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Document:	TU56DECtape Transport Maintenance Manual
Order Number:	DEC-00-HRTC-D
Revision:
Pages:	86
Original Filename:	DEC-00-HRTC-D%20TU56%20DECtape%20Transport%20Maintenance%20Manual.pdf

OCR Text

TU56DECtape
transport
maintenance manual

L....------digital equipment corporation. maynard. massachusetts-------'

TU56DECtape
transport
maintenance manual

DEC-OO-HRTC-D

digital equipment corporation · maynard. massachusetts

I st Edition, June 1970
2nd Printing (Rev) March 1971
3rd Printing, October 1971
4th Printing, March 1972
5th Printing, June 1972
2nd Edition, July 1972
7th Printing, January 1973
8th Printing, September 1973

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

The following are trademarks of Digital Equipment
Corporation, Maynard, Massachusetts:
FLIP CHIP
UNIBUS
PDP

DECtape
DECsystem-IO
DECmagtape

CONTENTS
Page
CHAPTER 1 GENERAL INFORMATION
1.1
1.2
1.3
1.4
1.4.1
1.4.2
1.4.3

1-1
1-1
1-3
1-4
1-4
1-5
1-7

Introduction
Specifications
Options
Major Assemblies and Systems
Controls and Indicators
Tape Motion System
Power Supply

CHAPTER 2 INST ALLATION
2.1
2.2
2.2.1
2.2.2
2.2.3
2.3
2.4
2.4.1
2.4.2

Unpacking and Inspection
Mechanical Installation
Mounting Support Plate Bracket and Spacer Block Installation
Spacer Support Bracket Installation
Transport Installation
Electrical Installation
Operation
Tape Loading and Unloading
On-Line Operating Procedures

2-1
2-3
2-3
2-3
2-4
2-6
2-8
2-8
2-8

CHAPTER 3 THEORY OF OPERATION
3.1
3.1.1
3.1.1.1
3.1.1.2
3.1.1.3
3.1.1.4
3.1.1.5
3.1.1.6
3.1.1.7
3.1.2
3.1.2.1
3.1.2.2
3.1.3
3.1.3.1
3.1.3.2
3.1.3.3
3.2
3.2.1
3.2.2
3.3
3.3.1

Interface
Input Interface Lines - Command Cable - A06/ A07
Select 0-7
CON STOP
CONGO
CON REV REM
CON FWD REM
CON ALL HALT
CON PWR UP DLY
Output Interface Lines - Command Cable - A06/A07
Select Echo
Write Echo
Bi-Directional Interface Lines - Information Cable - AB 10/ AB 11
Timing Track (TT)
Mark Track (MT)
Data Tracks (DO-D2)
Functional Information
Read/Write Head
DECtape Format
Local (off-line) Operation
Forward Tape Motion

iii

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

CONTENTS (Cont)
Page
3.3.2
3.3.3
3.4
3.4.1
3.4.2
3.4.2.1
3.4.2.2
3.4.3
3.4.4
3.4.5
3.5
3.5.1
3.5.2
3.5.3
3.5.4

Hold Tape Motion
Reverse Tape Motion
Remote (on-line) Operation
Tape Transport Addressing
Error Checks
Select Echo
Write Echo
Tape Motion Control
Write Operation
Read Operation
Module Description
G847 Dual Motor Voltage Control
G848 Motor Control Module
G859 Clock Regulator Module
G888 Manchester Reader/Writer Module

3-5
3-5
3-6
3-7
3-7
3-7
3-8
3-8
3-9
3-11
3-11
3-11
3-11
3-12
3-12

CHAPTER 4 MAINTENANCE
4.1
4.2
4.2.1
4.2.2
4.2.3
4.3
4.3.1
4.3.2
4.3.2.1
4.3.2.2
4.3.2.3
4.3.2.4
4.3.2.5
4.3.3
4.3.3.1
4.3.3.2
4.3.3.3
4.3.3.4
4.3.3.5
4.4
4.4.1
4.4.2
4.5

Recommended Tools and Test Equipment
Preventive Maintenance
Weekly PM Procedure
Monthly PM Procedure
Tape Care and Cleaning
Corrective Maintenance
Control Panel Lamp Replacement
Reel Motor
Motor Removal
Motor Replacement
Reel Hub Clearance Adjustment
Reel Motor Electronic Brake Adjustment
40-Hz Oscillator Adjustment
Read/Write Head
Head Removal
Head Replacement
Head Output Check
Head Skew Check and Adjustment
Write Enable Circuit Check
Troubleshooting
Initial Checks
Signal Source and Termination Tests
Recommended Spare Parts

APPENDIX A REFERENCE DRAWINGS

4-1
4-1
4-1
4-2
4-2
4-3
4-3
4-3
4-3
4-4
4-5
4-5
4-5
4-5
4-5
4-7
4-7
4-8
4-11
4-11
4-11
4-14
4-18

ILLUSTRATIONS
Title

Figure No.
I-I
1-2
1-3
2-1
2-2
2-3
2-4
2-5
2-6
3-1
3-2
3-3
3-4
3-5
4-1
4-2
4-3
4-4
4-5
4-6
4-7

Controls and Indicators
Tape Motion System
Power Supply Location
Outer Packaging
Inner Packaging
H950 Cabinet Support Plate
Tubular Cabinet Spacer Support Bracket
Faceplate Removal
Hub and Reel
TC08 to TU 56 Logic Connection
Functional Block Diagram
Read/Write Head Arrangement
Off-Line Manual Operation Flow Chart
Read/Write Technique
Reel Motor Removal
Reel Hub Clearance
Head Connector Location
Skew Tester to Head Cable Connection
Head Skew Waveform
G848 Motor Control Module Waveforms
M908 Module Layout

Page
1-4
1-6
1-7
2-1
2-2
2-3
2-4
2-5
2-7
3-1
3-3
3-4
3-6
3-10
4-4
4-6
4-8
4-9
4-10
4-13
4-15

TABLES
Table No.
1-1
1-2
1-3
2-1
2-2
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8

Title
Performance Specifications
Logic Modules
Controls and Indicators
TU56 and TU56H Interface Cabling
Interface Module Substitution
Recommended Maintenance Equipment
Reel Motor Malfunctions
Control Panel Malfunctions
Local Malfunctions
Left Transport Source Test Points
Right Transport Source Test Points
Right and Left Transport Termination Test Points
Recommended Spare Parts

Page
1-1
1-3
1-4
2-6
2-7
4-1
4-11
4-12
4-12
4-15
4-16
4-16
4-18

TUS6 DECtape Transport

CHAPTER 1
GENERAL INFORMATION

1.1 INTRODUCTION
The TU56 (Dual) or TU56H (Single) DECtape Transport is a solid state, bi-directional, low cost, magnetic tape
data storage device. The Manchester Phase encoding method used in this transport ensures reliable data transfer
and reduces tape skew problems. Each tape track is redundantly paired with a second, nonadjacent track, thus
permitting dependable use of a lower cost (instrumentation) tape without requiring a closely controlled environment.
The TU56 tape speed is 93 inches per second, with a data transfer rate of 33,300 3-bit characters per second.
The simple tape transport mechanism has no capstans or pinch rollers. Tape motion is controlled by two ac
induction reel motors. The internal H725 Power Supply furnishes dc operating power for the reel motors only.
DC logic power is externally supplied by the tape controller through connectors located on the back of the
power supply. To maintain proper tape tension during forward tape motion, full torque is applied to the forward
reel motor while reduced torque is applied to the reverse reel motor. Similarly, during reverse tape motion, full
torque is applied to the reverse reel motor while reduced torque is applied to the forward reel motor. Electronic
braking ensures a positive stop from either direction, without appreciable tape backlash.
With the use of optional interface modules, the solid state switching circuits in the TU56 can be made compatible
with the relay switching circuits in the TU55 and 555 DECtape Transports. This versatile tape transport can
therefore be used in a variety of installations, including those not employing Digital Equipment Corporation
(DEC) computers.
1.2 SPECIFICATIONS
Table 1-1 lists the performance specifications of the TU56 DECtape Transport.
Table 1-1
Performance Specifications
Characteristic

Parameter

Controller Type and Output Levels
Integrated Circuits

F = ground
T=+5Vdc

Relay

F = open
T = closed

Solid State

F = ground
T=-3Vdc
(continued on next page)
1-1

Table 1-1 (Cont)
Performance Specifications
Parameter

Characteristic

Electrical Requirements
Input Voltage

115/220 Vac, 50/60 Hz @ 3A
+5 ± 0.5 Vdc @ 0.8A }
+10 ± 1.0 Vdc@ 0.8A
either +5 or +10 Vdc, but not both*
-15 ± 1.5 Vdc @ 0.8A

Power Dissipation

TU56 = 325W (1073 Btu/hr) max
TU56H = 162.5W (536.5 Btu/hr) max

Environment
Ambient Temperature
Relative Humidity

20 to 80% (no condensation)

Storage Medium
Type

Mylar sandwich, magnetic recording tape

Width

3/4 in.

Thickness

1.25 mil

Data Capacity

2.7 x 10 6 bits (unformatted)

Format

Manchester Phase Encoding

Tape Reel
Outer Diameter

3-7/8 in.

Diameter Ratio

Approximately I: 104 (min. to max.)

Capacity

260 ft

Tape Motion Times
(90% full speed)
Start

150 ± 15 ms

Stop

100 ± 10 ms

Turnaround

200 ± 50 ms

Backlash

<1.0 in. tape motion after braking

Tape Transport
Speed

93 ± 12 in. per sec (ips)

Recording Density

350 ± 55 bits per in. (bpi)

Transfer Rate

33,300 3-bit characters per sec

Dimensions and Weight
Width

19 in. (0048m)

Depth

17-3/4 in. (0043m)

Height

10-1/2 in. (0.27m)

Weight

80 Ib (37 kg)

* Either +5 or + 10 Vdc external voltage may be used; however, the internal logic requires +5 Vdc for normal operation. If + 10 Vdc is
used, ensure that it is connected to the correct rear terminal; otherwise circuit damage will result.

1-2

1.3 OmONS
The TU56 DECtape Transport is available in the following standard models:
• TU56 (Dual) Transport
• TU56H (Single) Transport
In addition, two customer options, designated TU56M (Dual) and TU56HM (Single), permit the standard transport models to be used alone or connected with other nonstandard peripherals. If either option is used, five G888
Read/Write Amplifier modules must be inserted into slots A 13, A 14, B 13, B 14, and B 15 of the logic mounting
block. Interface cabling as indicated in Table 2-1 must be used. If more than one transport is connected to a
single controller, only the first transport of the "daisy chain" need contain the G888 modules. If the transport is
connected to a controller that has relay driver outputs, the M941 Jumper modules in slots A04 and A05 must be
replaced with W513 Level Amplifier modules. Table 1-2 lists the logic module complement of each transport model.

Table 1-2
Logic Modules
Quantity
TU56
Dual Transport

TU56H
Single Transport

I
I

(I) G742

I
I
I
1
1
I
2
1
2
2
2
5
1
I
I

G859
(2) M941
(I) M531
M040
G851
MI17
Mll3
M302
G848
M908
W032
(3) G888 option
M922
(3) M923 option
G847

2
I
2
2
2
3
1
4
2
2
5
2
I
2

Module Name

Type

Positive Logic Jumper Card
Clock Regulator
Jumper Card
Bus Converter
Solenoid Driver
Relay
6-4 Input NAND Gate
10-2 Input NAND Gate
Dual Delay MV
Motor Control
Connector
Cable Connector
Manchester Reader/Writer
Cable Connector
Cable Connector
Dual Motor Voltage Control

(I) MS3l used with negative logic controller. G742 used with positive logic controller.

(2) Replace with a WSl3 when transport is connected to a relay driver controller.
(3) Required only when transport is connected with nonstandard peripherals, or is to be used alone.

1-3

1.4 MAJOR ASSEMBLIES AND SYSTEMS
1.4.1 Controls and Indicators
The controls and indicators (Figure I-I) required for normal operation are located on the front of the transport
cabinet. Table 1-3 describes the function of each control or indicator.

Figure I-I Controls and Indicators

Table 1-3
Controls and Indicators
Controls and Indicators
REMOTE/OFF/LOCAL
(rocker switch)

Logic Symbol

Description

SW2

Placing this switch in one of the following positions
accomplishes:
a. REMOTE - disables the Fwd/Hold/Rev switch
and places the transport under computer control
(on-line).
b. LOCAL - enables the Fwd/Hold/Rev switch and
removes the transport from computer control
(off-line).
c. OFF - removes power from the reel motors and
removes the transport from computer control.

(continued on next page)

1-4

Table 1-3 (Cont)
Controls and Indicators
Controls and Indicators

Logic Symbol

Fwd/Hold/Rev
(rocker switch: spring-loaded to
Hold)

SW3

- -

Description

Placing this switch in the Fwd position (provided
REMOTE/OFF/LOCAL is in LOCAL) moves the
tape from left to right across the read/write head.
When this switch is in the spring-loaded Hold position
(provided REMOTE/OFF/LOCAL is in LOCAL), the
tape remains stationary.
Placing this switch in the Rev position (provided
REMOTE/OFF/LOCAL is in LOCAL) moves the tape
from right to left across the read/write head.

Address Select
(0 to 7 thumbwheel switch)

SWI

Configures the transport logic to respond to the address indicated on the thumb wheel.

WRITE ENABLE/WRITE LOCK
(rocker switch)

SW4

Placing this switch in the WRITE ENABLE position
lights the WRITE indicator and allows a write operation.
Placing this switch in the WRITE LOCK position turns
off the WRITE indicator and prevents a write operation.

REMOTE SELECT
(indicator)

Lights when the transport is in the remote (on-line)
mode and is selected by the controller.
Goes off when the transport is in the off or local
(off-line) modes or is deselected by the controller.

WRITE
(indicator)

Lights when the WRITE ENABLE/WRITE LOCK
switch is in the WRITE ENABLE position.
Goes off when the WRITE ENABLE/WRITE LOCK
switch is in the WRITE LOCK position.

