NBS H^^LK,!,, OF STAND S. TECH PUBLICATIONS | COMPUTER SUici^CZ^i TECHNOLOGY:

COMPUTER PERIPHERAL MEMORY

SYSTEM FORECAST

QC

100

U57

#500-45

1979

NBS Special Publication 500-45

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards' was established by an act of Congress 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 performed 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 — Thermodynamics and

Molecular Science — Analytical Chemistry — Materials Science. THE NATIONAL ENGINEERING LABORATORY provides technology and technical

services to users in the public and private sectors to address national needs and to solve national problems in the public interest; conducts research in engineering and applied science

in support of objectives in 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 traceabihty 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 utlimate user. The Laboratory consists of the following centers:

Applied Mathematics — Electronics and Electrical Engineering- — Mechanical

Engineering and Process Technology^ — Building Technology — Fire Research —

Consumer Product Technology — Field Methods.

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 divisions:

Systems and Software — Computer Systems Engineering — Information Technology.

'Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted; mailing address Washington, D.C. 20234. ^Some divisions within the center are located at Boulder, Colorado, 80303.

The National Bureau of Standards was reorganized, effective April 9, 1978.
NBS

RESEARCH

INFORMATION 'TER COMPUTER SCIENCE & TECHNOLOGY:

Computer Peripheral Memory

System Forecast

Robert B. J. Warnar, Peter J. Calomeris,

and Steve A. Recicar

Institute for Computer Sciences and Technology

National Bureau of Standards

Washington, DC 20234

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Issued April 1979
Reports on Computer Science and Technology

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

Government 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 v^'ill 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.

National Bureau of Standards Special Publication 500-45

Nat. Bur. Stand. (U.S.), Spec. Publ. 500-45, 147 pages (Apr. 1979) CODEN: XNBSAV

Library of Congress Catalog Card Number: 79-600036

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1979

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402

Stock No. 003-003-02039-7 Price $3.25

(Add 25 percent additional for other than U.S. mailing)
NOTE

Reports on conmercial developments included in this publication were obtained from the open literature, supplemented in most cases by site

visits and meetings with appropriate company representatives. No proprietary information of any kind is included. Opinions about comparative merits of the developments were found in the published literature,

and were not generated by the authors of this report. Inclusions or exclusions of specific developments are strictly reflections of the

published literature. NBS did not experimentally verify the accuracy of

the statements from the published literature or any of the companies

cited. Specific references to companies and developments in this report

cannot be construed as recommendation or endorsement by the National

Bureau of Standards.

iii
PREFACE

The Institute for Computer Sciences and Technology (ICST), National Bureau of Standards (NBS), develops and recommends Federal

Information Processing Standards; provides advisory and consultative services to other agencies of Government to support the formulation of ADP management and procurement policies and to assist

in solving specific computer application problems; and conducts

research and provides technical services designed to aid Government agencies in improving cost effectiveness in the selection,

acquisition, and utilization of automatic data processing equipment. In the course of discharging these responsibilities, ICST

staff members prepare technical reports , technology assessments,

and summaries or proceedings of conferences and symposia which

the Institute sponsors and conducts. Resulting publications may

appear in NBS publications media, in professional or technical

journals, or as separate volumes such as proceedings or monographs .

This forecast of computer peripheral memory systems was prepared

as a preliminary input for the identification of areas for possible future standards development. Conclusions drawn from current

trends in these technologies, such as are reflected in this report, will be a basis for standards development.

Also , this forecast was prepared as a service to Federal computer

managers who are active in the ADP management field. In order to

improve the utility of this information, this publication has incorporated a section with decision trees which are intended to

perform as aids in the purchasing phase of computer peripheral

memory equipment. The information offered by the decision trees,

technical parameter tables, market trend graphs, and associated

text is made available to keep the Federal ADP manager current

with changes in contemporary developments and the emerging of

equipments in computer peripheral memory systems.

The Institute for Computer Sciences and Technology, National

Bureau of Standards, acknowledges its appreciation to all the

participants in this technological forecast. Many individuals and

companies have contributed information, ideas, constructive criticisms and their talents , all of which were indispensible for

the completion of this document.

The authors would like to mention the invaluable contribution

made by the numerous manufacturers in the generation, assembly

and review of the Computer Peripheral Memory Forecast. We would

like to provide special credit to Barbara Moran and Walter Lee

for compiling the data for our document, to Dennis Donovan for

preparing our figures, to Jaqueline Jones for assistance in the

off-line data search, and to Barbara Peterson, Joan Knoerdel , and Terri L. Rau for inputting and editing the report using an on-line text editing system.

iv
CONTENTS

Page

Note iii

Preface iv

Table of Contents v

List of Tables ix

List of Figures x

Abstract 1

I. Introduction to Computer Peripheral Memory Systems 1

A. Categories 1

1. Rotating cylinder or disk memory systems 1

a. Drums 2

b. Disks 2

(1) Moving-head disks 3

(2) Stationary-head disks 3

2. Tape storage memory systems 4

a . Mass tapes 4

(1) 1.27 Centimeters (1/2 Inch) 4

(2) other 4

b. Cartridges 5

c. Cassettes 6

d. Floppy disks 6

3. Optical data storage memory systems--Laser beam .... 7

4. Solid-state peripheral memory systems 7 a. Charge-coupled devices 7 b. Magnetic bubble memories 7 c. MOS (metal-oxide-semiconductor) memories ...... 8

5. Random-access magnetic memory systems--

Core memories 8

6. Alternate memory systems 9 a. Videodisk memory systems 9

b. Beam addressable memory systems 9

II. Development--Parameters of the Various Peripheral Memory

Systems - 10

V

1
1. Drums and Disks 11

a. Drums 12

b. Moving-head disks (fixed media) 12

c. Moving-head disks (removeable media) 15

d. Stationary-head disks (fixed media) 15

e. Cartridge-disks 15

2. Mass storage systems 19

3. Cartridges and Minicartridges 20

4. Cassettes and Minicassettes 20

5. Floppy disks and minifloppy disks .... 23

6 . Laser beam 27

7. Charge-coupled devices 29

8. Magnetic bubbles 32

9. MOS 34

10. Cores 37

11. Videodisks 39

12. Beam addressables

.

41

I. Conclusions for Each Peripheral Memory System 44

A. Advantages and disadvantages of the described peripheral

memories--A comparison of price/performance characteristics of peripheral memories 44

1. Rotating cylinder or disk memory systems ....... 44

a. Drums 44

b. Disks 44

(1) Moving-head disks 44

(2) Stationary-head disks 45

2. Tape storage memory systems 45

a. Mass tapes 45

b. Cassettes 47

c. Cartridges 48

d. Floppy disks 48

3. Optical data storage memory systems--Laser beam .... 49
4. Solid-state peripheral memory systems .... 49

a. Charge-coupled devices 49

b. Magnetic bubble memories 50

c. MOS (metal-oxide-semiconductor) memories 50

5. Random-access magnetic memory systems--Core

memories 51

6. Alternate memory systems 51

a. Videodisk memory systems ...... 51

b. Beam addressable memory systems 52

B. Applications of the various peripheral memory systems--

major and minor applications 52

1. Rotating cylinder or disk memory systems . . . . . . . 52

a. Drums 52

b. Disks 53

(1) Moving-head disks 53

(2) Stationary-head disks ....... 53

2. Tape storage memory systems . 53

a. Mass tapes 53

b. Cartridges/minicartridges 54

c. Cassettes/minicassettes 55

d. Floppy disks/minifloppy disks . . . 56

3. Optical data storage memories systems--Laser beam . . . ; 57

4. . Solid-state peripheral memory systems ...... . . 57

a. Charge-coupled devices 57

b. Magnetic bubble memories .... 58

c. MOS (metal-oxide-semiconductor) memories ..... 59

5. Random-access magnetic memory systems--Core

memories 59

6. Alternate memory systems 59

a. Videodisk memory systems ...... 59

b. Beam addressable memory systems . 60

C. Projections for various peripheral memory technologies--

current trends in developments and markets ........ 61

1. Rotating cylinder or disk memory systems 61

a. Drums ..... .......... 61

b. Disks ....... 61

vii
2. Tape storage memory systems 67

a. Mass tapes . 67

b. Cartridges 68

c. Cassettes 72

d. Floppy disks 74

e. Summary graph of tape technologies ........ 76

3. Optical data storage memory systems--Laser beam .... 79

4. Solid-state peripheral memory systems 80

5. Random-access magnetic memory systems--Core

memories 86

6. Alternate memory systems 89

a. Videodisk memory systems 89

b. Beam addressable memory systems 90

IV. Summary and Overall Conclusions 91

A. A summary table of the various peripheral memory

technologies 91

B. Conclusions 95

V. Bibliography

.

117

viii
List of Tables

Page

Table 01 - Drums 13

Table 02 - Moving-Head Disks - Fixed Media 14

Table 03 - Moving-Head Disks - Removeable Media 16

Table 04 - Stationary-Head Disks - Fixed Media 17

Table 05 - Cartridge Disks 18

Table 06 - Tape Mass Storage Systems 21

Table 07 - Cartridge and Minicartridge Drives 22

Table 08 - Cassette and Minicassette Drives ..... 24

Table 09 - Floppy Disk and Minifloppy Disk Drives 25

Table 10 - Laser Mass Memory System 28

Table 11 - Charge-Coupled Devices 30

Table 12 - Magnetic Bubbles 33

Table 13 - Metal-Oxide-Semiconductor (MOS) 35

Table 14 - Cores 38

Table 15 - Videodisks 40

Table 16 - Beam Addressables 42

Table 17 - Typical Values and Features of Computer Memories ... 92

ix
List of Figures

Page

Figure 1 - Drums Shipped by U.S. Manufacturers 62

Figure 2 - Disks Shipped by U.S. Manufacturers 66

Figure 3 - U.S. OEM 1.27 centimeters (0.5 inch) Tape Drive

Market 69

Figure 4 - U.S. Tape Cartridge Drive Market 71

Figure 5 - U.S. Cassette Drive Market 73

Figure 6 - U.S. Floppy Disk Drive Market 75

Figure 7 - Summary Graph of U.S. Tape Cartridge, Cassette,

Floppy Disk, and OEM 1.27 centimeters (0.5 inch)

' .:. Tape Drive Systems 77

Figure 8 - Estimated CCD Memory Market Trends 82

Figure 9 - Estimated Magnetic Bubble Memory Market Trends .... 84

Figure 10 - Estimated MOS Memory Market Trends .......... 85

Figure 11 - Estimated Core Memory Market Trends 88

Figure 12 - Upgrade a Large Computer System - Increase On-Line

Memory Capacity 97

Figure 13 - Upgrade a Large Computer System - Increase Off-Line

Memory Capacity 99

Figure 14 - Upgrade a Large Computer System - Increase Computer

Thruput Via Fast Auxiliary Memory 100

Figure 15 - Upgrade a Large Computer System - Replacement of

Peripheral Memory System 101

Figure 16 - Upgrade a Small Computer System - Increase On-Line

Memory Capacity 102

Figure 17 - Upgrade a Small Computer System - Increase Off-Line

Memory Capacity 104

Figure 18 - Upgrade a Small Computer System - Increase Computer

Thruput Via Fast Auxiliary Memory 105

Figure 19 - Upgrade a Small Computer System - Replacement of

Peripheral Memory System 106

Figure 20 - Purchasing a Large Computer System - Determine

On-Line Memory Capacity 108

Figure 21 - Purchasing a Large Computer System - Determine

Off-Line Memory Capacity 110

Figure 22 - Purchasing a Large Computer System - Increase

Computer Thruput Via Fast Auxiliary Memory . Ill

Figure 23 - Purchasing a Small Computer System - Determine

On-Line Memory Capacity 112

Figure 24 - Purchasing a Small Computer System - Determine OffLine Memory Capacity 114

Figure 25 - Purchasing a Small Computer System - Increase Computer

Thruput Via Fast Auxiliary Memory 116

X
COMPUTER PERIPHERAL MEMORY SYSTEM FORECAST

Robert B,

Peter J,

Steve A.

J. Warnar

Calomeris

Recicar

ABSTRACT

This document describes and forecasts computer peripheral memory

technologies as displayed by U.S. research and manufacturing

facilities. Specif '.cally, both technical and economic criteria are discussed. The presented peripheral memories include contemporary

and emerging systems, all of which are compared in graphs, tables,

and decision trees. The document contains an extensive bibliography

(in ANSI format) to support certain main points that are supplemented

by information supplied by the Institute for Computer Sciences and

Technology (ICST) resources. Additional information and verification

was received from private interviews with various U.S. technical

experts and equipment manufacturers.

Key Words: Beam-addressables ; cartridges; cassettes; core memories;

disks; drums; floppy disks; laser beams; magnetic bubbles; masstapes;

solid-state memories; video disks.

I. Introduction to Computer Peripheral Memory Systems

Computer Peripheral Memory Systems are considered to be those

principally auxiliary storage devices or subsystems that are a significant part of the computer system, but are logically

separated from the mainframe. The mainframe is considered to

usually include the Central Processing Units , or CPU(s),

primary memory and closely coupled equipment such as Input/Output

(I/O) channel units.

Computer Peripheral memory systems generally supply data that is

destined to be stored in the computer main memory. The peripheral

memory systems supply large quantities of information at relatively

slow rates to the computer. This information is then selectively

routed to the computer internal memory, such as the main memory.

The peripheral memory hierarchy thus serves the computer with

large quantities of information that the computer needs to fulfill its

requirements. The peripheral memory function of thirteen types of such

memories is presented in this report and their cost/performance characteristics are compared.

A. Categories

1. Rotating cylinder or disk memory systems

a . Drums

1
A magnetic drum is a cylinder-type device that is capable of being

rotated rapidly. It is coated with a magnetic material in which bit

patterns may be recorded and be read from. The bit patterns run in

bands or tracks around the drum. A drum system may have many drums in

it.

Read-write heads are positioned in rows near the drum surface. As the

drum revolves, different parts of a track or band are read or written on by the associated read-write (R/W) head. There is a separate R/W head

for each track. [HELSA 70]

Magnetic drums form part of the storage system, and serve as primary or secondary memory. A magnetic drum has a shorter access time than most

magnetic disk systems; access time for drum memory is approximately

one-sixth that of movable head disk memories. Magnetic drums are much

faster in operation than magnetic tapes, and slower than magnetic cores.

b. Disks

The magnetic disk is one of the most widely used devices for direct

access to data. The recording medium is a set of metal disks coated

with magnetic material, such as gamma-ferric oxide. The disks are mounted on a rotating spindle. Data are recorded on tracks on the disk

surfaces and are read or written as the disks rotate. The concept of

disk storage is similar to that of a phonograph record except that the

tracks are concentric instead of spiral. The stack of disks is referred

to as a disk volume, and if the volume is removable, it is referred to

as a disk pack. [KATZH 74]

Data are recorded on both surfaces of a disk (except the top and bottom

surfaces of a volume that are used for protection, or perhaps servo information) and a single access arm controls two R/W heads--one for the

upper surface and one for the lower surface of each disk. (Some manu- facturers use two or more heads per surface). The access arms form a comb-like assembly that moves in and out together. Usually, a single

R/W head is used to access a single surface, however some disks have a separate head assigned to each track. [KATZH 74]

The components that perform reading and writing are the magnetic core

and winding of a head. The rest of the head is the mechanical assembly

which supports these components at the correct position with respect to

the disk surface and the electrical leads to access the windings. To

write information on a disk, current is driven through the windings

around the gapped core in the head. The current magnetizes the core which in turn magnetizes the magnetic material on the disk surface

directly under the gap. Alternating the polarity of the current results

in alternating the magnetization direction in the medium as the medium

moves past the core. In reading the track of information, the same winding is involved. It senses previously written magnetic transitions

in the disk and produces an output voltage across the winding.

2
Each, track can store the same number of bits and is identified by a track address. Each surface is identified by a head address (that is,

the R/W head used to read the surface). The heads are switched electronically when a given surface is to be read. Each track is identified

by (and located by) a track number and a head number. A magnetic disk

is read or written by first moving the access arms to the proper track

address prior to the input or output operation and by then switching on

the desired R/W head. Disk seek refers to the process of moving the R/W

head to the proper place. The time necessary to retrieve information

from disk storage is therefore a function of three variables: seek

time, the time necessary to rotate to the desired position on a track,

and data transfer time. [KATZH 74]

A disk storage module has three major components: the disk volume, the access arms and R/W heads, and the disk mechanism that causes the re- cording surfaces to rotate and works in conjunction with the access arms and R/W heads to record and retrieve data.

A disk storage unit is usually classified by several factors:

1. Whether the heads move or are fixed

2. Whether the disk volume is removable or not

3. Seek time and rotation speed (access time)

4. The number of disk storage modules per unit

5. The number of recording surfaces per module

6. The capacity of each track and the number of tracks

per surface [KATZH 74]

(1) Moving-head disks

Hard disk systems are said to offer a highly cost-effective means of

storing digital data. Hard disk systems consist of a continuously

rotating magnetic medium and at least one magnetic head. Moving-head

disk systems, especially, have dominated the peripheral, random-access

data storage market and will probably continue to do so in the forseeable future.

In response to the requirement for the lowest possible cost in rigid

disk devices, several manufacturers are marketing fixed disk, moving arm

devices. Movable head disks provide large quantities of reliable low

cost memory.

(2) Stationary-head disks

Stationary-head disks are sometimes called fixed-head disks or head-pertrack disks. When compared to other disks, fixed-head disks provide the

fastest access times because the heads are permanently positioned above

each track, therefore, seek time is zero. Since they have fewer moving

parts they are also more reliable because many tight, mechanical tolerances are eliminated. The head-per-track disk ranks between floppy

disks and moving-head disks when capacity is considered.

3
2. Tape storage memory systems

Tape storage memory systems feature sequential-access. Sequentialaccess storage occurs when stored data becomes available only in serial

sequence, regardless of whether or not all the information, or portions

thereof, is desired.

The medium of the tape storage memory systems is a mylar tape coated on

one side with a magnetizable material which may be magnetically altered

in some way. It is the recording of data that magnetically orients the

medium. The recording is nondestructive, this means that the orientation can be changed. Thus, the medium is erasable.

a. Mass Tapes

1. Magnetic 1.27 centimeter (cm) wide tape

The 1.27 cm wide tape has been the industry standard since 1953 when it was first commercially available. Magnetic tape units generally use

reels of tape up to 26.67 cm (10.5 inch) in diameter, holding up to 732

meters (2400 feet) of 1.27 cm (0.5 inch) wide tape. As the mechanism of

the tape drive causes the tape to move, data are recorded on and read

from the tape as it moves past the magnetic R/W heads.

The data are recorded on the tape in serial-by-character format in seven

or nine tracks. On a nine track tape, there is an eight-bit character

plus a parity bit for error detection which are recorded side by side on

the nine tracks. On a seven track tape, there is a six-bit character

plus a parity bit.

The capacity of each reel of tape is a function of the recording density, which is the number of characters recorded in a given length of

tape. The range of the densities available is from 7.87 bpmm (200 bpi)

to 246 bpmm (6250 bpi). A 7.87 bit-per-millimeter density means that

7.87 characters can be recorded in one millimeter of tape. In a 732

meter length of tape, the maximum range of unformatted capacity is from

5.76 to 180 million characters respectively at the density extremes

specified previously. However, in practice, the data are recorded in

variable length blocks with gaps of blank tape separating them for

convenient buffering of the data blocks, thus providing easier data

transfer. Therefore, this practice reduces the capacity of a tape to a lesser capacity, called formatted capacity.

2. Magnetic tape greater than 1.27 cm wide

We have surveyed four of the latest models of mass storage systems.

Mass storage systems combine the inexpensive cost of tape as a storage

medium with the operating advantages of semi-random, on-line access.

There are two systems whose main objective is to utilize the short tape

cartridge systems; this design improves access time by making the tape

4
shorter and wider. In other words, the shorter and wider the tape, the

better the access time.

To provide efficient search of information within a mass tape cartridge,

the standard 1.27 cm tape was increased in width to 6.9 cm (2.7 inches)

and decreased in length to 19.6 m (770 inches).

The third system is a fully automated on-line tape library for standard

1.27 cm magnetic tapes. All three systems have experienced from one hundred to a peak of three hundred cartridge or tape loads per hour.

[THEID 78] Thus, its use is to eliminate manual tape mounting operations.

The fourth system takes advantage of videotape recording technology. It

is very similar to the magnetic tape systems with the exception that it

is written onto and read from magnetic 5.08 cm (2.0 inch) wide by

1158.24 m (3,800 feet) long videotape.

Magnetic Media for Small Computer Systems

Since the initial introduction of magnetic media products for small

coaputer systems, magnetic media products have grown and extended in the same direction as large-scale-integration circuit chips. Up until about

1973, the only magnetic media products widely used for small computer

systems were the tape cassette and magnetic card. Then the 0.635 cm (0.25 inch) data tape cartridge was introduced, followed in rapid suc- cession by the floppy disk, minicassette, minicartridge, and minifloppy

disk. This proliferation of magnetic media has led to a wider choice of

solutions for the equipment designer. In the case of tape magnetic

storage systems, the designer can choose a magnetic medium to closely

meet his requirements for storage capacity, access time, transfer data

rate, and cost. [MANLA 77B]

These three types of removable-storage recording media are at the present well established -- tape cassettes, tape cartridges, and floppy

disks. Each type has its own combination of performance characteristics. New designs are occurring constantly in each of these fields,

and further developments are expected.

b. Cartridge

The term "tape cartridge" defines a device wherein the tape medium is

enclosed in some type of container. In this container, there is either

an endless unidirectional loop of tape on a single reel or a bidirectional tape on two co-planar take-up reels driven by an elastic belt

drive. A typical tape cartridge contains 0.635 cm wide magnetic tape

capable of recording 63 bpmm (1600 bpi) (phase encoded) on up to 4

tracks. The speed of operation varies from manufacturer to

manufacturer

.

