Nice!
Well, if you're willing to dump the contents of the character generator ROM (and have a way to do it), that'd be awesome.
It's a pity about that nonstandard keyboard connector... although if the protocol and the KB controller are close enough to the standard XT scheme, perhaps it may be feasible to devise a cheap adapter for other XT keyboards?
I've seen references on this forum of people building adapters, so I'm hoping someone has any suggestions on pinout, as I'm super confused after putting a scope and multimeter on things --
1. I'm pretty sure I've found the 0V and 5V lines, but the 5V line puts out 3.7V when nothing is connected, and after some kind of handshake with the keyboard, it jumps to 4.8V.
2. All the other lines (presumably reset, clock and data) are at 4.8V constantly. Pressing keys on the keyboard doesn't drop these lines, nor do I see any pulse trains one way or another.
3. I went through all combinations of these lines I could think of to an XT keyboard through a DIN plug, but with power connected to another XT keyboard, the voltage is 1.2V (and the Corona machine complains no keyboard is connected).
4. During my probing / testing, with the original keyboard connected, only once, did I see a "6" showing up on the display.
My less than educated guess -- since I'm not familiar with keyboard protocol and workings, beyond some reading I did yesterday, is that the keyboard controller on the mainboard is probably ok (how else would I have seen a 6?), but something is wrong with the keyboard itself. And I've probably missed a combination of pins with an XT keyboard connected...
Incidentally, if it helps, it's a Key-Tronic keyboard, model 2402-41. Haven't found much on those online. But I have found some 2402-58s online that seem to come with a DIN plug. Not sure how different these guys are... Still googling! Hoping it's just a different connector, and not a completely different protocol, etc...
Oh, and if you know how to find the character ROM (would it be readable in memory space?, if not, if it's socketed, I should be able to read it out on my EPROM burner -- what am I looking for on the board?)