1.4.2 Tape Motion System
Each half of the dual tape motion system (Figure 1-2) consists of: two ac induction reel motors (mounted
behind the hinged mounting panel), two tape reel hubs, a tape guide assembly, and a read/write head. Tape
motion from the supply reel, over the tape guides and read/write head, and onto the take-up reel is directly
controlled by the two 600-rpm induction reel motors that drive the reel hubs. The solid state switching circuits
that control the reel motors govern the amount of torque applied to each motor. For forward tape motion, full
torque is applied to the forward motor (take-up reel) and reduced torque is applied to the reverse motor (supply
reel). This condition establishes the direction of the tape motion and maintains the proper tape tension without
the use of capstans, pinch rollers, or drag pads. Similarly, the opposite reel motor conditions are necessary for
reverse tape motion.

1-5

•~:~~~f
'"'

'ttW

..
T

READ/WRITE
HEAD

IIUIOTE.

on.

WIIITC

• laC"

...

,-oe ......

TAPE
GUIDE

TAPE
REEL

REEL HUB

A. Mounting Panel (closed)

TB2

REEL
MOTORS

B. Mounting Panel (opened)
Figure 1-2 Tape Motion System

1-6

Since a separate track containing timing information plus a Manchester Phase encoding technique is used, tape
speed can vary as much as ±20 percent without affecting the read/write reliability. Dynamic braking of the
reverse motor causes a positive stop without adverse tape backlash. Whenever the tape is motionless, both motors
apply partial torque to maintain the tape position.
NOTE

During tape motion, the high harmonic content of the 40-Hz
square wave that supplies the tape reel motors produces small,
cyclic variations in the power output of the motors. These
variations cause an audible hum which varies in intensity as the
reel being driven by a particular motor fills with tape. Such
behavior is normal and has no effect on the performance of
the transport.
1.4.3 Power Supply
The H725 Power Supply, located in the left rear portion of the transport cabinet (Figure 1-3), furnishes + 18 and
+38 Vdc operating power for the reel motors only. A convenience outlet on the back of the supply furnishes
110/220, 50/60 Hz ac power. AC operating power for the cooling fan is obtained directly from the input line
voltage, through terminal connector TB2 located on the front of the power supply. The +5 Vdc logic operating
power is supplied by either an external source or is generated internally by a voltage regulator on the G859 Clock
and Regulator module. When + 10 Vdc is connected to TB I (+ 10 terminal) of the power supply, the regulator
reduces this external level to +5 Vdc for internal use. When +5 Vdc is connected to TBI (+5 terminal), the
regulator is bypassed and the external level is directly used internally. For this reason, it is important that the
external dc power connection be made to the correct TB 1 terminals.

POWER
SUPPLY

TB1
LOGIC
MODULES

CONVEN I ENCE
OUTLET

Figure 1-3 Power Supply Location

1-7

CHAPTER 2
INSTALLATION

2.1

UNPACKING AND INSPECTION

Do not drop or subject the transport to unreasonable impact. Carefully unpack the TU56 DECtape Transport as
follows:
I.

Open the outer carton (Figure 2-1) and remove the top four toro pad cushions.
TOR 0
8

PAD

PLACES
4 TOP
4 BOTTOM

INNER SHIPPING CARTON

OUTER SHIPPING
~_ _ _ _ _ _ CARTON

Figure 2-1 Outer Packaging

2-1

Lift out the inner carton and open it (Figure 2-2).

Remove the back and side support laminated pieces.

Lift the transport out of the inner carton and unbolt the shipping bracket. Replace the shipping
bracket screws in the transport chassis and retain the packing materials for possible return shipment.

Inspect the transport and report any damage to the carrier and Digital Equipment Corporation.

POWER
SUPPLY

SHIPPING
BRACKET

=
000

SIDE SUPPORT
LAMINATED PIECE (2)

REAR OF TRANSPORT
VIEW A

BACK SUPPORT
LAMINATED PIECE

CORNER SUPPORT
LAMINATED PIECE

~
~

FOAM TAPE
GUIDE PROTECTOR

BACK SUPPOR T

L"d!!:ll+-_ _ _ LAMINATE D PI ECE

INNER CARTON

Cp-0282

Figure 2-2 Inner Packaging

2-2

2.2 MECHANICAL INSTALLATION
To install the TV56 DECtape Transport in the cabinet, two different mounting support brackets are available.
The mounting support plate bracket with spacer blocks (7408321 and 7408322) is for transport installation in
an H950 cabinet. The V-shaped spacer support bracket (7408009) can be ordered separately and is for transport
installation in a tubular-type cabinet. The following paragraphs describe the bracket installation procedures for
both cabinet types.
2.2.1 Mounting Support Plate Bracket and Spacer Block Installation
1.

Place the mounting support plate (7408321) in the H950 cabinet and secure it to the front of the
cabinet mounting rails (Figure 2-3).

Install the spacer blocks and secure them to the side of the cabinet mounting rails.

Secure the spacer blocks to the mounting support.

2.2.2 Spacer Support Bracket Installation
1.

Place the spacer support bracket (7408009) in the tubular cabinet and secure it to the cabinet front
with the mounting hardware (Figure 2-4).

Attach four clip-on speed nut fasteners to the spacer support bracket.

1/4/20 TRUSS HEAD SCREW
WITH KEEPER NUT (2)
MOUNTING BRACKET (7408321)
SPACER
BLOCK (2)
(7408322)

FRONTOFCABINET

10/32
TRUSS HEAD(2)

CABINET
MOUNTING
RAILS

CP-0032

Figure 2-3 H950 Cabinet Support Plate

2-3

EMOUNTING
CABINET
HOLES (4)

_____

__________ U

___

m~~

l::

~============~

SPACER SUPPORT
sP- 02BI

Figure 2-4 Tubular Cabinet Spacer Support Bracket

2.2.3 Transport Installation
The tape transport may be installed in a cabinet without removing the transport mounting panel; however, the
mounting panel weight makes this practice difficult. It is best, as described in the following procedure, to first
remove the mounting panel, then install the transport.
1_

Remove the M922 Ribbon Cable Connectors from slots B04 and B 17 of the logic module mounting
block at the rear of the transport (Figure 2-5A).

Disconnect the 22-pin Amphenol head cable connector from the rear of the G851 Relay modules in
slots AB09 and AB 12.

Turn the mounting panel side locking fasteners (Figure 2-5B) one-quarter turn to unlock the mounting
panel.

Carefully lower the mounting panel until the support struts are fully extended (Figure 2-5C).

Disconnect the reel motor cable connectors (Figure 2-5C) by pressing the locking tabs, which extend
from one of the Mate-N-Lok connectors, against the side of the connector body and separating the
connector halves.
NOTE
If the reel motor connectors are held to the chassis by a nylon
cable holder, remove the top of the holder and free the cable.

Route the head and ribbon cables from the back to the front of the transport.

Support the mounting panel and remove the support strut mounting screws.

Tilt the mounting panel slightly upward, pull it forward, then lift up the rear to free it from the
transport.

Mount the transport in the cabinet with four Phillips No.1 0-32 truss-head screws and keeper nuts.

10.

Reinstall the mounting panel by performing Steps 1 through 8 in reverse.

2-4

AMPHENOL
HEAD
CONNECTORS

REEL MOTOR
CONNECTOR

A. Transport Rear View

LOCKING
FASTENER

SUPPORT
STRUTS

C. Mounting Panel Opened

B. Locking Fastener Location

Figure 2-5 Faceplate Removal

2-5

2.3 ELECTRICAL INST ALLATION
l.

After the transport has been installed in the rack (Paragraph 2.2.3), visually inspect the cables and
logic modules to ensure that the modules are securely seated in the correct slots of the logic mounting
block. (Refer to Drawing MU-TU56-0-MU for the correct logic module and slot locations.)

Connect the appropriate interface cables (Table 2-1) to the logic mounting block and ensure that the
correct interface modules for the corresponding controller type (Table 2-2 and Drawing MU-TU56-0-MU)
are installed.
Table 2-1
TU56 and TU56H Interface Cabling
Cable Origin

TDIO
TCOI
TC02
TC08
TC09
550
551
552

Command Cable Termination
(Slots A06/A07)

(I) Information Cable Termination

(Slots ABIO/ABll)

M908B Module,
70-06223 Cable

W032 Module,
74-5152 Cable

TU56

M908B Module,
BC-02X Cable

W032 Module,
74-5152 Cable

TU55

M908B Module,
70-06223 Cable

W032 Module,
74-5152 Cable

TC15

M908B Module,
BC-02X Cable

W032 Module,
74-5152 Cable

TCll

M908B Module,
BC-02X Cable

W032 Module,
74-5152 Cable

TD8/e

(2) 70-08447 Cable

(2)

70-08447 Cable

(1) For a TU56M or TU56MH Transport: controller-to-transport information cable = 70-06412, transport-totransport (other TU56 or TU56H in system) information cable = 74-5152. See Note 2 for TU56M or

TU56MH connected to a TD8/e Controller.
(2) When a TU56M or TU56MH is connected to a TD8/e Controller, only one 70-08447 cable is used for both
commands and information. This cable has both a single-height and a double-height connector module on
the termination end. Insert the single-height connector into slots A061 A07 and the double-height connector
into slots AB 101 AB I I.

Check the clearance between each reel hub and the flange on the mounting panel (Figure 2-6) with
the feeler gauge supplied with the transport. If the gauge does not fit, loosen the Allen screws on the
hub and make the necessary adjustment. Retighten the Allen screws.
CAUTION
Do not repeatedly loosen or tighten the hub Allen screws. These
screws are serrated cup type and may become damaged with excessive use.
(continued on Page 2-8)

2-6

Table 2-2
Interface Module Substitution
Required
Module

Quantity

Position in
Mounting Block

Integrated Circuit

G742
M94l

1
2

AOS
Al8, A04

F=O
T=+S

Relay

WSl3
MS3l

2
1

A04, Al8
AOS

F = open
T = closed

Solid State

M94l
MS3l

2
I

A04, Al8
AOS

F=O
T=-3

Control Type

Logic Level

TAPE REEL

SMALLER
CI RCUMFERENCE

.017

r - - - - - - - HUB CLEARANCE

1+-_ _ _ MOUNTING
PANEL

MOTOR
SHAFT

31."REEL-

_ _ _ _ J~\

10-0178

Figure 2-6 Hub and Reel
2-7

Check the transformer tap connections of the H72S Power Supply (Drawing CS-72S-O-I) to ensure
that the power supply is configured properly for the input power to be used.

Insert the ground, -IS, and + 10 or +S Vdc spade lugs into the proper TB I terminals on the rear of the
power supply.

Plug the power cord into the ac line receptacle.

Load a tape (Paragraph 2.4.1) and operate the transport in the local mode to ensure proper electrical
and mechanical operation.

2.4 OPERA nON
2.4.1 Tape Loading and Unloading
To load tape, proceed as follows:
I.

Set the REMOTE/OFF/LOCAL switch to OFF.

Position a full tape reel so that the labeled side is out and the smaller circumference is against the left
hub (Figure 2-6). Press the reel fully onto the hub ensuring that the reel is evenly seated (not cocked).
NOTE
If the transport is connected to a PDP-12 system, mount the full
reel on the right hub since forward tape motion for the PDP-I 2
is from right-to-Ieft instead of left-to-right.

Mount an empty take-up reel on the right hub as described in Step 2.

Route the tape from the left reel, over the tape guides and read/write head, to the right side of the
take-up reel.

Hold the free tape end against the take-up reel hub and rotate the take-up reel clockwise, winding four
or five turns of tape onto the reel.

Verify that power is applied to the transport and set the REMOTE/OFF/LOCAL switch to LOCAL.

Press and hold the Forward switch ( - ) for about 3 seconds, allowing approximately 15 turns of tape
to wind onto the take-up reel. (Press the Reverse switch ( - ) for a PDP-I 2 system.) This action
ensures that the data portion of the tape is positioned over the read/write head.

To unload tape, proceed as follows:
1.

Set the REMOTE/OFF/LOCAL switch to LOCAL.

Press and hold the Reverse switch (_ ) until the tape has completely rewound onto the left supply
reel (right supply reel for a PDP-I 2 system).

Set the REMOTE/OFF/LOCAL switch to OFF and remove the supply reel.

2.4.2 On-Line Operating Procedures
I.

Verify that power is applied to the transport and load the appropriate tape (Paragraph 2.4.1).

Set the Address Select switch of the transport to be used to the desired address and position the
WRITE ENABLE/WRITE LOCK switch as desired.

Set the REMOTE/OFF/LOCAL switch to REMOTE.

2-8

CHAPTER 3
THEORY OF OPERATION

3.l INTERFACE
Standard interface connection of the TU56 DECtape Transport is made with an information cable to slots AB I 0
or AB II and a command cable to slots A06 or A07 of the logic mounting block. (Refer to Table 2-1 for the
controller model and corresponding interface cable type, and Table 2-2 for the module substitutions.) These
connector slots are parallel-wired so that up to eight transports may be serially connected in a multi-transport
"daisy chain" configuration (i.e., connectors AB I 0/ AB II and A06/ A07 of the first transport are connected in
series to connectors AB I 0/ AB II or A06/ A07, respectively, of the following transport, etc.).
If the TU56 is connected to a TC08 Controller, the following logic considerations must be understood. Command
signals leave the controller M623 Bus Driver module via a 70-06223 cable. In the transport, these signals pass
through an M941 Jumper module to an M531 Bus Converter module. If the input to the controller M623 module
is ground, the output is ground; if the input is +3V, the output is -3V. The M531 module in the transport has the
input/output requirements reversed from those of the M631. That is, a ground input produces a ground output;
however, a -3V input produces a +3V output.
Figure 3-1 illustrates the TC08 to TU56 logic connection. If BMR 0 I (1) L is true, GO H is false. To maintain
compatibility between the various available controllers and the transport, signals such as CON GO, CON STOP,
CON REV REM, and CON FWD REM are reversed inside the 70-06223 cable (i.e., the actual signal appearing at
point 2 in Figure 3-1 is T STOP L). For this reason, the 70-06223 cable must not be installed backwards. If the
cable is reversed, the system will not operate.

