Apple Macintosh Performa 6100 Series - Manual (Page 104)

8 Locate the expansion slot on the main circuit board.
The expansion slot is at the far left edge of the circuit board as you face the
front of the computer.
9 Insert the connector on the adapter card into the expansion slot.
Line up the connector with the slot. Then press down gently but firmly on the
adapter card until the connector is fully inserted.
Expansion slot
Expansion slot connector
NuBus adapter card assembly
Expansion slot Power supply
94 Appendix B