Even though the tape cartridge appeared on the market before the floppy

disk, its impact has not been felt until recently. The storage capacity

5
is approximately four times that of the cassette since the tape car- tridge has four tracks instead of two and writes at twice the density

or 126 flux transitions per millimeter (3200 flux transitions per inch)

instead of 63 ftpmm (1600 ftpi).

Recent technological advancements allow densities as high as 252 ftpmm

(6400 ftpi) which with double encoding give densities of 252 bpmm (6400

bpi). This yields data transfer rates as high as 192 Kbits per second

in the serial mode with a storage capacity 16 times that of a standard

cassette

.

Minicartridge is the miniaturized version of the standard tape cartridge

utilizing the same technology. It is about the same size as that of a standard cassette with a very small, inexpensive, and simple drive,

nearly as low in cost as the minicassette drive; but the minicartridge

cost is close to the cost of a standard tape cartridge.

Packaging in a sturdy, well built, compact data storage device as in the

standard cartridges, confers reliability and high system performance.

The unit cost is approximately twice that of a cassette even though the

capacity is approximately one-half of the standard cassette. The minicartridge contains a 0.381 cm (0.15 inch) wide by 42.67 m (140 ft) long

high-performance magnetic tape capable of recording 63 bpmm on up to 2

tracks.

c . Cassettes

The cassette is a mature product and one of the earliest products from

the class of specialized, removable, magnetic media for mass memory on minicomputers and microcomputers. The digital cassette has been on the

market for about seven years and originally evolved from the audio

variety to a reliable digital memory. The technology is well understood, including its advantages as well as its limitations.

Manufacturers claim that the level of reliability for the cassette is

high with mean-time-between-failure (MTBF) as great as 15,000 hours;

the encoded information, if reasonably protected from the environment,

is reliable for over a year. Although many units use the simple mechanical drives typical of older audio cassette systems, there is a trend

toward capstan and servo motor controlled drives, particularly as higher

tape speeds and packing densities become more common. [CONWJ 77A]

Undergoing a "mini" revolution, the minicassette has reached the stage

of proposed ANSI Standards. These minicassettes are used where size,

weight, power consumption and cost are major considerations.

d. Floppy disks

"Floppy disk", "diskette", and "flexible disk" are several names for the

low-capacity, low-cost answer to block-random-access storage for small j computer systems. The name "floppy disk" is most commonly used. A

' floppy disk is in effect a large, circular piece of magnetic tape. Why

6

I
was it called a floppy disk? Because its recording medium is a disk of

oxide-coated mylar, unlike the rigid aluminum disks and drums which had

been used in previous storage devices.

The major use of floppy disks is in data-entry systems; but intelligent

terminals and remote-batch applications are not far behind. Blockrandom-access capability is the strongest attribute of the floppy disk.

Random-access memory is a storage technique in which the time required

to obtain information is independent of the location of the information

most recently obtained. The storage system can access any piece of data on the floppy disk in less than one-half of a second.

3. Optical data storage memory systems--laser beam

Optical laser beam addressable memory techniques have been recognized as one alternative to conventional magnetic memory technology. These

optical techniques for data storage have advanced significantly during

the last decade. The introduction of optical techniques to computer

mass memory applications is undergoing a cautious evolutionary process

because of the lack of widespread commerical success in optical re- cording even though there are some unique devices that have been suc- cessfully demonstrated. Secondly, it is said that there is a continuous

advancement in magnetic recording technology. Its projected performance

improvement is of sufficient magnitude to satisfy the marketplace until

at least 1980. Thirdly, even though the optical memory technology has

proved technically feasible, some projections indicate that such systems

are not yet economically competitive with existing mass memory technologies. [CHEND 75]

4. Solid-state peripheral memory systems

a. Charge-coupled devices

A charge-transfer device is a generic term that is applied to a family

of several types of integrated circuit semiconductor devices, one of

which is the charge-coupled device. A charge-coupled device (CCD)

stores minority carriers in potential wells and transfers this charge as

a packet by translating the potential minima parallel to the device

surface. This operating characteristic can be used for developing large

serial-block oriented solidstate memories. Since CCD, LSI memories are reported to be less costly to fabricate than conventional random-access

semiconductor memories, several manufacturers have announced that they

are developing CCD memories for applications such as fast-auxiliarymemories (FAMs) or peripheral mass memories. Because of their cost

advantage and relatively faster operating speeds, CCD memories are found

to compete strongly with drums and fixed-head disks in the rotating mass storage media.

b. Magnetic bubble memories

Magnetic bubble memories are currently fabricated from synthetic garnet

materials. Magnetic cylindrical domains, located in a thin magnetic

garnet film that is grown on a non-magnetic substrate, are capable of

7
storing information for memory purposes. Thus, bubble memories differ

vastly from semiconductor memories since these are currently fabricated

for the most part from silicon materials. This basic material difference and high cost of initial product is said to have led to a generally low acceptance factor of this technology in the past. Bubble

memories are reported to offer potentially higher information storage

densities at extremely low-power operation when compared to any other

R/W memory technology. In addition, bubble memories also provide non- volatile information storage. Recent developments, using these advantages, have started to break through the aforementioned resistance

barrier. Based on these developments, several manufacturers are now offering magnetic bubble devices for use as information storage devices

in terminals, point-of-sale equipment and other applications.

c. Metal-oxide-semiconductor (MOS) memories

MOS large-scale-integration (LSI), random-access (RAM) circuitry is

currently found in many computer main frame memories as the basic storage element. This application was formerly completely dominated by core memory systems. Many of the MOS product manufacturers are reporting

that their products are now displacing core memory in existing systems

(as replacements) and in new designs. Moreover, recent advertisements

have announced the introduction of MOS LSI RAM into another portion of

the computer memory hierarchy - the peripheral mass storage level.

Supporting articles justify this introduction since they claim that MOS

memories are now less costly than before and are offering operating

advantages, such as unconditional random-access and a nonrotating medium, not previously available at this memory level.

5. Random-access magnetic memory system--Core memories

Random-access magnetic core memories once accounted for nearly 100

percent of computer main frame storage. This memory technology depends

on the magnetic properties of donut-shaped magnets for storing information. These core magnets are strung on several wires in order to gain

electronic access to magnetically stored data.

Since core memories have been in existance longer than solid-state

memories manufacturers of these devices are able to reduce their costs

significantly each year by relying on accumulated past experience. In

addition, progress in semiconductor LSI circuits has aided the further

development and cost reduction of core memory systems. Where before

many discrete components were required, now a single LSI chip on a core memory card often performs the entire required function. The advent of

microprocessors is said to even further enhance core memory development.

However, say many core manufacturers, despite all of these improvements,

solid-state memories have eroded the core memory market.

One of the latest core memory developments has occurred in what manufacturers call bulk core store. This new development has resulted in a number of products that are designed to function as mass storage systems

8
on the computer peripheral level. Manufacturers of these units believe

that the excellent data reliability and data retention of this equipment

are advantages over most solid-state memories.

6. Alternate Memory Systems

a. Videodisk memory systems

Videodisk memory systems can record and transmit data in various formats. At present, these memory systems are mostly directed towards the

television video-recorder/playback market, hence their name of videodisk

systems

.

A few manufacturers are developing videodisk systems for computer mass memory applications this application is addressed in the contents of

this forecast.

Information contained in a videodisk system is found to exist in various

forms (both analog and digital) and is embedded within the material of a disk not unlike a phonograph record. Most of these devices are optical

write and optical read systems; however, some of these systems rely on mechanical, contact readout devices like capacitance, pressure, or magnetic stylus-like pickups.

The amount of information that can be packed into a videodisk is as- tonishing. This information packing density is achieved by making use

of advanced fabrication tools such as laser or electron-beam systems.

As a result, the videodisk bit size is allowed to shrink to about 1.5

square micrometers (at an estimated error rate of 1 in 10 billion)

.

The single disk storage capacity of this read-only memory (ROM) technology is reported to be about 10 billion bits. One manufacturer believes that future system specifications of a quadrillion bits of storage, data rates of 50 megabits per second, and information access times

of tens of milliseconds are possible. According to researchers, such a system because of its high data transfer should improve the processing

data rate of most computers significantly while at the same time data

reliability is said to be strongly enhanced.

b. Beam Addressable Memory Systems

Electron beam technology, which dates back to first-generation computer

memories, is currently again considered by several companies as a promising technology for fast mass storage. Sometimes called EBAM (electron

beam addressed memory), Beam Access, or EBEAM (electron beam addressable

metal-oxide-semiconductor), this type of memory system relies on information storage in MOS chips placed inside and near the face of a cathode-ray tube. The tube's electron beam is used to both write into

and produce data from the MOS chips.

Electron beam memories have advanced significantly due to major progress

in areas such as MOS technology, high voltage power regulation, and

analog-to- digital (AD) converters. This memory combines large data

9
capacity, relatively fast access times and high data transfer rates with

long-term retentivity; storage of data is rated in months without

application of power.

According to manufacturers, electron beam memories are cost-effective

over core and semiconductor memories when large amounts of storage (over

30 billion bits per module) capacity is required. Electron beam memories

are attractive when used as fast auxiliary or peripheral mass storage

memory in computer systems.

II. Development--Parameters of the Various Peripheral Memory Systems

The following sections provide a comparison of various peripheral memory

systems with associated specific parameters. The systems and their

parameters are shown in tables each of which covers a specific memory

technology.

Certain yardsticks have evolved whereby one attempts to measure the

merit of any given peripheral memory device or system. Capacity, access

time, data transfer rate, and cost per bit are the basic performance

characteristics of mass storage devices. Each mass storage unit has its own particular attributes, and many applications require that a hierarchy or mix of devices be connected in the same computer system. The

short access times and high data rates of fixed head drums or disks save

on main memory size, thereby reducing systems cost. However, the relatively higher cost per bit of these devices generally makes them too

expensive for file storage, and movable head disk structures of higher

capacity (and lower cost per bit) but longer access time are used.

Generally, the lower level in a memory hierarchy includes tape for the

archives and for data whose processing can be well scheduled in advance

since further economies in cost of storage are possible at the expense

of even slower access times. When designing or selecting a peripheral

memory system, all these parameters and their effects on the system

application must be considered. [HOAGA 72]

Following are some general definitions for these performance

characteristics

:

Formatted storage capacity - the net amount of storage available to the user excluding reserved space for sectoring and other overhead storage

requirements expressed in megabits.

Unformatted storage capacity - the total amount of space on the medium

for storing data with no reserved space for data organization, as for

distinguishing between blocks of data.

Transfer rate - the speed at which data may be read from the unit in

bits per second exclusive of seek and latency delays.

Average access time - the average period required to make the unit ready

to address a specified memory location.

10
Price per bit - this value is obtained by dividing the price of the

device by the unformatted capacity of the device, where this capacity is

expressed in bits. The prices used are End User prices. If End User

prices are not available, Original Equipment Manufacturer (OEM) prices

are used and flagged according to the information available.

Before a prospective buyer of peripheral memories makes a commitment, he

should ascertain how the price in cents per bit was derived. Obviously,

there are at least three methods that could be used:

a. The device alone - the price of the device divided by the capacity

of the device in bits.

b. The device and its associated controller - the sum of the price of

the device and the price of the controller divided by the capacity

of the device in bits.

c. The controller and the maximum number of peripheral memory devices

that can be connected to it - the sum of the price of the controller

and the prices of all the individual memory devices that can be

connected to it divided by the total capacity of all the memory

devices

.

Depending upon the given circumstances and the method used, one can obtain surprisingly different results.

1. Drums and Disks

A little elaboration on some of the definitions for performance characteristics as they apply to drums and disks follows:

Storage capacity - ordinarily the capacity would be expressed in eight

bit bytes for drums and disks, but in this report we are using bits to

make comparison with other memory devices easier. In those cases where

our sources had expressed the capacity of a device in bytes, we merely

multiplied by eight to get the capacity in bits.

Also, for the sake of comparison, we use unformatted capacity where

possible. In those cases where unformatted capacity is not available,

formatted capacity will be provided and flagged as such. For a given

device, formatted capacity will always be somewhat less than unformatted

capacity because of reductions due to overhead, such as error correction

codes, etc.

Average access time for the drum or fixed-head disk - average access

time is calculated differently for different technologies." In this case

it refers to the period required to rotate a selected section of the

drum or disk track into position under the appropriate head. This

length of time is called latency time. On the average, latency is

one-half the time required for one revolution.

Average access time for the moving-head disk - refers to the interval

the moving head requires to shift into position over the appropriate

track and to begin transmitting information. This time is the sum of

11
the latency time and the average head movement time. Average head

movement time is the sum of all move times divided by the number of moves. It generally equals the time to move across one-third of the

tracks. [DATPR 77B] However, some manufacturers define average access

time as the time to do all possible seeks divided by the number of all

possible seeks; they do not include latency time. In providing the

figures in this forecast we have done our best to follow the first of

the two definitions.

Data transfer rate - is a function of the packing density on the track

and the rotational speed of the drum or disk.

Price (per bit) - this value is obtained by dividing the price of the

device by the capacity of the device, where the capacity is expressed in

bits. In those cases where the only price available included the price

of the controller we have used that price in our computation and flagged

the result.

a . Drums

Parameters of some drums which appeared to be typical are listed in

Table 01. One manufacturer said that his firm would produce a drum to

the user's specifications, but the drums listed in Table 01 are offthe-shelf equipment. The most significant parameter of the drums, when

compared to other rotating memories, is fast average access time. The

capacities and average access times of these typical drums are quite

similar to the same parameters for the stationary head disks shown later

in Table 04.

The capacity of the typical drums listed in the table range from 33.6 to

114.4 megabits. Transfer rates range between 4 and 11 megabits per

second and average access times range from 4.3 to 8.7 milliseconds. The

price per bit covers a wide range, from 22 to 560 millicents per bit.

b. Moving-head disks (fixed media)

Table 02 contains the parameters for several typical moving head disks

that have fixed media. The disks that are listed are currently in

production and being marketed to the end-user by the manufacturer. When

comparing this category of disk with others, one notices the outstanding

feature to be capacity that is larger than the other disks. From reading open literature and talking to manufacturers, it has been determined

that the approximate capacity range for this category of disk to be 1640

megabits to 2540 megabits The most popular disk in this category has a capacity of about 2400 megabits per spindle. Often two spindles are in one unit, thereby providing a total capacity of about 4800 megabits per

unit.

Numerous manufacturers were asked for the ranges of the parameters for

this type of disk. Transfer rates for this type of disk have an approximate range of 1.5 to 38.7 megabits per second. Average access time

12
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14
ranges between 33 and 269 milliseconds. Cost to the end-user is approximately 1.5 millicents per bit.

c. Moving-head disks (removeable media)

Several typical moving-head disks with removeable media (removeable

packs) are listed in Table 03. These disks are currently in production

and being marketed to the end-user by the manufacturers. These disks

with removeable packs usually have less capacity and cost more per bit

than the moving head disks with fixed media.

Numerous manufacturers were asked for the ranges of the parameters for

this type of disk. Indications are that moving-head disks with removeable packs have an approximate range of capacity of 4.9 to 300 megabytes. The range of the transfer rate is 1.2 to 9.7 megabits per

second. Average access time ranges between 30 and 135 milliseconds.

End-user prices of this category of disk when supplied by a computer

manufacturer are in the area of 2 to 20 millicents per bit.

Magnetic disks have offered large-capacity on-line R/W storage with

relatively low cost and reasonable speed as compared to other memory

devices. Disk files have become the dominant large-capacity storage

medium due to its low cost, which is achieved through the large number

of bits in the inexpensive storage medium sharing the expensive mechanical drive, servomechanism, channel electronics, control units, and

other equipment. The large number of bits on platters mounted on the same spindle is made possible by high storage density. [CHAM 75]

d. Stationary-head disks

Table 04 lists the parameters for several stationary-head disks. All

these disks are currently being manufactuuered . The last disk listed is

sold in the OEM (Original Equipment Manufacturer) market only. The most

outstanding feature of disks in this category is fast average access

time

.

Ranges of the parameters for this type of disk were obtained from nu- merous manufacturers. Our studies indicate the range of average access

time to be approximately 2.5 to 17.0 milliseconds for disks of this

category. Generally, capacities are in the range of 4.0 to 76.8 megabits. Transfer rates are between 4.1 and 8.8 megabits per second. The

price per bit is in the area of 180 millicents.

e. Cartridge-disks

Parameters of several typical cartridge-disks are shown in Table 05.

Generally, these disks are of relatively low capacity and slow average

access time. The last disk entered in the table, besides having a removeable cartridge, also incorporates a fixed platter. Its capacity

is much higher and its unit price per bit is much lower than the pure

cartridge-disks we looked at. There are many such cartridge-disks (with

15
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18
fixed and removeable platters) available in the market place, but most

have a lower capacity.

After making inquiries to numerous manufactuers , we obtained the range

of parameters for cartridge-disks. Disregarding the last entry in the

table, capacities for the cartridge-disk ranged between 19.2 and 50.4

megabits, transfer rates ranged between 1.44 and 5 megabits per second,

and average access times ranged between 41.5 to 90 milliseconds.

Generally, the price per bit fell between 7 and 17 millicents.

2. Tape mass storage systems

The following definitions are provided to give a better understanding of

the performance characteristics of the magnetic tape storage system.

Unformatted storage capacity - The unformatted storage capacity of

magnetic tape is a function of the recording density, which is the

number of bytes recorded in a given length of tape. Densities are available from 8 bpmm (which means 8 bits can be recorded on a single

track in one millimeter length of tape) up to 246 bpmm. In 731.5 meters

of magnetic tape, the maximum storage capacity is 5.8 million to 180

million bytes when written at these densities. In reality, the data is

recorded in variable length blocks with interrecord gaps of blank tape

separating the blocks for easier access. This reduces the maximum

capacity of magnetic tape and is called the formatted storage capacity.

The total storage capacity of various magnetic storage media varies with

block length and block length also affects access time.

Average access time - The average access time is the average time interval between the instant at which information is called for storage

and the instant at which delivery is completed. If you access a large

data file on tape, you can assume, according to manufacturers, that

average access time to any data block equals half of the time required

to read through the entire file.

Transfer rate - The transfer rate is directly proportional to the R/W

speed. It is the product of that quantity and the drive's recording

density. The read/write speeds usually vary with the type of drive

mechanism employed. The transfer rate comparisons can be deceptive

because of the fact that data is always written in a blocked format

containing gaps of blank tape between blocks. These inter-record gaps

must be long enough to allow the tape drive to stop and start between

data blocks. With high density parallel recording, convenient block

sizes turn out to be much shorter than interrecord gap lengths, so the

tape consists primarily of gaps. Thus, this not only reduces the storage capacity but also lowers the effective transfer rate. Since no data

are stored in a gap, the effective transfer rate of blocks of parallel

data can be only a small fraction of the theoretical maximum transfer

rate

.

Price - The price per bit for the tape storage system was established by

dividing the advertised price of the system by the unformatted capacity.

19
Table 06 shows the different ways these mass storage systems combine the

inexpensive cost of tape as a storage medium with the operating advantages of semi-random on-line access. This table compares the characteristics of the four latest kinds of mass storage systems that were sur- veyed. The lowest price per bit of the four systems is an automatic tape

library mass storage system with 29 microcents. However, it is not the

fastest in terms of average access time. The mass tape cartridge storage system has an average access time of seven seconds which is the

average time to receive the data cartridge and to deliver it to the R/W

station. As opposed to the other mass tape cartridge storage systems,

the average access time is 15 seconds which is 8 seconds slower. One

way to improve access time is to utilize shorter and wider tape. [THEID

78] In term of cents per bit of the two systems, the difference is 70

microcents which is the price paid for shorter access time with 0.35

terabits less than the other mass tape cartridge system. The video tape mass storage system has an unformatted capacity of 2.86 terabits at a price of 40 microcents per bit.

3. Cartridges and minicartridges

The previous definitions for mass storage systems hold true for the tape

cartridge systems; however, the densities are different.

The densities of the cartridge systems are available from 63 bpmm (which means 63 bits can be recorded in one millimeter length of tape on a single track) up to 252 bpmm (6400 bpi). [MANLA 77C] The maximum storage capacity, at these densities, on 91.4 meters of cartridge tape is

5.8 (using just one track) to 23 (using 4 tracks) million bits.

Table 07 shows the characteristics of the tape cartridge and mini car- tridge. The typical standard size cartridge has an unformatted storage

capacity of 23 million bits with a transfer rate of 48 kilobits per

second. The average time is 20 seconds. The price per bit ranges from

3.7 to 13 millicents depending upon the application requirements. The

minicartridge unformatted storage capacity is from 2.7 to 6.2 megabits

depending upon packing density and number of tracks. The minicartridge

has up to 2 tracks whereas the standard cartridge has 4 tracks. The

price per bit for the minicartridges ranges from 4 to 14 millicents.