I TU56

Teos

I
I
1

COMMAND CABLE 70-06223

I
I
010
I
I
I

GND

T GO L

GND

---------------~------------CP-02B7

Figure 3-1 TC08 to TU56 Logic Connection
3-1

Figure 3-2 illustrates and the following paragraphs describe the function of each interface line when the transport
is connected to a solid state controller with logic levels of -3V =T and ground = F.
3.1.1 Input Interface Lines - Command Cable - A06/ A07
3.1.1.1 Select 0-7 - These eight lines and the eight-position Address Select thumb wheel on the control panel
determine the transport address assignment and selection. In a particular transport, only one of these lines is
internally connected (via the Address Select switch) to the transport select logic. In order to select a transport,
the controller places a ground level on the desired SELECT line. This line then remains at ground during the
entire read, write, or control operation. When the transport is not selected, the SELECT line is at -3V.
3.1.1.2 CON STOP - This line transmits a signal to stop tape motion. The controller places a -3V level on this
line to reset the Motion L flip-flop and thus terminate tape motion. (CON GO and CON STOP are complementary
signals.)
3.1.1.3 CON GO - This line transmits a signal to initiate tape motion. The controller places a - 3V level on this
line to set the Motion L flip-flop. During normal operation, a CON REV REM or CON FWD REM signal must
accompany this signal. (CON STOP and CON GO are complementary signals.)
3.1.1.4 CON REV REM - This line transmits a signal to designate reverse tape motion. The controller places a
-3V level on this line to reset the Direction L flip-flop and thus reverse tape motion. During normal operation, a
CON GO signal must accompany this signal. (CON REV REM and CON FWD REM are complementary signals.)
3.1.1.5 CON FWD REM - This line transmits a signal to designate forward tape motion. The controller places a
-3V level on this line to set the Direction L flip-flop and thus initiate forward tape motion. During normal
operation, a CON GO signal must accompany this signal. (CON FWD REM and CON REV REM are complementary signals.)
3.1.1.6 CON ALL HALT - This line transmits a signal to stop tape motion whenever the computer program is
halted. If the computer program halts, either by instruction or operator intervention while the tape is in motion,
the tape would continue to run off the reel. To prevent this, the controller places a -3V level on this line to
reset the Motion L flip-flop whenever the computer program halts.
3.1.1. 7 CON PWR UP DLY - This line transmits a signal to prevent tape motion while initial power is applied
to the computer. During the computer power-on sequence, the controller places a ground level on this line that
applies a +18V brake signal to both reel motors. When the computer is successfully powered-up, this line goes to
-3V.
3.1.2 Output Interface Lines - Command Cable - A06/A07
3.1.2.1 Select Echo - This line transmits an analog signal to indicate the transport selection status. When the
transport is in the remote mode, a -6 to -9V signal on this line indicates that only one transport has been
properly selected. A OV signal indicates that no transport has been selected. A -9 to -15V signal indicates that
more than one transport has been selected. (Refer to Paragraph 3.4.2.1 for a detailed description.)

3-2

B04
~

I Bwe,,,
I
I
WRITE
LOCK

SELECT 0-7 (81

OFF 0

LOCALD

r-------.

L FWD LOC

STOP

CON ALL HALT

CON PWR UP DLY I

SELECT ECHO

L MOi1l

FWD REM

MOTION a
DIRECTION
LOGIC

ALL HALT

L BRAKE

HEAD
RELAY

J ",lOOms I
I

DLY

R/W
HEAD

REV
MOTOR

FWD
MOTOR

I
I
I
I

I
I

(31

REEL MOTOR
DRIVE LOGIC

I
I
I

I
I

1
PWR UP DLY

DO (31

•

L DI R1

t----

TT (31
MT (31

j D2 (31

L DIRi1l

L M01

REV MEM
BUS
CONVERTERS

I
I
I

L SELECT

CON FWD MEM

SOLENOID
DRIVER

'--'

A05

L OFF

L HOLD

SELECT
LOGIC

L SELCODE

L REV LOC

WRT ECHO

L REMOTE

CON GO
CON REV MEM

"."COB

L WRT ENABLE

I
I
CON STOP

[I]

ENABLE

L OISCONNECT

R/W DATA (151

CP-0285

Figure 3-2 Functional Block Diagram

3-3

3.1.2.2 Write Echo - This line transmits a signal to indicate the transport "write protect" status. If the transport
is write protected (write capability inhibited), this line is at - 3V. If the transport is not write protected, this line
is at ground.
3.1.3 Bi-Directional Interface Lines - Information Cable - AB 10/ AB 11
3.1.3.1 Timing Track (TI) - This line transmits timing pulses to or from the transport timing tracks.
3.1.3.2 Mark Track (MT) - This line transmits mark channel information to or from the transport mark tracks.
3.1.3.3 Data Tracks (00-02) - These lines transmit data or control words to or from the transport data tracks.
3.2 FUNCTIONAL INFORMATION
Since the TU56 DECtape Transport is a dual system, each transport contains identical logic. Figure 3-2 is a
functional block diagram of only the left (L) transport logic. The following paragraphs describe the detailed
logical operation of the left transport when it is connected to a negative logic (T = -3V, F = OV) controller. The
right (R) transport operates in an identical manner as the left and is therefore not described.
3.2.1 Read/Write Head
The recording device (read/write head) contains ten read/write coils which are electronically connected in nonadjacent pairs. When the tape is loaded, each coil covers a narrow path along the tape (Figure 3-3). Since it is
possible to write in the data tracks (inner tracks) and simultaneously read from the timing and mark tracks (outer
tracks), the timing and mark coils are slightly separated by additional shielding from the data coils. During a
write operation (Paragraph 3.4.4), each coil pair records identical information. During a read operation (Paragraph
3.4.5), the output from the coil pairs is connected in series to differential amplifiers. Since the differential amplifiers use a zero-crossing detection scheme, the effects of amplitude changes over a wide range are negligible. The
analog sum of the coil pair signals determines the correct value (either logical I or 0) of the recorded bit. Thus,
for a read operation, information from one track combines with redundant information from another nonadjacent track to generate a single channel output signal. This redundant read/write scheme greatly reduces the
possible loss of recorded information due to foreign matter on the tape or head. In addition, the pairing of nonadjacent tracks minimizes the adverse effects of tape skew.
3.2.2 DECtape Format
The TU56 Transport uses the standard DECtape formatted tapes, furnished by DEC, as a storage medium. These
blank tapes are supplied with the timing and mark tracks prerecorded at the factory by a write head with zero
skew. Consequently, these tapes may be used on any transport where the head skew is within specifications. The
timing and mark tracks can also be recorded on used tape by a customer tape system. However, unless the
customer write head has less than a 200-microinch skew, it is possible that the formatted tapes generated on a
customer transport may not be interchanged among all other transports.
There are ten tracks across the 3/4-inch wide DECtape (Figure 3-3). The two outer tracks (timing tracks) are
electronically paired to form one timing channel that is used to synchronize and control read/write operations.
The timing track is prerecorded with alternating positive (TPO) and negative (TPI) flux reversals at a fixed frequency. During a write operation, these alternating flux reversals are read from the timing track. The positive
flux reversal (TPO) loads the data to be recorded into a write buffer in the controller for transfer over the data
lines. The negative flux reversal (TPI) complements the write buffer and by so doing, reverses the write current

in the write coils. Thus, if a 0 is to be written, the write current is switched negative, resulting in a negative flux
reversal on the tape. Conversely, if a 1 is to be written, the write current is switched positive. During a read
operation, TPI generates a strobe within the controller that allows sampling of the data lines during peak data
signal amplitudes.
The two tracks directly adjacent to the timing tracks (mark tracks) are paired to form a mark channel that designates the type of information (either control or data words) contained in the data tracks. A unique 6-bit code in
the mark track identifies the tape location (e.g., beginning of block, end of block, data, etc.) and the type of
information stored at that location. Since a read or write operation can be performed while the tape is moving
forward or reverse, the mark track bits, when decoded, are identical (symmetrical) for data read from either
direction. In addition to being symmetrical, the mark track codes are designed so that a single bit error can not
change one valid code into another.
The six inner tracks (data tracks) are grouped at the center of the tape where they are least affected by tape skew.
These six tracks are coupled to form the three data channels. A control word in the data channel is six frames
long (as determined by the 6-bit mark track code) and contains 3 bits per frame (18 bits total). These control
words store address and checking information and provide compatibility between computers using 12, 16, 18,
32, or 36-bit words. A data word in the data channel contains stored information and occupies at least four 3-bit
frames (12 bits).

TRANSPORT
MOUNT I NG
PANEL

3/4 INCH
MAGNETIC
TAPE

.....

READ/WRITE

.....

COILS

NOTE:
Each coil poir is actually wired in series, with two wires
connected to a differential amplifier. However, for simplicity,
only a single wire from each poir IS shown.
CP-0284

Figure 3-3 Read/Write Head Arrangement

3-4

3.3 LOCAL (off-line) OPERATION
Figure 3-4 illustrates and Paragraphs 3.3.1 through 3.3.3 describe the logical sequence of events during off-line
manual operation of the transport.
3.3.1 Forward Tape Motion
Placing the REMOTE/OFF/LOCAL switch SW2 (Drawing BS-TU56-0-TLD, sheet 2) on the control panel in
LOCAL, applies ground to the center wiper of the Forward/Hold/Reverse switch SW3. If the spring-loaded SW3
switch is pressed and held in the Forward position, L FWD LOCAL (Drawing BS-TU56-0-TLD, sheet I) goes low
and is applied to both pin H I of the M 117 Direction L flip-flop, and pin B I of the Motion L flip-flop. This action
sets both flip-flops, generating the L MOl and L DIRI high signals. These signals are then ANDed at gate Ml13
pins PI and Rl. The low M 113 pin S I output is inverted high and applied to the G847 module, then applying
a +38V run signal to the forward motor. Simultaneously, input pin N2 of the G847 module goes low, applying
a + 18V drag signal to the reverse motor.
When SW3 is released, the center wiper returns to the Hold position. This action generates the L HOLD low signal,
terminating tape motion.
3.3.2 Hold Tape Motion
Placing the REMOTE/OFF/LOCAL switch SW2 (Drawing BS-TU56-0-TLD, sheet 2) on the control panel in
LOCAL, applies ground to the center wiper of the Forward/Hold/Reverse switch SW3. With SW3 in the springloaded Hold position, L HOLD (Drawing BS-TU56-0-TLD, sheet 1) goes low and is applied to inverter G859 pin
K2, generating L RESET low.
If forward tape motion is occurring when the Hold switch is enabled, L RESET, when applied to pin E2 of the
MI17 Motion L flip-flop, resets the flip-flop generating L MOl low. This action triggers the IOO-millisecond
L Brake one-shot to produce the L BRAKE high signal. L BRAKE and L MOO (high because the Motion flip-flop
is now reset) are ANDed with L DIRI at gate MI17 pins T2, S2, and R2. The low MI17 pin V2 output is inverted
high and applied to the G847 module, thus applying a +38V brake signal to the reverse motor.
If reverse tape motion is occurring when the Hold switch is enabled, L DIRO is high and the +38V brake signal is
applied to the forward motor.
If no tape motion is occurring when the Hold switch is enabled, the Motion flip-flop is already reset when
L RESET is produced. Consequently, the L Brake one-shot is not triggered and the L BRAKE signal is not
produced. If this occurs, the outputs from inverters M 113 pins K I and K2 are both low, and + 18V drag signals
are simultaneously applied to both the forward and reverse motors. Thus, tape tension is retained while the tape
is motionless.
3.3.3 Reverse Tape Motion
The logical sequence for reverse tape motion is similar to forward tape motion except that L REV LOCAL resets
the Direction L flip-flop, causing the +38V run signal to be applied to the reverse motor and the +18V drag signal
to be applied to the forward motor. (Refer to Paragraph 3.3.1 for a detailed description of forward tape motion.)

3-5

- -

GROUND

FWD/HLD/REV
SW3

~----------------~--------------G)

APPLY +IBV
TO FORWARD
8 REVERSE
MOTORS

RESET
DIRECTION 8
SET MOTION
F LI P- FLOPS

8 +IBV TO
REVERSE
MOTORS

APPLY +3BV
TO REVERSE
8 +IBV TO
FORWARD
MOTORS

YES

APPLY +3BV
TO FORWARD
MOTOR

CP-0283

Figure 3-4 Off-Line Manual Operation Flow Chart

3.4 REMOTE (on-line) OPERATION
The actual remote transport operation is relatively simple, however, a minimal explanation of the controller
operation is also included in the following description. This additional controller explanation is necessary for a
comprehensive understanding of the overall system operation. If the transport is connected to a controller other
than the one previously described (Paragraph 3.1), optional logic converter modules as indicated in Table 2-2 and
on the logic drawings must be used.

