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EK-RP04-OP-001

November 1976

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Document:	RP04 Device Control Logic User's Manual
Order Number:	EK-RP04-OP
Revision:	001
Pages:	25
Original Filename:

OCR Text

RP0O4 dev iICé
(&) o o 3= S 0 O O =
user ‘s manual

digital equipment corporation - mcgnard, massachusetts

RPO4 device
control logic
user's manual

EK-RP04-OP-001

digital equipment corporation - maynard, massachusetts

Ist Edition, November 1976

DISCLAIMER

Removable media involve use, handling and maintenance which are beyond DEC’s direct
control. DEC disclaims responsibility for performance of the Equipment when operated

with media not meeting DEC specifications or with media not maintained in accordance
with procedures approved by DEC. DEC shall not be liable for damages to the Equipment
or to media resulting from such operation.

The material in this manual is for informational
purposes and is subject to change without notice.

Digital Equipment Corporation assumes no responsibility for any errors which may appear in this
manual.
Printed in U.S.A.

This document was set on DIGITAL’s DECset-8000
computerized typesetting system.

The following are trademarks of Digital Equipment
Corporation, Maynard, Massachusetts:
DEC

DECtape

DECCOMM

DECUS

RSTS

DIGITAL

TYPESET-8

DECsystem-10
DECSYSTEM-20

MASSBUS

PDP

TYPESET-11

UNIBUS

CONTENTS
Page

CHAPTER 1

INTRODUCTION

1.3

e e e
. . . o o e e e e e e e e e e e e e e e e e
GENERAL
... ...
...
.
..
.
.
.
.
.
MANUALS
N
INSTRUCTIO
APPLICARLE
e e e e e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
o
. . . . o
SPECIFICATIONS

CHAPTER 2

PHYSICAL DESCRIPTION

1.1

1.2

2.3

CARD NEST AND CABLE ASSEMBLY . . . . . . ... ... ... ...
. . . . . . . . « .« . . .. o000
Hex Printed Circuit Boards
MASSBUS and MDLI Interface PCBs . . . . . . . . . . ... .. ...
e
e e e e e e e e e e
POWER SUPPLY . . . . . .
e e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
o
.
POWER MONITOR . . . . .

CHAPTER 3

DCL FUNCTIONAL DESCRIPTION

2.1
-

2.1.1

2.1.2

2.2

3.1
3.2

3.2.1
3.2.2
3.3

3.4
3.5

.
DUAL CONTROLLER OPERATION . . . . . . . . o v oo v v
..
...
...
.
..
.
READ/WRITE DATA TRANSFERS . . .
o0 e e
Disk Pack Formatting . . . . . . . . « . o
Other Read/Write Commands . . . . . . . . . . . . ...
DISK ADDRESSING TECHNIQUES AND RELATED COMMANDS . . . ..
e e e
... ... e
DCL INTERFACE REGISTER . . ...
oo oo v oo o
ERROR CORRECTION CAPABILITY . . . . . . . .

1-1
1-2
1-2

2-1
2-1
2-2
2-2
2-2

3-1
3-1
3-1
3-2
3-2
3-2
3-3

ILLUSTRATIONS
Figure No.
1-1

2-1
2-2
2-3

24
2-5

Title

o o000
. . . . . . . . . . .«
RP0O4 Drive and DCL Assemblies
. . . . .
RPO04 Drive and DCL Assemblies Back View, Rear Panels Removed
. . . ..
.
.
.
.
.
Extended
Assembly
Cable
and
DCL Rear View, Card Nest
...
...
...
..
.
.
.
Card Nest and Cable Assembly PCB Layout . . . .
DCL Assembly Front View, Front Panel Removed
DCL Assembly Power Supply, Front Panel Removed

Page

1-1
2-3
2-4
2-5

CHAPTER 1

INTRODUCTION

1.1

GENERAL

This manual describes the Device Control Logic (DCL) incorporated in the RP04 Disk Drive. The
RPO04 is divided into two major functional parts (Figure 1-1):

The DCL which houses the necessary logic circuits to interpret and implement all commands executable by the RP04 and allows for access by two different controllers.

The DEC 773 Disk Storage Drive which houses the circuits for: rotating the disk pack,
positioning the read/write heads at the addressed cylinder track and sector; and writing /reading bits on the disk pack surface.

