Editing Processor Direct Slot (section)

=== IIfx PDS (Motorola 68030) ===
The [[Macintosh IIfx]], introduced in 1990, included a PDS that was almost identical to the SE/30 and IIsi,<ref>DCDMF3, p. 329.</ref> but not entirely. In particular, the clock signal is running at 20 MHz like the IIsi but the CPU is running at 40 MHz. The clock signal is also on a different pin from the IIsi and SE/30. Unlike other PDS, the connections to the processor signals are not direct, with intermediate buffering needed to handle the different clocks based on the physical address requested - some address would be accessed with the 20 MHz clock, and some other with the (not directly available on the slot) 40 MHz CPU clock ("fast slot space").<ref>DCDMF3, p. 355.</ref> The physical space available for the board was also different from the SE/30 and IIsi.