3-6

3.4.1 Tape Transport Addressing
For greater flexibility in a multi-transport system, the transport address can be changed by changing the position
of the Address Select thumbwheel SWI (Drawing BS-TU56-0-TLD, sheet 2) on the control panel. The eight
SELECT interface lines (numbered 0 through 7) are directly connected to the contacts of the correspondingly
numbered SWI switch positions. Placing this switch in anyone of the eight positions connects the wiper arm to
the associated SELECT interface line.
NOTE
On a dual transport (TU56) there are two Address Select switches
that function independently. These switches are not interlocked.
Therefore, if the operator should inadvertently configure two or
more transports for the same address, the controller will detect a
select error (Paragraph 3.4.2.1).
The wiper arm output is then applied through an M941 Jumper module (Paragraph 1.3) to pin S2 of the M531
Negative Bus Converter module (Drawing BS-TU56-0-TLD, sheet 1). When the controller applies ground to the
appropriate SELECT interface line, L SELCODE goes low. This signal is then applied through inverter M 113
pins T2, U2 (Drawing BS-TU56-0-TLD, sheet 2) to M113 pin E1.
If the REMOTE/OFF/LOCAL switch is in the REMOTE position, L REMOTE, applied through inverter M 113

pins P2, R2 (Drawing BS-TU56-0-TLD, sheet 1), ANDs with the Ml13 pin V2 inverter output (Drawing
BS-TU56-0-TLD, sheet 2) to generate L SELECT high, plus L DISCONNECT high. The L SELECT high signal
allows the transport to perform the various control and read/write operations. The L DISCONNECT high signal
energizes the head relays connecting the read/write coils to the interface data lines. In addition, L DISCONNECT
is applied to connector M922 pin S 1, lighting the REMOTE indicator on the front panel.
3.4.2 Error Checks
If a Write Command is issued to a transport that has not been selected or the transport is write protected, one or

both of the echo signals described in the following paragraphs are generated. If this occurs, an error flag signal is
produced in the controller which prevents further transport operation until the error is corrected.
3.4.2.1 Select Echo - If a transport has been properly selected by the controller (Paragraph 3.4.1), L SELECT
is at ground. This signal, applied to solenoid driver M040 pin J2 (Drawing BS-TU56-0-TLD, sheet 1), produces a
negative output at pin S2. The negative M040 pin S2 output, when applied through a lOO-.Q resistor, results in a
-6 to -9V SELECT ECHO analog signal at A06 pin PI. The analog output at PI is then transmitted over the
interface lines to a transport detector module in the controller. A -6 to -9V input at the transport detector produces a +3V output, indicating that only one transport has been selected.
Selection of morc than one transport places the I OO-.Q resistors of the respective transport SELECT ECHO circuits
in parallel and thus decreases the SELECT ECHO signal level below -9V (-9 to -15V). When this occurs, the
output from the transport detector goes to OV, indicating an error condition.
If no transport is selected, the SELECT ECHO output at A06 pin PI is OV. A OV input at the transport detector
also results in a OV output indicating an error condition. Thus, if the operator inadvertently chooses the same
address for more than one transport, or if no transport address is chosen, an error flag is generated in the controller
that prevents further tape operation on the affected transports until the selection error is corrected.
NOTE
When the transport is connected to a 550, 551, or 552 controller, the preceding select error detection method is not used and
the external 100-.Q resistors are removed.
3-7

3.4.2.2 Write Echo - In order to record information on a selected transport, the WRITE ENABLE/WRITE
LOCK switch (SW4) on the control panel must be in the WRITE ENABLE position. If this is the case, the left
wiper of SW4 (Drawing BS-TU56-0-TLD, sheet 2) closes to complete the Ll (WRITE ENABLE) ground return
and light the indicator.
If the transport has been properly selected (Paragraph 4.3. I), the signal L DISCONNECT at M922 pin S I is at
ground. L DISCONNECT at ground applies an approximate ground to the diode/resistor biasing junction of
the right SW4 wiper. With this circuit configuration, a slightly positive turn-on voltage is applied to the base of
the 2N6531 transistor, causing it to conduct and produce a ground (L WRT ENAB high) at M922 pin A I. Once
the 2N6531 transistor conducts, the three 0664 diodes form a voltage regulating network to maintain a nearly
true ground at pin AI. L WRT ENAB high, applied through the M941 Jumper module (Drawing BS-TU56-0-TLD,
sheet I) to connector A06 pin S I, produces WRITE ECHO high. WRITE ECHO high is then transmitted over
the interface lines to the controller, indicating that the selected transport is available for a write operation (not
write protected).
If the transport has not been selected, the signal L DISCONNECT is at - I 5V. L DISCONNECT at -15V applies
approximately - I 3.5V to the diode/resistor biasing junction (Drawing BS-TU56-0-TLD, sheet 2). With this circuit configuration, a negative cut-off voltage is applied to the base of the 2N653 I transistor, allowing current
flow through the 12K emitter resistor to produce - 3V (L WRT ENAB low) at M922 pin A I. Similarly, if the
WRITE ENABLE/WRITE LOCK switch is placed in the WRITE LOCK position, the Ll indicator is turned off
and the diode/resistor biasing junction is completely disconnected, thus producing -3V at M922 pin AI. With
pin AI at -3V, the WRITE ECHO signal is suppressed, preventing the computer from issuing a Write Command
to a transport that has not been selected or one that is write protected.
3.4.3 Tape Motion Control
The following paragraphs describe tape motion control for a forward read or write operation. A reverse tape
operation is similar to a forward operation except that the opposite command interface conditions are necessary.
To perform a forward read or write operation, the controller first receives a Read or Write Command from the
computer. Specific bits within the command structure designate the transport address. the direction the tape is
to be moved, and the desired block number. The controller than simultaneously addresses the appropriate tape
transport (Paragraph 3.4.1), places a - 3V level on the CON GO and CON FWD interface lines, complements the
CON STOP and CON REV REM interface lines, and triggers an internal up-to-speed delay which inhibits read
data sampling until the tape has reached a sufficient speed for reliable data transfer.
NOTE
It is possible to deselect a transport without stopping the tape
motion and then reselect the transport at a later time. If this
is the case, the controller does not trigger the up-to-speed delay
and data can be transferred as soon as the transport is reselected.
This capability requires additional program instruction and is
therefore not described in this text.
When CON GO and CON FWD REM go low, they are inverted high by the M531 Bus Converter module
(Drawing BS-TU56-0-TLD, sheet 2) and applied to the Motion L and Direction L flip-flops (Drawing
BS-TU56-0-TLD, sheet I). FWD REM and L SELECT are then ANDed at gate MI 13 pins 02 and E2 to set the
Motion L flip-flop and generate L MOl high. L MOl and L DlRl are then ANDed at gate MI 13 pins PI and RI.
The low MI13 pin SI output is inverted high and applied to the G847 module, applying a +38V run signal to the
forward motor. This action causes the tape to move forward. Simultaneously, pin N2 of the G847 module goes
low, applying a + I 8V drag signal to the reverse motor, thus maintaining the proper tape tension while the tape is
in motion.
3-8

When the internal up-to-speed delay times out, a controller circuit compares the frequency of the incoming pulses
from the tape timing channel to a one-shot output in the controller. Once the two frequenci({s match, the tape
has reached a sufficient speed for reliable data transfer and the controller then compares the first incoming block
number from the tape mark channel to the desired block number specified by the command. If the incoming
block number is smaller, forward tape motion continues until the desired block number is reached. At this point,
read or write data is transferred (Paragraphs 3.4.4 and 3.4.5). If the incoming block number is larger, tape motion
must be reversed (turned around) to reach the desired block number. If this is the case, the controller triggers an
internal turnaround delay that inhibits further data reception and complements the CON FWD REM and CON
REV REM interface lines. This action initiates reverse tape motion in a similar manner as the forward tape motion
just described.
After the internal turnaround delay times out, the block numbers are again compared, as previously described,
until the desired block number is detected. When this occurs, the tape is again turned around (CON FWD REM
and CON REV REM complemented) and once sufficient tape operating speed is acquired, read or write data is
transferred (Paragraphs 3.4.4 and 3.4.5).
3.4.4 Write Operation
The DECtape system of recording is unique in that regardless of whether data is being written on or read from the
data channels, the timing and mark track amplifiers are always reading the information contained in those two
channels.
Once the tape has been properly positioned (Paragraph 3.4.3) and a write operation initiated, the following events
occur. The alternating positive and negative flux reversals prerecorded in the timing track (TT) produce a nearly
sinusoidal output (Figure 3-5A) at the terminals of the corresponding read coil. The read amplifiers in the controller detect the zero-crossings of this waveform. Zero-crossings in which the signal changes from a negative to a
positive level generate a train of TPO timing pulses. Positive-to-negative transitions generate a separate train of
TPI timing pulses. Physically, these pulses are generated when the timing track read/write coils are positioned
between two adjacent flux reversals.
When data bits are being written, each TPO pulse causes three data bits to be loaded into the data buffers in the
controller. The following TPI pulse then automatically complements all three buffers. Each buffer is in direct
control of the write current flowing through the corresponding read/write coil. Thus, depending on the previous
state of a given data buffer, the TPO pulse mayor may not cause the data buffer to change state and write a flux
reversal on the tape. The TPI pulse, however, will always cause the buffer to change state and write a flux
reversal.
The TU56 magnetic head has been designed in such a way that flux reversals in the magnetic circuits do not occur
instantaneously, but lag the reversal of the write currents by 6 to 10 microseconds. This delay is necessitated by
the fact that each flux reversal is recorded on tape at a point which is displaced from the center of the write coil
gap (Figure 3-5B). The magnitude of this displacement is about 75 percent of the write coil gap width, and the
direction of the displacement is the same as the direction of tape motion. As a result of this delay, the flux
reversals in the data tracks are positioned between the flux reversals in the timing track. Figure 3-5C iIIustrates a
tape in which the pattern 00778 has been written.

3-9

TPO

__L
---lnL--_--InL-__--'nL--_--InL-___

~~-----,n~---,n~---,n~

TPI _ _

DATA TRACK 0

A. Read/Write Waveforms

B. Head Flux Recording Location

MT
DO

o
o

L.
L.

o
o

L. . POSITIVE FLUX REVERSAL

o.
-

NEGATIVE FLUX REVERSAL

• NO FLUX REVERSAL
CP -0289

C. Recorded Tape

Figure 3-5 Read/Write Technique

3-10

3.4.5

Read Operation

When the section of tape shown in Figure 3-SC is read, the relative positions of the timing and data track flux
reversals ensure that the two signals will be read back 90 degrees out of phase. Therefore, if the tape is read
while moving in the same direction as it was written, (i.e., the tape was written, rewound over the head, and
read), the TPI pulses will occur close to maxima of the signals from the data tracks.
In order to read the tape, the signals from the data amplifiers are fed to the inputs of the data buffer, and
loaded into the buffer when TPI occurs.
Figure 3-SA illustrates the timing track, TPO, TPI, and data track 0 signals which are generated when the
section of tape shown in Figure 3-SC is read while moving in the same direction as it was written. Note that
each TPI pulse occurs at a maximum of the data track signal, and that the polarity of the data track signal
at that time defines the value of the bit that was recorded there.
3.5

MODULE DESCRIPTION

Circuit information for the FLIP CHIP modules used in the TUS6 DECtape Transport is cataloged in the DEC
Digital Logic Handbook, C-IOS. Schematics of these and noncataloged modules are contained in Appendix A.
The following paragraphs describe only the non cataloged modules.
3.5.1 G847 Dual Motor Voltage Control
The G847 Dual Motor Voltage Control module (Drawing B-CS-G847-0-1) selects the voltage level that is
applied to the tape reel motors. This module contains two 3-stage circuits for control of the two reel motors.
When the run signal is high, Q I is biased on. Q2 and Q3 are then, in turn, biased on. With Q3 conducting, a
high output voltage (approximately +38V) appears at Eout 1. Diode D4 is then reverse biased following the
higher output voltage.
Diodes D2 and D9 ensure that the potentials at the base of Q3 and the collector of Q2 do not exceed their
design ratings.
When the run signal is low, QI, Q2, and Q3 are off and D4 conducts; thus, the lower voltage (approximately
+18V) appears at Eout 1. Eout 1 is at +38V during run and brake time and at +18V when drag is required
on a particular motor. Eout I is also at + 18V when the REMOTE/OFF/LOCAL switch (SW2) is in the OFF
position.
3.5.2

G848 Motor Control Module

The G848 Motor Control module (Drawing C-CS-G848-0-1) is a transistorized bridge circuit designed to operate
an ac tape reel motor from a de source. The operational ac is obtained from an external 40-Hz clock oscillator,
whose OSCO and OSC 1 outputs are 180 degrees out of phase with each other.
The bridge circuit controlling the ac tape motor consists of two PNP transistors (QS and Q8) and two NPN
transistors (Q6 and Q7). The OFF signal can remove power from the motor for an indefinite period.
Transistor turn-on, RC time delay networks (RIS and C4; R24 and C3; R23 and C2; and R3 and Cl) prevent
two opposing arms in the bridge network from being biased on at the same time. The time delay from turnoff to turn-on is approximately I millisecond.

3-11

When the OSCI input is high, Q II is biased on, and C2 discharges through the low impedance path of the
transistor to ground. When C2 discharges, Q I 0 turns off. When C4 has sufficiently discharged through D 12,
R15, and Q II, Q9 is turned on and provides a path from the motor power supply to the base of Q7, turning
Q7 on.
When the OSCI input is high, the OSCO input is low, biasing Q2 off. CI charges through R3, which in tum
causes Q3 to be turned on. Once Q3 is biased on, it turns Q5 on. Diode D8 is then reverse biased, Q4 is
biased off, and C3 charges through R25. A current path now exists from the motor power supply, through
Q5, through the motor windings, and through Q7 to ground.
The opposite operational characteristics occur when OSCI input goes low and OSCO goes high. For this change
of state, QII, Q9, Q7, Q5, and Q3 are now reverse biased, and Q2, Q4, Q6, Q8, and QIO are forward biased.
The two halves of the bridge network oscillate at the 40-Hz clock rate, generating ac current through the
motor winding and inducing motor motion.
3.5.3

G859 Clock Regulator Module

The G859 Clock Regulator module (Drawing B-CS-G859-0-1) contains a divide-by-two flip-flop (Q6 and Q7),
an 80-Hz oscillator (Q2 and Q3), and a voltage regulator (Q5). The 80-Hz oscillator output is fed through
capacitors C3 and C4 to the flip-flop. The resulting 40-Hz square wave output is then connected through two
emitter followers (QI and Q4) to the G848 Motor Control module.
NOTE
During tape motion, the high harmonic content of the 40-Hz
square wave that supplies the tape reel motors produces small,
cyclic variations in the power output of the motors. These
variations may cause an audible hum which varies in intensity
as the reel being driven by a particular motor fills with tape.
Such behavior is normal, and has no effect on the performance
of the transport.
When + I OV is connected to pin A2 of this module, the +5V regulator circuit reduces this input voltage to the
+5V level required for logic operation. If +5V is available from an external power supply, the regulator circuit
is bypassed.
3.5.4

G888 Manchester Reader/Writer Module

The G888 module (Drawing B-CS-G888-0-1) consists of two portions. The upper read portion of the schematic contains the following:
a.
b.
c.

a linear amplifier (E I) with a gain of 100
a zero-crossing detector (E2)
a limiter (QI)

During a read operation, the 10 to 12 m V read signals from the read head are applied to pins D and E of
linear amplifier E 1. The approximately I V amplified output (test pin H2) is then transmitted to zero-crossing
detector E2 pin 2. The square wave E2 output is clamped, by limiter Q I, to the standard DEC logic levels and
applied to output gate E3. The signal at output pins U and V is then transmitted via the interface lines to the
controller read/write buffer.

