On Wed, Aug 26, 2026 at 1:34 AM Gerrit Heitsch <gerrit_at_laosinh.s.bawue.de> wrote: > 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. > > Gerrit > Thanks, Gerritt. If you click on the fuzzy image of the whole board, you should be able to see the full resolution version. Same for the other photos. Hopefully this link will go directly to the full-size image: https://www.icloud.com/sharedalbum/#B1f5BydzFLHLGD;D5AA8DA6-B68C-4B33-BE11-9AAD6C64CFC8 - Alex > > >Received on 2026-08-26 12:00:02
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