The 1571 parallel port
You need the following parts to build this port:
Step 1. Solder one end of the cable right onto the CIA periphery chip inside the drive.
Step 2. Cut a hole on the case of the drive, glue or screw the game port into it and solder the other end of the short cable onto the port. You should have the following connections:
You can find the description of all parts used on the diagrams at the legend page.
Source: The Joe Forster-STA homepage