On 8/26/26 06:42, Alexander Jacocks wrote: > Folks, > > I've had this C64 for a few years, and it would need some attention to > be functional, but it was immediately obvious to me that it wasn't a > normal machine because it has a flat-flex keyboard cable. Then, when I > looked closer, most of the chips are normal, but: > > 1) The ROM is an EPROM, and appears to be a combo basic/kernal > 2) The IC in U6 is purple ceramic, and clearly has a hand-stamped label, > "240431", which doesn't match anything that I am aware of. Based on > location, it's a 6510 of some variety, but maybe a test production run > of the 8500? > 3) There are extra wires on the keyboard itself (which is a Mitsumi > membrane) > 4) The board has a SuperPLA, 251715-1 > 5) The RAM is 2 64k x 4 HM50464-15 chips like the 250266 and 250469 > > I'm sure that there are other oddities. I've shared a quick album of > photos here: > https://www.icloud.com/sharedalbum/#B1f5BydzFLHLGD <https:// > www.icloud.com/sharedalbum/#B1f5BydzFLHLGD> > > I've not attempted to power up the machine and would need to at least > dump the ROM first. > > Any thoughts/comments are welcome. That looks like an early version of what would become the 250469 board. Some ICs are in a different position or orientation, but the general layout is there, including the 251715-01 PLA. The contents of the EPROM should be identical to the 251913-01 ROM which is pincompatible with a 27128 EPROM. That IC with the 240431 number is probably the 8500 CPU. The 8500 also appeared on some 250425 boards. Also, a photo of the full board would be nice. The only one that comes close is fuzzy. GerritReceived on 2026-08-26 07:00:01
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