4. Cassettes and minicassettes

The definitions in the previous mass storage systems hold true for the

cassette systems; however, the range of density is different.

The densities of cassettes are available from 32 bpmm (800 bpi) (which means 32 bits can be recorded in on millimeter length of tape on a single track) up to 63 bpmm. The maximum storage capacity, at these

densities, on 91.4 meters of cassette tape is between 2.9 megabits for

single track and 5.8 megabits for a two-track unit.

20
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22
Table 08 shows the characteristics of the cassette and minicassette.

The unformatted capacity of a typical cassette is 5.4 to 5.8 megabits.

The typical transfer rates range from 8 to 24 kilobits per second.

There are some cassette units that have transfer rates up to 60 kilobits

per second. [CASWS 75C] The typical average access time is 20 seconds.

Their price per bit ranges from 8.3 to 13.0 millicents depending upon

the application.

5. Floppy disks and minifloppy disks

The following definitions are applicable to the floppy disk system.

Unformatted storage capacity - This is the total amount of space on the

floppy disk for storing data without reserved space for data organization which is necessary for distinguishing between blocks of data.

Formatted storage capacity - This is the net amount of storage available

to the user excluding reserved space for sectoring and other overhead

storage requirements.

Transfer rate - This is the speed at which data may be read from the

unit exclusive of seek and latency delays.

Average access time - The average access time is the average time in

milliseconds required to make the unit ready to access a specified

location on the floppy disk. By industry standards, average access time

is computed by multiplying one-third the number of tracks by the trackto-track stepping rate and then adding head settle time and the average

latency, which is one-half the rotation time. [CASWS 75A]

Price per bit - The price is established by dividing the advertised

price of the system by the unformatted capacity.

The characteristics of the floppy disk and minifloppy disk systems are shown in Table 09. The typical single density floppy disk capacity is

3.2 megabits with the transfer rate of 0.25 megabits per second. The

typical double density double sided floppy disk capacity is 6.4 megabits

with a transfer rate of 0.50 megabits per second. The average access

time for both single and double density floppy disks range from 162 to

286 milliseconds. The price per bit is 19 millicents for single density

floppy disk. For double density floppy disk the price range per bit is

9.4 to 10.2 millicents.

The single density minifloppy disk capacity is 0.87 to 0.88 megabits

with a transfer rate of 0.125 megabits per second. The range of average

access time for single and double density floppy disk is 162 to 566

milliseconds. The double density minifloppy disks capacity is 1.8

megabits with 0.25 megabits per second transfer rate. The price per bit

range for single density minifloppy is 4.4 to 45 millicents. For double

density, the price per bit is 22 millicents.

23
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6. Laser beam

The following definitions are provided to give a better understanding of

the performance characteristics of the optical laser mass memory systems .

Unformatted storage capacity - The information of the laser mass memory

system is stored in a track-oriented format on metal film strips. Each

strip contains 13,000 user tracks and each track can contain 15,385

eight-bit user bytes. The total formatted capacity per strip is 1.6

billion bits. In addition, there are approximately 37 percent more bits

on the strip which are used for overhead functions such as preamble,

error recovery, record markers, check code, etc. The data tracks are spaced 7.44 microns center-to-center and the data is recorded down the

track in 3.6 micron diameter areas. The unformatted capacity per strip

is aproximately 2.2 billion bits. [PI 77]

Transfer rate - The transfer rate of the laser mass memory is the speed

at which data may be read from or written to the R/W unit. The burst

transfer rate is 400 kilobytes per second. The typical writing transfer

rate is 320 kilobytes per second and the typical reading transfer rate

is 300 kilobytes per second.

Average access time - Average access time is the average time interval

between the instant at which information is called for storage and the

instant at which delivery is completed.

Price - The price per bit of the laser mass memory system was established by dividing the advertised price of the system by the unformatted

capacity.

Table 10 shows the characteristics of present as well as planned laser

mass memory systems. At the present, the unformatted capacity of laser

mass memory is 1 terabit with 3.2 megabits per second transfer rate.

The average access time is less than 20 seconds. The price per bit for

the present system is 360 microcents.

The potential archival laser mass memory system capacity will be from 2

terabits for single side glass slides with the metal strip embedded to 4

terabits for double side slides. The projected transfer rate is 4.75

megabits per second with an average access time of 10 seconds. The

projected bit price for one side slides is 10 microcents and for double

side slides is 5 microcents.

The potential library laser mass memory capacity will be 1000 terabits

with the same or better transfer rate and average access time. The

projected price per bit is 1 microcent which is one order of magnitude

less than the previous single side price.

27
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7. Charge-Coupled Devices

In order to provide a better understanding of the performance characteristics of charge-coupled device memories, some definitions that apply

specifically to them follow:

Storage capacity - Various memory word lengths were found to be used in

the different designs of this emerging memory technology. In each case,

with word lengths ranging from 8 to 56 bits, the total memory word

capacity was multiplied by the number of bits per word in order to

arrive at the total bit-capacity of the memory as presented in the

table.

Also, to make comparisons easier the unformatted capacity of each memory

is presented in the table.

Average access time - For CCDs these parameters vary substantially from

system to system. The reason is that CCDs are primarily serial devices

and the organization of these structures has significant effects on access time. Generally, these memory systems allow the addressing of

blocks, or lines, of data; after this data entity is addressed, a serial transmission of the data block, or line is performed. In this

process, a certain number of cycles have to be performed serially to

arrive at the correct address of the desired block of information.

Transfer rate - The transfer rate of CCDs is highly dependent on the

speed of the individual memory chips and the structure in which these

chips are arranged and addressed. Thus, if a CCD chip features a 10

megabit per second transfer rate and the chips are arranged to form

60-bit words (parallel operation) , the transfer rate could be as high as 600 megabits per second.

Price - This particular parameter is obtained by dividing the advertised

(or projected) price of the memory by its total capacity in bits. Care

should be taken in order to obtain meaningful comparisons. For instance, in some cases the memory price could not be extracted from the

price of the total computer system while in other cases electronics

overhead, such as controllers, interfaces, etc., was considered part of

the price. The most basic price per bit of the CCD can be found by

dividing the chip capacity by the chip price. Many such values are presented in the table.

Table 11 shows typical designs of the CCD memory. One design, not truly

a peripheral memory, is called the "file" memory system. In this system, the file memory is placed on a 1.25 megaword (56 bits per word) per

second bus that interconnects both with the parallel and control processor of a new computer system. Each processor has its own fast bipolar

random-access-memory (RAM) that can be loaded, upon request, by the file

memory. The CCD file memory strongly enhances the numerical computation

capability of the machine and allows 50 million floating point operations per second through "file" use. In this case, the cost/perfor29
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mance advantage of CCD implementation is realized since their cost is

lower than bipolar RAM. CCD memory designs of Table 11 show capacities

that range from 40 kilobits to 3,752 megabits. Oddly enough the higher

capacity was not found in the peripheral but as an extension of the

computer main memory. Transfer rates of 4 megabits to 600 megabits per

second were encountered with the higher rate again in the nonperipheral

application. CCD peripherals generally show transfer rates in the

middle ten megahertz. Access times are comparable in these memories 100

to 500 microseconds. The smaller systems showed the shortest access

time, indicating that larger systems used a more serial design approach;

on the average, the table shows a price of 250 millicents per bit. A

shorter access time generally results in a higher price per bit or as high as 940 millicents.

Clear cost/performance advantages were as yet not found in the CCD

electronic disks designed as replacement units for magnetic disks. Only

the CCD memory access time appeared better -- CCD electronic disk ca- pacity was found to be less, price was higher, while data rates appeared

to be about the same but are improving.

8. Magnetic Bubbles

In order to provide a better understanding of the performance characteristics of magnetic bubble (MB) memories some comments that apply specifically to Table 12 follow:

Storage capacity - The memory word length of the magnetic bubble memory

was usually found to be 8 bits, or 1 byte. In each case, the total

memory word capacity was multiplied by the number of bits per word to

obtain the total memory capacity in terms of bits.

Magnetic bubbles (MBs), at this time, differ from other memories in that

some of their memory is considered redundant. This means that a certain

fraction of the MB memory is allowed to be defective to gain advantage

in production yields -- an outside semiconductor, read-only-memory is

necessary to identify, and thereby avoid these defects. In the accom- panying tables, the unformatted capacity has been reduced by the re- dundancy factor and the parameter thus identifies only the number of

operating, and directly available data bits of the memory.

Average access time - As with CCD's, magnetic bubble memory access times

vary according to specific system design since these memories are also

primarily serial in nature. Block random-access is common and again is

quite similar to the CCD approach. At this time MB access times are still relatively slow since their shift rates, a primary factor in

establishing access time, have not yet peaked out and should be improving shortly.

Transfer rate - Transfer rates of MBs are still being improved. The

current speeds, according to researchers, are not yet representative of

what this technology is capable of in the near future. Transfers are

32
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serial in nature, like magnetic disks -- parallel transfer occurs by

placing many bubble chips in parallel and then addressing and transferring their data simultaneously.

Price - The price per bit for the magnetic bubble memory was established

by dividing the advertised price of each design by the unformatted

capacity as indicated in the table. The most basic price of the bubble

bit was found by using the single magnetic bubble package price (small

quantities) and dividing it by its unformatted capacity. This value,

when compared to other values in the table provides a "feel" of how much

overhead cost is required for a system design.

Table 12 shows typical MB memory designs. As in CCDs, the capacity of

these systems vary greatly and a range of 640 kilobits to 105 megabits

was encountered. The larger capacity memories were generally employed

in military systems while smaller capacities were found in commercial

products. The range in transfer rates was 50 kilobits to 2.4 megabits

per second. In this case, the difference in rates can be attributed to

different products from separate manufacturers that are competing in

this area. MB access time varied with the size of the system--the

bigger the capacity the longer the access time. A range of 15 to 500

milliseconds was encountered. The price range as shown in the table

appears rather chaotic and ranged from 110 to 620 millicents per bit.

The chip capacity of 92 kilobits is higher than any other solid-state

chip commercially available at this time. Its low-end price per bit is

also less than most LSI memory circuits although researchers feel that

current values have not stablized because this garnet technology is new

to the solid-state memory market.

Magnetic bubble memories, unlike other solid-state memories, are non- volatile. Their magnetically stored data remains in memory without

external supply of power. In addition, radiation exposure levels

usually intolerable to semiconductor memories, have little effect on

MBs.

In comparison to magnetic disks, magnetic bubbles at this time excel in access time according to Table 12. There is no comparison in either

system capacity, data rate, or price per bit; however, rapid improvements are expected in these areas in the near future.

9. MOS

The following comments are presented in order to provide a better understanding of the MOS performance characteristics of Table 13.

Storage capacity - Metal-oxide-semiconductor memory designs of Table 13 are random-access memories. The inherent design, packaging, testing,

etc. of these types of memories is more difficult and consequently more

costly than most serial memories. For this reason large, peripheral MOS

mass memories are not found and probably will not be available in the

34
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near future. The indicated unformatted capacity was found by multiplying the word, or byte, capacity of the particular design by the number

of bits per word. Byte word lengths of 8, 16, 18, 22 bits or more were

found to be common in the encountered MOS designs. It should be remem- bered that all the bits of the memory word are usually not available for

data. Some memory system manufacturers revealed that as much as 5 bits

of the 16 bit words might have to be used for memory data error cor- rections thus leaving 11 bits for data storage.

Average access time - The average access time of both static and dynamic

MOS memories is much faster than other memories covered in this report.

In addition, the access of MOS memory data is achieved in a completely

random fashion. As indicated in the table, access times of hundreds of

nanoseconds or less are quite common in this memory technology.

Transfer rates - The transfer rates of MOS memories can be relatively

high, depending partly on the number of parallel MOS memory chips used

in the design. This rate is also greatly enhanced since access and

cycle times are very fast when compared to other memories discussed in

this report. MOS RAM was generally found in that part of the computer

memory hierarchy where flexible handling and fast transfer of data were highly desirable.

Price - The MOS memory price per bit (see Table 13) is currently among

the highest encountered in the memory market. To offset this high

price, MOS memories offer some of the most powerful data manipulation

available today. As indicated by the table, some MOS memory systems

could cost as much as 1 cent per bit, or more. Researchers predict that

the price of the MOS dual-in-line memory package (DIP) should remain

relatively constant - the DIPs capacity, however, is still projected to

increase at regular intervals. Thus, with increasingly more bits available per package, the price per bit is expected to drop fast in the near

future

.

The bit price was calculated by dividing the advertised price by its

total capacity in bits.

Table 13 shows various MOS memory designs that were thought to exhibit

the potential to be used as peripheral memory. The range of capacity of

these designs is from 1,440 to 6,144 megabits while the transfer rate

appeared to be in the upper teens of megahertz per second. Access times

of 0.28 to 2 microseconds were common. The price per bit ranged anywhere from 600 to 3000 millicents per bit, depending upon the particular

design of overhead electronics and extra features desired.-

Metal-oxide-semiconductors and other semiconductors are currently displacing magnetic core memories in the mainframe memory hierarchy of

computers. These memories are made up of MOS packages, or dual-inlinepackages (DIPs) that are arranged on printed circuit cards (PCs).

According to the Table, the highest bit capacity of the MOS chip (in

each package) is about 16,000 bits. Each one of these bits can be

36
individually, or randomly, addressed as opposed to the serial operation

of CCDs and MBs. Thus these types of memories manage their data with

far greater flexibility than serial memories. Generally, the drawback

for using the MOS memories, as indicated in Table 13, is high price -- however, these systems offer very high performance and low-power

operation.

According to interviews with MOS manufacturers, large MOS peripheral

mass memories have as yet not fared well. Some products that were made

available in this type of mass storage are said to have been withdrawn

from the market at this time because of poor sales.

10. Cores

Some corranents as they relate to Table 14 are presented to provide a better understanding of core performance characteristics.

Storage capacity - Core memory capacities have grown tremendously since

their first use as computer main memories in 1955. Today, new designs

were found to reach capacities anywhere from 640 kilobits of main memory

to over 81,920 megabits of computer peripheral memory. Magnetic core memories are random access in nature and operate similar to MOS

memories

Many core manufacturers claim that core memory capacity is more realistic than advertised solid-state memory capacity since little or no error correction is required (and therefore little data loss in the

word) with core memory. Thus virtually the whole memory word (minus the

parity bits) is available for data storage.

Average access time - The access time of core memory is moderately fast

when compared to most peripheral mass memories like magnetic disk or tape (see Table 14). In some cases, according to the table, the core access time approaches those of some solid-state memories. The range of access times varies with particular designs. According to our searches,

the larger the system the slower the access time. Small systems ex- hibited 250 nanoseconds access and large systems varied between 0.62 and

2.5 microseconds access times.

Transfer rates - The term transfer rate is not commonly used in core memories. To determine how fast bits are transferred, access time and

cycle time are often specified as sufficient parameters. Thus, transfer

rates must be calculated from these parameters while bearing in mind

that word lengths and interleaving methods are other factors to consider. In order to verify results, the calculated transfer rates were

checked by each manufacturer. As indicated in the table, the calculated

of 3.2 to 13.3 megabits per second transfer rate is typical for large

peripheral core memories.

Price - Several manufacturers are currently producing bulk, or peripheral, core memory systems. The advertised prices of these large sys37
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terns appear to be between 100 to 200 millicents per bit. Manufacturers

of these systems claim that this price competes well with other random

access mass memories, including MOS , when designed as high-storage

capacity peripheral memories.

The peripheral core meihory systems as shown in Table 14 range from 2.621

megabits to 81.920 megabits. These systems are constructed of many

large cards so that other configurations are also possible. Typical

single card capacities, not necessarily applying to peripheral memories,

are shown to have a range of 0.288 to 1.114 megabits. Generally, the

greater the capacity of the system, the slower the transfer rate and access time--ranges were 3.2 to 12 megahertz per second and 0.62 to 2.5

microseconds consectively for these core memories. Price is very com- petitive and varies between 100 to 200 millicents per bit for some large

systems.

Core memory system manufacturers are exploring the computer peripheral

memory market with their products. These systems are said to compete

well in these applications since large core memories offer fast access

times, have good data reliability, are nonvolatile, and cost less in

large capacity store designs.

These designs compare favorably with fixed head magnetic disk systems in

operating speeds since core memories present faster access times. One

manufacturer claims a 3000 to 1 advantage.

On the other hand, this feature is costly since the price per bit is

about 200 millicents for core and 2 millicents per bit for fixed disk.

[AMPEX ND], [KIMP 77], [WARNR 77R]

11. Videodisks

The following comments about optical videodisk memories are rendered in

order to provide a better understanding of the performance characteristics of Table 15.

Storage capacity - The information stored in proposed commercial videodisks is in analog format. The information is presented by a one micrometer wide variable length pit (or oblong hole), the length of which is

representative of the stored data. Up to six bits of data can be stored

per pit. The disk can be divided into 32 sectors of 14,498 bits each.

Since up to 40,000 spiral tracks can be stored per side on each disk,

the total unformatted capacity of a commercial disk could be as high as

10 billion bits.

Average access time - The average access time of an optical videodisk is

the time required to bring the "reading" laser to the right spiral track

plus the necessary time for the desired data to appear under the reader

optical head. In the projected systems of one trillion bits capacity,

access times in the range of 50 to 1000 milliseconds were found. In more advanced systems, multiple disk packs in "juke box" arrangements of

39
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one quadrillion bits capacity (using double-sided recorded disks), the

average access time is anticipated to be about 16 seconds.

Transfer rates - The transfer rate of an optical videodisk is primarily

dependent on three factors:

The rotational speed of the disk

The packing density of the data pits

The analog-to-digital discrimination capability of the data

pit analog values

Thus it follows, if the rotational speed is increased, or if more data

pits are recorded on each spiral track, or if more data bits can be

decoded per analog value of the recorded pits, the transfer rate is

accordingly increased. Scientists estimate, if these parameters can be

maximized, that future data rates of OVD mass memory systems can become

as high as 50 megabits per second or more.

Price - As yet, OVD computer memory systems are still experimental and

price is thus difficult to predict. Based on current costs of the few

commercial optical videodisk playback systems, manufacturers estimate

that a terabit read-only computer memory system could be priced at

$200,000 in the near future.

Optical videodisk memories as shown in Table 15 are still experimental

in nature, but manufacturers assured us that these systems are plausible. Capacities range from one million megabits to a thousand times

that value while transfer rates of 20 to 200 megabits per second are predicted. Access time of 50 to 1000 milliseconds are not considered

difficult goals to attain. At this time, the price per bit for the

system is approximately 20 microcents and .01 microcent for its medium.

An optical videodisk read-only peripheral mass memory offers potential

advantages, such as a low-cost and efficient storage medium and improve

archival storage. The media costs, when compared to either magnetic

disk or tape media of mass storage systems, are much less.

According to one research facility, the medium cost per bit of magnetic

disk is 0.4 of a millicent, of tape (246 bpmm) 2.2 microcents, and of

the proposed optical disk is 15 nanocents. In addition, the storage

density of the optical disk is said to be 48 times better than the 246

bits per millimeter of tape. [KENNG 77]

The archival properties of OVDs are predicted to save data in excess of

ten years and some estimate over 100 years. Of course, these storage

techniques only allow the read-only capability, as yet.

12. Beam addressables

In order to provide a better understanding of the performance character

istics of beam addressable memories, some comments that apply specifically to Table 16 follow:

41
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Storage capacity - The total memory capacity of a beam addressable, or electron-beam-addressable memory system is made up of several modules

each of which contains a memory tube. Experimental memory tubes were

found to range from one million bits to 32 million or more bits in

storage capacity. Several of these modules can be connected in parallel; systems with 8, 16, and 22 modules and other configurations have

been designed and are operating successfully. Generally, the parallel

operation of these modules functions to form both the parallel words and

the error correction storage needed to produce low error rates. [SMITD

78] , [GENEL ND]

Average access time - The average access time for beam addressable

memories is relatively fast when compared to magnetic disk or tape

memories. On the average, the access to any data bit was specified to

be in the tens of microseconds or about 1000 times faster than for

magnetic disk. Data access is accomplished by addressing a block of

information which is then read out serially. Because of this peculiar

approach, this type of memory is sometimes called a Block-OrientedRandom-Access-Memory , or BORAM.

Transfer rate - As mentioned before, beam-addressable memories are designed with many modules in parallel. Thus, if 16 data modules are connected in parallel and each module has a transfer rate of 10 megabits, the system read transfer rate (see Table 16) would be 160

megabits

Price - Beam addressable memories are, as yet, not commercially available. Thus pricing information is based on predictions. On the av- erage, most research and manufacturing facilities predicted that early

systems would be priced less than 1 millicent per bit in the 1980' s. The 1 millicent figure is thought only to apply to very high capacity

systems where system overhead electronics can be shared by multiple

tubes. For example, a system with less than 4 million bits of storage

would be priced far above the 1 millicent per bit; at this time systems

with 2 billion bits are projected at prices well below 10 millicents

[HERBJ 76] , and a price as low as 1 millicent is not considered unreasonable .

