EAI 680: A Hybrid Computer to Grow With
EAI'I!?ILE~(E)
A HVBRlDi COMPUTER TO =ROW WITH
APPLICATIONS
Applications in the Rocass Industries
During the early stages of the EAI 680 development, a
team of applications specialists from the EAI Research
& Computation Division made an extensive survey of
significant analog and hybrid problems. They analyzed
in depth hundreds of problems solved at EAI Computation Centers as well as the equipment used in the
solution of these problems. This study had a strong
influence on the development of the EAI 680 system.
Major applications were considered on thebasis of a
"paper" system design before the actual development
of hardware for the EAI @was begun.
Problems associated with the Process lndustries were
studied by the team of EAI applications specialists.
Consequently, the EAI 680 Scientific Computing System
has been designed to handle applications such as: the
simulation and design of both analog and digital process
control systems; studies of complex reactor dynamics;
design of heat exchangers; parameter optimization, such
as in non-linear chemical kinetics studies; simulations
involving large, fixed or variable time delays; automatic
data fitting; staged system simulations; simulation of
processes and control systems for operator training;
and, the system design for nuclear reactor/heat exwith its
change and control. The compact EAI -6
rugged, welded steel frame construction, low power requirements, zero temperature coefficient capacitors,
and temperature compensated non-linear equipment is
ideal for operation in normal laboratory environments.
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The University and the EBB 680
The new EAI 680 hybrid system will play a significant
role in univers~researchand teaching programs. Many
university science faculties are planning t o make modern, analog/digital machine combinations available to
students on an undergraduate level. The EAI 680
Scientific Computing System is well-suited for this; it
is a powerful hybrid computer - yet available on a
university budget.
The role of the modern, analog/hybrid computer in the
university is three-fold: first, to provide a tool for
instructing students in the programming and design of
a modern, scientific computer; second, t o demonstrate
t o the students the dynamic behavior of physical systems
hybrid simulation is uniquely capable in aiding
student understanding of process and system performance; third, to enable the solution of significant problems in graduate and faculty research.
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A professor in a leading engineering school recently
stated that hybrid/analog computation can help to produce an enlightened group of graduates who will appreciate that computers are more than just sophisticated
calculators. Hybrid computation is a powerful tool and
a key to the future; the students must be made familiar
with its applications, he concluded.
E A 1 6 2 in the Life Sciences
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The life science requirements
on-line signal processing and powerful data reduction - are required in
EKG and EEG studies and were carefully considered in
the design of the EAI 680. This new hybrid system is
well-suited to solving these problems, and to the simulation of a wide variety of physiological systems, such
as circulatory systems which require the solution of
partial differential equations. Other applications in the
life science area include pattern recognition studies.
These involve learning systems and general training
where the observer of the simulation receives a unique
insight into the dynamics of visible systems. Potential
users in the life sciences area may also take advantage
of regularly scheduled EAI courses on bio-engineering
applications of analog and hybrid simulation.
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The EAI 680 for krospaca Sirnulatlon
The analog/hybrid computer is a necessity in the simulation for design of all aircraft, missiles, and space
vehicles. The EAI 680 Scientific Computing System is
of interest to the aerospace engineer because of its
considerable computing power-per-dollar. It can be
adapted to operate with existing one-hundred volt equipment and operates at comparable accuracies. Further,
its ultra high-speed computing capability and wide bandwidth make it ideal as a high-speed expansion to existing slower large-scale computers.
General Industry Applications
EAI application surveys indicate that the EAI 6 8 0 computer offers definite aduantages in many other application areas. The studies that were made include control
system design, heat transfer problems, statistical analysis, optimization studies, and learning and recognition
problems.
HYBRID CAPABILITY
Mgh-Speed Capabilitr
The EAI 680 is an economical, operator-oriented computing system that has been expressly designed as a
hybrid computer. The full hybrid capabilities of this
computer are reflected in its solid-state addressing and
readout system, automatically adjustable potentiometers, extensive parallel digital logic, high-speed capability, complete analog-digital patch panel termination,
and system expansion facility.
Efficient hybrid operations rely heavily on the highspeed capabilities of the system's analog components.