3-12

The lower write portion of the schematic contains a push-pull amplifier (Q3 and Q5). During a write operation, write data from the controller is ANDed with the T/M ENAB signal at input gate E3 pins 9, 10, 12, and
13. Either output pin J or K, depending upon the polarity of the input signal, drives current to the read/
write heads. The applicable G888 module specifications are as follows:
Write Amplifier
Inputs:

Standard TTL voltage.
Load at OV is I unit.
R2 should be tied to +3V when not used.

Outputs:

Can drive 100 rnA in either direction.
Pins L2 and M2 are the outputs of the 7400 TTL gates.
Pins 12 and K2 are the outputs that drive the tape unit write head.

Read Amplifier
Inputs:

Can detect an input voltage as low as 500 JJ.V.

Outputs:

Pins U and V are standard TTL voltages.

Fan Out:

Pin U2 = 9 unit loads
Pin V2 = 10 unit loads

Test Point:

Pin H2 is a test point for the first stage output.

Power Dissipation

50 mW at +5V
250 mW at -15V

3-13

If necessary, use a pointed wooden dowel that has been soaked in cleaning solvent to remove very
old, hard oxide deposits from the edges of the tape guides.

Clean the tape guide path and the top of the read/write head with a clean, lint-free cloth moistened
with head cleaning solvent.

Using a dry, lint-free cloth, wipe the excess cleaning solvent from the read/write head and tape guides.

Allow at least 60 seconds for the remaining solvent to evaporate, then reload the tapes.

Check for proper operation of the reel motors and electronic brakes by momentarily pushing the
Forward (-) and Reverse ( - ) tape motion switches and observing that the tape moves in the
corresponding direction. If the tape does not stop smoothly, adjust the electronic brake (Paragraph
4.3.2.4).

4.2.2 Monthly PM Procedure
If the tape transport is operated on a standard eight hour shift, perform the following procedure once a month.
If the transport daily operation exceeds one shift, perform the following procedure more often. Stagger the
monthly checkout for individual transports evenly throughout each month.
1.

Clean the exterior and interior of the cabinet with a vacuum cleaner and clean cloths moistened, if
necessary, in a nonflammable solvent. DO NOT USE SOLVENTS THAT WILL REMOVE PAINT.

Clean the air filters at the top or bottom of the equipment rack as described in the preventive maintenance section of the appropriate controller maintenance manual.

Clean the most frequently used tapes by placing a clean, dry, lint-free cloth over the read/write head,
loading the tape on the transport and manually running the tapes over the cloth.

Clean the take-up reels, if heavy use has caused oxide build-up around the hub.

Inspect the over-all condition of the transport.

Inspect the cable and logic modules to ensure that the modules are securely seated in the logic
mounting block.

Exercise both the transport and the associated controller in all possible modes and directions. Applicable programs for these operations are listed in the appropriate controller maintenance manual. Log
all errors to provide a malfunction history as an aid in troubleshooting.

Interchange tapes among all transports and use the maintenance program read routines to ensure that
all transports can read tapes generated by other transports. If Step 7 was performed satisfactorily, any
malfunctions that occur during this step are probably due to head skew. Measure the head skew
(Paragraph 4.3.3.4) and if it is not within specifications, consult a DEC field service engineer. (Transports with misaligned heads must be realigned by a qualified DEC field service engineer.)

4.2.3 Tape Care and Cleaning
To obtain maximum longevity and efficiency from DECtapes, observe the following precautions and practices:
a.

Store the tapes where the temperature and relative humidity do not exceed 40 to 90°F and 20 to 80%
humidity.

Since strong magnetic fields can distort or destroy the flux reversals on the tape, protect the tape from
exposure to magnets or electrical coils.

Do not allow cleaning fluids to contact the DEC tape or painted surfaces.
(continued on next page)

4-2

If necessary, use a pointed wooden dowel that has been soaked in cleaning solvent to remove very

old, hard oxide deposits from the edges of the tape guides.
5.

Clean the tape guide path and the top of the read/write head with a clean, lint-free cloth moistened
with head cleaning solvent.

Using a dry, lint-free cloth, wipe the excess cleaning solvent from the read/write head and tape guides.

Allow at least 60 seconds for the remaining solvent to evaporate, then reload the tapes.

Check for proper operation of the reel motors and electronic brakes by momentarily pushing the
Forward ( - ) and Reverse ( - ) tape motion switches and observing that the tape moves in the
corresponding direction. If the tape does not stop smoothly, adjust the electronic brake (Paragraph
4.3.2.4).

monthly checkout for individual transports evenly throughout each month.
1.

Clean the exterior and interior of the cabinet with a vacuum cleaner and clean cloths moistened, if
necessary, in a nonflammable solvent. DO NOT USE SOLVENTS THAT WILL REMOVE PAINT.

Clean the air filters at the top or bottom of the equipment rack as described in the preventive maintenance section of the appropriate controller maintenance manual.

Clean the most frequently used tapes by placing a clean, dry, lint-free cloth over the read/write head,
loading the tape on the transport and manually running the tapes over the cloth.

Clean the take-up reels, if heavy use has caused oxide build-up around the hub.

Inspect the over-all condition of the transport.

Inspect the cable and logic modules to ensure that the modules are securely seated in the logic
mounting block.

4.2.3 Tape Care and Cleaning
To obtain maximum longevity and efficiency from DECtapes, observe the following precautions and practices:
a.

Store the tapes where the temperature and relative humidity do not exceed 40 to 90°F and 20 to 80%
humidity.

Since strong magnetic fields can distort or destroy the flux reversals on the tape, protect the tape from
exposure to magnets or electrical coils.

Do not allow cleaning fluids to contact the DECtape or painted surfaces.
(continued on next page)

4-2

Periodically clean the tapes by placing a clean, dry, lint-free cloth over the read/write head and then
running the tape over the cloth.

Do not use adhesive-backed tape to start the DECtape on the take-up reel. In time, this practice
accelerates oxide buildup on the hub and results in uneven tape packing on the take-up reel.

4.3 CORRECTIVE MAINTENANCE
4.3.1 Control Panel Lamp Replacement
Before performing this procedure, note the position of all burned-out indicators.
1.

Remove power from the transport.

Turn the mounting panel side-locking fasteners one-quarter turn to unlock the mounting panel.

Carefully lower the mounting panel until the support struts are fully extended (Figure 4-1).

Remove the backing plate from the control panel logic module by removing the two Phillips-head
screws.

Remove the four Phillips-head screws from the control panel logic module and lift the module free
from the mounting panel.

Unsolder and replace all burned-out indicators.

Reassemble the transport and restore power.

4.3.2 Reel Motor
4.3.2.1 Motor Removal
I.

Remove power from the transport.

Remove the tape reel from the hub.

Loosen the two hub Allen screws and slide the hub off the shaft.

Turn the mounting panel side-locking fasteners one-quarter turn to unlock the mounting panel.

Carefully lower the mounting panel until the support struts are fully extended (Figure 4-1).

Unplug the reel motor cable connector by pressing the locking tabs that extend from one of the
Mate-N-Lok connectors against the side of the connector body and separating the connector halves.
NOTE
If the reel motor connectors are held to the chassis by a nylon

cable holder, remove the top of the holder and free the cable.
7.

Remove the four screws securing the reel motor to the mounting panel and lift the motor and friction
bushings free from the mounting panel.

4-3

i~~~__ REEL MOTOR

CONNECTORS

SUPPORT
STRUT

HEAD
COLLAR

REEL
MOTOR

BACKING PLATES

Figure 4-1 Reel :\fotor Removal

4.3.2.2 Motor Replacement
1.

Inspect the friction bushings (PIN 12-09926) and spring (PIN 12-09917), and replace them if necessary.

Slide the friction bushings and spring onto the motor shaft, ensuring that the bottom tip of the spring
is properly seated between the wings of the C-ring retaining the motor bearing.

Insert the reel motor shaft through the opening in the mounting panel (Figure 4-1) and attach the
motor with the previously removed hardware.

Reconnect the reel motor cable connector.
(continued on next page)
4-4

Close and lock the mounting panel.

Slide the reel hub onto the motor shaft and lightly tighten the hub Allen screws.

Perform the hub clearance adjustment (Paragraph 4.3.2.3).

Restore the transport power and perform the electronic brake adjustment (Paragraph 4.3.2.4).

4.3.2.3 Reel Hub Clearance Adjustment
1.

With the hub gauge (P/N 74-08010), check for .017 inch clearance between the tape reel hub and the
flange on the mounting panel (Figure 4-2).

If the clearance is incorrect, loosen the Allen screws on the hub and make the necessary adjustment.

Retighten the Allen screws.
NOTE
Do not repeatedly loosen or tighten the hub Allen screws.
These screws are serrated cup type and may become damaged
with excessive use.

4.3.2.4 Reel Motor Electronic Brake Adjustment
1.

Load a tape on the transport to be tested.

Set the REMOTE/OFF/LOCAL switch to LOCAL.

Press and hold the Forward ( - ) tape motion switch. When the tape is up-to-speed, release the switch
and observe that the tape braking action is smooth without overshoot. If tape motion stops, then
reverses slightly when the switch is released, the braking time is too long. If the tape coasts, the braking
time is too short.

If necessary, adjust the top R2 (left transport) or bottom R 13 (right transport) potentiometer on the
M302 module to obtain the correct brake indications.

4.3.2.5 40-Hz Oscillator Adjustment
If, during remote turnaround operations, consistent mark track or read errors occur, check and adjust the 40-Hz
oscillator output in the following manner. Connect an oscilloscope to A03M2 or A03N2 and, if necessary, adjust
R2 of the G859 module to obtain a 25-millisecond (40-Hz) square wave.
4.3.3 Read/Write Head
4.3.3.1 Head Removal
I.

Remove power from the transport.

Remove the tape reels from the hubs.

Turn the mounting panel side-locking fasteners one-quarter turn to unlock the mounting panel.

Carefully lower the mounting panel until the support struts are fully extended.

Disconnect the 22-pin Amphenol head cable connector from the rear of the G851 Relay module
(Figure 4-3).

Route the Amphenol connector and cables from the rear to the front of the transport.

Remove the backing plate from the control panel logic module by removing the two Phillips-head
screws (Figure 4-1).
(continued on next page)
4-5

.Of7
r - - - - - - - - - HUB CLEARANCE

1]4-_ _ _ MOUNTING

PANEL

MOTOR

SHAFT

10-0178

Figure 4-2 Reel Hub Clearance

Remove the two head screws through the access holes in the control panel logic module.

Pull the head away from the mounting panel and remove the head collar by pushing on the back of the
collar to break the adhesive bond, then lifting the collar free from the front of the mounting panel.

10.

Thread the head cables through the mounting panel. Turn the Amphenol connector sideways and push
it through the hole in the mounting panel.

4-6

4.3.3.2 Head Replacement
I.

Clean the new head mounting face and the mounting area on the transport mounting panel with a
clean lint-free cloth moistened with head cleaning solvent.
NOTE
To ensure proper head alignment, the mating area of the head
and mounting panel must be entirely free from foreign matter.

Turn the 22-pin Amphenol head cable connector sideways and insert it through the hole in the mounting
panel front.

Install the head on the mounting panel with the previously removed hardware and ensure that the head
retaining screws are tightened securely.

Route the Amphenol connector and cables from the front to the rear of the transport and plug the connector into the rear of the G851 Relay module (Figure 4-3).

Open and close the mounting panel and ensure that the head cables do not chafe or bind.

6.,

Replace the backing plate on the control panel logic module (Figure 4-1) with the previously removed
hardware,

Restore power to the transport and perform the head skew check and adjustment (Paragraph 4.3.4.4).

Close and lock the mounting panel.

Refasten the head collar to the mounting panel and remount the tape reels on the hubs.

4.3.3.3 Head Output Check
To accomplish this check procedure, a single-channel oscilloscope with a high-gain differential preamplifier
(Tektronix type D plug-in) capable of handling millivolt signals over a 0- to 60-kHz bandwidth is required. If the
heads have been replaced or if consistent read errors indicate that the heads are not operating satisfactorily, clean
the heads and perform the following:
I.

Load a DECtape on the transport to be tested.

Manually run the tape forward until each reel contains approximately one-half of the tape.

Disconnect the 22-pin Amphenol head cable connector from the rear of the G851 Relay module
(Figure 4-3).

Set the oscilloscope controls as follows:
• sweep time
• vertical sensitivity
• trigger

10/ls/div
= 0.2mV/div(ifXIOprobes)
auto internal

Attach the scope probes to pins Band C, (Figure 4-3, insert) and the ground clip to pin D of the head
connector.

Press the Forward (_ ) or Reverse ( - ) tape motion switch and observe the scope display for an
approximate 10- to 12-mV peak-to-peak waveform.

Repeat Step 5, attaching the scope probes to pins F-H, P-R, U-V, and Y-Z. These signals may not appear
sinusoidal (as they do for pins B-C), but the peak-to-peak amplitude should be 10 to 12 m V. If this is
not the case, replace the head (Paragraph 4.3.3.1). (Only a qualified DEC field service engineer can
replace the heads in the field.)