Table 16 shows a variety of experimental electron-beam-addressable

memories (in order to avoid using trade names, we refer to these memories as beam addressables) . The range in system capacity is seen to be

between 40 to 2,000 megabits, but these figures are not thought to be

directly representative of the huge bit densities these memories are capable of. Read transfer rates of 32 to 160 megabits per second and

write transfer rates of 1 and 16 megabits per second were uncovered.

Access time ranges from 3 to 20 microseconds depending again on design,

while price per bit showed a span of 8 to 20 millicents.

Beam addressable memories are still in the experimental stage but manufacturers project that some systems should become available in the

1980' s. These memory systems feature high data storage capacities of up

43
to 2 billion bits with fast access times of tens of microseconds. The

memories are block-random accessed and have nonvolatile storage of data.

No moving parts are found in these systems. Many manufacturers believe

that beam addressables should be preferred over magnetic disk systems in

the military environment since beam-addressable are very rugged and have

the ability to withstand much shock and vibration. [GENEL ND]

III. Conclusions for Each Peripheral Memory System

A. Advantages and disadvantages of the described peripheral

memories -- a comparison of price/performance characteristics

of the assessed peripheral memories

1. Rotating cylinder or disk memory systems

a. Drums

Advantages

High reliability

Low maintenance requirements

Relatively small in physical size

R/W capability

Fast access time

Disadvantages

Small storage capacity

Expensive (between .02 and 3.5 cents per bit, depending upon drum

size, bit packing density, motor speed and the number and type of

R/W heads)

Drum units offer advantages in special situations. These advantages are high transfer rates, fast access time and ruggedness. Drums withstand

severe environments in terms of physical shocks. [DATPR 77C]

b. Disks

1. Moving-head disks

Advantages

Less costly than drums or fixed-head disks

Comparatively large storage capacity

R/W capability

Disadvantages

Relatively long access time

Moving-head fixed media drives have a couple of major advantages over removable media drives. They are 30 to 40 % cheaper for the same capacity, and they are more resistant to harsh environments. Since they are fairly well sealed, the disk is protected against particulate contaminants, as well as operator induced damage, such as dropping.

44
2. Stationary-head disks

Advantages

Fast access time

R/W capability

Disadvantages

Small storage capacity

High cost

In summary, disks and drums with similar parameters compare as follows:

Disks have the advantage in terms of capacity per unit volume

Drums have the advantage of high speed operation and good mechanical shock resistance

Fixed-head arrangements have the advantage of high speed operation.

Moving-head arrangements have the advantages of lower cost and

higher storage capacity

Removeable-media units have the advantages of unlimited offline

storage capacity and operational flexibility [DATPR 77C]

Fixed-media units have the advantage of simplicity of design,

requiring fewer adjustments and providing simpler servicing and

greater reliability

Rotating memories have the key advantage of flexibility for use in

many applications

2. Tape storage memory systems

a. Mass Tapes

There are three types of mass storage systems: one is an automatic

on-line tape library. The second is a videotape mass storage system.

The third is a mass storage data cartridge system.

The following advantages can be realized for a fully automatic online

tape library:

Uses standard 1.27 cm tape

Media interchangeability

Completely automated magnetic tape storage and retrieval system

System makes a tape library, a mass storage device, by combining

the inexpensive cost of tape as a storage medium with the operating advantages of automatic on-line access Modular, can be expanded to 32 tape drives

Eliminates human intervention

Storage on tape is much less expensive than storage on disk

Tapes are secured in a closed, protected environment until they

are requested by the CPU

Off-line storage of 1 microcent per bit

45
Can be manually mounted

Improved tape and file maintenance

Some of the disadvantages associated with the automatic online tape

library:

Serial access Mechanical in nature

Physical size may be large

The following advantages can be realized for videotape mass storage

systems:

On-line random access Plug-compatible with most major computer systems

Transverse recording technique allows the data to be recorded bit

serially, as opposed to byte parallel, while retaining high

channel rates

Self-contained

Can be used in a stand-alone environment

Rapid random access is achieved by block address searches at a tape speed of 25.4 meters per second (mps) bidirectionally

Eliminate conventional disk and tape libraries

Compress off-line archives

Reduce on-line requirements for tape and disk resources

Improve host system throughput due to high data transfer rate

Magnetic videotape technology is a mature technology

Magnetic videotape achieves much higher densities

Reduction of floor space required (10 square meters versus 195

square meters, with the equivalent bit capacity of 220 typical

disk drives)

Currently, there are two mass storage data cartridge systems available

and each of the systems has unique characteristics. One difference is

the size of the blocks of data handled: one cartridge stores up to 50

megabytes whereas the other cartridge stores up to 8 megabytes. The

data transfers of the one are oriented toward data sets of 2 megabytes

or more whereas the other transfers 1 megabyte or more. Another difference is that the first required dedicated disk units to serve as staging devices whereas the other uses a common pool of disk drives, all

under control of the operating system, for system staged, and unstaged

operations. Still another difference is that the implementation re- quires user program modification for the first system but not for the

second system. Another difference is that the first has two accessor

mechanisms where the second accessor serves as an alternative to an inoperative first accessor or both accessors can operate simultaneously

depending on the model. The other system has only one accessor mechanism. Another difference is that the first uses a helical scan and

video technologies rather than the longitudinal recording which means

that the first system must perform considerable more error correction

[GILDJ 75] . The actual data transfer rate is higher for the second

system than the first.

46
The following advantages can be realized for the second mass storage

data cartridge system:

Low price/bit for on-line capacity

Eliminates physical congestion and human errors involved with

manual handling

Faster access time than cassettes

Automatic tape loading and unloading

Mass storage system which utilizes tape and disk without inherent

drawbacks of either medium

Reduced floor space required

Modular - permits field expansion by module add-on

Some disadvantages associated with the mass storage data cartridge

system:

Small capacity per cartridge

Highly mechanical in nature

Serial access

b) Cassette

When applying the cassette to a computer peripheral memory system, the

following advantages should be realized:

A mature technology

Recording standard widely accepted

Economical ($6 to $10) medium

Package is the easiest of the three media to handle

Can be stored and mailed because it is small and not easily

damaged

Drive mechanism is smaller than floppy disk but the same size as cartridge drive

Cassette drive operates on a battery and requires no standby power

unlike the floppy disk drive

Cassette's plastic case provide some protection for the tape

against the environment (Better protected if stored in its case)

Minicassette is about one-third smaller and lower in cost than the

standard cassette

Minicassette requires a low-powered drive

Higher capacity than minifloppy disk

Nonvolatile

Portable

Some of the disadvantages associated with cassettes are:

Cassette's plastic case does limit performance

The access speed for the data is limited because of the more complicated servos required for tension control and the mechanical

limitations in the roller and guidance systems

47
Cassette case contains more parts than floppy disk, so the

cassette tends to be less reliable

Cassette drive requires at least two motors: one each for the take

up and supply reels, and one more if a capstan drive is used

Slow access time

c) Cartridges

The following advantages can be realized when using cartridge storage

systems

:

Bidirectional

Tape cartridge has four times the storage capacity of cassette

Cartridge has four track (cassette has two tracks)

Comes in more rugged case than cassette

Cartridge housing protects the tape better than cassette

Faster than the tape in the cassette drive due to its own mechanism within the cartridge itself

Cartridge drive can be made more economical than a cassette drive

because only one drive motor is needed to drive the elastic belt

which provides the tape tension

Increased bit density is available (252 bpmm and higher)

Cartridge price per bit is lower than cassette and floppy because

it stores more data

Minicartridge is smaller and cheaper than the standard cartridge

drive

Lower power consumption

Some of the disadvantages associated with cartridge storage systems are:

Cartridge medium price ($20) is two to three times as much as a cassette or floppy disk.

Even though the cartridge is relatively immune to handling damage,

it, like any flexible medium, should not be exposed to high

temperatures or rapid temperature changes.

(After such exposure or after extended periods of storage, it is

recommended that the cartridge be operated through a tensioning

pass from beginning of tape (BOT) to end of tape (EOT) and

return before attempting data recovery)

.

d) Floppy disk

The following advantages can be realized when using floppy disk:

Data can be accessed in less than one second

Easy to file because it is thin

Heads on both sides of the floppy disk drive lower the access period

Some of the disadvantages associated with floppy disk are:

48
The disk drive and controller are larger, more complex and ex- pensive than the cassette's or cartridge's drive

Disk wear - especially in the hub area Varying manufacturer-to-manufacturer "compatibility" specifications

Medium has environmental problems. It is, like tape, sensitive to

temperature and humidity extremes

Medium must be handled carefully

Magnetic tape media have been researched at NBS for an extensive period

with the result that many standards and standard reference materials

have been established. Furthermore, numerous articles pertaining to

tape technology have been published that address tape characteristics in

a definitive fashion and describe these characteristics in exact detail.

Several such articles [CELLS, 74] [CELLS, 76] highlight archival data

storage and the definitions of terms such as storage content, static and

dynamic decay rates, lifetimes (of both medium and content), content

density, cost factors, and other archival quality factors. These

sources are therefore recommended as an additional guide.

3. Optical data storage memory systems - laser beam

The following advantages can be realized when using the laser beam mass storage unit:

Modular unit

Low cost (200 to 300 microcents per bit)

Permanent medium does not degrade while stored or from repeated

access Compact -- over 3.08 million bits/square centimeter recording

density. Off-line storage of 1 trillion bits in less than 0.28

square meters of floor space

Can be a stand-alone system or a hybrid system

Reliable

Longer shelf life than any other archival magnetic media

Lower error rate

Multiple searches and strip mount/dismount can occur simultaneously

Reduces human intervention

Immune to electro-magnetic radiation and computer power failures

The disadvantage associated with the laser beam mass storage system is

that optical storage is in its infancy.

4. Solid-state peripheral memory systems

a. Charge-coupled devices

When applying the charge-coupled device to a computer peripheral memory

system, the following advantages should be realized:

49
Low maintenance, non-moving part solid-state peripheral memory

Fast access times

Low-power operation

Block-random-access design

High bit-storage density

Some of the disadvantages associated with CCD memories are:

A still maturing technology

Not yet bit-random-access

Volatile data storage

Poor radiation resistance

Solid-state, CCD peripheral memories offer advantages in special situations where fast access time, relatively low capacity, low-power, and

low-cost operation are requirements. This situation occurs in the access gap -- or, the level in the computer memory hierarchy between

main memory and mass memory. Also, these designs should offer good

volumetric efficiency for small system size operation.

b. Magnetic bubble memories

The following advantages can be realized when using magnetic bubble

memories

:

Nonvolatility of stored data

Low-power operation

Radiation resistant

Block-random-access designs

Some of the disadvantages are:

A still maturing technology

Relatively large electronics overhead

Low-speed data rates

Magnetic bubble memories offer advantages in special situations where

nonvolatility, low-power and low-cost operation with block, or page,

random access are requirements. Magnetic bubble memories are also very

rugged and tolerate high radiation, high shock environments. Thus, at

this time, bubbles are found as record storing memories in terminals and

in space flight event recorders.

c. MOS (metal-oxide-semiconductor) memories

Very few MOS peripheral mass memory applications were found. Some of

the advantages would be:

Fast access times

Low-power operation

50
Relatively good volumetric efficiency

High data rates

The main disadvantage would be:

High cost

5. Random-access magnetic memory systems - Core memories

When using bulk core memories as computer peripheral mass stores the

following advantages should be realized:

Nonvolatility of stored data

Low-cost

Exceptional data reliability

Fast access times

Random-access

Matured technology

Some of the disadvantages would be:

Relatively high operating power

Relatively narrow operating temperature range

New application of old technology (A reason mentioned by solidstate memory manufacturers)

6. Alternate memory systems

a. Videodisk memory systems

Videodisk computer peripheral memory systems, as yet not available,

should be able to offer the following advantages in the near future:

Very high storage capacities

Very low cost per bit

Low static and dynamic wear of media

Nonvolatility and long-term retentivity of stored data

Portable media

Relatively fast access times

Some of the disadvantages that might be encountered are:

Immature technology

Low-competition technology (as yet, very few manufacturers are involved)

Read-only operation

Moving parts system

Videodisk memories should excel in applications that require high volume

storage of archival data. This application affords mass storage at the

very low cost per bit that optical video disks (OVDs) offer. Because of

the nature of the OVD medium, loss of data should be extremely rare and

51
data integrity should be very good. Also, videodisk memory systems will

require little floor space when compared to disk or tape memory systems.

Manufacturers claim that OVDs will be the first terabit memories that

are easily portable.

b. Beam addressable memory systems

When electron-beam-addressable memories are to be designed in future

computer memory systems, the following advantages should be realized:

Non-moving part memory

Block random-access

Fast access High data rates

Nonvolatile data storage

Low-cost per bit for large systems

High bit-storage density

Some of the disadvantages that might be encountered are:

Relatively large electronics overhead

Immature technology

Low-competition technology (as yet, few manufacturers are involved)

High voltage system operation

Electron beam memories are still developing and should find applications

to fill in the access gap area by the early 1980' s. This technology,

because of high data storage capability, rapid access time and data

rate, paired with low-cost per bit and other factors should also strongly compete with magnetic disk memory systems.

B. Applications of the various peripheral memory systems -- major and minor applications

1. Rotating cylinder or disk memory systems

a. Drums

The drum is used for information of two types:

Transient (temporary) information that changes very quickly

Important information that must be accessible very quickly [FLORI

755]

The drum is very useful for a program that produces a large amount of

intermediate results. It is also used to store a copy of the operating

system. Routines in the operating system are needed quickly and used

frequently. Sometimes the system cannot proceed until it receives these

routines. [FORI 75]

According to one source, another use for the drum is in multiaccess

computing. Here many users see the computer system as though it were a

52
small console with a large amount of storage. Multiple programs are being run concurrently. When there are large programs, we may wish to

bring in new copies of the program at frequent intervals, taking out the

copy of the program which is presently running. The drum provides a place to keep a copy of programs. The act of interchanging these

programs is called swapping. [FLORI 75]

Drums provide a page-swapping area for some systems using virtual memory. Drums can be used to store frequently used utility software and

perform buffering and queueing tasks. Message switching for Telex

networks and telephony are some typical examples of drum usage. Because

of their ruggedness and high reliability drums are used in many military

applications where these characteristics are required.

b. Disks

1. Moving-head disks

Moving-head magnetic disks are used in applications where the head

positioning time can be tolerated because fast access time is not a requirement. Spooling, multiprogramming and time-sharing are some applications. On-line data entry, data communications, data base man- agement and information retrieval are some other applications. [DATPR

77C]

Moving-head disks are used as buffers, paging devices and file storage

in computer systems. Most of the modern concepts of information handling and processing that are leading to wider application of computers

stem from the presence of disk storage units. [DATPR 77C]

2. Stationary-head disks

Fixed-head magnetic disks are logically the same (in a computer sense)

as magnetic drums. Fixed-head disks may be used for the same type of

applications as drums, except in those areas where drums are used be- cause of their ruggedness. They may be used to store a copy of an operating system or to store intermediate results in applications where

a program may generate many such results. They are used in multiaccess

computing applications.

Fixed-head disks are appropriate in applications where the head positioning time of moveable head disks cannot be tolerated. Some uses include process control, power distribution, numeric control and seismic

applications. Sometimes they are used as buffers or paging devices in

computer systems.

2. Tape storage memory systems

a) Mass tapes

According to the results of our searches, tape mass storage systems are reported to be used in many applications. Specifically these systems

are designed to:

53
Replace manually-mounted magnetic tape

Allow installations to service ever growing numbers of interactive users Place fast growing data bases on-line particularly in a multicomputer environment

Eliminate human intervention

Improve resource management control and file maintenance

Consolidate data bases

Reduce operational cost

The operational cost of running an installation today accounts for a third of the average computing budget [MORGW 75]. The search for

savings in this area has led to the development of automatic on-line

tape libraries. Some manufacturers of these systems claim that this

primary application reduces the cost in the areas of space, personnel,

media damage, CPU partition time, errors, reruns, delay and inefficient

equipment utilization. Also, the operational complexity of scheduling

jobs, media, and machines is reduced.

b) Cartridges/Minicartridges

A practical application of cartridges to computer storage requires the

following:

High-density recording capability

A design of sufficient precision and simplicity to yield

reliability and interchangeability

A design which can be produced at low-cost

A large enough capacity to meet most computer applications

The prime application area for cartridge drives is for unattended data

logging, particularly in harsh environments where dust, dirt, heat and

cold are problems. Most high volume data logging operations usually

cannot permit too many errors to occur. For instance, a system that

monitors a chemical plant operation could create a hazardous condition

if the logger erred too often. Other applications of tape cartridge

drives include:

Replacement for paper tape punch/reader

Numerical control of machine tools

Small business system

Program and data storage with microcomputer system

Data logger for the telephone industry

Printing industry which is beginning to use ma-gnetic tape control

of press operations

Minicartridge intended for point-of-sale terminals, automatic typewriters and similar equipment in which size is critical.

54
c) Cassettes/Minicassettes

Cassettes have the following applications:

Operate in hostile environment

Data logging

Numerical control of machine tools

Seismic/hydrological survey

Airborne equipment

Terminals

Remote batch

Data entry

. Point of sale

Telecommunications

Minicomputer

Program load

Data storage

Master file

Subroutine files

Calculator

Calculator programs

Calculator data

Business systems

Word processors

Automatic typewriters

Editing typewriters

Programmable calculators

Cassette drives, with their relatively small size and low power requirements, are highly adaptable for remote data collection. Also, they are used as archival storage systems on low cost minicomputers and for data

file storage on many small business systems.

Cassettes are used as mass storage memories for microprocessor con- trolled data acquisition systems such as those used to monitor industrial machinery. Cassette drives have been used for many years in

portable inventory equipment. The inventory count is entered by a keyboard that is hand-held or carried on a strap or belt and then made

available for use on data processing equipment. Some systems are capable

of being connected over telephone lines to a large central computer

which collects and processes the data. The same cassette drive is used

for collection and transmission. Using the cassettes for word proces55
sing systems, two drives are required so that new data can be merged and

old data can be arranged by taking the old data set from one drive,

modifying and adding to it, then recording the new data on the second

drive

.

Minicassette applications are:

Hand-held terminals

Desk top calculators

Microprocessor program loader

Data acquisition storage

Word processing

Minicomputer storage

With low power, small size and light weight, minicassettes are ideal for

remote and portable battery-powered applications. The drive requires

less than 1 watt when operating and almost zero standby power. The data

storage requirements are low, and many days' worth of information can be

collected on a single minicassette.

Also, they are suitable for the personal and home computer market due to

their low cost and relatively low data transfer rate.

d. Floppy disks/minifloppy disks

Floppy disks have the following applications:

Data entry systems

Minicomputer systems

Terminals

Telecommunication

Word processing systems

Word processing systems are one of the most demanding areas of

storage:

. Storage medium must be easy to store and load into its drive,

since few operators are experienced with computer controlled

devices

. Searching for data when editing requires rapid accessibility

Applications for floppy disks began with data entry to replace punched

cards, but have grown to include uses such as disk systems on minicomputers and storage devices for word processors. Using the floppy disk

for word processing systems offers two advantages: both the new and old

data set can be contained on the same floppy disk, and data can be

accessed faster than with cassette or cartridge -- in less than one

second. A cassette/cartridge requires longer searching time -- from

several seconds to more than a minute. But, by the same token, the

floppy disk may be less desirable than a cartridge if more data must be

stored (20 pages) than the floppy disk can handle (see Table 17 for

56
comparisons). This is the tradeoff in term of capacity versus access

time. Minifloppy disks have the following applications:

Word processing

Data entry level microprocessor systems

Intelligent calculators

Program storage

Hobby computer systems

Intelligent terminals

Small business machines

The minifloppy disk device, with its small size and random access capability, is compatible with the fast growing word processing and programmable calculator market. The drive is one fifth the volume of the

larger floppy disk drive and uses a battery drive motor, consuming 15 w running and 7.5 w in standby.

3. Optical data storage memories systems--Laser beam

The applications associated with the laser beam mass storage system as an EDP peripheral are:

Provide mass storage for data bases and libraries

Replace archival tape files

Very high density data storage for archival purposes

Program backup

Security files

The laser beam mass storage systems can be a stand-alone or a hybrid

system. It can provide both EDP mass memory storage and document image

storage in the same system. [PC 77]

4. Solid-state peripheral memory systems

a. Charge-coupled devices

Charge-coupled devices are reported to be used in the following applications :

Computer file, or swap memories

Fixed-head disk replacements

Microcomputer memory systems

Intelligent terminal memories

Fixed-head drum replacements

The above memory applications of the CCD can be classified into two

categories

Mass, block-random-access memory

File, or page, swapping memories

57
In mass storage applications, CCD BORAMs are currently available as separate subsystems while file memories were found to be part of new computer main memory designs.

It occurs often that electronic computing systems need to be upgraded.

In this process difficulties are soon encountered in rearrangement of

old and new subsystems because of rigid space, power, size, interface

requirements and other criteria. Manufacturers of CCD, disk replacement

memories, advertise that their systems are very adaptive and should fit

easily in upgraded or new systems. The small size, nonmoving, low-power

characteristics of their products are their reasons for advertising a more flexible design than their mechanical counterparts.

