HYDAC Hybrid Digital-Analog Computer Series 2000
HYBRID DIGITAL-ANALOG comMpurTER_. series 2000
a general purpose computing system combining analog and digital operations
FAI ELECTRONIC ASSOCIATES, INC. Long Branch, New Jersey
The EAI HYDAC Computer, Series 2000, represents a significant
step forward in computer design . . . it introduces a new concept
to engineering and scientific computation . . . that of providing
the research and design engineer with a convenient means of
applying both analog and digital techniques in the solution of
his problem.
The HYDAC computer provides an economical alternative to the
costly process normally associated with hybrid computation,
namely that of tying up a complete data processing computer
with an analog computer. HYDAC will be found to be an attrac-
tive first step to hybrid computation and, in many instances, a
more practicable and effective approach. Analog and digital
operations are combined in one integrated system to achieve a
computational efficiency that is well beyond the limits of either
analog or digital computers alone. The traditional advantages
of both analog and digital computers . . . the analog computer’s
speed, lower cost and ease of programming and the digital com-
puter’s unique capacity for data storage or memory, exceptional
logic flexibility, and time sharing of components . . . have been
combined to expand problem-solving capabilities at lower cost.
Since the digital operations required for hybrid computation
schemes involve mainly those of timing, selection, sequencing,
memory look-up, and calculation of simple functions, such schemes
can be accomplished without the cost of large, data processing,
digital machines. Digital operations can become an integral
part of the expanded general purpose analog computer, making
them available to computer laboratories that have no digital
computers or during those periods when time is available on
the latter. With the Series 2000 HYDAC, analog and digital
computation can be centralized in a single laboratory eliminating
costly scheduling and training difficulties.
HYDAC twin control consoles place best features of analog an
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PROGRAMMING of the Series 2000 HYDAC is con-
veniently similar in principle to the approach familiar
to analog computer users. Designed from the point
of view of the computer user, by computer users,
HYDAC affords complete flexibility in the organiza-
tion of a problem solution. The transition from the
use of relays and switches in the general purpose
analog computer to logic devices is made very easy
. extensive retraining of analog programmers is
unnecessary.
ANALOG OPERATIONS of summation, inversio
continuous integration, multiplication, division, an
function generation are performed by the experienc
proven PACE 231R computing system that has becorr
the standard of the industry. All-electronic, wic
bandwidth computing components ensure high dj
namic accuracy for real time or repetitive mode ¢
operation . . . multiplication and other non-line
operations are performed with signal frequencies i
the kilocycle range . . . full advantage of the hig!
speed digital circuits may thus be realized.
digital computation at the fingertips of the using engineer
-ERIES 2000 is backed by Electronic Associates’ experience in the development,
, and application of general purpose analog computers. Incorporating all of the proven
‘he famed PACE Computers, it adds a new level of intelligence to the analog computer
reaching advantages. In computing flexibility, design, and in quality of workmanship—
|, is the most versatile scientific computer ever produced.
DIGITAL OPERATIONS are performed by general
purpose digital building blocks . . . housed in a digital
console. Five major groups of components are avail-
able to provide: Programmed Digital Logic. .. Digital
Memory ... Analog Memory . . . Analog-to-Digital,
Digital-to-Analog Conversion . .. Advanced Digital
Arithmetic Operations. They may be obtained in any
combination in the Series 2000 HYDAC Digital Con-
sole ... this may consist of just one major group for
special requirements or . . . it could include a selection
of all major classes to provide general purpose problem
solving capabilities.
MODULAR DESIGN of digital building blocks per-
mits fullest advantage of the economy and flexibility
of the pre-patch panel concept to be realized. Digital
switching circuits employing one basic type of uni-
versal gating circuit for maximum flexibility and
added economy are used to perform basic digital
operations. Completely solid-state .. . with 20-mega-
cycle switching capabilities . . . these basic circuits
are combined in standard plug-in modules to perform
complex operations.
