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

From: Terry Raymond <traymond160_at_gmail.com>
Date: Mon, 8 Mar 2021 11:16:22 -0700
Message-ID: <CAJ+D7=Mk-M4sQmgD1vTn5w4radqbcqt8aVrh+iP1JQhSo0AdjQ_at_mail.gmail.com>
Hi Bill,

Is one chip there a ceramic chip?

Terry Raymond


On Mon, Mar 8, 2021 at 11:12 AM Gerrit Heitsch <gerrit_at_laosinh.s.bawue.de>
wrote:

> On 3/8/21 6:39 PM, Jim Brain wrote:
> > 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.
>
> The numbering suggests that it's older than the 250466 design. Same goes
> for the datecodes on the chips on it. But it shows a lot of details that
> later appeared on the 250469 boards.
>
> It would be interesting to know which VIC goes onto that board, is Pin
> 13 of the VIC socket connected to +5V or something else? Where does the
> 6581 SID gets the +12V from?
>
> My guess is this board was supposed to replace the 250425, but they ran
> into some kind of problem(s) and had to make the 250466 as a stopgap
> until the 250469 was ready.
>
>   Gerrit
>
>
>
>
>
>
Received on 2021-03-08 20:00:53

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