that the system is intended to support. Typical

classes include:

o administrative/management

o scientific computation

o software development

Our experience to date suggests that users should select a system

that operates within the boundaries of or is primarily directed toward

a single class. Each class provides the user with a wide and growing

variety of functions that can be performed. Among the

responsibilities of the selector is the choosing of the desired

functions and prioritizing them. Although it is not possible to place

quantitative figures on the relative importance of each category of

application, within Federal agencies, that of

administrative/management appears to be of particular significance.

Some typical administrative/management functions include:

0 document preparation

0 financial analysis

0 personnel management

0 data management

0 budget preparation

0 briefing material presentation

0 f orecas ting

Also involved in this step is the specification of any

limitations or constraints imposed on the choice of solutions. These

might include such things as:

0 agency policy and/or guidance

o Federal regulations

o budget limitations

0 compatibility with installed systems

0 familiarity of staff with the systems under consideration
THE RECOMMENDED SELECTION PROCESS Page 2-4

0 availability of support structures both within and external

to the organization

o availability of an off-the-shelf solution

Unless the system to be selected is to be used exclusively as a general learning tool, it will be necessary to define the specific

functional capabilities that it needs to support, when those

capabilities need to be available, and the priority or importance of

each functional requirement. The last is important because it is

possible that one system may not be capable of simultaneously

satisfying all requirements given the imposed constraints. Related to

functional capabilities are the performance and capacity requirements

of the system to be selected. These too must be identified and

prioritized.

One distinction among types of off-the-shelf application software

is that between those that perform a specific application function

(eg, inventory control, project scheduling, education, bill of

materials) vs those that provide the user with a general tool that can

be tailored to the specific problem. Word processing, spread sheet,

database, graphics are examples of this general tool category. It is

recommended that for administrative/management applications that

systems be required to provide as a minimum a workable set of these

latter capabilities. Further, it is recommended that there be a requirement for some level of integration among them.

An area of requirement that should be considered relates to how

the user interacts or interfaces with the system and the desired

degree of user friendliness. Factors such as previous user training

and experience and the sophistication and complexity of the system to

be selected should be considered.

Yet another area of requirement to be specified is the degree to

which the system to be selected must interface and communicate with

other work stations and mainframes and the method(s) for accomplishing

this. The extent to which the full range of these interactions can be

anticipated and specified can impact the extent to which costly later

adjustments are necessitated or avoided.

2.2 IDENTIFY AND EVALUATE ALTERNATIVE SOURCES FOR APPLICATION

SOFTWARE

This step consists of seeing what application software exists to

satisfy requirements and choosing from among the alternatives within

the imposed limitations and constraints. In identifying alternatives

it is important to make some distinctions among types of off-the-shelf

packages. One distinction is between commercial vs public domain

software. On the obvious level public domain software has the

"apparent" cost advantage. While some public domain software is

extremely good, especially in the area of communications, it is

frequently plagued by no or poor documentation and by lack of a
THE RECOMMENDED SELECTION PROCESS Page 2-5

maintenance and support structure behind it.

Some agencies do make extensive use of such software with a central support group performing the appropriate tailoring,

documenting, distributing, and consulting. A recent development has

been the use of company (and public) libraries to distribute diskettes

of public domain software much the same as books are loaned to users.

A large inventory of administrative/management software of commercial

and public domain software is available. The inventory is increasing

practically daily. However, the quality, utility, documentation, user

friendliness, and training aids associated with this type of software

vary considerably. Therefore, while the use of public domain software

may be viable, a decision to go that route should be made with an

appreciation of the potential problems and the non-apparent costs.

Decisions about microcomputers will necessarily be in the absence

of complete knowledge. Therefore, questions that need to be addressed

include

o what level of information is necessary to operate with some

degree of confidence - short of devoting an inordinate amount

of time and energy?

o to what extent is expert assistance/opinion necessary and/or

adv isable?

Equally important to the user as the selection of a software

product may be the selection of a software vendor. A reputable vendor

(developer and distributor) increases the likelihood of:

0 responsive service including the availability of

knowledgeable technical staff

0 a tested, documented product

o the availability and honoring of appropriate

warrantees/ gua ran tees

o upward and downward compatibility within a vendor's line

o continued product enhancement

A vendor's ability to provide these types of support should be an

important consideration in the vendor selection process.

Unfortunately, it is extremely difficult, if not impossible, to apply

quantitative measures to this process. In the absence of such

metrics, reliance on one's own intuitive and professional judgements

and those of people whose opinions are respected may be necessary.

