Apple PC Serial and Parallel Card - Manual (Page 19)

Preparing the slots
7 Unscrew and remove the port access covers for the slots you need.
If you are installing the PC Serial and Parallel Card at the same time you are
installing a PC Compatibility Card, unscrew and remove the port access
covers to the top two PCI slots.
If you already have a PC Compatibility Card installed in your computer, then
unscrew and remove the port access cover to the top slot.
Position your hand so that the screw and the port access cover do not fall onto
the logic board.
Remove the screw that holds
the top port cover in place.
7" PC Compatibility Card
Top PCI slot Port access cover
19 Installing the Card in a Power Macintosh 6400 or 6500