Apple PowerBook (3400 series) - Manual (Page 51)

Inserting a PC Card
To insert a card, do this:
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Insert the card, connector first and label up, into the slot. Make sure the card is level.
A Type III PC Card
must be inserted in the lower slot.
A Type I or Type II PC Card can be
inserted in either the upper or lower slot.
51 Using Expansion Bay Modules and PC Cards