PCS over time offered 5 different CPU boards for the Cadmus line of workstations. They were simply numbered from 1 to 5, and this number also went into the model designation. For example, a 9600/3 was a small case with a /3 CPU board, while a 9900/5 was a big case with a /5 CPU board. The CPU boards had the following characteristics:

• The /1 CPU board has a 10 MHz 68010 CPU and no FPU. The FPP board that adds a National NS32081 coprocessor was an option, though all /1-based systems I have seen did have the FPP board.
• The /2 CPU board has a 10 MHz 68020 CPU plust 68881 FPU. 'Oops...', you might say, '...Motorola never manufactured such a slow 68020!' Surely, but this board was thought as a drop-in replacement for the /1 processor to allow customers use MUNIX/32 with their old memory boards. At least that's the way it was advertised in a brochure of PCS, and I have almost no info on this board and never saw such a beast in reality.
• The /3 CPU board has a 12.5 MHz 68020 CPU plus 68881 FPU. It was the low-end board of the MUNIX/32 capable systems.
• The /4 CPU board has a 16.67 MHz 68020 CPU plus 68881 FPU and additionally an L2 cache of 16 Kbytes (remember the 68020 has an internal L1 instruction cache of 256 bytes!). This board occupies two Qbus slots.
• The /5 CPU board was the high-end board and the last offering before PCS switched to Mips-based systems. It has a 25 MHz 68020 CPU plus a 20(!) MHz FPU and an additional cache of 64 Kbytes. This board again only needs a single Qbus slot.