Talk:Processor Direct Slot

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[edit] VL Bus

The PDS has more in common with, and is contemporary with the VESA Local Bus slot PCs used in the 1990's. The VL Bus was originally intended only for high speed video with a single slot but high speed IDE controllers and multi-IO boards quickly appeared, with motherboards having up to three slots.

Unlike the PDS, CPU upgrades and network cards weren't made for VL Bus. The Quadra 900/950 did have a PDS SCSI controller option in their A/UX server configuration.

Contrary to the article, it is possible to connect multiple cards to the PDS in some Macintosh computers. There are websites showing how to connect up to four cards to an SE/30 or the LC PDS while adaptors were commercially available to install two IIsi-SE/30 cards in those Macs, or one IIsi-SE/30 card and one IIci (also IIvi, IIvx, Performa 600) card. By exploiting the passthrough PDS connector on many IIsi-SE/30 cards it's possible to connect up to three cards to the PDS in those Macs, though it may strain the IIsi's power supply.

It would've been possible to design a Macintosh with more than one PDS connector, but since Apple was the only company building Macintosh computers, they chose not to.