Slot purposes on Apple II computers

  • Apple II computers come with 7 expansion slots built into the motherboard.

  • When the Apple II boots, it scans the slots for bootable devices from the highest-numbered slots downward (7→1).
  • Typically the primary boot device is on slot 6, and a secondary drive is on slot 5.

Common slot purposes

Apple ][Apple IIgs
Slot 1Printer interface card
Slot 2Modem
Slot 3 On the original Apple II and Apple II Plus, this slot is usually used by the 80-column expansion card to enable 80-column display mode.


On the Apple IIe, this slot is usually left empty, as the IIe has an auxiliary expansion slot which is designed to accept an expansion card which enables 80-column mode, and the auxiliary slot overrides most cards in slot 3.
On the Apple IIgs, 80-column display support is built into the firmware and no expansion card is required for it, but slot 3 is still reserved for this purpose (typing PR#3" at the Applesoft BASIC prompt will put the IIgs into 80-column mode) and thus it should be avoided for most types of expansion cards except those which will not interact with the computer's firmware.

Slot 4Mouse or memory expansion card
Microsoft Softcard (CP/M)
Slot 53.5" disk drive interface card Smart Port
Slot 65.25" disk drive interface cardDisk Port
Slot 7AppleTalk card or other expansion cardYour Card
ReActive Micro Drive/Turbo

Boot from a slot

  • From the * Prompt, you can boot any slot by typing: Cx00G
    where x is the slot number.

  • To boot slot 5:

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