EAI TR-20 User manual

COMPUTER·
DPERATDR'S REFERENCE
HANDBODK
© ELECTRONIC ASSOCIATES. 1NC. 1964 • PR1NTED IN U.S.A. • PUBL. NO. 00 800.2003-1 • .JUNE 1967

RELATED PUBLICATIONS
The table below lists other publications which may be of interest to the
readers of this manual. Unless otherwise indicated by title or footnote,
all are maintenance handbooks. Note that maintenance handbooks directly
applicable to a particular system are normally supplied with the system.
Title
Handbook of Analog Computation
TR-20 Maintenance Manual
Repetitive Operation Display Units,
Models 34.034 and 34.035
Pub"lication Nl.nllber
00
800.0001-3
00 800.2006-0
00 800.2024-1

M226-3
NOTIC E
In order to enable us to process your requests for spare parts and replacement items quickly
and efficiently, we request your conformance with the following procedure:
1. Please specify the type number and serial number of
the basic unit as well as the EAI part number and de-
scription of the part when inquiring about replacement
items such as potentiometer assemblies or cups, re-
lays, transformers, preciSion resistors, etc.
2. When inquiring about items as servo multipliers, re-
solvers, networks, printed circuit assemblies, etc.,
please specify the serial numbers of the major equip-
ment with which the units are to be used, such as:
Console, Type 8811, Memory Module, Type 4.204,
Serial No. 000, etc. If at all possible, please in-
clude the purchase order or the EAI project number
under which the equipment was originally procured.
Your cooperation in supplying'the required information will speed the processing of your requests
and aid in assuring that the correct items are supplied.
It is the policy nf Electronic Associates, Inc. to supply equipment patterned as closely as possi-
ble to the requ':.:rements of the individual customer. This is accomplished, zt'ithout incurring the
prohibitive cos:is of custom design, by substituting new components, modifying standard com-
ponents, etc., wherever necessary to expedite conformance with requirements. As a result,
this instruction;. manual, which has been written to cover standa'rd equipment, may not entirely
concur in its cr:Jnte.nt with the equipment,supplied. It is felt, however, that a technically quali-
fied person wirJ find the manual a fully adequate guide in understanding, operating, and main-
taining the equ~pment actually supplied.
Electronic Associates, Inc. reserves
the right to make changes in design,
or to make additions to or improve-
ments in its product without imposing
any obligation upon itself to install
them on products previously manufac-
tured.
PRINTED IN U.S.A.

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COMPUTATION CENTERS
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Los Angeles Computation Center: 1500 East Imperial Highway, EI Segundo, California, Tel: [phone], TWX 910-348-6284
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West Long Brani:h, N. J.
. Other Departments, Divisions and Subsidiaries
Instrument Division: Lon!: BranCh. New Jersey. Tel: [phone], TWX 510·239·9208, Cable: PACE West Long Branch. N. J.
Pacific Data Systems, Inc.: 1058 East First Street, Santa Ana. California. Tel: 714·547·9183, TWX 714·531·0188
Scientific Instruments Department: 4151 Middlefield Road, Palo Alto, California. Tel: 415·321·7801. TWX 910-373·1241
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CONTINENT
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Bulletin No. IL·64104-6
June, 1966

MANUAL REViSION NOTICE * ELECTRONIC ASSOCIATES INC.
~
TEM
PAGE
PARA
LONG BRANCH NEW JERSEY
REVISION
Included in the accessory items shipped with each computer is a
strip of 100 pressure sensitive labels (EAI 00 342.0572-0). These
labels may be attached to the connector blocks to identify the
computing components associated with a particular problem.
DATE 3/30/65 MANUAL TITLE TR-20 COMPUTER OPERATORS
REViSION NOTICE
NO. 65-13
P l<'k'l<'P k'l\Tr l<' U 1\ l\Tn p'oOJ(
*THIS MANUAL REVISION NOTICE IS ISSUED TO INCORPORATE IMPROVEMENTS OR
CHANGES OF ROUTINE OR MINOR NATURE IN THE SUBJECT MANUAL.
SH. 1 OF 1 SH.

CONTENTS (Cont)
6. QUARTER-SQUARE MULTIPLIER ......•••................•.•..• 26
~. General Description ....••.•••.••.•..•.....•.••.• ...• 26
b. Multiplication...................................... 26
£. Division. . . . . . . . . . . . . . . . . • . . • . ••. • . • • . •• . . • • • • • . • . • • 26
7. X2 DIODE FUNCTION GENERATOR •..•.••••.•.••.••••••••••. ,.. 28
a.
General Description ..•..•••..•.•....••.•.•...•..•...
28
E..
Generating the Square of an Input Voltage (Single
Polarity) ........•..•••...••••..•••..••..•.•.•••••
29
Generating the Square of an Input Voltage (Bi-Polar).
29
8. LOG X DFG AND 1/2 LOG X DFG .............................. 29
a. General Description................................. 29
E.. Pa tching •...•..•....••.•..•.••......••....•.....•••. 32
9. VARIABLE DIODE FUNCTION GENERATOR GROUPS 2.645 AND 2.713. 32
a. General Description ..•...••.•.•....•......•...•••••• 32
b. Setup Procedure (Fixed Breakpoint VDFG's) ••••••••••• 34
£. Setup Procedure (Variable Breakpoint VDFG's) ••.••.•. 34
d. Paralleling Fixed Breakpoint VDFG's ...•..•..•.....•. 46
10. SIGNAL COMPARATORS AND FUNCTION SWITCHES •.•...•••••.•.•. 47
a. Relay Comparator ..•••••••••••.•.......•.•••...•.•... 47
b. Electronic Comparator .•• ,............................ 47
c. Dual Function Switch Group 2.127 ...•.........•...••• 50
ii