The DCL is capable of handling data transfers in either 16 or 18-bit format making the RP04 compatible with the PDP-11, PDP-15, and DECsystem-10. Each system has its own specialized controller

that interfaces the RP04 with the related processor.

DRIVE ASSEMBLY

DEVICE
CONTROL

LOGIC (DCL)
ASSEMBLY

Figure 1-1

RPO04 Drive and DCL Assemblies

1-1

CHAPTER 1

INTRODUCTION

1.1

GENERAL

This manual describes the Device Control Logic (DCL) incorporated in the RP04 Disk Drive. The
RPO04 is divided into two major functional parts (Figure 1-1):

The DCL which houses the necessary logic circuits to interpret and implement all commands executable by the RP04 and allows for access by two different controllers.

The DCL is capable of handling data transfers in either 16 or 18-bit format making the RP04 compatible with the PDP-11, PDP-15, and DECsystem-10. Each system has its own specialized controller
that interfaces the RP04 with the related processor.

DRIVE ASSEMBLY

DEVICE
CONTROL

LOGIC (DCL)
ASSEMBLY

Figure 1-1

RPO04 Drive and DCL Assemblies

1-1

1.2

APPLICABLE INSTRUCTION MANUALS

Instruction manuals bearing upon use of the RP04 depends on whether the device is configured in a
PDP-11 or PDP-10 system environment (or both). When used with the PDP-11, applicable instruction

manuals are:
e

RPO4 Disk Drive Installation Manual

Model 733 DEC Disk Storage Drive Operation, Service and Diagrams Manual

RJP04 Moving Head Disk Drive Maintenance Manual

RHII Controller Instruction Manual

RP04 DCL Print Set

When the RP04 is used with the PDP-10 system, related handbooks are:

1.3

RP04 Disk Drive Installation Manual

Model 773 DEC Disk Storage Drive Operation, Service and Diagrams Manual

RHI10 Controller Instruction Manual

RP04 DCL Print Set

SPECIFICATIONS
Data Format Option:

20 sectors per data track (256 18-bit words per sector data field).
22 sectors per data track (256 16-bit words per sector data field).
Error Handling:
Error Detection and Correction Capability.

Interface Characteristics:

MASSBUS Controller to device interface Dual Controller capability.

System Compatibility:

Can be used in PDP-11 or PDP-10 system configuration.
Data Transfer Modes:

|
Single sector or multisector (spiral or extended read/write) transfers.

Operating Temp. Ranges:

15° C minimum to 32° C maximum.
Humidity Range:

20% minimum to 80% maximum.

1-2

Dimensions:

9-inch wide by 35-inch high by 32-inch deep.
Weight (DCL only):
100 Ib (approx).

Operating Voltages DCL only:
|
+5 Vdc
-15 Vdc
+15 Vdc

1-3

CHAPTER 2

PHYSICAL DESCRIPTION

The DCL itself is a 9-inch wide by 32-inch deep by 35-inch high unit that attaches at the left of the
Drive assembly when the RP04 is viewed from the front (Figure 1-1). The DCL assembly is attached to
the drive assembly by four 2-inch long 1/4 X 20 bolts. The DCL assembly also has its own casters for
easy roll-away when disconnected from the Drive assembly. Levelers are attached to provide stability
when the DCL is permanently installed.

Physcialy, the DCL is comprised of three main subassemblies: The Card Nest and Cable Assembly, the

Power Supply, and the Power Monitor (Figures 2-1 and 2-2).
2.1

CARD NEST AND CABLE ASSEMBLY

The card nest and cable assembly is accessible through the rear of the unit by lifting the entire rear
cover panel and drawing it free of the assembly. This exposes the two fasteners that are used to hold
the card nest and cable assembly (Figure 2-1) in an upright position. Then access to the printed circuit
cards is gained by:

Loosening the two fastener screws and carefully swinging the assembly outward until it rests
in a horizontal position.

Loosening the two fastener screws (Figure 2-2) on the air flow cover and swinging the cover
to the vertical position. This exposes the hex and interface printed circuit boards (PCBs).

