The Macintosh SE/30 is a personal computer designed, manufactured and sold by Apple Computer from January 1989 to October 1991. It is the fastest of the original black-and-white compact Macintosh series.
Macintosh SE/30
Mainboard of the SE/30
A processor direct slot (PDS) is a slot incorporated into many older Macintosh models that allowed direct access to the signal pins of a CPU, similar to the functionality of a local bus in PCs. This would result in much higher speeds than having to go through a bus layer, such as NuBus, which typically ran at a slower 10 MHz speed.
LC PDS Ethernet card. PDS connector is at bottom left of photo. The card was mounted parallel to the main logic board, unlike most computer busses in which cards are inserted at right angles to the motherboard.