Printer Programmer's Manual

The cable interface for PC null modems is shown below.
9474 PC
FG 1 1 FG
TD 2 2 TD
RD 3 3 RD
RTS 4 4 RTS
CTS 5 5 CTS
DSR 6 6 DSR
CD 8 8 CD
DTR 20 20 DTR
SG 7 7 SG
2-6 Communication Requirements