The Series 2000 HYDAC is the result of a compre-
hensive design study by experienced computer users,
programmers, and designers concerned with the basic
requirements of hybrid computation. General purpose
in concept and design, it consists of two major sub-
systems; the PACE Series 231R general purpose analog
computer console with associated expansion equipment
and a digital console. The digital console is designed to
take fullest advantage of the economy and flexibility of
the prepatch panel concept . . . interchangeable, modu-
larized digital building blocks capable of performing
basic digital operations permit the Series 2000 HYDAC
to have many diverse capabilities by employing various
combinations of building blocks .. . this flexibility results
from a unique design employing standard connectors and
plug-in components. Reliability ... economy... ease of
maintenance result from an all solid-state design.
THE DIGITAL CONSOLE houses the digital building
blocks that perform the DIGITAL OPERATIONS of
logic, memory, basic arithmetic, data conversion, and
switching, plus . . . facilities for control and slaving of
the console to the’ analog computer, selector switches,
flip-flop indicator lights and control buttons, power
supplies with necessary wiring, etc., and the 3450-hole
pre-patch panel system. A Clock Unit with timing signals
terminated on the patch panel provides control timing
and synchronization for the entire system.
CONSOLE EXPANSION units available include:
© Input/Output Unit consisting of paper tape reader
and punch, electric typewriter, 10-key keyboard, an
output display register and an oscilloscope.
® Binary-to-Decimal and Decimal-to-Binary Conversion
Unit.
® Control Unit for advanced digital arithmetic units.
ANALOG/DIGITAL CONVERTERS include:
Standard EAI ADDALINK building blocks... .
e Analog-to-digital converter; 4000 words/sec., up to 13
bits and sign available.
© Digital-to-analog converter; 2 channels per chassis, up
to 13 bits and sign available; with two digital storage
registers per channel.
e 20-channel analog multiplexer.
e 20-state ring counter.
e Control units to link to IBM-7090, 1401;
160/160A; G-15; PB-250; etc.
CDC-
PATCH PANEL
PATCH BAY
PLUG-IN UNITS
WELDED
CIRCUIT
MODULE
Digital Basic Building Block. Circuit
components are stacked in “cordwood”
fashion for maximum density, welded
and potted for reliability.
Control signal converters...
© High speed, solid-state analog comparator, with output
for use with digital logic circuits.
© High speed analog switch controlled from digital logic.
@ Voltage-to-pulse-rate converter.
LOGIC BUILDING BLOCKS provide logic functions of:
e OR, AND, NOR, NAND
@ RST flip-flops, 4-bit shift registers, one-shot multi-
vibrators.
¢ up/down counters, pre-set counters, ring counters,
BCD counters, differentiators, buffer registers.
© adders, multipliers, special control units, timing units.
DIGITAL MEMORY BUILDING BLOCKS, known as
Serial Memory Units, are provided in four different sizes:
e SM-8: 256 words (16 bits per word)
e SM-6: 64 words (16 bits per word)
e SM-4: 16 words (16 bits per word)
¢ MB, Memory Buffer: one word (16 bits)
ANALOG SWITCHING AND MEMORY including:
¢ MICRO-STORE, a combination package containing one
high-speed comparator, two high-speed electronic
switches with storage capacitors.
e Multiple-Point Analog Memory provides many points
of capacitor storage per analog amplifier.
e Electronic comparators and switches.
e High-speed electronic mode switches for analog com-
ponents.
ADVANCED DIGITAL ARITHMETIC UNITS consist
of accumulators, adders, summers, input units, constant
storage units, and comparators. These units provide the
analog computer with digital units capable of high-
precision computation. They may be interconnected to
solve sets of non-linear differential equations, much as
the analog computer does, but with digital hardware and
discrete algorithms.
Digital Building Blocks are housed in modularized units
which plug into standard connectors behind the patch
panel... each is terminated in a four-by-ten-hole area
of the patch panel.
