In the process of reverse engineering the Sega SP-400 plotter, I found something weird. It mounts a HD6805V1, which according to
this datasheet is an Hitachi clone of motorola's 6805.
The problem is that the datasheet does not match at all what is on the board. The chip on the board has VCC on pin 40, gnd on pin 20, crystal on pins 5 and 6. The closest things I found are
MC146805G2, which matches power, but not the crystal, and
MC146805F2 which matches the crystal as well, but has less pins (I guess less I/O).
I would like to dump the content as done
here but I have no idea on where the ports are located. The plotter board does not give particular clues, other than that pins 25 to 32 are probably the same port.
Have you ever seen a version that matches the pinout I have?