Journal Charles Gaudette's Journal: Apple Alchemy Logic Board Notes
The Apple Alchemy L2 Cache slot might be thought of as a Processor Direct Slot (PDS). However, the slot is not designed like a true PDS.
Apple used the term PDS to label a slot that was designed to be an upgrade slot like those found in the Macintosh LC III and the PowerMac 7100. In true PDS machines the PDS can be used for video, networking, CPU upgrades, and so forth. Apple encouraged upgrades through the PDS.
The Alchemy board L2 Cache slot is direct access to the CPU; in that sense, it is a processor direct slot. Apple never designed the L2 Cache Slot (High Performance Module slot) for anything but L2 Memory. The plastic shoulder is barely enough to hold a DIMM and no external panel lines up with the slot.
A 227 page Apple Service Source manual for the Performa/Power Macintosh 6400 and 6500 Series only states the following.
"The optional 256K (512K for the 6500/275 and 6500/300) level-2 cache is on a 160-pin DIMM card that plugs into a 160-pin edge connector on the logic board and includes an integrated cache controller."
