Laser Compact XT Restoration project- ISA slot and graphics card


So I’ve done a bit more testing.

First, the ISA slot situation. ISA is a very simple protocol. Simply wiring in additional slots to an ISA system should work to add more slots, though eventually you can run into issues. Continuity testing with my multimeter shows that the header I have is in fact wired into the bus, so adding a slot there should be fairly easy. Just solder in an actual card edge connector rather than the header style connector and I’m good. I can get an ISA extension box later if I need more than the one slot.

One exciting prospect was that there was also an EGA version, and I though the expansion slot was only an option on that version. So having so much of the expansion slot present, there seemed to be a chance I might have EGA… but no. I found the output shift register for the card, and continuity testing all of its outputs to the RGB port output and I only get 7 lines that are connected. All 9 lines would have continuity to some output from the register if it were EGA. CGA only has seven that are connected. So those hopes are dashed, it’s a CGA card.

But, if the ISA situation works out as I’m expecting it to, I should be able to add EGA on a separate card should it make sense to do so.

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