HP 24SII - Manual (Page 35)

The pin assignment for the DB-25 connector is similar to the IBM PC
parallel connector and uses the following signals for communication:
DB-25 STANDARD CENTRONICS TTL LEVELS
BayTech Cable part # MC25S010
PIN # SIGNAL
1 - Strobe
2 +Data Bit 0
3 + Data Bit 1
4 + Data Bit 2
5 + Data Bit 3
6 + Data Bit 4
7 + Data Bit 5
8 + Data Bit 6
9 + Data Bit 7
10 - Acknowledge
11 + Busy
12 + P. End (out of paper)
13 + Select
14 - Auto Feed
15 - Error
16 - Initialize Printer
17 - Select Input
18-25 Ground