All control logic circuits are housed on the hex PCBs that extend the full length of the card nest and
cable assembly. The PCBs that interface with the drive assembly and the two controllers are the
smaller PCBs situated to the left of the assembly when viewed from the top. Figure 2-3 shows the
layout of the PCBs within the card nest and cable assembly.
2.1.1

Hex Printed Circuit Boards

There are five hex PCBs. Designations for these cards are based on the principle control circuits
housed on a particular PCB. For example, the Error Correction (EC) PCB is so designated because
there are more ICs used for this function than for any other control function on this particular board.
This does not mean, however, that other ICs on this same PCB are not used for control functions
completely unrelated to error correction. The designations used are simply a convenient means of
labeling and identifying the hex PCBs.

The hex PCBs are broken down as follows:
R G (Registers) PCB: This board contains most of the registers used to interface the DCL with the

controller.
DP (Dual Port or Dual Controller) PCB: This card logic used to to implement DCL accessing by
either of two controllers.
SS (Seek and Search) PCB: This board primarily includes the control logic to execute all mechanical operations.

SN (Synchronous Transfer) PCB: Much of the logic on this board inplements synchronous data
transfers between controller and disk pack.
EC (Error Correction) PCB: Approximately half of the logic on this PCB implements the error
correction process. The remaining logic is used for error registers and timing.

2.1.2

MASSBUS and MDLI Interface PCBs
Of the eight interface PCBs, six are used to convey signals between the DCL and MASSBUS
A/MASSBUS B. Each of these six PCBs has two cable connectors (J1, J2) mounted directly on the
card to accommodate the appropriate MASSBUS cables. Figure 2-3 shows the MASSBUS PCB locations and designations.
The two interface cards closest to the hex PCBs house the transceiver circuits for conveying signals
between the DEC 733 Drive and the DCL. These PCBs are called the MDLI interface cards (Figure 23).

2.2

POWER SUPPLY
|
The front of the DCL Assembly houses the H764 supply that develops operating voltages for the card

nest and cable assembly. This unit is accessible from the front of the DCL assembly when the front
panel is removed (Figure 2-4). Access to the voltage adjust potentiometers is via the metal hole plugs.
The power supply components can be replaced by removing the four front panel screws (Figure 2-5).

The power supply attaches at its base to a mounting bracket located in the center of the DCL assembly. The top attaches to a bracket directly above the front panel.
2.3
POWER MONITOR
The power monitor is situated beneath the power supply (Figure 2-4) and provides a constant check of
the power supply output voltage conditions. When any voltage (line or dc output) strays from the
required tolerance (ac low or dc low), this unit notifies the system. The power monitor also provides
the “power OK” signal used to initialize the RP04 following power up. The power monitor attaches at
the base of the DCL assembly with four mounting screws.

2-2

DRIVE
ASSEMBLY

DCL

MLt v,

Rl CPRRREfaae LOOVGRY

ASSEMBLY

. FASTENER
SCREWS

CARD NEST

AND CABLE

ASSEMBLY

Figure 2-1

RP04 Drive and DCL Assemblies Back View,
Rear Panels Removed

2-3

AIR FLOW
COVER

CARD NEST

AND CABLE
ASSEMBLY

7097-9

Figure 2-2

DCL Rear View, Card Nest and Cable Assembly Extended

DRIVE

INTERFACE PCB

HEX PCBS

CONTROLLER A
INTERFACE PCBs

DRIVE

INTERFACE PCB
LOCATIONS FOR

CONTROLLER B
INTERFACE PCBs
7097-4

Figure 2-3

Card Nest and Cable Assembly PCB Layout

H764 POWER SUPPLY

OUTPUT
VOLTAGE

ADJUSTMENTS

POWER
MONITOR

7097-3

Figure 2-4

DCL Assembly Front View, Front Panel Removed

7097-1

Figure 2-5

DCL Assembly Power Supply, Front Panel Removed

CHAPTER 3

DCL FUNCTIONAL DESCRIPTION

3.1
DUAL CONTROLLER OPERATION
The DCL interface logic is designed to permit access by two different controllers (i.e., provided that

the dual access option is installed). The setting of the CONTROLLER SELECT switch on the control
panel determines whether a single or both controllers are allowed to access the RP04. When set to the