When anticipating introduction of these new systems, software changes

should be looked at before making a firm decision. Changes of this kind

might be necessary since system throughput should be upgraded -- some electronic disk memories are reported to increase data transfer to the

computer as much as 40 times. Thus, as part of the reconfiguration

estimate, it is suggested that software costs be discussed with the

memory manufacturer.

b. Magnetic bubble memories

According to the literature and interviews with MB manufacturers, the

following system replacements are considered feasible depending on the

application:

Cassette replacement

Flexible disk replacement

Paper tape replacement

Solid-state semiconductor memory replacement

Mechanical, moving memories, identified as the top three in the above

applications are said not to perform as well as some MBs

.

For example, one MB design shows three times the bit rate of a flexible

(floppy) disk, uses one tenth the power, measures one tenth in size, and

operates at 1000 times better error rate. This comparison applies to a bubble module with an advertised capacity of half that of a floppy disk.

[ROCKW ND] , [ELECT 76B]

Another application is found in a memory data terminal product line that

became recently available. These types of terminals can keep track of

permanent records and can be used in applications such as credit verification, real estate inquiries, wholesale and retail, order entries,

just to name a few. [DIGID 776], [TEXAS ND8]

A future application of magnetic bubbles is said to exist in handheld

calculators. Instead of using solid-state semiconductor memories,

bubble memories can be designed into handheld calculators to store much

larger programs. MBs display an advantage over semiconductors in this

58
application since MB data storage is nonvolatile and MB storage capacity

is greater per unit volume. Calculators with bubble memories thus

retain their information when the power to the unit is turned off.

c. MOS

Metal-oxide-semiconductor peripheral memories are said to be still too

costly for immediate use. Manufacturers who relate this information

express the opinion that too few applications would require such MOS mass memories at this time; however, this could change in the near

future.

5. Random-access magnetic memory systems -- Core memories

According to the literature and interviews with core manufacturers, the

following applications were found:

Computer peripheral memory (sometimes referred to as bulk core

store)

Swapping disk memory replacement

Minor applications such as video storage, multiprocessor shared

memory and high-capacity buffer

Computer main memory used to be dominated by core memories -- as of this

date this application of core has been reduced significantly since the

advent of semiconductor memories. However, core memories still enjoy

long life, especially in large memories. Core memory modules are becoming larger and larger. Whereas formerly 8 kilobyte modules were

popular, now 256 kilobyte single card systems are available. [DATRM

NDJ]

Core modules of this size can be configured into complete systems with 2

megabytes of directly accessible storage. One manufacturer claims that

his products can be configured into systems of up to 1000 megabytes.

[WARNR 77V]

Systems of such high capacities coupled with data retentivity and

random-access storage find applications in the mass peripheral and access gap areas of the computer memory. In the latter area, bulk core offers increased performance over swapping disks; in mass peripheral

memory, 1000 megabyte bulk core systems exceed the storage capacity, access times, error rates, and system ruggedness of many multiple spindle magnetic disk systems. Transfer rates are comparable.

6. Alternate memory system

a. Videodisk memory systems

According to our resources and interviews with manufacturers of future

computer optical disk memory systems, the following major applications

were proposed:

59
Computer large mass, archival storage

Computer controlled information storage and retrieval systems

The ultrahigh packing density, wide bandwidth, and high signal-to-noise

ratio potential of future OVD memory systems, coupled with its potential

for ease of handling of the platters and instant record and playback,

have made this technology attractive for many information storage applications [KENVR 78] Also, the storage medium is said to display ex- tremely good archival properties paired with excellent portability.

Another advantage of using computer OVD memory over other types of mass storage is that its medium, or disks, experience little or no wear both

when in use and in storage. It, thereby, differs from tape for example,

which wears when in use. This OVD characteristic can be a costsaver

since recorded information would not have to be rerecorded as frequently

because of wear.

In applications such as archival mass storage, OVD's appear more promising than magnetic disk and mass tape systems. Of course, this com- parison ignores the fact that OVD's are read-only memories and magnetic

disks and tape are R/W, erasable memories.

b. Beam-addressable memory systems

According to the literature and interviews with manufacturers of future

beam-addressable memory systems, the following applications were suggested:

Fast auxiliary memory

On-line, random-access peripheral memory

Main memory extension (in combination with semiconductor cache)

Electron beam addressable memories should initially be cost-competitive

with fast auxiliary storage designs, and eventually with most on-line

random-access peripheral memories, but with superior performance over conventional memories. Equally important is their potential use as main

memory extension in combination with semiconductor cache. In this

application they are said to have a large price advantage at comparable

performance. [SPELD 75]

In a price/performance trade-off and using the figures supplied by the

system parameter tables, it was found that beam addressables look between 10 and 100 times cheaper then slow MOS solid-state memory systems

(over 40 megabytes in electron beam addressable capacities).

In main memory extension, or fast auxiliary memory applications, beam

addressables show about a ten times slower access time; but they can approach MOS transfer rates when many memory tubes are connected together in the design for parallel transmission of data bits.

60
C. Projections for Various Peripheral Memory Technologies - Current Trends in Developments and Markets

1. Rotating cylinder or disk memory systems

a. Drums

Nothing significantly new or different has occurred recently in drum

technology nor does there seem to be anything on the horizon, except

that bit density (per track and per device) has been increasing over the

years, with decreasing cost per bit as the result. One manufacturer

expects this to continue, estimating halving of the bit cost in the next

two years. Interest of manufacturers and users has shifted primarily to

the disk market.

Drums are becoming a smaller percentage of the total peripheral memory

market, although the drum market itself is growing slightly. In many

cases, fixed head disks are used instead of drums because they are logically the same, generally cost less and have greater capacity.

There is now only one major computer manufacturer that is actively

marketing a wide range of drum units. These are offered only for the

larger computer systems. [DATPR 77C] A couple of Original Equipment

Manufacturers (OEM) provide drums on a regular and continuing basis.

There is one other manufacturer that will fabricate and supply a drum

upon receipt of a specific order.

Figure 1 depicts the dollar value of drums shipped by U.S, manufacturers. Only one source, a drum manufacturer, was willing or able to

provide us with the data for this chart. This manufacturer felt that

the drum market remained at 40 million dollars from 1975 through 1977

and that it would increase to 50 million dollars by 1980. Although

losing ground to magnetic disks on a percentage basis, this manufacturer

felt that the dollar volume of drum business would remain fairly steady.

Other manufacturers told us that they felt the future for drums was not

bright but were unable to provide specific figures.

The collected information on drums shows a great probabability that

eventually drums will be almost totally replaced by other types of

memories. It is therefore recommended that initiation of standards not

be implemented in drums for this reason.

b. Disks

According to one source, performance through 1980 will remain essentially unchanged from today's levels, but a price reduction approximately

20% each year will be experienced. Although improved disk drive performance is possible, difficulties in implementing it could spur the use

of currently experimental, serial, non-mechanical storage technologies.

[FETHG 76]

Over the past few years the prices per bit of moving-head disks have

decreased at 20 to 25% per year, primarily due to increased storage

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62
capacity per drive. At the same time, performance has improved through

increases in recording density and their accompanying higher data rates.

[FETHG 76]

Although some continuation in disk drive price decreases are probable in

the next few years, difficulties in attaining further performance in- creases are predicted. An order of magnitude improvement in density,

while theoretically possible, will require finer mechanical tolerances

and the use of non-removable disks to achieve them. [FETHG 76]

It is safe to say that limits are being pressed in magnetic media,

beyond which increased density becomes prohibitively expensive. The

estimated ceiling of 394 tracks per centimeter (1,000 tracks per inch)

is only a generation of devices away, and bit density limits of even

5905 bpcm are not far off, being little more than double present high

densities. By 1980, disk storage density will increase at most by a factor of 10, with most of the development going on in moving-head types

of drives

But even if such density improvements occur, raising a disk drive's

access rate to reflect these improvements will still prove difficult.

Faster access time will require the use of multiple heads for each disk

surface or multiple access mechanisms for each spindle, both costly

alternatives. [FETHG 76] Higher RPM is not too likely because of higher

power and cooling requirements.

The trend in disks is toward non-removeable media. Primarily this is so because fixed disks offer lower cost and higher reliability.

Today's disk drives are smaller and lighter than they were previously

and therefore require less space. In instances where the drives are part of a computer system in which the central processing unit (CPU) and

other peripherals require a computer room environment, the size of the

disk memory system becomes a significant cost factor in view of the

price per square meter of such facilities. However, many of today's

drives do not demand a computer room environment since the trend is to

include an internal air filtration system to cope with all but the most

extreme conditions of air contamination. Current disk drive engineering

also results in today's disk drives being comparatively tolerant of

temperature changes. [BARCM 77]

For example, today two 300 megabyte drives have the storage capacity

previously achieved by six 100 megabyte drives. This improvement shows

approximately a 30 percent reduction in electric power consumption.

Since there is a reduction in required pack changes, fewer operators are necessary and because of a reduction in the number of disk drives, fewer

maintenance engineers are required. As a result of these improvements

operation and maintenance costs have been significantly reduced. [BARCM

77]

63
The size of the market for very high capacity devices will be dwarfed by

the growth of demand for smaller, simpler devices in the business system

area. The biggest growth in disk drive sales over the next few years

will certainly be in the 10-50 megabyte range. This will be due to the

reduction in small business system prices which will open up a whole new market area. [BARCM 77]

One of these smaller simpler devices is the disk cartridge drive. Most

systems use a disk cartridge that includes a front-end loaded or top

loaded, removable, single platter. The disk cartridge capacity is 1.24

M bytes to 5 M bytes. Access times range from 35 to 75 milliseconds and

data transfer rates from 200 K to 300 K bytes per second. [REGIS 77D]

In addition to the removeable cartridge, many of the disk cartridge

drives have one or more fixed disks with moveable heads, which provide

additional capacity. It is understood that multiple fixed heads are about to become available on one or more of the fixed disks that will be

incorporated in future systems. This is important for real-time time

sharing systems that require a lot of program and file swapping from

disk to mainframe memory. [DATPR 77B]

Magnetic R/W heads with sensors of thin-film materials have left the

laboratory and are entering the commercial world. They bring with them

the promise of a new generation of computer disks with larger storage

capacities at lower costs per bit and higher data transfer rates.

Thin-film technology represents a breakthrough in head design. A thinfilm head being produced by one manufacturer is a combination of vacuum- deposited sensors and traditional housings packaged into a complete

recording head. It offers designers of disk drives at least five significant advantages:

Improved frequency response because the sensors are made with

laminated layers of magnetically oriented films that better couple

flux between coil and gap

Higher bit-packing density because of the improved characteristics

of the head's magnetic field

Higher track density with more cost-effective, precise track

definition

Increased reliability and longer head life because of an integrated structure, better uniformity in manufacturing processes,

and new materials

Cost advantages in volume production because of automated

fabrication [ROSCT 77]

For disk drives with multiple-track fixed heads, thin-film technology

permits increasing the number of tracks under each head. This achievement permits twice as much data storage as before with the same number

of heads (or the same amount of storage with half as many heads). The

combined improvements in bit and track densities result in three or four

times greater data storage of fixed-head disks when compared to the same machines with conventional heads. [ROSCT 77]

64
More and more computer users are moving to interactive applications

because they give managers control of their operations. Files are kept

constantly up to date, instead of being updated once a day or once a week, and decisions can be based on current information instead of dayor week-old data. With the cost of mass disk storage dropping steadily,

it is becoming less difficult to justify the switch to interactive

processing. [REGIS 77E]

Batch processing is a sequential processing operation. Batch processing

requires only those files to be on line that apply to the applications

program currently being executed. These files are on line only briefly

and then are returned to off-line storage.

Every interactive application, however, requires that all related files

be on-line all the time because they may be needed at any moment. This

movement from batch to interactive systems does not necessarily require

a more powerful computer but it does increase the need for expanded on- line storage by as much as an order of magnitude or more. This pressure

for more capacity has caused suppliers to make higher and higher capacity disks available to users. [REGIS 77E]

Dual spindles for fixed and removeable disks have become popular because

each spindle and head share the same electronics. This dual arrangement

lowers system cost per spindle. [REGIS 77B]

Some companies now make controllers capable of handling a sizable number

of spindles. Gonsequently , for a disk controller capable of handling up

to eight spindles, the electronics cost per spindle is about one-eighth

of the cost of a single spindle unit. Also, this type of multispindle

controller permits designers to implement systems with a number of

computers connected to one disk storage system. [REGIS 77B]

At least one company is planning to develop a semi-intelligent, microprocessor-based controller for its mass storage systems. It expects

that the controller will perform many of the functions now supplied by

the host computer. As an example, the controller could supply the file

management function for converting mass memory to a virtual device.

This type of controller could also provide transfers between devices

without tying up the computer. [REGIS 77B]

Figure 2 shows the dollar value of disks shipped by U.S. manufacturers.

Source A and source B are both professional consulting services. Source

A's studies indicate a steady market growth for magnetic disks, reaching

2.85 billion dollars by 1980 and 3.77 billion dollars by 1985. On the

other hand, source B looked for more aggresive growth into 1979, peaking

at 2.7 billion dollars at that time. From there source B anticipates a decline, precipitated primarily by charge-coupled devices (and possibly

magnetic bubbles) making inroads into the peripheral memory market.

The wide acceptance of magnetic disks has necessitated the development

of several categories of standards. Those standards that have been

65
66
completed have proven beneficial to the user and the manufacturers.

Other standards development is in progress and is expected to continue

for the forseeable future.

2. Tape storage memory systems

a. Mass Tapes

The current trends and developments in 1.27cm magnetic tapes are as follows: [DIGID 771]

Minicomputer throughput rates increased in the last five years,

and tape-drive speed and throughput have kept pace.

Many minicomputers now provide 200 to 750 kilobytes per second

throughput rates, compared with 10 to 30 kilobytes per second five

years ago. But system throughput limitations still mandate tape

speeds in the 63.5 cmps (25ips) to 127 cmps (50ips) range for the

bulk of minicomputer applications.

Common 7-track tape drives are finding less application and now represent only about 3% of the total tape drive market. The trend

toward 9-track recording will make 7-track units more expensive

for future users who will require them. [DIGID 77i]

New tape drives primarily use phase encoded recording techniques

although some of the most recently introduced units offer com- binations of phase encoded and group coded recordings. This dual

capability allows designers to achieve simplified system

architecture

Future tape drives with 246 bpmm recording density, trading off

higher price for increased throughput and the greater reliability

that group code recording provides, are foreseen. All 246 bpmm

units will accommodate existing 63 bpmm formats.

A new tape medium similar to the 6.35 cm data cartridge of

a mass storage system could replace the 1.27 cm tape. The

industry is moving away from 1.27 cm tape as a primary backup

storage medium; however, 1.27 cm tape's demise lies far in

the future

Future transfer rates and format of the new tape medium will be

equivalent to and interchangeable with disk storage.

The number of installations of each on-line tape mass storage device

tells its own story. There are over 100 mass tape cartridge storage

systems with the 50 megabyte cartridge that have been installed and only

16 of the similar systems with 8 megabyte cartridge that have been

installed. Also, there are over 30 automatic tape library mass storage

systems (1.27 cm magnetic tape) compared to over 5 videotape mass storage systems. The era of mass storage systems (MSS) is just beginning.

Much work remains to be done by MSS suppliers, operating system designers, and application system designers to utilize the full potential

of MSS. The practical applications of MSS abound, and more will be

discovered as the technology matures. [HOWIH 76]

67
Figure 3. "U.S. OEM 1.27 cm tape drive market," shows the original

equipment manufacturer (OEM) value rather than the end-user value. This

projection shows the dramatic growth for the OEM tape drive market for

two types of tape drives: tension arm and vacuum column. Overall U.S.

tape drive unit shipments from 1975 projected to 1980 are 22,400 to

30,800 respectively. The major growth areas comprise miniperipheral

,

vacuum column drives. The advent of 246 bpmm drives will be felt in

this category. "Supermini" applications are expected to create demand

in this market for tape drives for disk backup. These applications will

require high transfer rates and 246 bpmm will be a desirable feature.

By 1980, more than 50% of the vacuum column tape drives' demand will

come from supermini applications. It is estimated that 10,000 to 12,000

of these tape drives will have 246 bpmm capability. [IDC 77]

Magnetic tape (1.27 cm), even though not suitable for random access applications, remains one of the most popular storage media. This main

shortcoming is offset by other versatilities and low cost.

Magnetic tape technology quietly continues to advance with new hardware,

higher density recording, and new tape packages.

The manufacturing of reel-to-reel tape drives is no longer a growth

industry. Caught between the random-access capability of disk drives on one side and the handling convenience of cassettes and cartridges on the

other, the tape drives seem to be just holding their market. [MINIC

76A]

The emergence and acceptance of high-capacity, relatively rapid, tape mass store memories are indications that tape systems have, and will

have a major impact on the future computer environment. Manufacturers

are confident that these systems will be in demand to meed the vastly

increasing data storage requirements. Since these systems are large,

they are likely to survive competition of any new technology currently

in view, and since the price per lot is extremely low, introduction of

standards for these types of mass tape storage devices has been

beneficial and should be continued in the future.

b. Cartridge

The current trends and developments in tape cartridges are as follows:

To improve storage capacity. The more data on each cartridge,

the more competitive the drives become with each other and with

other types of memory.

Most manufacturers believe that this tape medium has not reached

the theoretical capacity limit. Thus, manufacturers are still

working to increase bit density and the number of tracks on the

tape. The results of this development for a drive with even greater storage capacity may appear in the near future.

[DIGID 77G]

68
69
The number of cartridge tape drives that record data at the 126

bpmm density is increasing rapidly. In round numbers, 80% of the

machines sold record at 63 bpmm (1600 bpi) and 20% at 126 bpmm.

In 1978, the rates will change to 70% and 30% respectively.

[DIGID 77G]

A 252 bpmm density is theoretically possible. The extra expense

encountered in the more complex recorder/playback electronics

seems to work against this potential increase because increased

product volume has been lowering the price of drives and therefore

making higher-priced machines less attractive.

Cartridge limitations have kept tape speed for data transfer

unchanged at 76.2 cmps and 114.3 cmps. Speeds are not expected to

increase because increased tape speed does not improve the

transfer rate as much as an increase in bit density, although a 304.8 cmps rewind speed offered by manufacturers does help system

throughput. [DIGID 77G]

.

Mechanism problems in cartridge drives are gradually disappearing.

Currently, cartridge drives from different manufacturers are very

competitive in the area of reliability, more so than they were in

the past.

Some manufacturers of low-end cartridge drives will introduce

ECMA- and ANSI-compatible models to replace cassette drives in

the hobby computer market.

We conclude that significant increases in the total number of tracks and

flux transitions per millimeter plus various mechanical improvements are very likely within the next ten years although no drastic changes will occur soon. Standards are already being formed in cartridges and minicartridges. A continuing effort is recommended until such time as this

technology peaks out.

Minicartridge drives were introduced in early 1977.

Manufacturers are working on increased bit density drives for

minicartridges

.

Manufacturers will design and build militarized versions of their

minicartridge tape drives. Commercial units are said to offer

about 20,000 hours Mean-Time-Between-Failure (MTBF) . Manufacturers expect that the military models will experience about

40,000 hours MTBF due to the drive's inherent simplicity and

hence, reliability.

Minicartridge drives can compete successfully with the minifloppy

drives in many applications since they store more data per unit of

medium, consume less power, and occupy less space.

In Figure 4, "U.S. Tape Cartridge Drive Market," shows the end-user

market value projected by a professional research study. [CASWS 75B]

Several manufacturers believe that it will reach its peak between 1977

and 1978 and decline to a constant level. It is expected that the

floppy disk, with increased bit density and capacity, will capture some

of the tape cartridge market.

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c. Cassettes

The following are current trends and developments in cassettes:

Cassette drives are said to offer a greater reliability than

floppy disk drives. Buyer confidence in product capability and

quality rather than technological changes has boosted sales by

about 40% in 1977. [DIGID 77G]

Application of cassette drives in instruments and systems operating in a hostile environment will grow in 1978.

Growing in popularity, distributed processing systems with terminals at a large number of remote locations require buffer storage

and perhaps local program loading. These terminals will absorb a large number of cassette drives in 1978.

Manufacturers will offer ceramic heads for their cassette drives

in 1978. These heads will wear longer and prolong media life.

Increased cassette drive volume will allow manufacturers to use customized LSI chips in the electronics to improve reliability and

reduce costs to remain very competitive with floppy disk drives.

Minicassette drives are accepted as useful products for instrumentation and program loading applications that require low-cost,

low-power and small size storage units. This drive is used when

the application does not require a faster data transfer rate or

as much storage capacity as provided by full-size drives.

Manufacturers improved the minicassette package in 1977 by re- placing the pin guides with rollers. This change extended the ex- pected number of passes across the head by an order of magnitude

from about 200 to about 2000. [DIGID 77G]

Manufacturers will start offering built-in interface electronics

in their minicassette drives so the customers can connect the

drives to their CPUs.

Increased cassette drive volume will allow manufacturers to use customized LSI chips in the electronics to improve reliability and

reduce costs to remain very competitive with floppy disk drives.

