TM 5-6675-323-14
Table 3-5. PCA A2 TALK HANDSHAKE MODE OPERATION - Cont
Sequence
Circuit and Signal Operation
Step
I N I T I A T I O N - Cont
U9 receives NBA false signal and clears talk handshake flip-flop
17
U17.
18
U 1 5 sets THS true.
DATA TRANSFER
1
Microprocessor on PCA A3 sends NBA true signal to talk handshake
flip-flop U17.
2
Computer sends ready for data (RFD) true signal.
3
U 2 5 sets data available (DAV) true and enables U15 to generate THS.
4
U2 and U14 transmit data byte from PCA A3 to IBTs U33 and U7.
5
U 3 3 and U7 are enabled by U27 and transmit data byte to computer.
6
M i c r o p r o c e s s o r on PCA A3 sets NBA false, clearing talk handshake
flip-flop U17.
7
C o m p u t e r generates data accepted (DAC) true.
8
Microprocessor sets DAV false.
9
U15 sets talk handshake (THS) false, thus, indicating completion of
transfer.
10
M i c r o p r o c e s s o r on PCA A3 sends new byte available (NBA) false,
causing THS to go false.
11
Sequence is repeated until all data (data bytes) is transferred.
TERMINATION
T e r m i n a t i o n can be initiated by microprocessor on PCA A3 by holding
1
N B A false.
2
Active termination is initiated by computer when it places an
address, other than plotter's preset address, on bits 1-5. This
action will send my address false.
3-21