A/B position, it allows for accessing by either controller on a “first-come, first-serve” basis. Once a
controller has gained access in the dual access mode, it retains control until it has completed its
operation. Normally, a controller releases the DCL by executing a release command to place the RP04
back in a device available status. However, if the accessing controller fails to execute such an instruction within a one-second time span (i.e., following the last operation), a timeout function produces the
same result.
3.2 READ/WRITE DATA TRANSFERS
Writing data words onto the RP04 disk pack or reading data words from the disk pack are termed
synchronous data transfers since such transfers are effected over the synchronous data bus portion of
the MASSBUS interface. Four read/write commands are implemented by the DCL logic. However,
the write header and data command must first be used to format a disk pack (divide the disk surface
into addressable sectors) as a prerequisite to executing the other three commands.
3.2.1
Disk Pack Formatting
Each new disk pack must be formatted to provide each sector with an identifying indicator or label

that defines sector number, track number, and cylinder number. This labeling information is inserted
into what is called the header area of a sector, which can also contain additional identifying information (key field data) under program control. Because the header area is positioned before the data field
of a sector, the header area information can be used to accurately address specific disk pack sectors for
read/write operation.
To format a new disk pack, use the write header and data command. Prior to executing this command,
the central processor writes the initial cylinder, track, and sector address information into the appropriate DCL registers. The central processor has the header information (cylinder, track, sector, and
key field words) ready on the synchronous data lines so that when the command is executed and the
addressed sector is found, the header information is present for writing onto the disk. The header
information is supplied to the RP04 by the operating system.
Executing the write header and data command causes the DCL to initiate the process of finding the
addressed cylinder, track, and sector. When all are found, the DCL informs the controller to send the
header information. At this time, the DCL also initiates the sequence for serially writing each header
word onto the disk surface. In this way, header information is introduced onto an addressed sector.
The write header and data command also allows for writing data words beginning at a fixed time
following the header. The area where data words are written is called the data field.

three .ther cominands to effect read/write transfers. For each of
these commands, the DCL makes proper identification of the header prior to initiating the transfer
process. The technique for header identification is to compare the cylinder, sector, and track addresses
of the header against those supplied prior to the read /write command initiation. Failure to detect a
matchup in all three addresses results in the DCL setting a header compare error bit that is eventually
sampled by the central processor.
A breakdown of the remaining read/write commands and their functions is given below:
Write Data Command: This command is used to write data words into the data field of an
addressed sector. The DCL executes this command by first finding and identifying the addressed
sector and then initiating the write transfer into the data field of that sector. The command can be

used for an extended (multi-sector) write operation in that the DCL continues to write into the
data fields of successive sectors for as long as the RUN line from the controller is asserted.
Read Header and Data Command: This command reads the header and data fields of an
addressed sector and sends both to the central processor via the controller. Reading the header
information may prove useful in analyzing faults after the DCL has indicated a header compare
error on a particular sector. By reading the header information (cylinder, track and sector
address) and comparing it against that supplied with the read header and data command, the
CPU is able to determine exactly what header (format) information is in error.

Read Command: This command is used to read the data field of an addressed sector. As is the
case with all read/write commands, the CPU must load the desired cylinder address and desired
sector/track registers prior to executing the command. Once the addressed sector has been found,
the DCL reads consecutive sectors for as long as the RUN line from the controller is asserted.
3.3

DISK ADDRESSING TECHNIQUES AND RELATED COMMANDS
The DCL executes two commands that are used solely to locate addressed areas of the disk pack - seek

and search. The functions carried out by these commands are broken down as follows:

Seek Command: This causes the drive read/write heads to be positioned over the addressed
cylinder. Cylinder and track information is supplied from the central processor prior to executing
the command. When the heads are correctly positioned, the drive informs the DCL which in turn
asserts the ATTENTION line to the controller.
Read /Write commands may also require positioning the read /write heads at the addressed cylinder. This activity is referred to as an “implied seek,” since the seek command is not used and the
ATTENTION line is not asserted.
Search Command: The search command is used as a method of optimizing the pack revolution
time. When the DCL detects the addressed sector, it asserts the ATTENTION line to the
controller.
3.4

DCL INTERFACE REGISTER
The DCL has 16 interface registers that can be accessed by the controller; they fall into the following

general categories:

Control - The control register receives the command (read, write, seek, etc.) codes from the
controller. The DCL control logic samples the content of this register and initiates the appropriate execution sequence.

Status — The bits of this register supply the central processor with DCL and Drive status
information.

Maintenance - The maintenance register is used by diagnostic programs to initiate various
maintenance functions.

Error Information - Three registers are provided to indicate error status within both the DCL
and the Drive.