(Interestingly, in the consumer market, a sometimes identified

decision criterion in buying a system is having a friend who has and

recommends a particular system and who can provide support,

encouragement, and hand-holding.)
THE RECOMMENDED SELECTION PROCESS Page 2-6

In evaluating specific application software and specific vendors

it is important to be aware of whether what is being considered

represents a "mainstream" in terms of both the technology and the

marketplace. Dealing with mainstream products that have a wide

customer base and constituency puts the users in a more flexible

position to have access to sources of support, a greater range and

depth of available products, a larger pool of knowledgeable technical

and user personnel, a stronger position to exert leverage on the

vendors to be responsive to product bugs and shortcomings.

Another advantage of dealing in the mainstream is that the

marketplace is more likely to be responsive to that environment. This

frequently translates into the availability of a variety of related

products that support, enhance or complement the primary product.

Another consideration concerns the user selecting application

software to address more than one function (e.g., spreadsheet and

graphics and database). In such a situation, where practical, it may

be advantageous to obtain that software from a single vendor.

Families of software packages and integrated environments (see related

discussion in the Appendix) are being offered by an increasing number

of vendors.

Integrated software packages offer two advantages. It is easier

to share data between the functional programs, and the functional

programs have similar user interfaces. Consequently, the operational

detail that the user must remember is minimized. On the other hand,

the functional programs in an integrated package, evaluated on an

individual basis, may not have the features or performance of similar

programs, where each is obtained from a different vendor.

2.3 IDENTIFY AND EVALUATE ALTERNATIVE SOURCES FOR OPERATING SYSTEM

SOFTWARE AND HARDWARE

Of prime importance in this step is that the selected system

software and hardware support the full range of application software

identified in the previous step. It is frequently the case that a particular application software package will go through an evolution

of improvements that take the form of successive versions. It is

important that the system software and hardware being considered

continue to support the latest versions as they become available.

(For example, a major vendor in the home computer market supports an

older version of a popular spreadsheet package, but not the enhanced

versions available on other systems.)

Many of the considerations used for selecting application

software and an application software vendor are also appropriate in

the selection of system software and hardware. Alternatives which

increase rather than decrease flexibility, which conform to de facto

standards, which put users in the mainstream, and which permit dealing

with a responsive and viable vendor are favored. Application packages

which force a marked variance from the perceived mainstream should be

carefully reexamined and the tradeoffs reassessed.
THE RECOMMENDED SELECTION PROCESS Page 2-7

This is especially important in this period of extremely rapid

change where a time frame of a little as six months to a year may

bring new products that can make previously acceptable ones less

desirable when compared to the new offerings. A user staying in the

mainstream of system software and hardware increases the likelihood

that new offerings will be available with only limited requirements

for system enhancements.

In attempting to find a system that supports a particular

application or set of applications, the potential user must be

extremely aware of the specific requirements of the system software

and hardware. The application may require a particular operating

system version. It may also require some minimum capacities - e.g.

random access memory (RAM), number of disk drives, amount of disk

storage, density of storage media, size of printer carriage, monitor

type and display size. It may also require additional components - e.g. a particular board for communications or graphics or color. The

absence of this level of detail may result in not being able to

utilize the full capabilities of a particular application package.

In evaluating the choices of operating systems it is important to

note the trend of a number of vendors to provide an "operating

environment." In such an environment the operating system may be

relatively transparent to both users and application developers. The

environment is typically implemented in a high level, widely

transportable language, such as C. Such an environment may provide

the user with some of the advantages of leveraged learning,

flexibility, and mainstreaming previously discussed.

2.4 IDENTIFY AND EVALUATE ALTERNATIVE SOURCES FOR SYSTEM SUPPORT

Support refers to the collection of activities necessary to help

users access the selected systems, correct problems, learn and

effectively use the systems, and evaluate alternative approaches.

Included in this category are maintenance, training, documentation,

demonstration centers, and package customization.

It is not necessary that support for the selected systems be

obtained from the same vendors. However, it is advisable, but not

essential, that the organization provide coordination of various

support activities so that users will both know what support is

available and how to obtain it. The coordination is particularly

important when a variety of in-house and outside support is being

obtained

Although certain types of support can be provided with little, if

any, knowledge of the users environment (for example in the case of

hardware repairs), many types of support require such knowledge. An

example of the latter is the determination of the applicability of a particular application package that must interface other organization

resources.
THE RECOMMENDED SELECTION PROCESS Page 2-8

A study conducted by Arthur Young for the Department of Defense

identified thirteen different categories of support. These included:

0 long range planning

0 requirements analysis

0 hardware selection

0 software package selection

0 procurement negotiation

0 application system development

0 installation

o training

0 operations

0 maintenance

A recent review of Federal agency microcomputer experience

performed by ICST, Microcomputers: A Review of Federal Agency

Experiences, NBS Special Pub 500-102, found many of the interviewed

agencies providing a subset of the full range of support, with none of

the interviewed agencies providing all. A centralized microcomputer

support group appeared to be the most commonly observed model.
CHAPTER 3

TECHNICAL CONSIDERATIONS

This section highlights several significant technical

considerations that should be factored into the decision to select a microcomputer system. The technical considerations are presented as

issues/questions and the ensuing discussion attempts to answer the

questions. There was no attempt to be exhaustive in the coverage to

technical issues. The particular issues presented were selected

because they are generic in nature and because we feel that the

discussion of these issues brings out those factors that are most

important to consider when selecting a microcomputer system.

