I posted a synopsis mirror of this thread on my web site, here: https://www.vintagecomputer.net/browse_thread.cfm?id=779 Please advise any corrections/revisions/removal requests. Thanks Bill On Mon, Mar 8, 2021 at 1:46 PM Gerrit Heitsch <gerrit_at_laosinh.s.bawue.de> wrote: > On 3/8/21 7:21 PM, Mario Kienspergher wrote: > > > > Am 08.03.21 um 18:39 schrieb Jim Brain: > >> On 3/8/2021 11:29 AM, Bill Degnan wrote: > >>> Hi, > >>> I have a strange C64C (I believe) motherboard with: > >>> > >>> PCB ASSY NO.250451 > >>> PCB No. 251915 Rev.2 > >>> > >>> ...printed on it. I don't see this board documented in the normal > >>> places and the PCB does not come up in a search, any ideas? The > >>> VIC-II is missing. > >>> > >>> > https://www.vintagecomputer.net/commodore/64C_250451/250451_251915_pic1.jpg > >>> < > https://www.vintagecomputer.net/commodore/64C_250451/250451_251915_pic1.jpg> > > >>> > >>> > >>> Thanks > >>> > >>> Bill Degnan > >>> > >> That's an odd one. Like a CR board, but with 8 DRAMs, though not ina > >> 2x4 config like on the 466 board. > >> > > Indeed, looks like they were testing it but trashing it because of > > problems, as the 250466 came much later with a NMOS VIC and old glue > logic. > > > > IC-stampings are from mid/late '84. Maybe the HMOS-II-Version of the VIC > > did not perform very well or the yield was too poor, or known problems > > with other HMOS ICs (7501, 7360) forced postponing. > > They did use the 8500 on 250425 boards. Problems with VIC are possible, > after all when the HMOS-II version came out, it was R2. > > And you can see on the right side that there is a space for a regulator > (VR1), so the board might have been able to use an NMOS VIC. > > Gerrit > > > > >Received on 2021-03-08 21:00:02
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