The series 2000 HYDAC is a versatile computing tool
for solving a variety of scientific problems
The combination of analog and digital operations not only
allows more economic analysis of certain classes of engi-
neering and scientific problems, but in many instances is
a far superior method. Until now, the emphasis and phi-
losophy of analog computers have been directed toward
the solution of initial condition problems of ordinary diff-
erential equations. Although the range of applications
falling under that definition is indeed wide, the additional
ability to store and process data, and to use the results of
this processing as input data for further calculations ex-
tends the scope of application of the analog machine. The
Series 2000 HYDAC provides these capabilities and thus
increases the range of problems that the analog computer
can solve economically, thus injecting new meaning into
the term “high-speed computation.”
Among the more important applications of
this computer are:
ITERATION AND OPTIMIZATION STUDIES — Prob-
lems of this nature arise in model building, process opti-
mization, parameter studies, and end-point boundary
value problems. A function dependent on the solution of
a set of differential and/or algebraic equations containing
adiustable parameters can be maximized or minimized by
trial-and-error methods. Computation time is reduced
markedly by the incorporation of suitable logic and
switching functions to allow the analog computer to pro-
ceed automatically through a complete iteration procedure
until an optimum is found. The same logic functions facil-
itate the automatic programming of parameter searches,
performance curve-fitting, and matching of boundary
values.
PARTIAL DIFFERENTIAL EQUATIONS—The solu-
tions of many scientific problems are represented by the
solutions of linear or non-linear partial differential equa-
tions. Solutions based on difference techniques utilizing
function storage and playback permit equipment savings
through the time-sharing of analog circuits. Such tech-
niques allow the time-domain simulation of field problems
where space variables are replaced by high-speed time
scanning. Hybrid operations also facilitate the solution of
boundary-value partial differential equation problems by
the method of characteristics or by integral equation
methods through the use of serial solution techniques and
time-multiplexing.
SIMULATION OF LOGIC FUNCTIONS—Often a prob-
lem being studied is partially represented in its physical
description by decision functions. Such problems occur
with increasing frequency in the study of space vehicle
characteristics and the control of complex processing. A
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prime example is the simulation of an adaptive control
system. Here the dynamic behavior of the system being
controlled is represented by normal analog elements while
the logic of the control system is represented by the avail-
able digital logic elements.
INTEGRAL EQUATIONS — This important class of
equations, whether arising directly, as in the application
of quantum mechanics to the theory of the scattering pro-
cess, or indirectly, as in the solution of partial differential
equations, can be solved efficiently by a combination of
analog and digital elements. More complex solutions now
become economically attractive.
AUXILIARY MATHEMATICAL FUNCTIONS —
Special operations such as multiplication, transport delay
simulation, function generation, slow integration, etc.
may be custom-designed, with suitable programming, for
combined operations with analog elements. This expands
the range of problems that the analog computer can solve
economically by increasing the number of basic opera-
tions available.
ANALOG AND INCREMENTAL COMPUTATION—
Certain sophisticated simulation problems have a require-
ment for greater computational flexibility in order to
achieve greater speed and accuracy of solution. Such
problems arise in the study of the performance of missile
and space vehicle characteristics. The inclusion of digital
arithmetic units in the analog computer permits the solu-
tion of such problems in faster-than-real time, with high
precision and increased dynamic range. Obvious econo-
mies result from the combined operation of analog and
digital computational elements in one centralized system.
Problems which have been programmed for
solution with the HYDAC at EAI’s
Princeton Computation Center include:
e a generalized optimization control program to optimize
any non-linear function of n variables that is programmed
for an analog computer.
e an eigenvalue problem for determining the normal
modes of a vibrating beam.
e a reaction-jet space capsule control problem.
© iterative solution of tubular reactor and control system
design problem.
e solution of partial differential equations by the method
of characteristics.
e integral equation solution of a boundary value problem.
Bulletin No. HC 6238-1