3.1 WHEN SHOULD MICROCOMPUTER SYSTEMS BE CONSIDERED AS ALTERNATIVES

AND/OR ADJUNCTS TO CENTRAL FACILITIES?

Ideally microcomputer systems should be viewed in the context of

an organization's overall information resources. Unfortunately, we

have found very few examples in which this is the case. Some of the

key reasons include:

o the difficulties of establishing and maintaining an effective

program for managing information resources

o the relative immaturity of the organization's experience with

the use of microcomputer systems as compared with the

experience in the use of conventional technologies

o the revolutionary pace in which information technology is

currently changing and is expected to continue to change over

the next few years

Because microcomputer systems have not been fully integrated as

part of an organization's information resources, these systems are

most often used as automated tools to assist individual workers in

processing information on an ad hoc basis to improve productivity and

to enhance personal job performance. This is in marked contrast to

conventional information systems technology which is primarily used to

support organizational rather than personal job functions.
TECHNICAL CONSIDERATIONS Page 3-2

The notion of "personal computing" is very much evident in the

present day microcomputer systems. These systems are most often

configured as single-user, multi-function workstations designed to

support applications in areas such as administration and management,

science and engineering, and software development. Although

multi-user systems are beginning to gain acceptance, single-user

systems dominate the marketplace and are expected to maintain that

dominance for some time.

There are no hard and fast rules which dictate when microcomputer

systems should be used. There are, however, some experienced- based

guidelines that are useful in identifying situations in which

microcomputers should be strongly considered. These include

situations in which:

o there is a need to facilitate applications that are highly

interactive and that have a large amount of terminal I/O.

0 the organization is confronted with a large applications

development backlog.

o there is a need for more end-user involvement and control of

the operational environment.

o there is need to reduce the lead time for implementing an

appl ica ti on

o an organization is considering alternative ways for dealing

with poorly structured, rapidly changing applications that

serve individual as opposed to organizational, job

performance needs.

There are also situations in which microcomputers should be

approached with extreme caution. These include situations in which:

o there is a strong requirement for data sharing.

o application needs require the development of custom software.

o user support requirements have not been identified and

prov ided

o there are stringent security requirements.

o the applications are critical to the mission of the

organization
TECHNICAL CONSIDERATIONS Page 3-3

3.2 HOW SHOULD MICROCOMPUTER SYSTEMS BE CONFIGURED TO ENHANCE THE

SHARING OF DATA AND THE SHARING OF EXPENSIVE PERIPHERALS?

There are two issues regarding data and resource sharing with

microcomputer systems. The first issue relates to sharing data and

resources among functions within a single multi-functional system.

The key concern here is the degree of compatibility among the various

functions provided by the system. The second issue relates to data

and resource sharing among a group of systems serving a multi-user

environment. The key concern here is the degree of compatibility

among the various systems. These two issues will be discussed in the

paragraphs which follow.

3.2.1 Intra-System Data And Resource Sharing

The ability to expand functionality is one of the most important

characteristics of microcomputer systems. Expanded functionality can

be achieved by both software and hardware methods. The method

recommended for achieving expanded functionality is via software.

This can be accomplished simply by obtaining software packages that

provide the desired functions. Problems typically arise when the

software is developed as independent, stand-alone packages that are

not designed to operate together. The key problems are:

0 inability to share data among the various programs

0 lack of a common user interface among the various programs

There is a growing trend among commercial vendors supplying

software for administrative/management applications to integrate

mulitiple functions within a single program or family of programs.

These vendors combine commonly used functions into an integrated

package having a consistent user interface and with the capability to

use the output of any one function as input to any other function.

