Apple PC Serial and Parallel Card - Manual (Page 23)

Attaching the peripheral flex cable to the PC Serial and Parallel Card
13 Attach the peripheral flex cable to the connector located on the right side of the
PC Serial and Parallel Card as shown.
14 Push the peripheral flex cable down.
This allows room to reinstall the logic board in the computer.
15 If you are installing the PC Compatibility Card for the first time, return to the
PC Compatibility Card user’s manual now for the rest of the instructions.
16 Make sure all cables and cards are firmly connected.
Use this connector.
23 Installing the Card in a Power Macintosh 6400 or 6500