4-7

GB51

RELAY
MODULES

AMPHENOL
HEAD
CONNECTORS

Figure 4-3 Head Connector Location

4.3.3.4 Head Skew Check and Adjustment - Perform the following check whenever an individual transport
cannot read tapes that were generated by several other transports without an unusual number of read errors. To
accomplish this check procedure, a dual-channel oscilloscope and a special G500 Skew Test module are required.
I.

Load a new (unformatted) or blank tape on the transport to be tested.

Format the tape using one of the applicable DECtape formatting routines.

Remove and interchange the reels so that the full reel is on the right hub.

Reverse the tape so that the oxide side is up by threading the tape directly from the bottom of the right
full reel onto the top of the left empty reel. Do not thread the tape over the heads.

Set the transport to LOCAL and rewind the tape onto the left reel.
NOTE
To maintain tape tension during the rewind operation, apply
light hand retarding friction to the right tape reel.

Thread the tape, oxide side up, in the normal manner onto the right reel and run the tape forward until
each reel contains approximately one-half of the tape.

(continued on next page)

4-8

Configure the G500 Skew Test module as follows (all switches N.C. = down, N.O. = up):
a.

S2 - Selects the read/write split coil winding. Use the up position for heads manufactured by
Brush or Applied Magnetics; use the down position for Western Magnetic or General Instrument
heads. (If this switch is in the wrong position, the read signal at terminal SIG I of the skew tester
will have twice the amplitude of the signal at terminal SIG2.)

S3 - Selects the input voltage. If the supply voltage at TB I on the rear of the power supply is
+ I 0 Vdc, use the up position; if it is +5 Vdc, use the down position. (Use the down position for
M series transports and the up position for R series.)

Plug the skew test module into any available logic block slot except slots 03, 04, or 18.

Disconnect the 22-pin Amphenol head cable connector from the rear of the G851 Relay module
(Figure 4-3) and connect it to the skew tester module, ensuring that the head connector key is
positioned relative to pin A as illustrated in Figure 4-4.

KEY

TESTER PLUG

HEAD CDNN ECTDR

CP-0288

Figure 4-4 Skew Tester to Head Cable Connection

10.

Set the oscilloscope controls as follows:
•
•
•
•
•
•

sweep time
vertical sensitivity
trigger mode
trigger source
trigger slope
preamplifier

10llS/div
I to 5V/div (depending on signal amplitude), calibrated
AC LF reject, internal
channel A
negative
add

II.

Attach the A channel scope probe to terminal SIG I of the skew tester and the B channel probe to
terminal SIG2.

12.

Set the test module switch S I up and, while running the tape forward over the head, adjust the 10 kn.
potentiometer on the skew tester for the smallest signal.

13.

Reset the scope mode switch to ALT and ensure that both signals have approximately the same amplitude and that the zero crossings occur simultaneously.
(continued on next page)

4-9

14.

Run the tape forward over the head and. check for less than a 2-microsecond (one-half the displayed
time) skew reading as indicated in Figure 4-5. Ensure that this measurement is taken as near the
tape length center as possible and that the scope is triggered from only one channel. For best transport
operation, head skew readings should be as close to zero as possible; however, skew readings greater
than 2 microseconds indicate that the head must be realigned.

15.

If the correck skew reading is not obtained,remove the head (Paragraph 4.3.3.1), thoroughly clean the

entire head and the head mounting surface on the transport mounting panel with a clean lint-free cloth
moistened with head cleaning solvent.
16.

Replace the head and recheck the skew. If the skew reading is still incorrect, align the head as follows.
Use extreme care when performing Steps a through d. If care is not taken the heads may become so
badly misaligned that it is impossible to distinguish a head with zero skew from one with a skew equal
to the interbit distance of the timing track.
a.

Move the tape forward, oxide side up, over the head and determine whether STGl leads or lags
SIG2.

If SIG 1 occurs before (leads) SIG2, remove the head and add 0.5 mil (1 inch long by 0.1 inch
wide) shims between the left side of the head and the mounting panel. If SIG I occurs after (lags)
SIG2, add the 0.5 mil shims to the right side of the head.

NOTE
It is a general practice to use 3M reflective tape strips as head
shims. Always insert the shim close to the edge of the head.
Never use more than three shims per side. If more than three
shims are required, the shims are being placed on the wrong
side of the head or the transport has other malfunctions.

Repeat Steps I through 15 to recheck the skew reading after shimming.

Using one of the DEC exerciser routines, read a known good tape that was generated by another
transport. If the head skew is less than 2 microseconds after shimming and the transport is able
to read a known good tape without errors, the head has been adjusted correctly. (After head
alignment, some of the customers old tapes may become unreadable.)