Typical functions include:

o spreadsheet processing

o word processing

o business graphics

o database management

o communications (primarily terminal emulation)

The single integrated program, as a rule, allows for easier

switching from function-to-function than does the family of compatible

programs. On the other hand the family of compatible programs usually

provides a more extensive set of features than does the single

integrated program.
TECHNICAL CONSIDERATIONS Page 3-4

Expanding functionality via hardware is achieved by inserting

printed circuit boards that provide those functions into connection

slots on the internal bus. The following types of problems are

typically encountered when using this approach:

o different printed circuit boards require the same connection

slot on the internal bus. This of course means that the

functions provided by those different boards cannot coexist.

o lack of software support for functions provided in the

printed circuit boards.

o some new printed circuit boards require additional power and

cooling.

o ability to add functions is constrained by a limited number

of expansion slots.

Because of the level of technical expertise required, end-users

should proceed with extreme caution in attempting to expand the

functionality of their systems by hardware methods. It should be

avoided whenever practical; if it cannot be avoided, expert technical

assistance should be obtained.

3.2.2 Inter-systems Data And Resource Sharing

Some organizations may want to interconnect their microcomputer

systems. In addition, there is usually the need for microcomputer

systems to be connected to the organizations' central computing

facility. In scientific/engineering applications this interface would

be primarily used to provide access to a high-speed computational

capability; for applications in software development this interface

would be important for testing and integrating elements of a system

under development; and in administrative/management applications,

this interface would provide access to a shared corporate database.

In those situations in which there is a need for data and other

resource sharing among microcomputer systems, or between microcomputer

systems and a central computing facility, a few relatively simple

alternatives should be examined before pursuing the potentially

expensive and technically risky effort of acquiring a network. These

are

o interchanging diskettes by using format conversion software

o transfering files via a direct communications link

- o utilizing "shared resource" systems
TECHNICAL CONSIDERATIONS Page 3-5

Manually exchanging diskettes by using format conversion

utilities can be an effective method for data and resource sharing.

Incompatibilities, which cannot be solved by software utilities, can

occur because of differences in diskette drive design and the physical

characteristics of the diskettes. Software utilities can solve

incompatabilities based on the soft-sectoring of the diskette or the

logical structure of the files.

The next approach to data and resource sharing that should be

examined is electronically transmitting files via direct cable

connection between I/O ports (typically the RS 232C port) on the

systems. There are commercial and public domain products which

support this method of file transfer. The limiting factor in this

approach is that the systems involved must be located relatively close

(typically within fifty feet) to each other. A variant to this

approach that overcomes this distance limitation involves the use of

modems and telecommunication lines to establish the data path for file

transfers

Since most organizations already have terminal access to their

central computing facility using direct wire or telephone, data

sharing between a microcomputer and the central computer can be

accomplished over the existing terminal communication links.

Microcomputer to microcomputer data sharing can be accomplished by

using the central computer as the communication link. In this

approach, data from the sending microcomputer system is placed on the

mainframe. The receiving microcomputer accesses the mainframe to

obtain the data. There are two advantages to this approach. The

mainframe is presumably always up. Thus, the sending microcomputer

system may transmit at any time, and need not depend on the receiving

microcomputer being on. Secondly, two microcomputers may exchange

data even if they are unable to exchange physical media.

"Shared resource" systems are multi-user systems in which one or

more of the system components are shared among the users. The salient

characteristics that distinguish among these systems are (1) the

system resources that are being shared, and (2) the degree of autonomy

that exists among the users. In some systems, only a few peripherals

such as a Winchester disk or printer are shared, while in others all

of the system resources (including the processor) are shared among the

users. From a user's perspective, the key problems with the shared

logic approach are:

o users must give up some measure of control over their

individual operating environments

o degradation is likely to occur in performance due to the need

to schedule access to shared resources

A network (i.e., a collection of computer systems interconnected

by communications facilities to allow multi-user access to shared

resources) approach to data and resource sharing should be considered

only after careful analysis of requirements. The advantages of this

approach are:
TECHNICAL CONSIDERATIONS Page 3-6

o high performance, reliable access to shared data and

resources

o users can have the benefits of a multi-user environment

without surrendering autonomy of their individual operations

The process for selecting a specific network technology and

topology is very complex and requires expert technical assistance.

Equally important is the fact that operating and maintaining a network

is a difficult and highly technical activity. Such an effort requires

assignment of appropriate staff and other support resources. NBS

Special Publication 500-96 "The Selection of Local Area Computer

Networks" provides guidance on analyzing requirements and selecting

the appropriate network to meet those requirements. That publication

should be consulted before making a decision to proceed acquire a network.

3.3 HOW SHOULD APPLICATIONS SOFTWARE BE ACQUIRED IN ORDER TO MINIMIZE

DEVELOPMENT AND MAINTENANCE COSTS?

