HP QMS 1660 - Manual (Page 232)

Cable Pinouts
QMS 1660 Print System Reference B-10
IBM PC/XT, PC/AT, and Compatible Computers
The following diagrams show the serial cable pinouts for IBM PC/XT,
PC/AT, and compatible computers.
» Note: Not all serial cables are configured as shown and may require
an additional null-modem adapter. Check with your cable vendor for
compatibility.
» Note: To download printer system software via the serial port, your
hardware must have RTS and CTS support. Make sure that pins 4
and 5 on the 25-pin serial cable and pins 7 and 8 on the 9-pin serial
cable are criss-crossed as shown in this diagram.
To Printer
9-Pin
To CPU XT
25-Pin
Female
To Printer
9-Pin
To CPU AT
9-Pin
Female
1 Not Used 1 Not Used
RXD 2 2 RXD RXD 2 2 RXD
TXD 3 3 TXD TXD 3 3 TXD
DTR 4 20 DTR DTR 4 4 DTR
DSR 6 6 DSR DSR 6 6 DSR
GND 5 7 GND GND 5 5 GND
RTS 7 4 RTS RTS 7 7 RTS
CTS 8 5 CTS CTS 8 8 CTS
9 Not Used 9 Not Used