Apple PC Compatibility Card - Manual (Page 34)

34 Chapter 2
10 Prepare the first PCI expansion slot.
You need to install your PC Compatibility Card in the first PCI expansion
slot, the slot closest to the center of the computer. If there is already a card in
the first slot, move it to a different slot.
IMPORTANT If you will be installing a PC Serial and Parallel Card, you should
also remove any card in the second slot (next to the first slot).
11 Remove the port access cover behind the first expansion slot.
Port access opening to first slot
(back of computer)