Microcomputer systems have contributed to the growing trend

toward end-user computing. Their low price, ease of use, and quick

responsiveness enable many users to solve their own computing

problems, often bypassing the traditional DP organization. The

potential benefits of end-user computing are substantial and are well

recognized. The costs, however, can be equally substantial but are

not as well recognized. The risks that the cost of end-user computing

will negate the benefits are considerably increased in those

situations in which end-users write their own application programs.

End-users rarely have the skills required to produce software

comparable to that produced by an experienced professional.

It is for these reasons that we strongly recommend that users of

microcomputer systems buy, rather than build, their applications

software. Another reason for the recommendation to buy rather than

build is the large number of relatively inexpensive commercially

available application packages, particularly packages which support

administrative/management functions. Packaged software seldom meets

all of the requirements of a particular application. Users should

therefore be prepared to make reasonable compromises and must

carefully evaluate the need for a customizing effort.

In those situations in which it is determined that a customized

application is required, end-users should obtain the advice and

assistance of individuals with expertise and experience in software

development. Although the software development environment provided

by microcomputer systems is not yet comparable to that provided by

mainframes, there are a number of application development tools which

have been used successfully in the environment of microcomputer

systems. The tools which have been shown to be particularly useful

are spreadsheet processors and database management packages.

Spreadsheet processors are being used primarily for financial
TECHNICAL CONSIDERATIONS Page 3-7

modelling and budgeting while database management packages are being

used for the broad spectrum of database query and reporting

appl ica tions

.

3.4 HOW SHOULD THIS TECHNOLOGY BE "PACKAGED" TO MEET THE NEEDS OF

END-USERS?

Many of the new systems are being touted for their "userfriendly" features. Typically, this means that (1) it is relatively

easy to learn to use the basic features provided by the system, and

(2) once a user has learned to use a feature in one part of the system

(e.g., text editing in word processing), that learning is transferable

to other parts of the system (e.g., text editing in database

management). One of the advantages of integrated packages is that

they typically provide a more "user-friendly" environment than does a collection of packages developed independent of each other.

This notion of "user-friendly" does not mean that the end-user

can operate independent of technical support provided by individuals

with expertise in the particular system being used. There is still a need for specialized training and support for situations ranging from

insuring that peripherals (e.g., printers) are properly connected, to

evaluating alternative strategies for dealing with the problems that

invariably arise when using an automated system. Therefore,

regardless of the characteristics of a particular microcomputer

system, the fundamental issues for the end-user are:

0 what kind of training and support is required

0 where is the training and support available

Training and support are inextricably interrelated. The kind of

training required is, to a large degree, a direct function of the kind

of support that is available. The basic functions involved in

managing, operating and maintaining a microcomputer system are

essentially the same as those associated with larger systems. These

include

0 making sure that the system is configured properly

o maintaining a proper operating environment

o protecting the integrity of the system and data

0 maintaining supplies

o operating the system

o evaluating system performance (including error detection and

correction)
TECHNICAL CONSIDERATIONS Page 3-8

Someone must assume responsibility for these basic functions.

Since the typical microcomputer system operates in a completely

stand-alone environment, it may not be practical to assign many of

these functions (e.g., operating the system, maintaining a proper

operating environment, etc.) to a central support staff. The training

should be designed to address those particular functions expected to

be performed by the end-user.

3.5 HOW SHOULD SYSTEMS BE ACQUIRED TO FACILITATE ORDERLY MIGRATION TO

NEW TECHNOLOGY?

The rapid pace at which new technology is being introduced gives

rise to concern about becoming "locked-in" to obsolete system.s. Users

should examine system selection decisions in light of the need to

minimize the risks associated with obsolescence.

One of the best ways for a user to avoid becoming locked-in to

obsolete systems is to select products that have a large user

community. Vendors with products having a large user community are

motivated to provide a migration path to new technology. Users should

examine products to determine how well those products are being

accepted in the commercial marketplace, and how well the vendor

supports his products. Users should be especially careful about

products offering unique features to insure that those features don't

isolate that product to a narrow portion of the market. Users whose

requirements can be satisfied by products in the mainstream of the

marketplace will minimize the risks associated with obsolescence.

Users should also be cautious about selecting a product in the

later stage of its life-cycle. There is usually a trade-off between

selecting a product in the early stages of its life-cycle and

selecting a product in a more m.ature stage of its life-cycle.