Analog components available with the EAI 6 80 feature
wide bandwidth and high static accuracy. The system's
operational amplifiers operate with negligible velocity
limiting within their 500 kc bandwidth. Electronic mode
control, with extremely fast switching and reset times,
permits the control of individual integrators.
An electronic solid-state addressing and readout system
enables the digital computer to address and read out
any analog component. Designed to accept an entry,
byte-by-byte, the system is provided with the capability
for handling normal digital computer data.
Time scale changes of 1,000 to 1 and 10,000 t o 1
permit compressed time scale, repetitive and iterative
operations. Ultra-fast signal tracking (in under 1 microsecond) combined with low-drift storage is provided by
the system's track/store networks. Many other components - such as high-speed, digital/analog electronic switches - have been included as well.
Automatically Adjustable Pdsnti~meters
In many hybrid problems, analog potentiometers are set
to coefficients that are calculated by the digital computer. "Servo-set" potentiometers required for hybrid
computation form a part of the standard equipment
complement of the EAI 6 8 0 Scientific Computing System. These potentiometers can be read out or set up
by the digital computer using the electronic addressing
system. The desired potentiometer coefficient is transferred in digital form from the digital computer to a
built-in digital-to-analog converter. The latter converts
the digital information t o an analog voltage that in turn
is used to set the potentiometer addressed.
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Variables can be multiplied with high accuracy at speeds
in excess of one kilocycle-per-second. This enables the
EAI 680 to meet the high-speed multiplication requirements usually associated with hybrid, iterative-type
problems.
Patch Panel Terminal,#
The EAI 680 patch panel provides termination for both
digital and analog signals. Terminals are included for
control lines, sense lines, trunk lines, and other lines
required for hybrid operation. In addition, termination
is provided for digital-to-analog and analog-to-digital
conversion equipment.
Laic
Uncommitted parallel digital logic has been made available in the EAI 680 for decision making and control
requirements. When operating with the digital computer, the logic can be either synchronized with an
internal clock system or slaved t o an external signal
from the digital machine.
With logic level control, the mode and time scales of
all integrators in the computer can be controlled individually from the analog console or by the digital computer. This important feature facilitates the analog and
hybrid solution of iterative type-problems, such as the
solution of partial differential equations.
The EAI 680 Scientific Computing System is provided
with facilities for complete modular expansion of its
fully-wired, basic computer console - using a variety
of plug-in components. In addition, extensive trunking
and slaving facilities enable the combined operation of
several EAI 680 consoles as one large system.
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A TYPICAL EAI 6;3 HYBRID COMPUTING SYST-
OPERATOR ACCESSIBILITY
Designed specifically to provide engineers and scientists
with the capability for solving complex system problems,
the EAI
Scientific Computing System provides the
operator with the ultimate in accessibility and operating
convenience. For example - all system controls and
readout devices have been made accessible to the operator seated at the console. Special automatic setup
features have been included enabling the rapid setting
of potentiometers and the verification of their settings.
The amount of required control patching - the patching necessary to make a component function in its
normal mode - has been reduced to a minimum by
the use of normally closed switches on the patch bay
contacts. Variable diode function generators have been
mounted so that they can be set up by the operator
while he is seated at the console. These VDFG components and associated set-up controls are contained in
convenient slide out drawers to the operator's right.
And - the EAI 680 patch panel has been arranged in
modular symmetrical style t o facilitate operator familiarity with equipment assignment, component location,
patching, and program debugging procedures.
A flexible input-output system of the EAI 680 provides
complete close communication and control between
analog and digital sections and between the operator
and the machine - as required for effective hybrid
computation. Facilities provided can be expanded to
accomplish five basic functions when operating with a
stored-program digital computer: selection of analog
modes by the digital computer; sensing of analog modes
by the digital computer; selection and readout of all
addressable analog components; setting of potentiometers by the digital computer; and exchange of data
between analog and digital computer components. The
analog modes may be selected either manually, by timer
control, or by logic program control. The selection and
readout of analog components and the setting of potentiometers can be accomplished by the digital computer
under direct program control. The types of data and
control lines provided with the system include:
DIGITAL LlNE TERMINATIONS
Digital Trunks
A/D Sample Control
D/A Transfer Control
Linkage Address Control
Omperation Control Lines
Interrupt Lines
Sense Lines
Push-Button Lines
Monitorscope and Display
Control Lines
LNALOG LlNE TERMINATIONS
Analog Trunks
ADC Lines
DAC Lines
Display Lines
Platter
Recorder
The number of lines supplied is sufficient for handling
the majority of hybrid problems. However, if required,
the number of channels can be expanded for handling
unusual and highly complex problems - by special
patching.