Minicassette drives are accepted as useful products for instrumentation and program loading applications that require low-cost,

low-power and small size storage units. This drive is used when

the application does not require a faster data transfer rate or

as much storage capacity as provided by full-size drives.

Manufacturers improved the minicassette package in 1977 by re- placing the pin guides with rollers. This change extended the

expected number of passes across the head by an order of magnitude from about 200 to about 2000. [DIGID 77G]

Manufacturers will start offering built-in interface electronics

in their minicassette drives so the customers can connect the

drives to their CPUs.

Figure 5, "U.S. Cassette Drive Market," shows the end-user market value

projected by a professional research study group. [CASWS 75C] Cassette

design is a mature technology which has had a head start in minicomputer

applications. It is still growing in popularity.

72
73
Cassettes are not expected to improve as much as cartridges within the

next ten years. This technology appears to have matured and no drastic

changes are expected in the near future. Standards are already being

formed and will prove to be extremely beneficial for users--these standards should remain intact for reasonably long periods, while at the same time amendments of these standards will keep in reasonable pace with any

major changes in this technology.

d. Floppy disks

The current trends and developments in floppy disks are as follows:

Improved storage capacity in floppy disk drives would push prices

per bit down plus the fact that competition between Japanese and

U.S. manufacturers will probably force floppy prices even lower.

[DIGID 77G]

Two-sided recordings are being introduced.

Minifloppy drives are being introduced.

Manufacturers are increasing the use of LSI devices in their

products. [DIGID 77B]

Increased track density will become a reality in the 1980' s. It

may not first double but be incremental from 1.5 to 1.75 times its

1977 level. Some manufacturers believe that the next increase in

disk track density (or tracks per centimeter -- tpcm) will be from

the current 19 up to 38 tpcm's and possibly even up to 57 tpcm's.

[DIGID 77G]

Magnetic bubble memories will coexist with floppy drives in the

future. Since the drives use replaceable media that can implement

a library of information and bubble memories cannot, bubble memories will only displace floppies in a limited number of applications. By the 1980 's bubble memories will capture a segment of

the floppy market. Only when the manufacturers have learned to

produce low-cost pluggable bubble memories will these devices begin to replace floppy disk drives on a large scale. [DIGID 77G]

Development of a large capacity minifloppy drive by replacing the

usual 19 tpcm with 39 tpcm. The drives maintain their environmental tolerances within the temperature and humidity specifications of the oxide medium on a worst case basis.

Development of a two-sided minifloppy disk drive which will permit

storage of up to one megabyte of storage.

Figure 6, "U.S. Floppy Disk Drive Market," shows several projections of

the End-User market made by manufacturers and a professional research

study group. Line A shows that one of the leading manufacturers projects

a 70 million dollar floppy disk market by 1980. Plot B is in close

agreement with Plot A, and this prediction is made by one of the com- petitive manufacturers in the floppy disk market. Plot C is projected

by a professional research study group; they predict a 49 million

dollar market by 1980. Plot D is projected by one of th^ small manufacturers of floppy disk their estimate is close to that of source C.

74
75
The major growth in the use of floppy disks is in data entry systems,

but intelligent terminals and remote-batch applications are not far

behind. A professional research firm predicts that by 1980 terminals

will account for 23% of the total; 15% for data entry and 15% for point

of sale systems and 13% for peripherals for small computer systems.

Fewer will be used with programmable calculators and in word processing,

control, and test systems, in addition to the original use as a program

loader. [FRANP 75]

e. Summary graph of tape technologies

Figure 7, "Summary graph of U.S. Tape Cartridge, Cassette, Floppy Disk

and OEM 1.27 Cm Tape Drive Systems," shows the trends of the four media

markets. Plot C is the average of the plots A,B,C, and D of Figure 06.

In summary, several trends of development of small removeable media are

as follows: [SOLOL 75]

Keypunch sales, verifier sales and rental revenues will decline

throughout the decade.

Key-to-1.27 cm tape systems will decline due to technical obsolescence . Key-to-disk markets will grow as they take over the large scale

keyboard entry market.

Key-to-tape cassette or tape cartridge systems will be advantageous in very low-cost data collection applications. This

market will continue to expand in spite of competition from

the floppy disk.

The use of small business computers has grown substantially over the

last few years. In this market, cassette drives and floppy disk drives

constitute the favored storage media. Cassettes have the edge on cost

and storage capacity when compared to single density floppies but not

when compared to double density floppies; in any case, floppies exhibit

superior access times (see Table 17). Currently, cassettes find much

more extensive use than floppies. Floppies can be expected to make

increasing inroads, but cassettes will continue to expand in absolute

numbers, though they will decline in market share, through the 1980' s.

One of the major trends in data processing is. to capture data at the

source, rather than at some later keystroking station. Because it is

very costly to employ large amounts of keystroking labor, much data that

might be useful often gets ignored. Take, for example, the supermarket,

which takes its inventory by having stockpeople walking around the store

counting cans. This inventory could be automatically controlled if the

store knew which items passed the checkout. [SOLOL 75]

For this reason, it is expected that point-of-sale (POS) system markets

will grow very rapidly over the next three years. Furthermore, neither

cassette/cartridge drives nor floppy disk drives will play a role in POS

systems where many terminals are hooked up to a minicomputer in a store76
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wide system. They will be used in smaller systems and in systems where

each terminal operates independently.

Word processing - the composition, editing, and printing of text - uses magnetic cards, magnetic cassettes, or cartridges as its storage medium.

Floppy disks will play a major role in the next generation of word

processing systems because of their flexibility and storage capacity.

However, the inherently higher costs of the floppy disk insures the

continued use of cassette drives by independent manufacturers.

The floppy disk is the direct competitor to the cassette/cartridge.

Although the floppy disks incorporate essentially the same medium as magnetic tape, they are configured as flexible disks that resemble 45

rpm records and spin continuously.

Of all low-cost recording media, the floppy disks have impacted most

heavily on the cassette/cartridge market in minicomputer-based products.

Quick access time, about two orders of magnitude faster than a cas- sette's is its main feature. In data retrieval and erasure/replacement

of information, the floppy disk is superior to the cassette/cartridge

because it has a file structure. However, in remote data collection,

this feature is unimportant, so the terminal market for cassettes is

affected by floppies much less than the minicomputer-based market is.

Higher transfer rate is another feature of the floppy disk. [SOCOC 75]

The relationship of the floppy disk to the large, more expensive disk

drives parallels the relationship of cassettes/cartridges to the 1.27 cm magnetic tape drives. In the same way that certain applications dictate

a cassette/ cartridge drive instead of 1.27 cm tape, other applications

require floppy disk rather than large disk drives.

But where large computer systems use both disks and magnetic tape,

minicomputer systems commonly use either cassettes or floppies because

of cost factors. The medium selected depends on the user's application

and the relative merits of each device. [SOLOL 75]

There is very little direct competition betweeen cassette/cartridge and

1.27 cm magnetic computer tape. If the application calls for low cost,

small-size, maximum convenience and low maintenance, cassette/cartridge

is the answer. If it requires higher transfer rates and large storage

capacity, 1.27 cm tape is the medium of choice. The cassette/cartridge

is superior to 1.27 cm tape in convenience. Its medium is easy to load,

small, and easy to file. The drive size is much smaller than the 1.27 cm tape drive. Large tape drives require continued maintenance on a regular basis v;hereas cassette/cartridge drives require very little

care. [SOLOL 75]

Drive manufacturers will continue to improve their products by making

them store more data, while operating faster and more reliably than

ever; however, other nonmechanical technologies may begin displacing

them. [DIGID 77G] These displacements, by CCD's MB's (and maybe videodisks in some cases) could occur in the early 1980' s. 78
One of the immediate technologies that may displace the floppy disk

storage media of small systems are magnetic bubble memories. These

memories could displace electromechanical recording on magnetic media in

a large number of applications.

There is still a need for digital systems with a storage medium that

writes and reads at very high speeds, uses little power, occupies little

space - all at a very low cost per bit. An optical memory system seems

to be a potential solution to the storing of large amounts of data.

We conclude that floppies are still in the evolutionary stage of development and nonetheless these systems have become very popular in a short

period of time. Manufacturers are hesitant to make any long term projections of these new products, especially since this small disk technology appears to have future solid-state competitors.

Standards forming activities have been started in floppies and drafts

are currently being prepared. However, it is felt that, due to con- tinued rapid developments in this technology, standards will be formed

less rapidly than those for cassettes and cartridges. But, the effort

to follow up on standard setting of the floppy disk is warranted at this

time since these systems offer marked improvements over cassettes and

cartridges in many areas, and because of their anticipated wide use in

the computer environment.

3- Optical data storage memory system--Laser beam

The current trends and developments of laser mass memory systems are as follows: [GALOP 78]

New type of storage medium being developed as a slide with a measurement of 100 mm x 100 mm instead of the metal film strip.

This slide contains a metal alloy film sandwiched between two

glass or plastic sheets.

The capacity of this future medium is 10 billion bits per side.

It is equivalent to 87 reels of magnetic tape with 246 bpmm, 61

meters long, and 1.27 cm wide. There is a possibility of a double-side capacity of 20 billion bits.

The data information hole would be cratered instead of vaporized.

The size of the hole would be 1 micron instead of 3 microns.

Future system capacity of 10 billion to 1000 trillion bits would

be possible. A trillion bit storage device may occupy a volume

as small as a 76.2 cubic centimeters and may sell for as low as $40,000 in current dollars. [KACZE 77]

At this date, laser memories are still being developed and very few of

the laser mass memory systems have been installed.

This technology, although still in the developmental stage, should be

monitored as a possible future candidate for standards development. It

would be premature to begin standards work at this time because it is

79
possible that this technology will not be widely accepted by the com- puter community and not emerge as a viable peripheral memory device.

4. Solid-state peripheral memory systems

The following section provides an overview of developments and market

trends in solid-state memory technology as applied to peripheral memory.

The current trends in development of solid-state peripheral memory are identified as follows:

Increased capacity per chip, or module

Faster data access time

Faster transfer rate

More bit-storage per location (multiple bit per location in CCD)

Lower-power operation

Lower-voltage operation (to 1 volt)

Lower price per bit

More intelligence, or processing power with high-capacity/high

storage density chips, modules, or systems

Some of the drawbacks due to these improvements could be:

. Increased test difficulties in high-density components

This process should result in a lower bit price of system hardware

paired with faster availability of desired data. These trends are likely to continue into the 1980 's as is described by the following.

Manufacturers related to us that the basic solid-state chip, or module

characteristics, and consequently price per bit, are far from stabilized. In CCD's, the basic chip capacity is expected to jump from the

current 64 kilobits to 256 kilobits in 1979, to 1 megabit in 1982, and

to 4 megabits in the mid 80' s. System transfer rates are expected to

range from 5 to 10 megahertz, or higher (depending upon chip design)

while the price per bit is thought to end up at a few millicents per bit

by 1986. [GUIDM 78]

Existing system replacement by CCD systems is a strong trend. This means that CCD system manufacturers are aiming their new systems at

"old" and established design replacement such as fixed-head disks and

drums. Displacement of new disk memory systems might prove to be very

difficult (according to disk memory manufacturers) since these mechanical memories are still improving their characteristics and should

stave off solid-state memories like CCD's and others, as far as the late

80' s. [PUTHS 78]

Another introductory approach is the fast-access-memory (FAM) design.

This type of CCD system would fit into a memory niche, called the

"Access Gap," or the level of memory hierarchy where few or no systems

are currently residing. Systems that would fit in this niche should not

80
necessarily exhibit high capacities but should feature fast access times

and high transfer rates. [BHAND 78]

Since CCD's are fully expected to make inroads into the peripheral

memory market, this emerging technology should be watched closely in

anticipation of standards preparation. It is still too early to begin

standards development, but after determining the course current work

will take, standards making efforts should be initiated.

In MBs' current products are advertised at chip capacities of up to 92

kilobits manufacturers report that further developments will soon result

in the commercial availability of 256 kilobit and 1 megabit chips.

Transfer rates of hundreds of kilobits to one megabit per second should

accompany these developments

Some sources believe that the MB commercial system is a candidate for

replacing fixed-head disks and floppy disks later on. This potential

market is expected to reach 40 million dollars by 1983. However, at

this time MB memory technology is said to have made its best entrance in

military and space electronic systems, terminals, and telephony equipment. [HUH 78] [MINIC 78A]

Magnetic bubbles will probably be taking a course of development quite

similar to that of CCD's. As with CCD's, progress should be monitored

carefully. Not enough information is available yet for standards development, but efforts should be initiated if and when magnetic bubbles

establish themselves as peripheral memory devices.

MOS chip capacities are predicted to double each year through 1982--by

this time the chip capacity of the dynamic type is expected to reach 256

kilobits. Also access time and power dissipation are reported to be

improved accordingly. In peripheral memories, MOS will probably compete more with CCDs than with bubbles due to its inherent volatility and

other similar characteristics of these semiconductor memories. MOS is

expected to be priced 3 to 4 times more per bit per chip than CCD,

thereby, preempting MOS from entering into the computer peripheral

market except for special situations. [EARLJ 78] [BHAND 78]

Figures 8, 9, and 10 show the estimated memory market trends for CCD's,

MB's, and MOS memory systems. All these predictions do not necessarily

directly apply to computer peripheral memories but are related to, or display the potential to evolve into peripheral memories.

In Figure 8, curves A, F, and G were constructed from informatiou generated by "loose leaf information service" organizations. In other

curves, B,C,D, and E were constructed from information obtained from

interviews with manufacturers.

Most manufacturers felt that curves A and G (Source G predicts virtually

no market share by 1983) were not accurate and that the source for curve

F was too pessimestic. Information on curves B, C, D, and E were in81
82
dependently entered by the various manufacturers. Of these manufacturers, sources C, D, and E are said to form the largest part of semiconductor manufacturers in the U.S. These sources felt that the CCD

memory market would run between 100 and 200 million dollars in 1979 as shown in the Figure.

All sources except one (G) , felt that CCD's would do well in the early

80'sduring this time, sharply increasing market opportunities would

occur.

Estimated magnetic bubble memory market trends are suggested in Figure

9.

Points D and F are predictions made by two independent MB research

facilities. Neither of these provided enough information for plotting

complete curves. Both sources predicted about a 200 million dollar

market in either 1979 or 1980 as shown in the Figure. Both estimates

appear rather optimistic when compared with the rest of the curves.

Sources of curves A and B are major bubble research and development

facilities -- together they make up the largest part of MB manufacturers. Source B predicts about a 100 million dollar market in 1981

while source A feels that about a 200 million dollar market is more accurate

Sources E and C are "loose leaf information service" organizations.

Source E predicts that the market value of bubbles is somewhere between

the estimates of the two major manufacturers, or about 150 million

dollars by 1981. On the other hand, source C sees that magnetic bubble

memories will have virtually no market share by 1983.

Figure 10 shows the estimated MOS memory market trends through about

1980. Information for curves A and B were extracted from data gathered

by industry information specialists. Figures used to form plot A are manufacturers' estimates while plot B is generated by data from an independent information source. Sources for plots D and C are independent MOS manufacturers that were interviewed.

As in the previous graphs, the dotted portions of the curves are thought

to be the best continuations. These continuations are justified partly

by agreement with manufacturers or follow the general slope of the

existing plot.

With these assumptions in mind, it follows that sources B and C are approximately in agreement. Both show about a 300 million dollar market

for MOS in 1977. This figure is thought to double by 1979.

Sources A and D agree on a 600 million dollar market in mid 77. At this

time, source D felt that the MOS market could level off due to the

entrance of other, more advanced integrated circuit technologies. No

specific entrant was determined.

83
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85
Source A is the most optimistic. This information, transferred by MOS

manufacturers to an independent "loose leaf information service" organization, shows a billion dollar market in MOS by mid 1979.

Most of the MOS market was found not to be directed to the computer

peripheral memory market. Thus, the curves of Figure 76 apply mostly to

other computer memory applications such as mainframe memory or buffer

storage.

It is doubtful whether it will become necessary to develop standards for

MOS because little of the MOS market appears targeted for peripheral

memory. However, this technology should continue to be monitored in case

this condition changes.

5. Random-access magnetic memory systems -- core memories

The following section provides an overview of development and market

trends in core memory technology as applied to peripheral memory.

The current trends in development of large, core memory are identified

as follows:

Increased capacity of card or module

Faster data access time

More core elements per unit area in the core stack (smaller core elements)

Lower power operation

More use of LSI circuitry

Lower price per bit

More intelligence, or processing with high capacity/high storage

density cards, modules or systems

A reduced number of power supply voltages

A change from main memory application to other applications such

as peripheral mass memory

Some of the drawbacks that could influence these trends in improvements

are

:

Increasing fabrication difficulties of denser core stacks

Increasing software prices

Complex IC integration with core

One of the most important and successful memory devices is the ferrite

core. Magnetic thin films, plated wire, rod memories, waffle-iron memories: all of these technologies, at one time or another, were predicted to replace and displace core as the computers' most dominant main

memory element. None of these technologies appeared to have a significant effect on core; however, this trend changed when the integrated circuit appeared on the market. [KRUSG 75]

Thus, competition between IC and core manufacturers is resulting in the

pursuing and searching of similar design goals as can be seen when

86
comparing their listings of trends. As density, capacity, speed, and

complexity increases, both technologies will be required to resort to a substantial amount of on-site processing in order to electronically

respond quickly to the computer's commands and demands. This translates

into more software per bit in the near future for high capacity peripheral memory whether it be core, solid-state, or other -- a factor that

should be cleared up when considering these types of memories and that

should be discussed with manufacturers. Currently, most manufacturers

claim that their core mass memory products software is transparent when,

for example, core is installed instead of fixed head disk.

Core memory cards, or modules, formerly rated in 8 kilowords with 8 bits

per word (or 8 kilobyte modules) have constantly been growing. Today,

complete core memory boards of 131 kilobytes or 256 kilobyte modules,

and other designs, are commercially available. Progress is anticipated

to continue in this technology and most manufacturers of core feel that

it will never really disappear from the market although its growth rate

is said to be reduced. At this time at least three major core manufacturers are producing peripheral or bulk core memories. They all

expect to do well even though some IC manufacturers are expressing their

doubts

Trends indicate that the price per bit for core is losing out when core systems are small, or below 32 kilowords with 18 bits per word; but,

above this size and especially in the hundreds of kilobyte word range, we found that core is still priced lower.

Figure 11 shows the estimated market trends for core. All these predictions, or curves, do not only apply to peripheral core memory but are representative of the total core market. Specific figures for constructing curves on just peripheral memories for core were found not to be

available as yet.

Curves A [KRUSG 75] and C are predictions from semiconducter memory

manufacturers -- the figures for these curves were extracted from information obtained from open literature or private interviews. Sources

for curves B and D produce core or core/MOS memories and agree much with

sources A and C. Source E is an independent research source that also

agrees with the general thought of the previous sources.

All these sources, A, B, C, D, and E, claim that the core memory market

should drop below the 100 million dollar mark by 1982 -- or less than 10

percent of the estimated solid-state (MOS) memory market.

Sources F & G are major core memory manufacturers who felt that the

above views held by these other sources are entirely pessimistic -- these sources F & G claim that their shipments, and interest in their new designs by their customers, should result in at least double that

market, or 200 million dollars or more by 1982. Source F felt that the

1982 market could be as high as 250 million dollars a year. Both these

sources and others are investing large amounts of resources in these new

87
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88
products. Production assembly lines will be more and more computer

controlled, thereby perfecting fabrication to an even finer degree.

Such efforts can only point to the fact that many core manufacturers are confident that they can lower their prices even more and still be suc- cessful in competing with IC memories.

Although core memories are a mature technology, specific figures re- garding the number of installed peripheral core memories are not yet

available. Current indications are that there probably will not be a requirement for developing standards for peripheral core memories.

6. Alternate memory systems

a. Videodisk memory systems

This section provides an overview of development trends in optical

videodisk memory technology as it applies to future peripheral memory.

The current trends in development of optical videodisk peripheral memory

can be identified as follows: [KENVR 78], [KENG 77]

Ultra-high storage capacities (to a quadrillion bits)

Decreased block- random-access times (faster laser beam switching)

Faster transfer rates (wider bandwidth operation)

Extremely low-wear storage media (both when in use and when not in

use)

Extremely long-term, archival storage (from 10 to 100 years)

Increased ease of portability (to one trillion bits of portable

information)

Lower price per bit

Lower power dissipation per bit (in the ROM mode)

More intelligence, or processing with higher capacity systems

(such as microprocessor controlled functions)

A strong push towards error-free memory operation

Increasingly better signal-to-noise ratios

Increasingly smaller (in physical size) memory systems

Some of the hurdles that might be encountered in this developmental

process could be:

Slow market entry due to:

1. An apparent low number of involved manufacturers

2. A still maturing technolooy

3. Rotating media competition

Optical videodisk memory systems are not yet available. Most of the

above information, thus, refers to projections that are made by the few

manufacturers that are involved. However, commercial optical videodisk

playback systems are available and certain facts can be derived from

these systems since they bear similarity to the projected memory

systems

89
Optical videodisk players have been demonstrated to both commercial and

government interested parties. Program reproduction was what the producer said it would be -- better than the average television picture.

