Three DIP40 chips on a green PCB. The furthest away says MOS6522 and datecode 14th week of 1983. the next is a ROM MOS901869-01. And the last is the MOS6502 CPU from 17th week 1983.

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   root42 (root42@chaos.social)'s status on Sunday, 26-May-2024 01:50:51 JST root42

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   Now that we know that we have good voltages let’s have a look at the mainboard. The CBM floppy drives are peculiar in that they are multi CPU systems. The 8050 and its relatives have two 6502 CPUs. One, together with some SRAM, ROM, and a 6522 drives the IEE488 bus, also known as GPIB.
   The other 6502 drives the floppy mechanisms and decodes the GCR data.
   The ICs have a bit of corrosion on some pins. But luckily all the chips can be replaced if necessary.