Address Data - These are five registers that are associated with disk addressing:
e

Desired Cylinder Address Register

Current Cylinder Address Register

Desired Sector/Track Register

Offset Register, used to offset the disk read/write heads in fixed increments.

Look Ahead Register, can be used to subdivide the data field of a sector.

System Housekeeping — There are rwo registers used for system housekeeping, i.e., a drive type
register and serial number register.

Attention Summary Pseudo Register - This is a one bit register used to indicate that the RP04
requires the attention of the system. In one sense it can be considered an interrupt line.
Error Correction — There are two registers used to convey error correction information to the
central processor.
3.5

ERROR CORRECTION CAPABILITY

The DCL is equipped with error correction logic, which (provided it is not inhibited by the system)
becomes operative whenever an error is detected during a read operation. Once activated, the error
correction circuits proceed to locate the eare in the sector data field where the error occurred. When
this area is detected, the DCL makes available the following information to the operating system:
1.

Error correction code burst pattern.

Position with the data field where the error occurred.

Given this information, the software can determine the exact bits in error and correct them.

3-3

FIRST CLASS

PERMIT NO. 33

MAYNARD, MASS.

BUSINESS REPLY MAIL
NO POSTAGE STAMP NECESSARY IF MAILED IN THE UNITED STATES
Postage will be paid by:

Digital Equipment Corporation

Technical Documentation Department
Digital Park, PK3-2

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MAIN OFFICE AND PLANT

Maynard, Massachusetts, U.S.A. 01754 * Telephone: From Metropolitan Boston: 646-8600 « Elsewhere: (617)-897-5111
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DOMESTIC
NORTHEAST

MID-ATLANTIC (cont.)

REGIONAL OFFICE:

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Telephone: (617)-890-0330/0310
Dataphone 617-890-3012 or 3013

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Telephone: (609)-452-2940
Dataphone: 609-452-2940

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NEW YORK

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Telephone: (203)-237-8441/7466
Dataphone:

Long
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Telephone: (203)-255-5991

Huntington Quadrangle

Rochester

Telephone:

MASSACHUSETTS

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Telephone: (612)-854-6562-3-4-5

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Ex. 78

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Dataphone: 317-247-1212

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LOUISIANA
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Telephone: (918)-749-4476
Dataphone: 918-749-2714
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Dallas
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Telephone: (504)-337-0257

Dataphone: 214-620-2061

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7901

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Dataphone: 513-298-4724

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Telephone: (317)-243-8341

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Metuchen

Kettering Boulevard
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ulsa
3140 S. Winston

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Executive Park

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Dataphone: 216-946-8477
3101

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Dataphone: 615-584-0571

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Dataphone: 612-854-1410

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Dataphone: 313-557-3063

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516-293-5693

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Suite 189
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REGIONAL OFFICE:
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Telephone: (408)-735-9200
Dataphone: 408-735-1820

Detroit

Island

Dataphone:

NEW YORK

CENTRAL (cont.)
MICHIGAN
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Dataphone: 303-770-6628

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Telephone: (505)-296-5411/5428
Dataphone: 505-294-2330

OREGON
Portland

{
\

Suite 168
5319 S.W. Westgate Drive, Portland, Oregon 97221
Telephone: (503)-297-3761/3765
UTAH

Salt Lake City
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Dataphone: 801-467-0535

WASHINGTON
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8531 West Capitol Drive, Milwaukee, Wisconsin 53222
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Dataphone: 414-463-9115

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Telephone: (206)-545-4058/455-5404

Dataphone: 206-747-3754

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TORONTO
2550 Goldenridge Road, Mississauga, Ontario
TWX: 610-492-7118

108 Rue D'Arlon

MUNICH

COLOGNE
5 Koeln 41, Aachener Strasse 311
Telephone: 0221-44-40-95
Telex: 888-2269
Telegram: Flip Chip Koeln
FRANKFURT

Am Forstaus Gravebruch 5-7
Telex: 41-76-82

HANNOVER
3 Hannover, Podbielskistrasse 102
Telephone: 0511-69-70-95
Telex: 922-952

STUTTGART

9045 Cote De Liesse
Dorval, Quebec, Canada H3P 2M9

SWEDEN

Telephone: (514)-636-9393

Stuttgart
Marco-Polo-Strasse 1
Telephone: (0771)-45-50-65

Telex: 841-722-393

Suite 140, 6940 Fisher Road S.E.