One disk can be played one half-hour on each side. The amount of ma- terial on each disk is calculated to be 18.6 billion bits unformatted

and 10.5 billion bits formatted. Added electronics are said to keep the

error rate to less than 1 bit per billion. Each picture frame has its own spiral track on the disk and each track has its own identification

number and can thereby be addressed. These features and others plus

demonstrations of this commercial system at various locations provide

high confidence that optical videodisk memories are very likely to soon

come into being.

Small samples of the commercial videodisk playback units are scheduled

for release in the midwest by the end of this year (1978) . This is the

market strategy by one manufacturer. No information was made available

when the videodisk memory would be released -- but it is thought that

much of the timetable on producing this type of memory will depend on

the acceptance of the commercial player and associated videodisk sales.

Because this technology is still in the developmental stage, it would be

premature to begin standards work at this time. This technology should

continue to be monitored in order to keep abreast of any significant

progress.

b. Beam addressable memory systems

This section provides an overview of development trends in electron beam

addressable memory technology as it applies to future peripheral memory.

The current trends in development of electron beam addressable peripheral memory can be identified as follows: [KELLJ 75], [SMITD 78],

[POSSG ND]

Improved random-access times (to better than 10 microseconds)

Improved transfer rates

Lower cost per bit

Higher capacity storage tubes (to 10 or 100 billion data" spots)

Increasing memory tube lifetime (to 16 years)

Higher system capacity

Reduction and simplification of overhead electronics (deflection

amplifiers, power supplies, etc.)

Improved long-term retentivity of stored data (improved data

protection methods)

Some of the obstacles that could be encountered in the developmental

process could be:

Slow market entry due to the following:

1. Apparent low number of involved manufacturers

2. Still maturing technology

90
Refresh and calibration routines of this memory system (similar to

preventive maintenance)

Prototype electron beam addressable memories have been operational with

computer systems in laboratory environments. These experiments have

been successful and several major computer manufacturers are currently

investing in these memories. The actual areas of application have not

been established but research and development trends indicate that the

following is feasible: [SPELD 75]

Computer peripheral mass memory

Fast auxiliary memory (access gap memory)

Main memory extension

Most computer manufacturers that were interviewed did not reveal or were

not exactly sure where the electron beam memory was going to fit in.

However, a small number of manufacturers feel that this memory is a natural in the fast auxiliary memory (FAM) application.

The low-cost, beam addressable FAM would operate as a nonvolatile interstaging memory with high capacity/high transfer rate characteristics.

This area of application is currently pretty much a void, -- and it seems likely that, judging by the activities of large computer manufacturers, this is the entrance portal for electron beam addressables

[WARM 77]

The main question still to be answered is -- when?

Electron beam memories are large when compared to solid-state memories

and not yet accepted when compared to disk memories. Solid-state manufacturers can "sense" the market acceptance of their parts, like MOS,

CCD, and MB, much easier since these parts are easy to handle, and

operate, and can be applied to numerous applications, either small or

big. Beam addressables do not enjoy this luxury. The major commitment

of one, or more, large computer manufacturers will determine the ac- ceptance of this technology [THEID 78] Thus, it could be that the en- trance of the beam addressable is a surprise announcement that could occur within the next five years.

Progress of the technology should continue to be monitored because this

technology is still in the developmental stage. Although it would be

premature to begin work on standards at this time, continued progress

may dictate development of standards.

IV. Summary and Overall Conclusions

A. A suinmary table of the various peripheral memory technologies

The following computer peripheral memory system comparison (Table 17)

provides a quick overview of how each technology compares with others in

terms of technical parameters, physical arrangements and price. All

values are typical.

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B. Conclusions

The following information is provided for the Federal computer manager

as decision aids when purchasing, upgrading or leasing computer systems.

In this report, the computer peripheral memory area is specifically

addressed and we feel that it would be beneficial for Federal computer

managers to consider the suggested approaches.

Approaches and suggestions are based on the information as presented in

this report and are supported by a variety of views from sources such as manufacturers of computer systems and components, other forecasters and

assessors, and private and Federal computer users.

Approaches and suggestions for choosing computer peripheral memory are presented in a series of decision trees as shown in Figure 12 through

Figure 26. These decision trees represent most of the possible choices

that can occur in the selection of peripheral memory hardware. Small

computers are defined here as anything from micro-processors, microcomputers, and most minicomputers up to medium size computers -- large

computers are those systems above this size category.

Guidelines are considered to be very general -- especially when new or emerging technologies, or those that are still seeking their market

niche, are involved. Mostly, choices that are provided in the Figures

are based on manufacturer's and user's suggestions and (projected)

machine capabilities as represented in this report.

Important considerations in the selection of computer peripheral memory

systems are as follows:

One especially important consideration is that final decisions of these

kinds could be based on values other than technical; for example,

established policies, economic factors, schedules, and personal preferences tend to play large roles in this process.

Also, any new memory technology must be at least as good as, or better

than existing memories in terms of reliability, error rates, maintenance

costs, initial price, etc., to be accepted -- and even then, manu- facturers and users of proven technologies such as magnetic disk, core,

and tape feel that their products will never completely disappear from

the market because of continuous efforts to improve these technologies

and simply because these systems have continued to survive for a long

time.

Another frequently overlooked consideration is that any new memory

subsystem must be fully developed in terms of hardware, software, interfacing, and fitting existing environments before users will consider

purchasing it and installing it. [THEID 78]

And finally, users indicate that the particular application that needs

to be filled most urgently might, and many times does become the most

weighty factor in this decision process.

95
As a rule of thumb, our guidelines mostly consider the equipment's cost/

performance factors and the timing in introducing the suggested peripheral memory systems. Many of the above-mentioned factors are left to

the reader for additional considerations as might apply in individual

circumstances.

The decision trees treat significant alterations of computer peripheral

memories in the following manner:

Upgrading

1. Large computer system

2. Small computer system

Purchasing

1. Large computer system

2. Small computer system

:. Leasing

1. Large computer system

2. Small computer system

Within each computer system, the following alterations are considered

most common:

Increase on-line capacity

Increase off-line capacity

Increase computer thruput via FAM memory

Replace all, or some, of the existing memory

No information has been gathered in this report on the leasing of com- puter memory systems -- leasing should always be considered as a viable

alternative to purchasing. This choice is presented because, in some

cases, leasing could be advantageous for reasons such as possible better

servicing, and economics.

In upgrading a large computer system. Federal computer managers should

look at the following possibilities: (see Figure 12)

Peripheral bulk core store

Magnetic disk (moving head - fixed media)

Tape mass storage systems

The independent bulk core store can help improve the accessibility of

data to a speed not currently realized via other contemporary systems -- manufacturers assure us that hardware, software, and other parameters

look like fixed-head disks and should be transparent to the system.

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Moving-head, fixed media disks are good candidates when just a moderate

increase in thruput and a relative higher storage capacity is required - all at a relative low price per bit. These systems have matured well

and are considered very reliable.

Tape mass storage systems, up to one terabit, are being installed at

many locations with apparently good success. When anticipating a very

large data base requirement consisting of many records, these systems

should prove to be a good choice. Several large manufactures are competing for a place in this market and many of these project that

their systems will become very popular as the amount of on-line stored

data becomes too great for conventional storage in the not too distant

future

.

Figure 13 shows that the best practice for storing off-line data on conventional large computer systems is still tape. Special mass storage

systems are currently available that will load and operate with off-theshelf reels in tape libraries, while another manufacturer might provide

its own type of reel that might be wider.

The costs for transferring data from one reel to another should be

discussed in detail with each manufacturer.

For increasing computer thruput (if system is input/output (I/O) bound),

fast auxiliary memories such as peripheral bulk core store or fixed-head

disk can be considered (see Figure 14) . Both systems will help improve

I/O transfer rates. The fixed-head disk and the core system, both

priced about the same per bit, differ much in characteristics as can be seen in the data of Table 17. If fixed-head disks exclusively now make

up the peripheral storage media, adding other disks might be considered

best for fulfilling the new requirement; therefore, not affecting an already well-operating system. Possibly one may also look at a drum. In

other situations, the bulk core system would probably do better and

would have a vastly greater impact on the computer thruput.

Figure 15 suggests a situation wherein the existing gear needs to be

replaced for reasons such as being worn out, being outdated, etc. The

choice of replacement in this case could, of course, be extremely application sensitive. If an entire tape library system is involved, the

automated tape mass storage systems should be considered.

For somewhat lower capacities but faster access time, moving-head disk

systems are still very economical. On the other hand, manufacturers of

bulk core store claim that their products would be more advantageous

than fixed-head, fixed media disk in this case. But, when comparing

these two systems core would be more costly. Possibly one may also look

at a drum.

When upgrading a small computer system, as shown in Figure 16, it is

assumed that peripheral storage capacity is generally moderate. This

assumption introduces entirely new candidates for on-line storage that

are usually priced lower.

98
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Peripheral bulk core could be considered but if a higher price is objectionable, and fast speed not needed, a floppy disk system might fit

in as well. These systems have matured rapidly and are said to enjoy

very good reliability at low price for both system and media.

Another consideration is magnetic disk, either a cartridge or movinghead magnetic disk system. A cartridge disk system would fit well with

a small computer system because of small storage capacity, but the

moving-head disk system would probably be more costef fective (see Table

17).

To increase off-line memory capacity of a small computer system, car- tridge, cassette, and floppy disk storage systems should be considered

(See Figure 17 for this decision tree). In cassette and cartridge

systems, several sizes of the storage media such as standard or minicartridges and standard or minicassettes are available. In general, the

cartridge checks out a little better as shown in Table 17 at about equal

price per bit. However, in comparison the cassette system appears to be

somewhat cheaper than the cartridge system.

If serial access is objectionable, the block-random accessed floppy disk

system should be considered. It is about 200 times faster and slightly

cheaper on a price per bit basis than the cassette or cartridge. Also,

the data transfer rate of the floppy is better, about 10 times, than the

serial tape units.

Figure 18 is the decision tree for increasing the thruput of a small

computer system via a fast auxiliary memory (FAM) . Two possible choices

are offered -- the peripheral bulk core store and the fixed-head disk

system. If fixed-head disks are already in use with the system and

moderate upgrading is required, another fixed-head disk (or possibly a drum) could be considered. If considerable improvements are required,

then the core system would be a better choice. Price per bit should be

about the same.

Replacement of existing peripheral memory systems can be very much

application dependent. Generally, replacement could be necessary due to

wearout, increased requirements, change of mission, outdated equipment

or other reasons. Replacement might not mean that equipment had to be

upgraded. Perhaps, identical performance is desired at better re- liability. There are various choices: (See Figure 19.)

Moving-head, fixed media disk

Floppy disk

Peripheral bulk core store

Cartridge disk

Magnetic bubble storage

For smaller capacities, consider floppy disks; and perhaps magnetic

bubbles for special applications in hazardous, or secure environments.

For larger capacities, look at moving-head disks and cartridge disks.

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For special cases, where improvements in transfer rates and access times

are requirements, the new peripheral bulk core stores should be good

candidates. For the best price per bit, moving-head, fixed media disks

are best, while the floppy disk system represents probably the cheaper

system. When purchasing a new, and perhaps yet to be designed computer

system, some of the following choices should be considered (See Figure

20).

Charge-coupled device

Magnetic disk (moving-head, fixed media)

Peripheral bulk core store

Tape mass storage

Laser mass memory

Optical videodisk memory (archival storage)

Charge-coupled devices are currently used as main memory extensions in new computer designs. This approach vastly increases the throughput of

the machine at a reasonable increase in cost since CCD's are relatively

low-cost memories when compared to conventional semiconductor random- access main memory.

For relatively low-cost, high capacity demands, moving-head disk mem- ories are still good economical candidates. Bulk core store will provide a faster, relatively low-capacity storage system for meeting more stringent requirements. If very high capacity requirements are anticipated, the terabit tape mass storage systems should adapt well to new

and future computers

For extremely high-capacity storage, two types of optical mechanical

mass store systems should be evaluated.

Laser

Optical videodisk mass store

Laser mass store memories of up to one terabit are commercially available now -- optical videodisks are not (yet) available. Both of these

read-only-memories (ROMs) store more information per unit volume than

other mass storage systems and are more economical than these systems.

Unlike soft magnetic records that can be easily erased, laser data is

hard and any attempt at alteration can be detected. Laser-recorded data

will not deteriorate or print through and is immune to electro-magnetic

radiation and computer power failures. [MDATA 76A] Videodisks (see

Table 17) are expected to have better memory operating characteristics

than certain other laser memories; it is anticipated that these disks

are targeted for archival storage applications. For future archival

applications, either one of these systems should be considered as viable

alternatives over tape archival systems.

Off-line storage requirements for future computer systems in the form of

archival, or read-only-memories, could be filled well by optical videodisk memories. The videodisk materials of these memories are very

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108
durable, rugged, and lend themselves to excellent portability. It would

be excellent for off-line archival record storage.

Tape mass storage, claim many tape manufacturers, will always be around

for future computers. And, it is very likely that videotape off-line

mass storage will always be good for the recording and playback of large

quantities of information. However, data retrieval will be slow and not

as reliable as future optical memories; but, as opposed to videodisks,

data can be erased. This could be an advantage or a disadvantage,

highly dependent upon the application. Generally, most computer users

feel that archival memories should not be erasable. The decision tree

for this choice is shown in Figure 21.

The choice of a fast auxiliary (FAM) memory for a large, new computer

system is shown in Figure 22. A strong candidate to consider, in this

case, is the electron beam addressable memory, or EBAM. A multiple tube

system of this type for a future computer system would feature high

capacity, nonvolatility , fast transfer rate, and fast access time, all

at a reasonable price per bit if a relatively high capacity system

(multiple tube) can be justified. This type of memory could improve the

throughput of a large computer very noticeably.

Fixed-head, fixed media disks will still be available, according to

their manufacturers, as another alternative. Possibly one may also look

at drum memory. However, most computer users and manufacturers of other

computer memories feel that these memories are on the decline in future

applications

When purchasing a small computer system, many choices in peripheral

memories are available (see Figure 23). It is assumed that a small

system does not need a vast peripheral memory capacity (although there

are exceptions to this) and that some of these systems display operating

characteristics such as fast access time, fast transfer rates, etc.

The choices are as follows:

Charge-coupled device FAM

Magnetic bubble device as nonvolatile special purpose mass storage

Floppy disk storage system

Peripheral bulk core store FAM or special purpose mass store

Moving head - fixed medium magnetic disk

Cartridge magnetic disk (small system)

Optical videodisk ROM mass store

According to users and manufacturers, two computer requirements are bound to increase. They are:

Memory capacity and data accessibility

System thruput

The use of CCD and bulk core store as part of the computer memory hierarchy can improve both of these capabilities at a potentially low-price

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112
increase to the system. CCD's can be designed as part of the mainframe

or can, like the bulk core, be applied as an "in-between" FAM memory.

Magnetic bubble mass store will outperform semiconductor and other

magnetic memories in environments that need to be kept secure or are inherently hazardous in terms of radiation, shock or other adverse

conditions. These memories are, therefore, also very useful in special

applications since they are said to display excellent physical and

electronic reliability.

Floppy disks can be used in areas where quick data entry of small

records is routine. Some designs also use these disks as on-line memories (usually in very small systems). Floppy disks are excellent

recordkeepers , and they are easily stored. The medium cost is very

attractive and, since system cost is also very reasonable, many applications should be shifted towards the floppy.

For larger and faster (and more expensive) on-line storage, moving-head,

fixed medium disks and the lower capacity (but cheaper) cartridge disk

systems are good candidates for future, small computer systems. These

units can be staged through the previously mentioned FAMs (CCD and bulk

core store) for forming a fast 1/0 transfer peripheral system.

Optical videodisk memories of the future should lend themselves very

easily to both large and small computer systems. This is said to be so since video disk memories are relatively easy to operate and since their

volumetric memory efficiency is excellent (one terabit is said to be

portable). Of course, this would be a read-only application. When

deciding on videodisks, one should remember that, even though these

systems are ROMs, R/W operations can still be performed for many applications. For example, in recordkeeping and updating, enough "freespace" writing area can be allowed to satisfy the bookkeeping of most

records. And since the medium is cheap, takes up little space and does

not wear, old records can be kept on-line virtually indefinitely at

little or no extra cost. Of course, it must be kept in mind that a REWRITE over already written data is not possible in this technology, as yet.

Figure 24 shows some of the possibilities that exist for choosing offline storage for a new, small computer system design. The choices are

as follows:

Cartridge, cassette, and floppy disk

Magnetic bubble device (special off-line recorder)

Optical videodisk read-only memory system

The main off-line storage in most minicomputers will be on cartridges,

cassettes, and floppy disks.

Magnetic bubbles could, according to some forecasters and MB manufacturers, compete and be used as fast solid-state floppy disk substitutes in special applications.

113
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optical videodisk memories, when available, will offer a significant

off-line storage back-up to the small computer system. Their vast

data storage capacity, portability, ruggedness, and fast access should

make these memories particularly useful in applications such as video

recordkeeping, digital storage, education, training, graphics, and

equipment manual data presentations.

Figure 25 is the decision tree for choosing which peripheral memory

system might serve best as a fast auxiliary memory in an effort to

increase the system 1/0 thruput. The choices presented are:

Charge-coupled device

Magnetic bubble device (advanced, high-speed designs)

Peripheral bulk core store

Fixed head - fixed medium disk or possibly also a magnetic

drum (in special applications)

Of these choices, it is anticipated that CCDs and peripheral bulk cores will be the better developed systems -- their speed, system size, power

consumption and, hopefully, economics will make them quite attractive in

this application.

Magnetic bubble memories will find their place first in special applications as auxiliary memories -- and as their speed, price and designs mature, they will start to compete with the magnetic disk memory

systems in the near future.

Fixed-head, fixed medium disks might be used in very special applications, but it is anticipated that the demand for these units in this

particular application, as well as others, will diminish rapidly in the near future.

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[DATPR 77B] Datapro reports on Minicomputers. Advanced Electronics

Design AED2200; Delran, NJ; 1977 Datapro Research Corporation;

1977 October; M13-100-209 (Update Reference Source).

[DATPR 77C] Datapro reports on Minicomputers. Control Data 9427H;

Delran, NJ; 1977 Datapro Research Corporation; 1977 October;

M13-100-215 (Update Reference Source).

[DATPR 77E] Datapro reports on Minicomputers. Diablo Model 31; Delran,

NJ; 1977 Datapro Research Corporation; 1977 October; M13-100-221

(Update Reference Source)

[DATPR 77F] Datapro reports on Minicomputers. Minicomputer Disk

Storage; Delran, NJ; 1977 Datapro Research Corporation; 1977

October; M13-100-225, M13-100-228, M13-100-242 (Update

Reference Source)

[DATPR 770] Datapro reports on Minicomputers. Pertec D3311; Delran,

NJ; 1977 Datapro Research Corporation; 1977 October; M13-100-235

(Update Reference Source).

[DATPR 74] Datapro 70 the EDP Buyer's Bible. IBM system/360 Model

22-195: Delran, NJ: 1974 Datapro Research Corporation; 1974

January; 70C-491-03e to 70C-491-03g, 70C-49]-05h. (Updated

Reference Source).

[DATPR 75] Datapro 70 The EDP Buyer's Bible. Control Data 38500 Mass

Storage System; Delran, NJ; 1975 Datapro Research Corporation;

1975 September; 70D-263-21a to 70D-263-21d. (Updated Reference

Source)

[DATPR 76] Datapro 70 the EDP Buyer's Bible. IBM System/370; Delran,

NJ; 1976 Datapro Research Corporation; 1976 April; 70C-491-04x,

70C-491-04y. (Updated Reference Source).

121
[DATPR 77A] Datapro 70 The EDP Buyer's Bible. Control Data Cyber 170

Series; Delran, NJ; 1977 Datapro Research Corporation; 1977 June;

70C-263-12h to 70C-263-12i, 70C-263-12u. (Updated Reference

Source)

[DATPR 77B] Datapro 70 the EDP Buyer's Bible. IBM System/370; Delran,

NJ; 1977 Datapro Research Corporation; 1977 April; 70C-491-04w to

70C-491-04x. (Updated Reference Source).

[DATPR 77C] Datapro 70 The EDP Buyer's Bible. UNIVAC 1100 Series;

Delran, NJ; 1977 Datapro Research Corporation; 1977 January;

70C-877-lla to 70C-877-llgg. (Updated Reference Source).

[DATQS 76] Electronic Memories: Charge Coupled Devices and Magnetic

Bubble Devices. Dataquest Research Newsletter. 1976

November 5; 1-7.

[DATQS 77] MOS Memory - 4K Shipments. Dataquest Research Newsletter.

1977 March 25: 1-5 p.

[DATQS 78] MOS Memory - 4K and 16K Shipments. Dataquest Research

Newsletter. 1978 February 3: 1-6 p.

[DATRM NDA] Dataram Corporation. Add-in Memory for PDP-8/E,F and M.

Cranbury, NJ; [n.d.]. [2 p.].

[DATRM NDB] Dataram Corporation. Add-in Memory for Varian V70 Series.

Cranbury, NJ; [n.d.]. [2 p.].

[DATRM NDC] Dataram Corporation. Add-on/Add-in Memory for DEC PDP-11.

Cranbury, NJ; [n.d.]. [2 p.].

[DATRM NDD] Dataram Corporation. Add-on Add-in Mini-Memory, Cranbury,

NJ; [n.d.]. [1 p.].

