TM 5-6675-320-14
Table 4-4. PCA A2 ACCEPTOR HANDSHAKE MODE OPERATION - Cont
Sequence
Step
Circuit and Signal Operation
6
7
8
1
2
3
4
5
TRANSFER OF DATA - Cont
Computer sends DAV false.
U6, U27, and U19 set DAC false and RFD true.
Process is repeated until all data to be transferred from computer
i s t r a n s f e r r e d.
TERMINATION
Computer initiates termination by placing a 11111 bit on data bits
1 - 5.
U16, U4, and U26 decode bits 1-5 and input CLK false to U17A.
U17A is clocked by decoded bits 6 and 7 and sets listen (LST)
s i g n a l t o f a l s e.
LST signal to U19 is removed and U10 stops generating receive
handshake (RHS) signal.
Plotter has exited RHS mode.
Table 4-5. PCA A2 TALK HANDSHAKE MODE OPERATION
Sequence
Step
Circuit and Signal Operation
INITIATION
1
Interface bus transceivers U33 and U7 receive first data word from
computer and transmit it to bit decode circuits.
2
U4 and U5 receive and decode bits 6 and 7 from U33. A BIT 7 true
and BIT 6 false decodes a talk handshake (THS) mode and a talk
decode clock pulse is sent to talk flip-flop U18B.
3
Address comparator U20 compares bits 1-5 from computer to the five
bits from preset ADDRESS switch S1 on PCA A1. If bits are same,
U20 generates my address indicating that plotter is being
addressed.
4-19