Selecting a product too early runs the risk of having to deal with

problems typically associated with immature systems. Selecting a product too late runs the risk of early obsolescence. An assessment

of the technology underlying the product should be a key consideration

in making the trade-off. A well established product based on new

technology is the optimal choice. A new product base on old

technology should be approached with caution.
APPENDIX

CHARACTERISTICS OF MICROCOMPUTER SYSTEMS

A.I INTRODUCTION

This Appendix provides a more detailed technical overview of the

features and capabilities of microcomputer systems. The emphasis is

on the application areas of administration/management and

communications

Microcomputer systems are available with many diverse

applications software packages which are human engineered for both the

experienced and the inexperienced computer user. This software

explosion has been caused by two factors: the declining cost of the

hardware, and the ever increasing numbers of end users who own

hardware, and are demanding friendly, flexible software. The larger

software market means that huge revenues can be generated by selling

many copies of a successful software package. This potential return

on investment has attracted many talented, creative people to the

production of software.

The result has been the creation of software packages that are:

0 Original in concept

Since many software packages have little or no

resemblance in concept to the packages which have been

available for minicomputers or mainframes, even the

experienced computer user often gains new perspectives. Not

only do microcomputer systems solve new problems, they also

provide solutions to the old problems in new and original

ways

o Highly interactive

Systems are designed to take advantage of higher

bandwidth interactive techniques such as function keys,

"mouse" devices, and trackballs.

o Easy to use
CHARACTERISTICS OF MICROCOMPUTER SYSTEMS Page A-2

The system can be used with minimal reference to a manual. Help at both a novice and expert level is often

available on-line. In addition, the systems try to minimize

the possibility of data loss caused by user error.

o Easy to learn

The documentation for most packages includes not only

the traditional reference manual, but also tutorial materials

for the naive user. In some cases, tutorials are in the form

of computer aided instruction.

Two examples of software with these characteristics are the

spreadsheet processor and the integrated package.

The spreadsheet processor was initially conceived to automate

some of the accounting calculations performed on large accounting

spreadsheets. The basic concept of the spreadsheet processor is that

instead of just being able to enter a number in a spreadsheet cell, as

in the case with a paper spreadsheet, one can enter a formula which

represents the value of the number as ^ function of other cells. When

viewed on the display, the value of the formula is shown, and if a value of a cell is changed, then the numbers shown on the display,

which are a function of the cell changed, all change their values

instantaneously.

Since its introduction, the spreadsheet processor has been

applied to many other tasks beyond those associated with an accounting

spreadsheet. Such applications include financial modeling, the

preparation of tables to be included in documents produced by word

processors, and the maintainence of small databases. The spreadsheet

processor has its own form of "programming language" unlike

traditional programming languages. Using a spreadsheet processor is a learning experience for all users regardless of their backgrounds.

The spreadsheet processor has become so successful that it is now a required part of any administrative/management application.

Integrated packages are software packages which combine the

functionality of many traditionally separate processors into a single

processor with a single user interface. Before the widespread

availability of microcomputer systems, processors such as word

processors, database management systems, etc., often produced by

separate vendors, interacted with the user according to their own

philosophy of human-machine interfacing. These packages were

"integrated" by using the computer operating system which may have

been produced by yet another vendor. As a result, the user interface

was often inconsistent, confusing and inefficient. It was often

impossible to exchange data between the processors, such as, using a report generated by a database management system as part of a document

being prepared by the word processor.

The integrated package, produced by a single vendor, is one of

the solutions to these problems. The concentration on human

engineering and inter-function data portability in the design of

integrated packages has resulted in new ways of looking at the
CHARACTERISTICS OF MICROCOMPUTER SYSTEMS Page A-3

traditional functions, and in widespread use of interactive techniques

beyond the teletype keyboard.

For example, spreadsheet processors may be combined with

relational database systems by considering a record as a row in the

spreadsheet. The contents of a cell in a spreadsheet can be treated

as a document to which a word processor is applied. A rectangular

area of a spreadsheet can be a table from which a bar graph or pie

chart can be drawn. To this graph, special lettering or pictures may

be added by electronic "drawing." These operations are no longer

performed solely by typing commands on a keyboard. Commands to the

integrated environment are often entered through a special interactive

device such as a "mouse."

Microcomputer systems are being used to solve problems in almost

every application area. Among the most common application areas of

microcomputers are administrative/management and communications.

A. 2 ADMINISTRATIVE/MANAGEMENT APPLICATIONS

Administrative/management (or office automation) applications can

be grouped into the following catagories:

o Word processing

Word processing was the first office activity to be

automated, and is the most prevalent. Word processors were

also the first integrated packages in that, in addition to

text editing and formatting functions, most word processors

include the ability to manage small databases such as mailing

lists.

o Database management

Microcomputer systems support the three basic types of

data management systems, hierarchical, network, and

relational. Relational or relational-like database systems

are the most common implementation. These are general

purpose information management systems capable of most

database applications and limited only by the size of mass

s torage

o Spreadsheet processors

As described earlier, this electronic calculator has

become a necessary part of every office system. For many

integrated packages, the spreadsheet processor is the base on which each of the other processors (i.e. word processor,

database management system, etc.) is built.