[DATRM NDE] Dataram Corporation. Bulk core. Consider the implication

of this perspective twisting new product from Dataram Corporation.

Cranbury, NJ; [n.d. ] . [1 p. ]

.

[DATRM NDF] Dataram Corporation. Bulk Core Replacement for Data

General Novadisc. Cranbury, NJ; [n.d.]. [2 p.].

[DATRM NDG] Dataram Corporation. Bulk Core Replacement for DEC RC-11

and RF-11 Fixed-head disk systems. Cranbury, NJ; [n.d.]. [2 p.].

[DATRM NDH] Dataram Corporation. The DR-100 Family core memory

systems. Cranbury, NJ; [n.d.]. [6 p.].

[DATRM NDI] Dataram Corporation. Interdata-compatible Add-in Memory.

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122
[DATRM NDJ] Dataram Corporation. A New high in storage capability - bulk core. Cranbury, NJ; [n.d.]. [8 p.].

[DATRM NDK] Dataram Corporation. Nova-Compatible Add-in Memory.

Cranbury, NJ; [n.d.]. [2 p.].

[DATRM NDL] Dataram Corporation. Replace Fixed-Head Disc with Dataram

Bulk Core. Cranbury, NJ; [n.d.]. [] p.].

[DATRM NDM] Dataram Corporation. IK to 32K Bytes Microprocessor Core

Memory. Cranbury, NJ; [n.d.]. [2 p.].

[DAVIP 76] Davies, Paul. Disk Cartridge Driver. Modern Data. 1976

January; 9(1): 44, 45.

[DAVIS 74] Davis, Sidney. Update on Magnetic Tape Memories. Computer

Design. 1974 August; 13(8): 127-138.

[DIGID 75A] Electron Beam Memory Stores 32M Bits. Digital Design.

1975 June; 5(6): 15-18.

[DIGID 75B] Hard-disk drives. Digital Design. 1975 December. 15(12)

59.

[DIGID 76A] Cart/Cassette Drives. Digital Design. 1976 January; 6(1)

67.

[DIGID 76B] Moving-head Disks at Performance Plateau? Digital Design.

1976 June; 6(6): 16-18.

[DIGID 77A] With Help From Dual Microprocessors, Carousel Accesses 16

3M-type Cartridges. Digital Design. 1977 April; 7(4): 10-11.

[DIGID 77B] Bubbles debut in phone system announcer. Digital Design.

1977 May; 7(5): 22.

[DIGID 77C] Magnetic bubble memories. Digital Design. 1977 May; 7(5)

50-64.

[DIGID 77D] Minifloppy disk drive more than triples its capacity by

using 77 tracks. Digital Design. 1977 May; 7(5): 82.

[DIGID 77E] Small double-sided double density disk. Digital Design.

1977 August; 7(9): 19.

[DIGID 77F] Technology Trends: Floppy Drive Innovations: Challenging

Hard Disks. Digital Design. 1977 November; 7(11): 8, 10.

[DIGID 77G] Cartridge and Cassette Drives. Digital Design. 1977

December; 7(12): 58-59.

123
[DIGID 77H] Rigid and Floppy Disk Drives. Digital Design. 1977

December; 7(12): 68, 72.

[DIGID 771] Tape speed is up, but most systems need slow units.

Digital Design. 1977 March; 7(3): 16.

[DORIL 76] Dorie, Larry A. Floppy disks the lowcost storage medium of

the 70' s. Data Management. 76 January; 14(1): 6-8.

[EARLJ 78] Early, James M. S. VLSI Technology. Spring Compcon 78

Sixteenth IEEE Computer Society International Conference: 1978

February 28-March 3: San Francisco, CA. New York: IEEE Computer

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[EDN 77] Second generation minifloppy increases storage capacity by a factor of four. EDN. 1977 February 20; 22(4): 126.

[EDPI 74] EDP Industry Report. IBM 3850, NEE "OAK," Provides 472

Billion Bytes; Mass Storage Device Applies Virtual Storage

Concept to 330; Newtonville, MA. International Data Corporation;

1974 October 17.

[EDPI 76] EDP Industry Report. IBM 3850 Shipments and Shakedowns

Start to Roll Almost a Third of Large 370 Sites Expected to

Install by 1978; Newtonville, MA. International Data Corporation;

1976 March 12.

[EETIM 78] Bubble Memories Are Applied in Air Force Avionics.

Electronic Engineering Times. 1978 March 20; 125: 4.

[ELECN 74] See Floppy Disks Unprofitable Till '76. Electronic News.

1974 December 2: 43.

[ELECN 75] Floppy Disk Seen Firming in Second Half. Electronic News.

1975 May; 19: 51.

[ELECN 77A] Amperif Offers CCD Memory. Electronic News. 1977 January

10: 42.

[ELECN 77B] Tape Drives Emerge From Shadow of Disk Growth. Electronic

News. 1977 October; 3: 47.

[ELECT 76A] Data Handling: Floppy Disk in Miniature. Electronics.

1976 September 30; 49(20): 116.

[ELECT 76B] Prototype System Available From Rockwell. Electronics.

1976 September 30; 49(20): 19.

[ELECT 77A] Bubble Memory Gets NASA Check for Use in Space.

Electronics. 1977 January 6; 50(1): 31-32.

124
[ELECT 77B] Microprocessoos , Memories Dominate Digital Sessions.

Electronics. 1977 February 17; 50(4): 82-85.

[ELECT 77C] Tl Raises Curtain on Its 65-K RAM. Electronics. 1977

April 14; 50(8): 49-50.

[ELECT 77D] Five Technologies Squeezing more Performance From LSI

Chips. Electronics. 1977 August 18; 50(17): 92, 93.

[ELECT 77E] Two Heads Give Minifloppy On-Line 0.4 Megabyte Store.

Electronics. 1977 November 24; 50(24): 41-42.

[EMM ND] Electronic Memories and Magnetics Corporation. Technical

Manual Micromemory 3000 Memory System. Hawthorne, CA:

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[EXCEL 76] Ex-Cell-0 Corporation (REMEX) , Flexible Disk Drives: Data

Sheet RFD 1000 Specification and Interface. Irvine, CA; 1976. [6

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[FARMV 75] Farmer, Vic. CDC 38500 Mass Storage System For Big 370s

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[FETHG 76] Feth, George. Technology Trends: Moving-Head Disks at

Performance Plateau. Digital Design. 1976 June; 6(6):

16, 18.

[FLORI 75] Flores, Ivan. The Drum. Peripheral Devices. Englewood

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[FRANP 75] Franson, Paul. Floppy Disks Spin Into Systems.

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[FRASJ 75] Eraser, Jack. Disk and Tape-Mass Storage Moves in.

Electronic News. 1975 June 23; 20(1033): 1, 38-39.

[FRASJ 76] Eraser, Jack; Rosenberg, Ron. Interest Rising in Small

Diskette Market; Product Studies Under Way. Electronic News.

1976 September 13; 21(1097): 40.

[FRASJ 77] Eraser, Jack. Tape Drives Business Enjoying Quiet Revival,

Electronic News. 1977 October 3; 22(1152) 41, 46-47.

[FREEJ 77] Free, John. Here at last--disc players.' Popular Science.

1977 February; 210(2): 85-87, 140.

[GALUG 76] Galusha, Gary. Floppy disks: an update. Data Management,

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[CELLS 74] Geller, Sidney B. Archival Data Storage. Datamation.

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[CELLS 76] Geller, Sidney B. Erasing Myths About Magnetic Media.

Datamation, 1976 March; 22(3): 65-68.

[GENEL ND] General Electric Company. BEAMOS (Beam-Addressed Metal

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[GILDJ 75] Gilder, Jules H. Mass Memories raising speed, dropping cost

and storing billions of bytes. Electronic Design. 1975 October

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[GROSR 76] Grossman, Robert M. "Micro" peripherals - moving to meet

the microcomputer challenge. EDN. 1976 February 5; 21(3):

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[GUIDM 78] Guidry, Mark R. Charge Coupled Device Digital Memory - A

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International Conference; 1978 February 28-March 2; San Francisco,

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[HAUFK 75] Haughton, Kenneth E. An Overview of Disk Storage Systems.

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[HERBJ 76] Herbert, John P. Memory Prices Seen Dropping 40%/Year Until

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[HILLP 77] Hille, Peter F. ; Holder, Carl. Avoiding Defective

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[HNATE 77] Hnatek, Eugene R. A. User's Handbook of Semiconductor

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[HOAGO 72] Hoagland, Alberts. Mass Storage - Past, Present and Future.

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[HOBBL 76] Hobbs, L. C. Low-Cost Tape Devices. Computer. 1976 March;

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[HOWIH 76] Howie, H. Robert, Jr. More Practical Applications of

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[HUGHW 75] Hughes, William C, et. al. A Semiconductor Non-volatile

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[HUH 78] Hu, H. L. Bubbles--A New Magnetic Solid-State Technology.

Spring Compcon 78 Sixteenth IEEE Computer Society International

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[HUNTF 54] Hunt, Frederick V. Electroacoustics : The Analysis of

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[IDC 77] International Data Corporation Planning Service. OEM Storage

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[KACZE 77] Kaczorowski, Edward M. Optical Mass Storage. Spring

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[KALSD 76] Kalstrom, David J. Simple Encoding Schemes Double Capacity

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[KASHK 77] Kashkooli, Fred. MOS New Product Presentation. 1977

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[KATZB 77] Katziue, Bob. Matching Magnetic Media With Modern Machines.

Digital Design. 1977 June; 7(5): 20-34.

[KATZH 74] Katzan, Harry. Information Technology; the Human Use of

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[KELLJ 75] Kelly, John. The Development of an Experimental

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[KENVR 78] Kenville, Richard F. Optical Video Disc for Digital Mass

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[KINGG 77] King, George. Cassette, Cartridge and Diskette Drives.

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[KINNP 77] Kinnucan, Paul. A New Use for Core Memory. Mini-Micro

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[KRIER 76] Kriegler, Rudolph J. Recent Advances in MOS Technology.

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[KRUSG 75] Kruschke, Gene. Memories Core and Semicon: Prices to Fall,

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[KURTA 77] Kurtzig, Arnie. Thin Film Heads for High Performance Disk

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[LEAVD 77] Leavitt, Don; Bubble Device Put to the Test. Computerworld

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1977 February 7; 11(6): 1, 5.

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[MANLA 77A] Manildi, A. Bruce. Cassettes, A Mature Mass Memory for

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[MANLA 77C] Manildi, A. Bruce. Inexpensive Digital Storage Media:

Cassettes, Discs and Cartridges all have advantages. Let the

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1976 December 6; 24(25): 86-88.

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[MARTR 74] Martin, R. R. ; Frankel, H. D. Forecast of Computer Memory

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[MASSD 77] Massaro, Donald J. Advent of the Minifloppy (TM) . Spring

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[MDATA 75A] A Cassette Competitor is Born. Modern Data. 1975 August;

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[MDATA 75B] Semiconductor Memories as Seen from Wall Street. Modern

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[MDATA 75C] Peripherals Make the Mini. Modern Data. 1975 December;

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[MDATA 76A] Laser Mass Memory for Sensitive Agencies. Modern Data.

1976 February; 9(2): 10.

[MDATA 76B] The HP 9825A. Modern Data. 1976 March. 9(3): 52.

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[MINIC 76B] Minifloppy Offers Random Access in a Cassette Drive Sized

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[MINIM 76A] Memory Movements. Mini-Micro System. 1976 August; 9(8):

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[MINIC 76A] Tape Drive Technology Still Quietly Advancing.

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[MINIM 76B] A New Disk Head Develops. Mini-Micro Systems. 1976

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[MINIM 76C] A Mini Floppy for Micros. Mini-Micro Systems. 1976

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[PERPH 76] Intel Introduces Single Board Display Memory System.

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[SHUGA 77A] Shugart Associates. SA800/801 Diskette Storage Drive OEM

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May 19-22; Anaheim, CA. Montvale, NJ; cl975: 501-508.

[SPRAH 64] Spratt, Hector G. M. Magnetic Tape Recording. Toronto, New

York, London: D. Van Nostrand Company, Inc.; 1964: 123-151 p.

[STEWW 58] Stewart, W. Earl. Magnetic Recording Technique. New York,

Toronto, London: McGraw-Hill Book Company, Inc.; 1958. 128 p.

[STODD 75] Stoddard, David L. Lower Cost in Near Future. Aim of

Floppy Developers. Computerworld. 1975 April 9: 35.

[STORA ND] Storage Technology Corporation. STC 8000 Series Disk

Subsystems. Louisville, CO; [n.d.]. [6 p.].

[STRIA 77] Stricklin, Alan. A Videodisc for Education and Industry.

Videography. 1977 February. 2(2): 28-29.

[SURDE 77] Surdan, Esther. Memory for DG Novas Ampex Unit Replaces

Fixed-Head Disks. Computerworld. 1977 January 31; 11(5): 43.

[TASCA 76] Tasch, Al F. ; Frye, C. Robert; Fu, Horng-Sen. The ChargeCoupled RAM cell Concept. IEEE Transaction Electron Devices.

1976 February; ED-23: 126-131.

133
[TEXAS NDA] Texas Instruments Incorporated Semiconductor Group.

Magnetic Bubble Memories and System Interface Circuits from

Texas Instruments. Dallas, TX: Texas Instruments Incorporated;

1977 February. 62 p.

[TEXAS NDB] Texas Instruments. Product Announcement New "Silent 700"

Model 763/765 Memory Terminal. Houston, TX; [n.d.]. [4 p.].

[THEID 78] Theis, Douglas J. An Overview of Memory Technologies.

Datamation. 1978 January; 24(1): 113-131.

[THURR 76] Thuras, Rodger D. New Magnetic Materials Help Core Memories

Stay Alive. Computer Design. 1976 July; 15(7): 100-102.

[TURNR 74] Turn, Rein. Computers in the 1980s. New York, London:

Columbia University Press; 1974: 196-201.

[UPTOM 75A] Upton, Molly. Shugart Expects 1976 Sales to Climb to $9

Million. Computerworld . 1975 November 19: 51.

[UPTOM 75B] Upton, Molly. Venture Predictions Realistic: Vendors Say

Floppy Business Picking Up. Computerworld. 1975 August 27:

33-34.

[VADAL 71] Vadasz, L. L. ; Chua, H. T. ; Grove, A. S. Semiconductor

Random-Accesss Memories. IEEE Spectrum. 1971 May; 8: 40-48.

[VAUGF 77] Vaughan, Frank. Burroughs Unveils "Supercomputer" with

Array Design. Computerworld. 1977 April 11: 39.

[VITTJ 75] Vittera, Jim. Nonvolatile microprocessor Memory Uses 4K n- Channel MOS RAMs. EDN. 1975 April 20; 20(8): 53-56.

[VORNL 71] Vornerin, Lawrence J. Approaches for Making Bubble Domain

Materials. IEEE Transactions on Magnetics. 1971 September; 7: 404-409.

[WAGC ND] Wangco, Inc. Wangco Micro-Floppy Model 82. Los Angeles, CA;

[n.d.]. [2 p.].

[WARNR 77A] Warnar, Robert B. J.; Calomeris, Peter J. Foreign and

Domestic Accomplishments in Magnetic Bubble Device Technology.

Computer Science and Technology. 1977 January; Nat. Bur. Stand.

(U.S.) Spec. Publ. 500-1, CODEN: NBSAV.

[WARNAR 77B] Warnar, Robert B. J. (Interviewer). Phone Interview with

CCD Memory Manufacturer. 1977 March 21. 7 p.

[WARNR 77C] Warnar, Robert B. J. (Interviewer). Phone Interview with

CCD Memory Manufacturer. 1977 March 22. 7 p.

134
[WARNR 77D] Warnar, Robert B. J. (Interview). Interview with MOS

Manufacturer. 1977 March 23.

[WARNR 77E] Interviewer). Phone Interview with CCD Memory

Manufacturer. 1977 March 23. 7 p.

[WARNR 77F] Warnar, Robert B. J. (Interviewer). Phone Interview with

Magnetic Bubble Manufacturer. 1977 March 24. 7 p.

[WARNR 77G] Warnar, Robert B. J.; Calomeris, Peter J. (Interviewers).

Interview with MOS Memory Manufacturer. 1977 March 25 and April 1.

7 p.

[WARNR 77H] Warnar, Robert B. J. (Interviewer). Interview with Core

Memory Manufacturer. 1977 March 28. 7 p.

[WARNR 771] Warnar, Robert B. J.; Calomeris, Peter J. Interview with

Core Manufacturer. 1977 March 30. 7 p.

[WARNR 77J] Warnar, Robert B. J. Impact of Charge Transfer Device

Technology on Computer System. Computer Science and Technology.

1977 April; Nat. Bur. Stand. (U.S.), Spec. Publ. 5005. Coden:

XNBSAV

[WARNR 77K] Warnar, Robert B. J. (Interviewer). Phone interview with

Core Memory Manufacturer. 1977 May 14. p 7.

[WARNR 77L] Warnar, B. J. (Interviewer). Phone Interview with CCD

Memory Manufacturer. 1977 May 23. 7 p.

[WARNE 77M] Warnar, Robert B. J. (Interviewer). Interview with Core

Memory Manufacturer. 1977 May 24. 7 p.

[WARNR 77N] Warnar, Robert B. J. (Interviewer). Phone Interview with

Core Memory Manufacturer. 1977 May 24. 7 p.

[WARNR 770] Warnar, Robert B. J. (Interviewer). Interview with

Magnetic Bubble Memory Manufacturer. 1977 May 25. 7 p.

[WARNR 77P] Warnar, Robert B. J. (Interviewer). Phone Interview with

Core Memory Manufacturer. 1977 May 26.- 7 p.

[WARNR 77Q] Warnar, Robert B. J. (Interviewer). Phone interview with

Magnetic Bubble Manufacturer. 1977 May 26. 7 p.

[WARNR 77R] Warnar, Robert B. J. (Interviewer). Phone Interview with

Core Memory Manufacturer. 1977 May 27. 7 p.

[WARNR 77S] Warnar, Robert B. J.; Calomeris, Peter J. Technology

Assessment of Computer Memories. Dimensions. 1977 August; 61(8):

24-26.

135
[WARNR 77T] Warnar, Robert B. J. (Interviewer). Phone Interview with

EBAM Memory Manufacturer. 1977 August 18.

[WARNR 77U] Warnar, Robert B. J. (Interviewer). Interview with Core

Memory Manufacturer. 1977 September 21. 7 p.

[WARNR 77V] Warnar, Robert B. J. (Interviewer). Interview with Bulk

Core Memory Manufacturer. 1977 September 7. 7 p.

[WEITC 70] Weitzman, Cay. Optical Technologies for Future Computer

System. Computer Design. 1970 April: 169-175.

[WILDM 75] Wildmann, Manfred. Terabit Memory Systems: A Design

History. Proceedings of the IEEE. 1975 August; 63(8):

1160-1165.

[WORLE 75] Worley, Ernest. Core Memory State-of-the-Art . Modern Data

1975 August; 8(8): 54.

[YPMAJ 75] Ypma, J. E.; Gergis, I. S.; Archer, J. L. 64K Fast Access

Chip Design. Anaheim, CA; Rockwell International; 1975 December 1 Annual Conference on Magnetism and Magnetic Materials Presentation

8 p.

136
M3S-114A (REV. 8-78)

U.S. DEPT. OF COMM. aim if\n.o A QUiC data

SHEET

1. PUBLICATION OR REPORT NO. 2.00/1 Accession No. 5. R^ciptBJit's Acctjsioff No, NBS SP 500-45

4 TITLE II AND r^llw SUBTITLE ^ III

COMPUTER SCIENCES & TECHNOLOGY:

COMPUTER PERIPHERAL MEMORY SYSTEM FORECAST

5. Publication Date A^ril 1979

(. Performing Organization Code

7. AUTHOR(S)

Robert B. J. Warnar, Peter J. Calomeris, and Steve A. Recicar

8. Performing Organ. Report No. 650

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

10. Prolect/Task/Work iJnft No.

11. Contract/Grant No.

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS fSfre©*, aty, state, ZIP)

1 Same as Item 9

13. Type of Report & Period Covered Final through iy/o

14. Sponsoring Agency Code

' 15. SUPPLEMENTARY NOTES

this forecast covers thirteen peripheral memory technologies.

Library of Congress Catalog Card Number: 79-600036o

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

16. ABSTRACT (A 200-vrord or leaa [actual summary ol moat significant information. If document includes a significant bibliography or

literature survey, merition it here.) This document describes and forecasts computer peripheral memory

technologies as displayed by U.S. research and manufacturing

facilities. Specifically, both technical and economic criteria are discussed. The presented peripheral memories include contemporary

and emerging systems, all of which are compared in graphs, tables,

and decision trees. The document contains an extensive bibliography

(in ANSI format) to support certain main points that are supplemented

by information supplied by the Institute for Computer Scieaces and

Technology (ICST) resources. Additional information and verification

was received from private interviews with various U.S. technical

experts and equipment manufacturers.

C'.

KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name;

separated by semicolons)

eam-addressables; cartridges; cassettes; core memories; disks; drums; floppy disks;

laser beams; magnetic bubbles; masstapes; solid state memories; video disks.

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