Extremely fast digital readout of amplifiers and potentiometers is accomplished by using an electronic addressing system. And - facilities are provided for
displaying information associated with both high-speed
and real-time operation.
Q
patched to the top row which serves as the digital section. Clearly identified terminals combined with different patch-cord types and sizes prevent the possibility
of inter- patching analog and digital signals. Terminals
are provided for external as well as internal digital and
analog signals
an important feature for hybrid use.
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The analog section of the patch panel has been divided
into twelve modules each containing ten plug-in analog
trays. The tray positions within each of the twelve
modules are very similar. Therefore, it is only necessary for the user to become familiar with the organization of one module in order to understand the entire
patch-panel structure.
The trays in the logic section that are normally used in
communicating with the analog section are located directly above the corresponding analog trays. This greatly facilitates the location and patching of logic signals
for controlling the analog equipment.
e COMPUTER CONSOLE AND
PATCH PANEL
A compact console of rugged, welded steel frame construction, houses within a single unit, all computing
components and facilities for complete programming
and control of the EAI 680 Scientific Computing System.
The console's compact size (5' x 5' x 2%') results from
the use of modular packaging, solid-state circuitry and
high stability components which do not require ovens.
The use of solid-state devices rather than vacuum tubes
eliminates the need for expensive space-stealing airconditioning equipment. The reduced power requirements of a 10 volt system enable operation of the computer from any normal electrical wall outlet. Also with precision low-drift integrating capacitors, no bulky
ovens and related temperature control equipment are
required.
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Human engineering in the design of the console has
provided the operator with optimum accessibility to the
patch-panel, various controls, indicators and components. The patch panel is located in the upper righthalf of the console above an operating shelf containing
the machine's control panel. Analog signals are patched
to terminals on the patch-panel's bottom four tows
designated as the analog section. Logic signals are
The console's analog and digital indicators are mounted
on panels located to the left of the patch-panel. The
digital indicator and control panel provides complete
logic selection and readout - with the state of each
storage element and each AND gate indicated. Facilities
are provided for the selection and control of potentiometers, address readout and function relays. The
overload indicator panel located above the patch-panel
provides separate indication of an overload condition
in any amplifier, multiplier or variable diode function
generator.
The console's control panel, which is mounted on the
operating shelf at convenient desk height, consists of
three sections - digital control, addressing and analog
control. Flexible, multi-level control is made available
to the operator - for control of the entire system, for
multi-speed control of groups of components and for
control of individual components. This control is provided for both mode and time-scale programming. Certain control features that are particularly useful for
hybrid computation include: electronic mode control
that operates at microsecond speed; logic control of
individual integrators - with four time scales available; and, synchronous logic control that can be singlestepped when required to facilitate programming and
problem check-out.
Several other important features have been incorporated in the console's advanced design. For example a significant reduction it? cross-talk has been achieved
by careful, consistent shielding throughout and assignment of separate areas on the patch panel for analog
and digital signals. Wiring and power supplies have
been included in the console for plug-in logic expansion
of the basic computer. And - internal slaving equipment and controls enable the "on-line" operation of
each console as part of a large system or the "off-line"
operation of each console for individual problem solution.
COMPUTER COMPONENTS
The outstanding performance of the EAI 680 system is
based on its large complement of quality linear and
non-linear computer components. These components
- mounted in compact removable trays in the console
are characterized by their high-speed operation, low
drift and excellent static accuracies (0.01% for linear
components).
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The system's high-speed operational amplifiers perform
at full amplitude over their entire, 500 kc bandwidth,
with negligible velocity limiting. These amplifiers are
stable for wide values of feedback impedance and output loading. The amplifiers - up t o 156 in an expanded system - are used for many different operations. In the combination amplifier form, they may be
used as summing amplifiers, integrators, electronic
switches or as track/store units.
