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DIDS-402-2AMI3
EO 17325
Figure 1-2.
Model 402 -2AM13 Keyboard
1-2.2 Display Logic Board A13
The display logic board (see figure 1- 3) is a hinged printed-circuit
board
located
on the right side of the Display Terminal.
Logic circuits contained on
this board
are formed by transistor-transistor-logic (T2L) integrated circuits
which are solder-connected to etched-copper printed circuits.
The primary
function
of the se circuits is to act as a keyboard interface
by
accepting 7-
bit
digital
codes from the keyboard matrix.
These coded characters are then
transferred to
the delay-line electronics and the monoscope deflection amplifier
circuitry.
In
addition, numerous flip-flops on the display logic board
are used
to accomplish the various editing functions (such as step-left, step- right, erase
line) .
1-2.3 Communications Control Board A12
The communications
control
board (see figure 1- 3) is a hinged printed-
circuit board located on the right side of the Display Terminal.
Logic circuits
contained on this board are formed by T2L integrated circuits which are solder-
connected to etched-copper printed circuits
.
The
primary function performed
by the communications control logic
is
to provide a three-character buffer
storage for smoothly releasing data at the 1200-baud rate.
Steering logic and
decode
circuits contained on this board determine whether the Display Terminal
is in the transmit or the receive mode of operation.
1-4
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