Digital Equipment Corporation Ges.m.b.H.
VIENNA

TWX: 403-255-7408

Suite 202
644 S.W. Marine Dr., Vancouver
British Columbia, Canada V6P 5Y1

Digital Equipment Corp. A/S
SLO

Trondhe:msveven 47

Telephone: (604)-325-3231

Telex: 19079 DEC N

GENERAL INTERNATIONAL SALES
REGIONAL OFFICE
146 Main Street, Maynard, Massachusetts 01754

Digital Equipment Aktiebolag
COPENHAGEN

Telephone: (617) 897-5111
From Metropolitan Boston, 646-8600

Hellerupveg 66

FINLAND

TWX: 710-347-0217/0212

Cable: DIGITAL MAYN
Telex: 94-8457

UNITED KINGDOM

SF-00710 Helsinki 71
Telephone: (090) 370133

29/31 Birmingham Rd., Sutton Coldfield
Warwickshire, Englan
Telephone: 021-355-5501

Telex: 337-060

BRISTOL
Fish Ponds Road. Fish Ponds
Bristol. England BS163HQ

Equipment S.p.A.

Corso Garibaldi 49, 20121 Milano, Italy
Telephone: (02)-879-051/2/3/4/5
Telex: 843-33615

LONDON

SPAIN

House

Digital Equipment Corporation Ltd.
MADRID
Telex:

27560

MANCHESTER
House

Chester Road. Stretford, Manchester M32 9BH
Telex: 668666

printed in U.S.A.

6 Montrose Avenue
Norwood, South Australia 5067
Telephone: (08)-42-1339
Telex:

790-82825

BRISBANE
133 Leichhardt Street

Spring Hill
Brishane, Queensland, Australia 4000
Telephone: (072)-293088
Telex: 790-40616

CANBERRA

27 Collie St.
Fyshwick, A.C.T. 2609 Australia
Telephone: (062)-959073

Telex: 790-30700

Ataio Ingenieros S.A., Enrique Larreta 12, Madrid 16
Telephone: 215 35 43
Telex: 27249

BARCELONA
Ataio Ingenieros S.A., Granduxer 76, Barcelona 6
Telephone: 221 44 66

Coasin Chile Ltda. (sales only)
Casilla 14588, Correo
1
Telephone: 396713
Cable COACHIL

INDIA

BOMBAY
Hinditron Computers Pvt. Ltd.
69/A, L. Jagmohandas Marg.
Bombay-6 (WB) India
Telephone: 38-1615: 36-5344
Telex: 011-2594 Plenty
Cable: TEKHIND

Eugenia 408 Deptos. 1
Apdo. Postal 12-1012
Mexico 12, D.F.
Telephone: (905) 536-09-10

MANILA

Stanford Computer Corporation
P.O. Box 1608
416 Dasmarinas St., Manila
Telephone: 49-68-96
Telex: 742-0352

Telex:

790-20740

NEW ZEALAND

Digital Equipment Corporation Ltd.

AUCKLAND

Hilton House, 430 Queen Street, Box 2471
Auckland, New Zealand
Telephone: 75533

Rua Coronel Vicente 421/101
Porto Alegre —
RS
Telephone: 24-7411

PHILIPPINES

West Perth, Western Australia 6005
(092)-21-4993
Telex: 790-92140

Telephone:

SYDNEY
P.O. Box 491, Crows Nest
N.S.W. Australia 2065
(02)-439-2565

PORTO ALEGRE — RS

MEXICO

643 Murray Street

Telephone:

SP
Telephone: 52-7806/1870, 51-0912

Mexitek, S.A.

60 Park Street, South Melbourne, Victoria 3205
Australia

Telephone: (03)-699-2888

SAO PAULO

MEXICO CITY

MELBOURNE

PERTH

FPALY.
MILAN

43 Parker St., Holborn, London
WC 2B 5PT, England

Arndale

CH-8050 Zurich, Switzerland
Telephone: 01-46-41-91
Telex: 56059

Digital

EDINBURGH
Shiel House, Craigshill, Livingston,
West Lothian, Scotland
Telephone: 32705
Telex: 727113

Telephone: (061)-865-7011

Telex: 28 92 01

Schaffhauserstr. 315

Telephone: Bristol 651-431

Telephone: 01-405-2614/4067

Digital Equipment Corporation S.A.
GENEVA
20, Quai Ernest Ansermet
Boile Postale 23, 1211 Geneva 8, Switzerland
Telephone No. 022 20 40 20 and 20 58 93 and 20 68 93

ZURICH
Digital Equipment Corp. AG

EALING
Bilton House, Uxbridge Road, Ealing, London W 5.
Telephone: 01-579-2334
Telex: 22371

Management

SWITZERLAND

RIO DE JANEIRO — GB
Ambriex S.A.

