I bought a PC-8001 a while back, and it came with a couple of extras in it. One was a four-bank EPROM daughterboard that fit in a single socket on the motherboard. This is an option ROM that you can use to enhance your computing experience on the PC-8001 in an endless number of ways. In this case, we couldn't figure out how to get the code on the board to execute, but a fellow meetup member has dumped the contents of it at great effort.

The other is a programmable sound generator (PSG) for the PC-8001. Unfortunately I couldn't really get that working, either. The software loaded, it claimed to be playing, but no sound was generated. I am not sure if it was a hardware problem or just a general lack of knowledge.

They came preinstalled in the system. The daughterboard with socketed EPROMs is on the left, the PSG board on the right.

Here's a slightly better look at the PSG board. A couple of wires are crudely soldered onto the edge of the PCB, and they didn't seem all that solidly connected, but I don't necessarily think that was the problem with the operation.

I mentioned I got the software loaded, here is the interface for interacting with the board. I took these photos on the projector screen at my meetup venue, so the screenshots probably look quite a bit different from my usual style.