TRACK No.l0 (SIGll~

L ~

~~~/

~V
~TRACK

SWEEP TIME·5~s/OIV
VERT. SENS.=O.5V/DIV

No.1 (SIG2)

--..t *4J.lS I*Zero crossing time equals twice the skew time.
Actual skew: 2J,1.s. For best transport operation,

head skew should be as close to zero as possible.

CP -0286

Figure 4-5 Head Skew Waveform
4-10

4.3.3.5 Write Enable Circuit Check
I.

Set the WRITE ENABLE/WRITE LOCK switch to WRITE ENABLE and ensure that the WRITE
indicator lights.

Check for a ground signal at A06 pin S I (left transport) or A07 pin S I (right transport) when the
transport is selected.

Set the WRITE ENABLE/WRITE LOCK switch to WRITE LOCK and ensure that the WRITE indicator
goes off.

Check for a - 3V signal at A06 pin S I or A07 pin S I.

4.4 TROUBLESHOOTING
Tables 4-2 (Reel Motor Malfunctions), 4-3 (Control Panel Malfunctions), 4-4 (Logical Malfunctions), and Figure
4-6 list trouble indications and corrective check areas for specific portions of the transport. These tables are
intended to be used as a guide during trouble analysis and by no means do they cover all possible malfunctions
of the designated areas. When a transport malfunction occurs, perform the initial checks (Paragraph 4.4.1) before
proceeding to the tables.
4.4.1 Initial Checks
I.

Measure the ac line voltage to ensure that it is the correct value as indicated Qn the H72S Power
Supply label (Drawing C-CS-72S-0-1).

Meaure all the dc voltages at TB I on the rear of the H72S Power Supply. Ensure that either + I 0 or
+5 Vdc, but not both, is connected to the correct TB I terminal.

Ensure that the connections between the transport and the power supply are tight.

Ensure that all logic modules are securely seated in the logic block.

Ensure that the reel motor cable connectors (Figure 4-2) are tight.

Table 4-2
Reel Motor Malfunctions
Trouble Indications

Malfunction

Check

Motors do not run in LOCAL or
REMOTE.

No high or low motor drive
voltage.

3A SB fuse.

Motors turn freely by hand.

Oscillator not operating.

A03 (G8S9) module.

No drag on motors in LOCAL
or REMOTE Hold.

No low motor drive voltage.

SA fuse.

Motors have drag but do not
move ta pe in Fwd or Rev
LOCAL.

No high motor drive voltage.

6A fuse.

Motors do not run in LOCAL
or REMOTE. Motors do not
turn freely by hand.

Oscillator locked.

A03 (G8S9) module.

(continued on next page)

4-11

Table 4-2 (Cont)
Reel Motor Malfunctions
Trouble Indications

Malfunction

Check

Tape moves in one direction in
Hold. Tape moves in either Fwd
or Rev LOCAL, but not both.

No drive voltage to one motor.

SA fuse on B03 or B 18 (G847)
modules.

Tape does not move in Hold,
nor Fwd or Rev LOCAL.

Motor control module not receiving high drive voltage.

Output ofB03 or BI8 (G847) modules.

Tape moves but speed, acceleration, or smoothness is abnormal.

Motor not receiving proper waveshape.

Output of ABOI, AB02, ABI9,
AB20 (G848) modules.

Table 4-3
Control Panel Malfunctions
Trouble Indications

Malfunction

Check

WRITE indicator does not light
in WRITE ENABLE.

No -15V at indicator module.
Lamp burned out.

B04 or B I 7 (M922) modules.

Both transport REMOTE
SELECT indicators remain lit
in any position of the REMOTE/
LOCAL switch.

No +5V to indicator module.

Output of A03 (G859) module and
+5V terminal at rear of power
supply.

Address Select switch does not
select in one or more positions.

Select code not being received.

For -3V signal at faulty switch position or erroneous controller output.

REMOTE/LOCAL and Fwd/
Hold/Rev switches have no
affect. Motors run at all times.

No +5V at indicator module.

B04 or B 17 (M922) modules for
+5V.

Table 4-4
Logical Malfunctions
Trouble Indications
Tape does not move in either
direction.

Malfunction

Check
B07 or A 16 (M 11 7) modules.

No MOl signal.

Tape moves in only one direction. No DIRI or DIRO signal.

B05 or B 16 (M 113) modules.

Tape does not stop in normal
time, seems to coast to a stop.

No BRAKE signal. (Brake time
is less than 80 ms.)

Reel motor electronic brake (Paragraph 4.3.2.4).

Tape reverses after stopping.

BRAKE signal too long.

Reel motor electronic brake (Paragraph 4.3.2.4).

No remote control.

I/O signal not received.

Level converter (M 5 31 , W513, or
M941) modules required for interface with controller.

I/O signal not sent.

Controller output.
(continued on page 4-14)

4-12

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PART NO

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iTEM

MODEL

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TO!.,ERANCES
DECIMALS

,~~
~'*fj II, "i-1'1-:1_

.xxx - ± 1)05
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Figure 4-7 M908 Module Layout

Table 4-5
Left Transport Source Test Points
Test
Point

Wire Source
Color (TU56)

LMOI

via

B07-EJ

-+ LOCAL/ <-LOCAL
Hold*/REMOTE

high
low

M117-B07
M113-B06

L DIRI

blu

B07-LJ

-+LOCAL
<-LOCAL/REMOTE
Hold*

high
low
no change

M117-B07
M113-B06

L SELECT

grn

B05-N2

without REMOTE selection

low

M113-B05

LFWO LOCAL

yel

B04-MI

-+LOCAL
<-LOCAL/Hold */REMOTE

low
high

control
panel

L REV LOCAL

orn

B04-K I

<-LOCAL
-+LOCAL/Hold */REMOTE

low
high

control
panel

LHOLO

red

B04-PI

Hold*
low
-+LOCAL/<-LOCAL/REMOTE/OFF high

control
panel

LWRT ENAB

brn

B04-AI

WRITE ENABLE
WRITE LOCK

high
low

control
panel

L REMOTE

blk

B05-S2

REMOTE
LOCAL/OFF

high
low

M113-B05

Signal

Switch Setting

*Hold is the center switch position between -> and <-- .

4-15

Logic Level

Modules and
Locations

Table 4-6
Right Transport Source Test Points
Test
Point

Wire Source
Color (TU56)

RMOI

wht

AI6-E1

RDIRI

gry

RSELECT

RFWDLOCAL

Logic Level

Modules and
Locations

-+LOCAL/+-LOCAL
Hold*/REMOTE

high
low

Ml17-A16
Ml13-B06

A16-P2

-+LOCAL
+-LOCAL/REMOTE
Hold*

high
low
no change

M113-B06
M117-A16

via

B16-N2

without REMOTE selection

low

Ml13-B16

blu

BI7-Ml

-+LOCAL
+-LOCAL/Hold* /REMOTE

low
high

control
panel

RREVLOCAL

grn

B17-Kl

-+LOCAL
+-LOCAL/Hold */REMOTE

low
high

control
panel

RHOLD

yel

B17-Pl

Hold*
low
-+LOCAL/ +-LOCAL/REMOTE/OFF high

control
panel

RWRTENAB

orn

BI7-Al

WRITE ENABLE
WRITE LOCK

high
low

control
panel

RREMOTE

brn

B16-S2

REMOTE
LOCAL/OFF

high
low

M113-B16

Signal

Switch Setting

*Hold is the center switch position between -> and +- .

Table 4-7
Right and Left Transport Termination Test Points
Test
Point

Wire Source
Color (TU56)

via

A03-A2

NONE

+5 ± 0.5 Vdc

G859-A03

-15

blu

A03-B2

NONE

-15 ± 1.5 Vdc

Power
Supply

OSC 1 (left)
OSC 0 (left)
OSC I (right)
OSC 0 (right)

Cl
Dl
El
FI

grn
yel
orn
red

BOI-S2
BOI-D2
B20-S2
B20-D2

NONE
NONE
NONE
NONE

40 Hz
square
wave

LOFF

brn

BOI-R2

OFF
REMOTE/LOCAL

high
low

MI13-B05

ROFF

blk

B20-R2

OFF
REMOTE/LOCAL

high
low

M113-B16

LMOI

wht

B05-PI

-+LOCAL/+-LOCAL
REMOTE/Hold*

high
low

Signal

Switch Settings

Logic Level

Modules and
Locations

G859
A03

(continued on next page)

4-16

Table 4-7 (Cont)
Right and Left Transport Termination Test Points
Test Wire Source
Point Color (TU56)

Signal

Switch Settings

Modules and
Locations

Logic Level

RMOI

gry

B 16-PI

+-LOCAL/-+LOCAL
REMOTE/Hold*

high
low

LSELCODE

vio

BOS-U2

REMOTE and selected

high

RSELCODE

blu

B16-U2

REMOTE and selected

high

L RUN FWD

BOS-Kl

-+LOCAL
+-LOCAL/REMOTE/Hold
Release from +-LOCAL

high
low
high***

MlI3-BOS
MlI7-B07

LRUN 2 REV

yel

BOS-K2

+-LOCAL
-+LOCAL/REMOTE/Hold
Release from -+LOCAL

high
low
high***

M113-B05
M117-B07

R RUN FWD

B16-Kl

+-LOCAL
-+LOCAL/REMOTE/Hold
Release from -+LOCAL

high
low
high***

M113-B05
M117-B07

RRUN2 REV

B16-K2

-+LOCAL
+-LOCAL/REMOTE/Hold
Release from +-LOCAL

high
low

MI13-BOS
M117-B07

*Hold is the switch position between -.. and +- .
**Module depends on controller type.
·"High for 80 to 90 ms.

Controller Input Test Points
The following input signals from the controller are also available on this cable.
STOP

yel

A04-D2

Controller GO

red

A04-F2

Controller STOP

REV REM

blk

A04-12

Controller REV REM

FWD REM

gry

A04-L2

Controller FWD REM

ALL HALT

blu

A04-N2

Controller ALL HALT

SELCODE

yel

A04-R2

Transport Selected

*Voltage level depends on controller type.

4-17

4.5 RECOMMENDED SPARE PARTS
One of each of the modules listed in Table 4-8, plus three pica fuses (Part No. 1205747), should be retained at
the site as backup spares.
Table 4-8
Recommended Spare Parts
Module

Name

M531
M040
G851
MIl7
Ml13
M302
G848
M908
W032
G888 Option*
M922
M9230ption*
G847

Bus Converter
Solenoid Driver
Relay
6-4 Input NAND Gate
10-2 Input NAND Gate
Dual Delay MV
Motor Control
Connector
Cable Connector
Manchester Reader/Writer
Cable Connector
Cable Connector
Dual Motor Voltage Control

* Refer to Paragraph 1.3.

4-18

APPENDIX A
REFERENCE DRAWINGS

Title

Drawing No.

Rev

Page

TU56 Assembly
Transport Logic Diagram
Module Utilization
Wired Assy TU56
Motor Control G848
Dual Motor Voltage Control G847
Relay G851
Clock and Regulator G859
Manchester Reader/Writer G888
Solenoid Driver M040
One Shot Delay M302
10-2 Input Nand Gates M 113
6-4 Input Nand Gates M 117
Negative Bus Converter M531
Connector Module M908
Connector W032
Level Amplifier W513
Blank Module W990
Power Supply 725

E-UA-TU56-0-0
D-BS-TU56-0-TLD
D-MU-TU56-0-MU
D-AD-7006321-0-0
D-CS-G848-0-1
B-CS-G84 7 -0-1
B-CS-G85 1-0-1
B-CS-G859-0-1
B-CS-G888-0-1
B-CS-M040-0-1
B-CS-M302-0-1
B-CS-M 113-0-1
B-CS-M 117-0-1
C-CS-M53 1-0-1
B-CS-M908-0-1
B-CS-W032-0-1
B-CS-W513-0-1
B-CS-W990-0-1
C-CS-M53 1-0-1

K
K
F
E
J
D
B
C

A-3
A-7
A-II
A-13
A-15
A-17
A-17
A-18
A-18
A-19
A-19
A-20
A-20
A-21
A-22
A-22
A-23
A-23
A-24

A-I

E
L
C
E
A

E
A
C

-SC"cWDRI';"f< SLCT MUST BE VERTICAL TO I.~SURE
PROF,;; LOCKI~(; V."E.~ ~C.I IS IN CL2SED

..r----:-_____

-----'/~(-I---------

(3 (OPTIONAL)
Lj

3
19.00 REF

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00
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SPACING .017
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MOTOR NO.4}

WHEN DOUBLE UNIT

IS ORDERED

MOTOR NO.3

8
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CHASSIS

6REF

SECTION 8-B

SECTION

A-A

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DESCRIPTION

PART NO

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NO

PARTS LIST

FIRST USED ON OPTIONI MOOEL

TU56

TOLERANCES
DECIMALS

.xxx - ± D05
.xx = ± 1J2

- ± .1

NEXT HrG"E~ ASSV

E- UA - T U5 6- 0- 0

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200

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1)co)68

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~'-+ __________________~-,~~.~c.~·~~·-,C~'~~~U~,-,-'~B~OA~R~D
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10(.5'165

X-Y COORDINATE HOLE LOCATIO';

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1 '1

1300391

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9006402-4

07
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2.2K

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82K

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UNLESS OTHERWISE INDICATED'

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CONNECTOR IS JEC .1209340
CONNECTOR PINS ARE rEC .,<'09456
Fl, F2

ARE 5 AMP

NOTE. QI,02,04,05 HAVE VARIED PACKAGES
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ff'R-'t
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80TTOM

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MALE

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AF

AI-!

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133-022-03

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1-215-e

EQUIPMENT
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D!lB102

t
A-17

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4.1K

10"10

10%

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r--'_·_~~--4-~G~N'''~--+--4----.--4------.-4--4------C,GNO

.,,
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UNLESS OTHERWISE INDICATEO'

10%

RESISTORS ARE IK, l/4W,!5%
DIODES ARE 0664
CAPACITORS ARE .39MFD,IQOV, 10"10
TRANSISTORS ARE OEC6!534B
EI IS OEC740 I
PIN 14 ON EACH tC=+!SV
PIN 1 ON EACH IC"GND

L---4~~--~~-----.--~-+~--+-~-~--+---4~+--~------D,+5V

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h"~ SCH[MAliC IS IUF!NISH£O ONLY FOR TEST ANO MAINTENANCE PURPOSES
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TRANSISTORS ARE DEC 1008-S

£1,E2 ARE MCt709CG
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•
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2N'0098
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D[C FOII~ NO
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DEC
3190

UNLESS OTHEIII:WISE INDICATED:
DIODES ARE MR20el
TRANSISTORS ARE OECI5340
f I IS DEC1420N
PIN 7 ON IC • tND
PIN 14 ON IC" +5V
RESISTORS ARE 1/4W, 10%

PARTS

4,700

L -_ _ _ ._ _ _ _ _ _--4-_ _ _ _ _ _ _ _

--'-~

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L.IST A-PL-M040-0-0

THISSCHfM,\,TlC IS FUIINISH£QONLY FOil TESTANO MAINTENANCE PUIlPOSES THE
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r-------~--~----,----~~------~-------1---~-----f----~--~-:+~~

180

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330
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AI6
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330

UNLESS OTHERWISE INDICATED
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TRANSISTORS ARE 2N4214
RESISTORS ARE J/4W, ~%
DIODES ARE 0664
G38 Gil ARE MYLAR
EI IS OfC74H40N
PIN 7 ONIC'S= GND
PIN 14 ONIc'S= +5V
R2 8 RI3 ARE I1'ELITRIM POT .7SPR
I.OMFD CAPACITORS ARE TANTALUM
E2 IS DEC7413N

."
270

--i

PARTS LIST A-PL-M3pO"'2c:-;;0,;;-"'0=::-;-;;;;======,-,-_ _ _ _ _ _-,-;;;;-;-_ _ _ _ _ _ _ _ _ _

mDmDDma m~NE SHOT DELAY M302
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EQUIPMENT
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SIZE

CODE

.......... " ........ c ..........

PIIINTEDCIIiCUITRH

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THIS SCH[M ... TIC IS FUR"'ISH[O O"'lY FOR TEST "'NO M"'!NT[!II"NCE PURPOSES THE I