Integrating amplifiers are provided with individual time
scaling using any of four available time scales. A number of integrators can be operated simultaneously at
different speeds
a capability which is particularly
useful for iterative and hybrid computation. Also useful
in this regard, is the integrator's ability t o reset very
rapidly - from the operating mode to the initial condition mode - in approximately 1 microsecond. The
computer integrating capacitors have a negligible temperature coefficient thus eliminating the need for ovens
these capacitors have been
in the computer. Also
made adjustable to provide the long term drift compensation required for continual operating stability.
Among the other components in the console are variable
hard limiters of the feedback type and hard zero limiters.
The logic components included are general purpose
registers, flip-flops, AND gates, BCD counters, monostable units and differentiators.
All of the components have terminals for their interconnection on the patch-panel. The amount and type
of components available in an expanded EAI 680 system is summarized below:
Analog Equipment
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Extremely fast signal tracking (in under 1 microsecond)
combined with low drift storage is provided by the system's tracklstore units. The exceptional performance
achieved is based on the use of two capacitor sizes in
each unit. The tracking operation is performed using a
small-size capacitor; a larger capacitor is switched in
for the storage function.
The standard component complement of the EAI 680
Scientific Computing System includes 120 potentiometers. These potentiometers can be set manually or
automatically as required. When set automatically they
are adjusted by a "servo" system at a rate exceeding
one potentiometer setting per second. A "Joy Stick"
control enables manual adjustment of any potentiometer
during computation -a feature that is particularly useful for the model experimentation required in the simulation of physical systems.
The large complement of non-linear, special and digital
components includes electronic quarter-square multipliers, diode function generators, resolvers, comparators, limiters and logic components. The type of highspeed electronic multiplier used provides exceptional
computation accuracy. Available for use with each
multiplier is an uncommitted output amplifier mounted
in the same console tray.
Logic and Interface Equipment
Electronic Comparators ....................
D/A Electronic Switches ------------------D/A Relay (DPDT) .......................
Track/Store Units ........................
Four-Bit General Purpose Registers ---------AND Gates .............................
Monostable Timers (One-Shots, or Pulsers) ----Differentiators ...........................
BCD Counters (2-Decade, Bi-Directional) -------
Amplifier Complement
The complement of 156 amplifiers includes the
following:
Combination Amplifier (may be used as integrator,
summer, or high-gain amplifier) ----------Summer (may also be used as high-gain amplifier)
Inverter/High-Gain Amplifiet (may be used as
inverter or as output amplifier for non-linear
equipment; may also be used as multi-input
summer by patching additional resistors to
. , junction)
.
ampl~f~er
.....................
Output Amplifier for Quarter-Square Multiplier
(may be separated from its associated
multiplier, allowing independent use of
. .
. . ----------------multrpher and ampl~f~er)
Amplifiers Associated with Variable Diode Function
Generators (when DFG not in use, the output
amplifier is available as an inverter) -------Total
30
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42
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SYSTEM SUPPORT
The EAI 680 Scientific Computing System is supported
by many years of experience in hybrid computation. In
addition, a hybrid software library that contains programs and subroutines for various phases of hybrid
simulation will soon be available. Included will be typical hybrid problem solutions to aid the programmer
in problem analysis and simplification, programming,
problem check-out and problem documentation.
In addition to extensive software support, the EAI
system has the support of a world-wide field service
organization. This is the only service organization in
the computer industry, that is trained t o service all types
of scientific computing systems - analog, digital, and
hybrid. The organization operates in conjunction with
equipment repair and part support functions.
Other support is provided by an extensive training and
education facility. Comprehensive training courses at
EAI Computation Centers are made available - free of
charge - t o every EAI 680 user. Also available is an
applications reference library - the world's largest containing hundreds of analog and hybrid studies, that
have been compiled over a period of several years.
Rounding out this extensive support program for the
EAI 680 system are EAI Computation Centers located
throughout the world. These centers - completely
equipped with the latest scientific computing equipment
- are available to the customer for his use. The EAI
applications staff is available for consultation on programming, operation and maintenance.
EAI'
ELECTRONIC
ASSOCIATES,
I N C . West Long R m n c h , N e w Jersey
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