TM 5-6675-323-14
Is initiated by the computer. It clears the
(b) Interface clear.
listen, talk, poll, and service request flip-flops.
Is used as an aid in locating a defective stage. Self-
(c) Self-test.
test is initiated and controlled by the microprocessor on PCA A3. Self-test for PCA
A2 is accomplished by the microprocessor generating the following test functions:
T e s t Ready for Data
T e s t Data Accepted
Test Data Available
T e s t Data Enable
Test End or Identify
Test Attention
These functions, when applied in the appropriate sequence, will test all modes of
PCA A2.
Table 3-4. PCA A2 ACCEPTOR HANDSHAKE MODE OPERATION
This functional operation is designed to assist in troubleshooting the plotter.
All circuit references apply to PCA card A2.
Sequence
Step
Circuit and Signal Operation
INITIATION
C o m p u t e r sends data available (DAV) and attention (ATN) true
1
signals.
2
Control latch U19 generates ready signal indicated by micropro-
cessor upon sensing DAV true signal.
Interface bus transceivers (IBT) U33 and U7 receive first data word
3
from computer and transmit it to bit decode circuits.
Interface bus transceiver U34 receives ATN control work from compu-
4
ter and transmits it to bit decode circuits.
5
U6 receives ATN and READY signals and sets U19.
6
U19 receives ATN and READY signals and sets U8.
7
U8 transmits ready for data (RFD) true from U19 to computer.
T r a n s m i t s computer response, DAV true signal, to microprocessor
via U22.
D A V goes false.
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