The Commodore parallel cable
You should follow these instructions if you want to connect the cable directly onto the periphery chip in the drive.
You need the following parts to build this cable:
Step 1. Solder one end of the cable right onto the CIA periphery chip inside the drive.
Step 2. Solder the other end of the cable onto the user port plug. 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