0 Business graphics and graphic arts
CHARACTERISTICS OF MICROCOMPUTER SYSTEMS Page A-4

These packages effortlessly produce charts and graphs,

such as bar graphs and pie charts, suitable in an

administrative/management environment. Some also provide the

capability of adding customized artwork to the graphs, for

example, a corporate symbol or stylized lettering.

o Calendar managers

These packages vary widely in the extent of their

capability. At the minimum, they provide an electronic

desktop calendar on which appointments can be recorded. Some

calendar packages display messages when it is time for an

appointment. Some packages, when available on systems which

can communicate, will permit a manager to schedule a meeting

through the system. When given the participants in the

meeting, it will interact with the manager and access the

calendars of the participants to arrange a time when all are

available, and then, send a message to each participant and

mark their calendars.

o Electronic mail

This capability includes both mail between users of a multi-user system, and mail between between users of

different systems. Mail is an application of the more

general concept of data communications which is discussed in

a subsequent section.

o Voice processing

Some microcomputer systems provide the capability of

interfacing to a voice telephone system. The microcomputer

is able to do such things as answer the phone and receive

dictation, place calls and send voice messages, and mix voice

and digital data in data files which may be used as messages

in electronic mail.

Software packages for these application categories are available

in the public domain and from several vendors. As was mentioned

above, integrated packages which combine several application

categories into a single program with a consistent user interface are

also available. Users should be aware of several characteristics of

these software systems.

Since it is usually not possible to find a single package which

will perform all the desired functions, it is necessary for users to

do their own "integration" of systems from different vendors. Most

packages are able to input and output sequential files, consisting

solely of ASCII text, thereby providing the means of transferring data

from one package to another. Some formatting changes to these files

may be required and this can usually be accomplished by a text editor

or a small formatting program implemented by the user.
CHARACTERISTICS OF MICROCOMPUTER SYSTEMS Page A-5

A microcomputer software package is usually available to run on

more than one piece of hardware. A serious problem arises when there

is no single piece of hardware and/or operating system on which the

needed software packages will run. In the case where there is a single hardware system available, but each package requires a different operating system on that hardware, the use of files on mass

storage may still be a solution. However, this is unlikely since most

operating systems use different mass storage formats. The only

solution may be to have more than one microcomputer system to provide

the functions needed. Data transfer between systems is accomplished

either by direct communications between the systems or by each system

communicating with a mainframe.

Since many software packages are truly original in concept, it is

usually not immediately obvious that a particular software package can

meet the need. In order to make this determination, the user is

required to become familiar with the software under consideration. If

this is not done, the user may miss the opportunity to have access to

systems which do the required job in a comprehensive, satisfying and

efficient manner, once the initial investment in learning has been

made. The user should study the manuals and tutorials, consult user

groups, and spend a few hours using the system.

Not only should a software package be viewed in terms of whether

it performs the desired functions, but the manner in which the

functions are performed should also be considered. In using any

microcomputer system, certain sequences of operations, such as

transmitting data to a mainframe, will need to be repeated on a regular basis. One of the common problems with software packages,

particularly integrated packages, is that sequences of operations can

be performed only in an interactive manner. This may surprise the

experienced computer user who is familiar with systems capable of

automating sequences of operations by means of command procedures in

order to minimize end-user activity. The ability of a software

package to be programmed to automatically perform sequences of

operations should be carefully considered.

Because microcomputer software packages are designed to be

friendly, naive users do not remain naive for long. They quickly

learn the environment that the system provides, and demands new

capabilities. The vendors are aware of this phenomenon. They know

that the user population is constantly increasing its sophistication,

and that the sophistication of their products must increase

accordingly. Increasingly powerful and complex software is made

possible by the continuing increase in the power of the hardware.

A. 3 COMMUNICATIONS

A communications capability will always require a user system to

be connected through some communications medium to the systems with

which it is to communicate. This usually implies that the system will

either be multi-user, connected to a network, or both. The network

may be special purpose, such as a local area network, or a telephone
CHARACTERISTICS OF MICROCOMPUTER SYSTEMS Page A-6

system, such as a private business exchange (PBX) or the public

telephone system.