CONTENTS (Cant)
11.
REPETITIVE OPERATION
......................
53
~. General Description
................... 53
~. Using Repetitive Operation
54
12. DISPLAY NETWORKS
54
APPENDIX I - COMPUTER SYMBOLS
AI-l
APPENDIX II - CIRCUITS USING COMPUTATIONAL COMPONENTS
AII-l
APPENDIX III - AMPLIFIER CIRCUITS FOR SIMULATING TRANSFER
FlJN'CTIONS •••••••••••••••••••• 0 0 ••••••••••••
AIII-l
APPENDIX IV - BIBLIOGRAPHY
AIV-l
iii/iv

Figure
Number
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
ILLUSTRATIONS
Title
The TR-20 Desktop Analog Computer with Display Units ••
4
Inserting the Pre-Patch Panel ••••••••..•••••••••••••••
9
The 6.712 Dual DC Amplifier, Showing Use of Bottle
Plug s ..... 0 • 0 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 10
The TR-20 Control Panel 0 ••••••••••••••• 0 ••••••••••••••
Readout Circuit, Simplified Schematics ••••••••••••••••
An At tenua tor •••••••••• ' •••••••••••••••••••••••••••••••
Schematics and Symbols for Attenuators ••••••••••••••••
Operational Amplifier, Simplified Block Diagram
Patching an Amplifier as an Integrator~ Showing
Simplified Schematic of an Integrator Network
Patching an Amplifier to a Rep-Op Integrator,
.......
Showing Simplified Schematic of Integrator Network .•
Quarter-Square Multiplier Patching
....................
Division Circuit for a Quarter-Square Multiplier ••••••
X2 DFG Patching
X2
Generating + 10
Patching the Log
.......................................
for -10 ~ X ~ +10 ••••••••••••••••••••
X DFG t s ••••••••••••••••••••••••••••••
VDFG Mounting Locations •••••••••••••••••••••••••••••••
±VDFG Patching •••••••.••••••••••••• e •••••••••••••••••••
Sample Function and Setup
Information •••••••••••••••••
Breakpoint Setup Patching
.............................
+ Variable Breakpoint Diode Function Generator
11
14
18
18
20
23
25
27
30
30
31
32
33
35
36
38
SBItlP le Curve s ••• 0 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 40
Breakpoint Location Plot Patching •••••••••••••••••••••
42
v

Figure
Number
22.
23.
24.
25.
26.
27.
vi
ILLUSTRATIONS (Cont)
Title
Function Setup Patching
..........................
44
Relay Comparator, Simplified Diagrams and Setup
Patching ...................................... . 48
40.538 Electronic Comparator Unit
................ 49
Comparator Unit, Functional Block Diagram
51
Electronic Switch Unit, Functional Block Diagram
52
12.987 Display Network Patching Terminal Functions
55

CHAPTER I
INTRODUCTION
Many problems encountered in scientific or engineering work involve mathematical
equations or sets of equations whose solution in most cases is difficult or practi-
cally impossible to obtain by the classical approach to equation solution. The TR-20
Analog Computer provides the technical worker with a general purpose computer which
permits the rapid solution of linear or non-linear equations.
Although the analog machine is correctly termed a computer, it does not perform its
computations by serial calculations as does the desk calculator or digital computer.
Instead it performs the required mathematical operations in a parallel manner on con-
tinuous variables. In the TR-20, as in most modern analog computers, the continuous
variables are direct current voltages. The electronic analog computer makes it pos-
sible to build an electrical model of a physical system, where the voltages on the
computer represent the dependent variables of the physical system. Except for a
constant of proportionality, or scale factor, each voltage will behave with time in
a manner similar to the physical system variable. Thus, if the vertical position
of the center of gravity of an automobile oscillates with time during a disturbance,
then the voltage representing the height of the center of gravity above the surface
will also oscillate; if the temperature of the coolant at the exhaust port of a con-
denser rises exponentially to a steady value, then so will the voltage representing
it on the computer.
It can be said that the actual system and the electrical mode~ are analogous in
that the variables which demonstrate their characteristics ar~ described by relations
which are mathematically equivalent. The actual system has thus been simulated
because of the similarity of operation of the electrical model and the physical
system. This capability of the analog computer is of great value in performing
scientific research or engineering design calculations because it permits an in-
sight into the relationship between the mathematical equations and the response
of the physical system. Once the electrical model is completed, well-controlled
experiments can be performed quickly, inexpensively, and with great flexibility
to predict the behavior of the primary physical system.
Although the analog computer utilizes electronic components in its operation, it
is not essential that the user have an extensive knowledge of electrical circuits.
The TR-20 is basically a set of mathematical building blocks, each able to perform
specific mathematical operations on direct voltages and capable of being easily
interconnected. By appropriately interconnecting these building blocks, an elec-
trical model is produced in which the voltages at the outputs of the blocks obey
the relations given in the mathematical description of a physical problem.
1