- Hewlett-Packard All in One Printer User Manual

DB-25 RS-232 Serial Connection — HP LaserJet 4 Plus/5
If the computer has a serial port with 25 pins, use the C2933A or
equivalent cable for the HP LaserJet 4 Plus.
Figure 3-10 C2933A Cable Pinout for 9 to 25 Pin Connector
3-38 Configuration