Among the problems to be solved in order for microcomputers to

communicate to other microcomputers, minicomputers or mainframes, are:

o Flow control

The transmitting system may send data at a different

transmission speed than the receiving system is capable of

accepting. For example, when data is transmitted from a microcomputer to a mainframe, the mainframe may become busy

with higher priority tasks and be unable to accept data from

the microcomputer, even though the microcomputer and

mainframe may be sending and receiving at the same

transmission speed. In order for communications to occur in

these situations the sending and receiving systems must have

some means of starting and stopping the transmission.

o Data integrity

There should be some assurance, at the time of transfer,

that the data which was transmitted is the data that was

received.

o Transmission of binary data

Many computer system communication links are designed

for transmitting 7 bit ASCII data only. In order to transmit

8 bit binary data, the 8 bit data must be encoded into 7 bit

data by the sender and subsequently decoded by the receiver.

o Connection initiation

The previous problems address the issues of how

communications proceed during the transmission of data. The

problem of connection initiation deals with how the

connection between two systems is established. Electronic

mail, an application of communications, requires that one

system be able to establish a connection to another system,

transmit the message, and then break the connection. Most

electronic mail systems are able to accomplish this task

without any operator intervention.

Three available methods of implementing microcomputer data

communications, in order of technical sophistication, are:

o Terminal emulation/file transfer systems

These are the simplest, most common solutions to

microcomputer communications. Since almost all mainframe and

minicomputer systems permit the attachment of terminals, this

class of communication system makes the microcomputer appear

to the remote system as a terminal. Data transfer from the
CHARACTERISTICS OF MICROCOMPUTER SYSTEMS Page A-7

microcomputer to the remote system is accomplished by the

microcomputer reading a data file from its mass storage and

sending the contents through the communications link as

though an operator were typing the data on a terminal. Data

transfer from the remote system to the microcomputer is

accomplished by the microcomputer storing data from the

remote system in memory and/or on mass storage. This type of

communications system may engage in some type of flow control

signalling with the remote system, or simply rely on a slow

transmission speed. However, there is normally no data

integrity checking, and no capability for the transmission of

binary data. Connection and disconnection with the remote

system, and data transfers are initiated by an operator on

the microcomputer. Terminal emulation systems are available

both in the public domain and commercially.

o Limited-function network systems

This class of communication system can perform the

functions of terminal emulation systems but, in addition,

provides for some data integrity and binary data

transmission. However, it still requires much operator

intervention to initiate transmissions. It also requires

that two systems be able to interact in a more sophisticated

manner. With terminal emulation, the remote system

communicated with what it saw as a terminal. Now, the remote

system must know that it is interacting with another computer

system according to an agreed upon set of rules or protocols.

While terminal emulation systems arose from a need for

microcomputers to communicate with mainframes, the

limited-function network systems arose from a need for one

microcomputer to communicate with another microcomputer.

Since it can be more difficult to implement communications

software on a large multi-user system than on a small

microcomputer system, the limited-function network

implementations have been available primarily for

communications between microcomputers. Limited-function

networks have been slow in becoming available for

communications between microcomputers and mainframes.

However, these implementations are becoming widely available

in the public domain and commercially.

o Full-function network systems

These systems provide complete, technologically

sophisticated solutions to the communications problems

mentioned at the beginning of this section. They are almost

always acquired from a single vendor who provides all of the

hardware and software. While some standards and conventions

exist, full-function network systems, because of their

complexity, have yet to reach the point in their development

where an inexperienced user may obtain interchangeable parts

of a network system from several vendors and/or in the public

domain. The Institute for Computer Sciences and Technology

within the National Bureau of Standards is contributing to
CHARACTERISTICS OF MICROCOMPUTER SYSTEMS Page A-8

the development of international standards for network protocols that will lead to off-the-shelf network products existing in a multi-vendor environment.
NBS-n4A (REV. 2-ec) U.S. DEPT. OF COMM. 1 PUBLICATION OR y P<»rfr»rmino Oro^in R^nrvrt KJ rv 3. Publication D3tc

BIBLIOGRAPHIC DATA

REPORT NO.

SHEET (See instructions) NBS SP 500-112 March 1984

4. TITLE AND SUBTITLE

Conputer Science and Technology: Selection of Microconnputer Systems

5. AUTHOR(S)

John Barkley, Dennis Gilbert, Al Hankinson

6. PERFORMING ORGANIZATION (If joint or other than NBS. see Instructions) 7. Contract/Grant No. NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE 1. Type of Report & Period Covered

WASHINGTON, D.C. 20234 Final

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Same as item 6.

10. SUPPLEMENTARY NOTES

Library of Congress Catalog Card Number: 84-601010

Document describes a computer program; SF-185, FlPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

This document is chiefly aimed at providing assistance to non-technical users

in evaluating the applicability of microcorputer-based systems in addressing

their needs and choosing appropriate systems. However, technical users providing

related support to their organizations should also find the material useful.

Similarly, while focussed for Federal users of administrative/managenient

applications, there is general applicability to other environments.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s i COTiputers; canputer evaluation; computer selection; corputer use; microcorputer

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