HP21MX booster board?

I am doing a little basement cleaning and pitching some things. Was tossing an HP frequency analyzer that was in bad shape and decided to pop the cover and grab the cpu board (the cpu board is a 21MX M-series). Also got 64k memory & controller :) My question is two fold -first, what's necessary to use this M series board as a regular processor. I see the base instruction set on the bottom plus two additional non-standard microcode cards. I can just remove those, but didn't know if any changes to the M series board were required. Second, there is a board I've never seen before mounted under the mainboard on the opposite end of the microcode. The board is labled "booster board" and is about 1/2 the size of the main cpu board. I would normally think this was just a specific board to the frequency analyzer, but, I think I've heard Bob Shannon talk about this booster board before in more general terms. Should I keep the booster board? Jay West