Editing Macintosh IIsi (section)

=== Expansion Slot ===

The IIsi has a single '''Processor Direct Slot (PDS)''' compatible with [[Macintosh SE/30]] expansion cards. The slot runs at 20 MHz instead of 16 MHz, so some SE/30 cards may not work.<ref>{{cite web |url=https://lowendmac.com/1990/mac-iisi/ |title=Mac IIsi |publisher=Low End Mac |access-date=2026-02-09}}</ref>

The '''Apple IIsi NuBus Adapter''' converts the PDS slot to accept standard 7-inch NuBus cards. This adapter also includes a socket for the optional 68882 FPU. With a slim hard drive, 12-inch NuBus cards may also fit.<ref>{{cite web |url=https://everymac.com/systems/apple/mac_ii/specs/mac_iisi.html |title=Macintosh IIsi Specs |publisher=EveryMac.com |access-date=2026-02-09}}</ref>