CIACUITS ... RE PROPJIIEUAY If\j f\jUURE ... ",OSHOUL08E TRE ... nO"'CCOROINGLY
COPYRIGHT 1••7 8Y OIGIUL EOUlPME",T CORPORUION

"V ---A'
NOT USED -15\1 - - - ••

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PIN 14 ON lEACH IC "+SV
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THRU E3
AND R3

INTEGRATED CkT. DEC7400N
RES. 750 1/4W 5% CC
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DUE

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1905575
1301401
1300293
1001610
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10-2 INPUT
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1r-----+-- ~g~~;R~~16~~ CS'IMI13-'O':~I'

THIS SCHEM ... TIC IS FURNISHED ONLY fOR HST "'ND M... INT(NUICE PURPOSES THE'I
CIRCUITS ... RE PROPRIET ... RY IN ","'TURE "NO SHOULD BE TRE"'T(O ... CCOROINGlY
COPYRIGHT , • • 78Y OIGIUL £QUIPME"'T CQRPQRUION

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TU56 DECtape TRANSPORT
MAINTENANCE MANUAL
DEC-OO-HRTC-D

READER'S COMMENTS

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Please describe your position.
Name _________________________ Organization __________________
Street _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
City _ _ _ _ _ _ _ _ _ __ State

Department
Zip or Country _ _ _ _ _ __

-FoldHere -

DoNotTear-FoldHereandStaple -

Postage wiD be paid by:

Digital Equipment Corporation
Technical Documentation Department
146 Main Street
Maynard, Massachusetts 01754

- - -- --

FIRST CLASS
PERMIT NO. 33
MAYNARD, MASS.
BUSINESS REPLY MAIL
NO POSTAGE STAMP NECESSARY IF MAILED IN THE UNITED STATES

DIGITAL EQUIPMENT CORPORATION

~DmDDmD WORLDWIDE SALES AND SERVICE

MAIN OFFICE AND PLANT
Maynard . Massachusells. U.S_A 0175<1 ' Telephone From Mefropol,I,m C(,l~lun 6468600 . Elsewhere (617)-8'97-5111
TWX 710 -347--0212 Cable DIGITAL MAYN TeleJl 94-8457

DOMESTIC
NORTHEAST

MID-ATLANTIC (cent.)

CENTRAL (cent.)

WEST

REGIONAL OFFICE
235 Wyman Street. WHitham, Mass 02154

Princeton

us Aoute I, Prlncoton, New Jersey 08540

MICHIGAN
Ann Arbor
230 Huron View Boulevard. Ann Arbor. Michigan -ca103
Telephone (313)·751-1150
Dataphone 313-769-9883
DetrOiI
23777 Greenfield Road
SUite 189
SouthfIeld Michigan 48075
Dataphone 31J..557·Xl63
MINNESOTA
MinneapoliS
8030 Cedi>r Ave South. MInneapolis. M lnnesote 55-420
Telephone (612)·85<1,6562·3· 4-5
Dataphone· 612-85-4-1410
MISSOURI
Kansas Clly
1'2-401 East43rd Street. Independence. Missouri 64055
Telephone (816}·252·2lXJ
Dataphone 815·-461·3100
SI Lou,s
SUite 110_ 115 Progress Parkway
Maryland Heights. MIssouri 5:J043
Telephone (31 4}-878-<l310
Dataphone 816·EI·3100

REGIONAL OFFICE'
310 Soquel Way. Sunnyvale California 94086
Telephone (408)-135-9200
Dataphone 4Q8..135·1820

Telephone, (617)-890-0330'031Q

Dataphone 61H!9Q.3012 or 3013

CONNECTICUr
Menden
240 Pomeroy Ave. Menden. Corm 06540

Telephone {20J)·231-844117466

Datllphone 203-237-8205

Fa,rfu~ld

127S Post Road. FBlrf'eld. Conn Cl64:ll
Telephone (203)-255--5991
NEW YORK

~~Ci~~~~ Creek Road , Rochester _New York

Telephone (716)·4St·t700

Dataphone

716244 -1600

Syracuse
6700 Thompson AOlld. Syracuse New York 13211
Telephone (315) 437-159317085
Dataphone 315-454-4152

MASSACHUSETTS
Marlborough

One Iron Way
Marlborouqh Mess 01752
Telephone (617)-481-7400

Tele~

710-3<17-0348

MID·ATlANTIC
REGIONAL OFFICE
U S Route 1. Princeton, New Jersey 08540

Te lE'pnone(609H52·2940
FLORIDA
Orlando
SUIte 130, 7001 Lake Ellenor Drive. Orlando. Florida 32IJ)9
Telephone (:xJ5}·851·4450
Dataphone 305-859·2360
GEORGIA
Atlanta
2815 Clearvlew Place. SUite HlO
Atlanta. Georqia 03)40
Telephone (40<1)·451·1411
Dalaphol'lE! 305·859·2360
NORTH CAROLINA
Durham/Chapel Hili
E~ecutlve Park
3700 Chapel Hill Blvd
Durham. North Carolina 27107
Telephone (919}·489-3347
Dataphone 919·489·7832

Telephone (600)·452,2940

Dataphon@

609-452·2940

NEW YORK
long Istand
1 Huntlflgton Oundrangle
SUlle 1507 Huntlnqlon Slahon, New Yo<lI 11 IE
Telephone (516}-694--4131 (21'2)--895-8)95
Dataphone 516·293-5693
Manhallan
810 7th Ave 22nd Floor
New Vorll . NY 10019
Telephone (212)-582-1300

PENNSYLVANIA
Philadelphia
Digital Hall
17-40 Walton Aoad. Blue Bell Pennsylvania 19422
Tetephone (215}-825-4200
TENNESSEE
Knoxville
6311 Kingston Pike, Suite 21E
KnO'lvdle. Tennessee 37919
Telepho .. e (615)-5886571
Dataphone 615-584-0571
WASHINGTON DC
L~ .. ham 30 Office Building
49(X) Princess Garden Parwway, Lanham. Mllrylll .. d
Telephone (301}459-79<Xl
Da!aphone :xJl·459·79OQ X53

CENTRAL

OHIO
Clevetand
2500 Euclid Avenue_ Euclid. Ohio 44117
Telephone (216)-946-8<1S4
Dataphone 216·9E·8-477
Dayton
3101 Kettering Boulevard
Dflylon. Ohio 45439
Telephone (513)·294 ,3323
Dataphone 513·298· 4124
OKLAHOMA
Tulsa

3140S, Winston

REGIONAL OFFICE
!8S0 Frontage Road Northbrook. illinois 60062
Telephone (312)-498-2500
Dataphone 312·498-2500

E, ,.

INDIANA
Indianapolis
21 Beachway Drive. SUlle C
Inchanapo1!s, Indiana 46224
Telephone (317)·243-8341
Dataphone 317-247·1212
ILLINOIS
Chicago
1850 Frontage Road
Northbrook. illinois 6006'2

Wmston Sq BldQ Sulle 4 Tulsa. Oklahoma 74135
Telephone (918)-749 4476
Dataphone 918·749-2114

PENNSYLVANIA
P,ttsburgh
400 Penn Center Boulevard, Pittsburgh. Pennsylvania 15235
Telephone {412)·243·9404
Dataphone 412·824·97:xJ
TEXAS
Dellas
Plaza North. Suite 513
2BOO.-.lBJ Freeway. Drtllas. Texas 75234
Telephone (214}·620·2051
Dataphone '214-620·2061
HOUSTON
66S6 Hornwood Dflve
Monlerey Perk. Houston , Texas 77036
Telephone (713}711·3471
Dataphone

ARIZONA
Phoenl~

4358 East Broadway Aoad. Phoen'x. Arizona 85040
Telephone (602)-268--3488
Dataphone 602-268-7371

CAL/FORNIA
Santa Ana
2110 S Anne Street. Santa Ana. California 92~
Telephone (71 4)979·2460
Dalaphone 714-979·7850
San Diego
6154 MISSion Gorge Road
SUite 110. San Diego. Californ ia
Telephone (714}-280-7880/7970
Dataphone 714-28Q..7825
San FranCISco
1400 Terra Bella. Mountam View. Calilornia 94040
Telephone (415}-964-6200
Dataphone 415-964-1436
Oakland
78SO Edgewater Drive, Oalllan(l, California 94621
Telephone {415},635-5<l5317830
Dataphone 415--5622160
West los Angeles
1510 Cotner Avenue. los Angeles. California 90025
Telephone (213)·4]9·3791/4318
Dataphone '213·418·5626
COLORADO
7901 E_ Bellevue Avenue
SUite 5. Englewood. Colorado 80110
Telephone (:xJ3)·770·6150
D!!taphone :xJ3·77o-6628
NEW MEXICO
Albuquerque
10200 Meflulil N E . Albuquerque. New Mexico 87112
Telephone (505)-296·5411/5428
Dataphone 505·294·2330
OREGON
Portland
SUI Ie 168
5319 S W Westgate Drive. Portland, O'egon 972'21
Telephone. (S03}·291-3761/3765
UTAH
Sal! lake City
429 lawn Dale Oflve_ SaIl Lalle C,ly. Ulah 84115
Telephone (801}<l874669
Oataphone 801·467-0535

NEW JERSEY
F,Hrfteld
253 Passaic Ave, Fairfield New lersey 070Cl6
Telephone (201)-227-9280
Dataphone 201·227·9200
Metuchen
9S Main Street Metuch(·n New Jersey 08B40
Telephon<i! (201)·549·4100/2000
Dataphone 201·548·0144

LOUISIANA
NewOrieags
3100 Aldgelake Drive, SUite 108
Meta"'e, LOUisiana 70002
Telephone (504)-837·0257
Dataphone 504-833·2800

EUROPEAN HEAOQUARTERS

UNITED KINGDOM (cont.)

ISRAEL

JAPAN

DI9'tal Equipment Corporal Ion International Europe
81 route de l'Aire
1211 Geneva 211 , Swilzerhlnd
Telephone oi2 79 50
Telex' 22 883

READING
Fountain Hous,., Butts Centre
Reading RGI 70N. EnQland
Tc:-Iephono (07 34)·583555
Tetu

DEC Systems Computers Ltd
TEL AVIV
Solte IOJ. Southern Heblllluk Street
Tel Av iv. I srael
Telephone (OJ) 44311 4/ 4-40163
Telex 922-33-3163

Digital EquIpment Corporal!on International
Kowa BuHding No 16 - Annex. First Floor
9·20 Ak "lIki !·Choma
M iflilio-Ku . Toh;ro 107 . 'eplltl
Telephone !i8e·2111
Tele>! 1-26-428
Hlkel Trading Co . ltd (sales only)
l(ol!llo-l(lIlken Bldg
No 18·14 Nishishimbashi 1-Chome
MinMo·l(u. Tokyo. Japan
Tf'lephbne 5915246
Telex - 781·4208

Dataphone 312·498·2500

713-777·1071

WISCONSIN
Milwaukee
8531 West Capitol Dnve_ Milwaukee. Wisconsin 53222
Telephone (414)·463 9110
Dataphone: 414-463·9115

WASHINGTON
Bellevue
13401 N E: Bellevue. Redmond Road. ~uile 111
Bellevue_ Washington 98005
Telephone (206)-545-4058/4.55·5404
Dataphone 206-747-3754

INTERNATIONAL

FRANCE
Digital EqUipment France
Centre S,lic - C,del( L 225
94533 AunqlS, France
relephone 687·/13-33
Telpx

GRENOBLE:
Digital Equlpm'!nt FrRnce
Tour Mangtn
16 Aue Du Gal Mangon
38100 Grenoble. France
Telepho .. e {76}87-'l6-O1

8483218

NETHERLANDS
D igital EquiPment N V
THE HAGUE
$" Winston Churchillian 370
Rijswljll/The Hague Netherlands
Telephooe 949220
Telex 31533

26840

CANADA
Digital Equ'pment of Cana(la. Ltd
CANADIAN HEADQUARTERS
PO Bo~ 11500
Ottawa, O'1taflo. Cl'IMdn
K2H 8Ka
Telephone {613}·592-5111
TWX 610-562·8732

BELGIUM
Tele~

212·32882

GERMAN FEDERAL REPUBLIC
Digital EqUipment GmbH
MUNICH
8 Muenchen 13,Wallensteonplatz2
Telephone 0811·35031
Telex' 524·226

COLOGNE
'i Koeln 41 AachenN Str~s!;e 311
Tell'ohof'" 022144 40 -9<;
Tele~ 888·2269
Teleqrilm Flip Chip Koeln
FRANKFURT
6078 Ne\I·ls.nnburg 2
Am FOfstnus Gravebruch 5-7
Tel.nphone 06102·5516
Te!e~ 41 ·76·82
HANNOVER
3 Hnnnover POdbipl!lklstr(lsse 102
Telephone 0511-69-70·95
Tetel< 922·952
STUTTGART
D-73Ot Kl'mn", SlutlqMt
MilrcoPolo·Strns~f' \
T('lephon(' {()7~1]4'jr,Q 6r,
Tete,," 84172'2.393

AUSTRIA
DIQil(l1 Eq"lpmenl Corporation Ges m b H
VIENNA
MilnahdlNslrllsse 136. 1150 V'enna 15. Austria
Telephone 855186

UNITED KINGOOM
Dlolt'll EQulomenl Co Ltd
U K HEADOUAATEAS
Fountalfl HOllse. BuH!; Cen""
Fleildlnq RGI 70N Enqland
T(,lf' 1l48J271l
Telephone (073 4) 5R15ss,
BfRMINGHIlM
M"IIl'y Budd,nqs
29/31 B"mlnohllm Ro1 Suno" Colo1f,,,ld
Wllrw.ekshlf(, Enqlf'lnd
Telf'phone 0'213'15-5501
T"I"7 337-060
BRISTOL
Fish Pono1s Anild FIsh Pono1s
BrIstol Enol"nd BSI61HO
Tpleohone B"slol 6<;1 431

Dlgllal Equipment N V IS A
BRUSSELS
108 Aue D'Arlon
1040 Brussels. Belgium
TelephonE' 02·139256
Tele~

TORONTO
2550 Goldenrldqe Aoad, Mlssissauga, Onlarlo
Telephone {416}·270-9400
TWX 610-oi92-7118
25297

Digital Equipment Corp A/S
OSLO
TrondhE'lmsveien 47
Oslo 5_ Norway
Telephone 02/68 34 40
Tele~ 19079 DEC N

Digital Equipment Ak!lt'bolag
COPENHAGEN
Hellerupveg 66
~900 Hellerup Denmark

FINLANO

D'Q'lal [QUlpmt'ni Austr~IIil Ply ltd
ADELAIDE
6 Montros" Avenue
Norwood South Allstr{ll'll 'i06i
Tel!,ptton.n (oa}42 1339
T('II'~ 790·82825

SWITZERLANO
Dig<lal EQUipment Corp or ill Ion S A
GENEVA
20. 011.'" Ern.nSI Ansermel
BroJt" Posta Ie '23.1'211 Geneva 8. SWitzerland
Tel('phon" No 022:?C 4e2C ilnd W:>8 9~ "nd 20 68 93
Tple> 289201 ..

ITALY

EDINBURGH
Sh,,,1 Housc . Cr1\lqshill I "II'1q510n
West lolhlM. Scotlllnc!
Telephone 3270<;
T"I ... 72;113

D'(1,t(l1 EQ'Hpfllf'nl S (),\
,,-"IILAN
Cursu G.'''b.lh!, 49 ?01;>I MdMIO, It.lly
Telephone (02}·879as 1/'2/3/4/5
Tele~

....MNCHESTER
"rndnl .. Ho'l!;"
C~est"r Ao'ld S!re!lorrl "-'.lnrh.n!;!!!r ~)37 9BH
T.nll"pht)!'l{' {OO1 )fI6<;.7Ql1
Tl"le~ 66!'l666

printed in U.SA

r·6OC>9

'000
79040616

CANBERRII
27 CollI" 51
Fyshwl c\< ACT 2609 A\lSlrall"
Telephone (061}·9'i9013

843·33615

GrilnduXN 76 Barcelon!! 5

SYDNEY
PO Bo> 491 . Cro,",s Npst
N S W !\"strilil" Xl6r,
T"lpnho"'" (O?) 419 7'./iS

T('lp.

BUENOS AIRES
Coasin SA
V'Hey del PIIlO. 4071
Telephone 523185

Buenos AIres
Telex 012·2264

BRAZIL
RIO DE JANEIRO - GS
Ambrlex S A
Rua Ceara. 104 2 e 3 andares ZC - 29
R,o De 1<lnelro - GB
Telephone 26-4-7406/0461/7625
SAO PAULO
Ambflex SA
Aua Tupl. S35
Sao Paulo - SP
Telephone 52-71106/1870,51--0912
PORTO ALEGRE - RS
AUil Coronel Vicente 421/101
Porto Alegre - AS
Telephone '2 4 7411

CHILE
SANTIAGO
CoaSIn Chile Ltda {sales only}
Cas>!l" 14588. Correo 15.
Telephone 396713
Cable COACHll

INDIA
BOMBAY
HlndJtron Computo;ors Pvt Ltd
69/A, l JnQmohandas Marg
Bombay·6(WB} Ind,a
Telephone 38·1615 36·5344
Cable TEKHIND

Tele~

MEXICO

PERTH
643 M"".l), Slr""1
West Puth . Wf'S!Nn AIISlr~I", 6(XY.
TC":phonr (0CI?PI49 Q1
Telex 700g21<10

D'9,lal EQUipment Corporiltlon Ltd
MADRID
tq.l<O Inq('n,('ros S A Enrique larreta 12 Mildfld 16
Tel"ohone '21~ 3'; 43
Tell" 27249

BARCELONA
/,111'0 Inq"",Nos S A
T('lf'phone 221 ~4 66

DRISBIINE
1.131..nlrhhilrrll Slr,nr,!
Sp""Q
Br<sh;ln ..
T",lephonp

MElSOIJRN[
6n Park S!'''r>t 5nl;t11 M('lboll"w . VIClO"il J2Q',
AuSlr;)I'a
T(,I('phonf' (03}6Cfl;>f\88
Te''''' 790-30700

SPAIN
'27"liQ

GENERAL INTERNATIONAL SALES

AUSTRALIA

Dlqllal Equipment AB
HElSINKI
T,ltsm<lantle6
SF-00710 HelSinki 71
Telephone (090) 370t33
C<1bl" Dlqlta l HelSinki

Bilton House. U~brodqe Road fallnQ Lono1on W 5
T"lephone 01·<;79·'2334
Telc~ '2'2371

House
Holborn. London
WC 2B r,PT, Ennlnnd
Tf'lephone 0140<;-2614/4067
TI'II"

VANCOUVER
Suite 202
644 S W MMln!? Dr Vilncouver
Bfltlsh Columbia C~"ada V6P 5Yl
Telephone (604)·315·3231
Tele~ 610·9292006

REGIONAL OFFICE
146MainStreel Maynard. Massachusetts 01754
Telephone (617)897·5111
From Melropolilan Boston, 6-46-8600
TWX 710347·021710212
Cable DIGITAL MAYN
Tele~ 948457

DENMARK

fAUNG

~.~Il".1q"!'I"'"nt
41 PM~rr 5t

ARGENTINA
6104224124

CALGARY tEdmonton
SUite 140. 6940 FISher Aoad S E
Calgilry. Alberta_ Conads
Telephone (-403) 435·4881
TWX 403·255-7408

NORWAY

ZURICH
D ,q,till EQUipment Corp AG
Sch.1Hhausf'rstr 31~,
CH 00"(1 Z,;r,ch $''-'''!I''r)""o1
T('I"nhnn" 01464191
T,.,I,.,.

LONDON

MONTREAL
9O<IS Cole De Llesse
Dorval Oueh'!C Canada H9P 2M9
Telepho"e (514)636·9393
Tele~

SWEDEN
Digital Equipment AB
STOCKHOLM
EnglundovaQen 7,17141 $olna, Sweden
Telephone 98 1390
Telex 1-) 50
C~ble
DJgltal Stockholm

PUERTO RICO
DiQ'tal Equipment Corpor~!lon De PUNtO RICO
407 del ParQue Sireet
Santurce Puerto RICO 00912
Telephone (809)·723-8058/67
TeleJl 385-9056

MEXICO CITY
Mel<ltell SA
Eugenla4()8DePIOs 1
Aodo Poslill 12·1012
Me~,co 12 :'0 F
T('lephone (905) ~09·10

PHILIPPINES
MANilA
Stanforri Computer Corooratlon
p 0 Bo~ 1608
416 DilSm""'lIIS St Manila
Telephone 496896
Telex 742-0352

790 2074Q

VENEZUELA
NEW ZEALANO
Dajltal (qllOpm('nt COrPOrMlon Ltrl
AUCKLAND
Hdlon HClIIse . 430 Oul'f'n Sireet . Box 2471
Auckland New Z('nland
T!'I!,phone 75533

CARACAS
CoaSln C A
Apartado 50939
Silbana Gr,1nde No 1 CAracas 105
Telephone 72-8667 72·9637
Cable INSTAUVEN

011·'2594 Plenty