The Sharp PC-1500 and PC-1600 can both be extended via one (two) module slots. Pretty common are memory extension cartridges, but there are also more sophisticated modules. I have a few that contain an (E)EPROM with program code on it. I have a few of the latter ones and to facilitate reading out their content I’ve built an adapter board:
The 40-pin connector was cut out of a regular PCI slot (not PCI Express). You can actually get two connectors out of one slot.
Pin headers allow easy access to the data, address, and control lanes of the cartridge. In many cases this allows easier debug access to the content of a cartridge (it EPROM) than reading (i.e. ‘beeping’ out) its content directly via the PC-1500/PC-1600 + PC-150 interface.
The adapter board works for me but it can be pretty annoying to get the pads of a module aligned with the connector pins in the 40-pin slot. It usually takes me a few retries to get good contact on all pins. Some kind of guide rail on both sides would be helpful, but hey, it’s a hack… 😉