CHILE

ADELAIDE

Cable: Digital Helsinki

BUENOS AIRES
Coasin S.A.
Virrey del Pino, 4071, Buenos Aires
Telephone: 52-3185
Telex: 012-2284

SANTIAGO

AUSTRALIA
Digital Equipment Australia Pty. Ltd.

Titismaantie 6

BIRMINGHAM
Maney Buildings

Telex: 385-9056

Telephone: 264-7406/0461/7625

Telex: 610-929-2006

Digital Equipment AB
HELSINKI

Reading RG1 70N, England
Telephone: (0734)-583555
Telex: 8483278

Santurce, Puerto Rico 00912
Telephone: (809)-723-8068/67

Rua Ceara, 104, 2 e 3 andares ZC - 29
Rio De Janeiro — G

Mariahilferstrasse 136, 1150 Vienna 15, Austria
Telephone: 85 51 86

Digital Equipment Co. Ltd.
U.K. HEADQUARTERS
Fountain House, Butts Centre

PUERTO RICO
Digital Equipment Corporation De Puerto Rico
407 del Parque Street

BRAZIL

Calgary, Alberta, Canada
VANCOUVER

2900 Hellerup, Denmark

AUSTRIA

Telex: 610-422-4124

CALGARY /Edmonton

Telephone: (403)-435-4881

DENMARK

Kemnat,

No. 18-14 NlShlShlmbaShl 1-Chome
Minato-Ku, Tokyo, Japan
Telephone: 5915246
Telex: 781-4208

ARGENTINA

MONTREAL

Digital Equipment AB
STOCKHOLM
Englundavagen 7, 171 41 Solna, Sweden
Telephone: 98 13 90
Telex: 170 50
Cable: Digital Stockholm

Oslo 5,
way
Telephone 02/68 34 40

4
\

Telephone: (416)-270-9400

Telex: 25297

NORWAY

6078 Neu-Isenburg 2

Kozato-Kaikan Bldg.

CANADA

Telephone: 02-139256

8 Muenchen 13, Wallensteinplatz 2
Telephone: 0811-35031
Telex: 524-226

9-20 Akasaka 1-Chome

Minato-Ku, Tokyo 107, Japan
Telephone: 586-2771
Telex: J-26428
Rikei Trading Co., Ltd. (sales only)

Telex: 922-33-3163

Digital Equipment of Canada, Ltd.
CANADIAN HEADQUARTERS
P.O. Box 11500
Ottawa, Ontario, Canada
K2H 8K8
TWX: 610-562-8732
Telephone: (613)-592-5111

1040 Brussels, Belgium

GERMAN FEDERAL REPUBLIC
Digital Equipment GmbH

Suite 103, Southern Habakuk Street .

Tel Aviv, lsrael
Telephone: (03) 443114/440763

BELGIUM

16 Rue Du Gal Mangin

D-7301

Digital Equipment Corporation International
Kowa Building No. 16
— Annex, First Floor

DEC Systems Computers Ltd.

Sir Winston Churchillian 370
Rijswijk/The Hague, Netherlands

GRENOBLE

Telephone: 06102-5526

JAPAN

TEL AV

Digital Equipment N.V.
THE HAGUE

Telex: 26840

Digital Equipment France
Tour Mangin
38100 Grenoble,

ISRAEL

Fountam House, Butts Centre
Reading RG1 70N, England
Telephone: (0734)-583555
Telex: 8483278

READ

NETHERLANDS

Digital Equipment France
Centre Silic — Cidex L 225
94533 Rungis, France
Telephone: 687-23-33

‘UNITED KINGDOM (cont.)

VENEZUELA
CARACAS
Coasin, C.A.
Apartado 50939

Sabana Grande No. 1, Caracas 105
Telephone: 72-8662; 72-9637
Cable: INSTRUVEN

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