Re: Attempting to ID an odd C-64 c (?) motherboard

From: Bill Degnan <billdegnan_at_gmail.com>
Date: Mon, 8 Mar 2021 13:42:28 -0500
Message-ID: <CABGJBucKDZ4TiNQJDdh=EfM=msFrCcJ4v4kYyoC1DWVBuWj-NQ_at_mail.gmail.com>
On Mon, Mar 8, 2021 at 1:37 PM Mario Kienspergher <contact_at_kinzi.net> 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
>
> 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.
>
> Anyway, a sensational finding. Where did you get it from, Bill?
>
> -kinzi
>

It came from the estate of David Diorio, CBM engineer.  It was donated to
kennett classic, the nearby computer museum.  There are a few CBM
prototype-y things there.  kennettclassic.com

Bill
Received on 2021-03-08 20:04:24

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