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CHAPTER II
THE TR- 20 COMPUTER AND COMPUTING COMPONENTS
1.
GENERAL DESCRIPTION
The PACE® TR-20 (Figure 1) is a general purpose analog computer composed of solid-
state computing components.
The TR-20 is compact in size and is able to operate with
stability and precision in a normal office or classroom environment.
Reliable, with
simplicity in functional design, the TR-20 is easy to use and can be a powerful aid
to the individual engineer in the rapid solution of scientific and engineering prob-
lems.
Table I lists the currently available computing components and accessories for the
TR-20.
The TR-20 utilizes a building block concept, in which individual computing
components may be easily interconnected to solve the required equations by forming
electronic models analogous to the system under study_
Each building block, either
individually or in combination with others, is capable of performing one or more
mathematical operations.
The computing components in the TR-20 occupy the area
above the slanting control panel area.
This area is divided into three rows; the
top row contains the coefficient attenuators; the middle row houses the integrator
networks, comparators, and other non-linear computing components; the bottom row
provides space for twenty (10 dual units) operational amplifiers.
The computing
components are constructed on plug-in chassis, and the front of each computing com-
ponent consists of a color-coded plastic patching block that contains the input and
output terminations for the unit.
The computing components are inter-connected by
placing patch cords or bottle plugs between the appropriate input and output ter-
minations.
Most TR-20's are equipped with a removable pre-patch panel that allows
problem patching away from the computer.
The pre-patch panel consists of a rigid
aluminum frame with individual rows that contain patching blocks identical with the
patching blocks that form the front panels of the components.
Contact between the
pre-patch panel and the computing components is accomplished by means of gold-plated
contact springs.
Below the patching area is the monitoring and control panel area which contains con-
trols and components that permit (a) switching the computer on and off, (b) mode
control of the computer, and (c) measuring statioriary problem voltages.
A hinged
cover plate directly below the control panel covers the amplifier balancing potenti-
ometers and the variable diode function generators.
2.
OPERATING CONSIDERATIONS
The TR-20 is completely tested and calibrated at the time of manufacture and is
shipped with all components in place.
~fter perform!gg_tl1e-pr~e_l~t!llinar,y-chJ~_c::k-g.p'!
procedure outlined in the TR-20 Maintenance Manual,..>. the c0IIl:puter is ready for
op~r-
a-tIo~':--'----' ~"------
~-
. .-------------- --. . . . . , . .
---~
. .
------.,~-.----.-
.. - . . . ,
It should be noted that the low voltage levels used in the TR-20 eliminate any shock
hazard to the operator when patching components with the computer turned on.
Current-
limiting circuits protect the reference supplies from damage during short-term over-
loading if they are inadvertantly patched to ground or to each other.
A patching con-
nection that is dangerous to a component usually triggers the overload alarm system.
3
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