Re: "Commodore 64 Prototype Project"

From: Gerrit Heitsch <>
Date: Sun, 06 May 2012 09:30:37 +0200
Message-ID: <>
On 05/06/2012 07:55 AM, Jim Brain wrote:
> On 5/5/2012 9:27 PM, Robin Harbron wrote:
>> Anyone know what this strange item is?
>> From the item description:
>> "This unit was great found in Mountain View (Silicon Valley, CA)
>> approx over 15 years.
>> The retired Commodore Engineer told us that this system was use for
>> the project of Commodore back years.
>> Other than that we have lack of info about what the project it had
>> used for, may be some Commodore collectors know about it."
>> It has a Rev. C C-64 motherboard so it's clearly not a C-64 prototype :)
>> Robin.
>> Message was sent through the cbm-hackers mailing list
>   * Interesting that it's "Symwar" on the KERNAL IC, and SYMAR on the
>     daughtercard 2732
>   * The 26 ICs confuses me. I was guessing DRAM, but 26 seems an
>     interesting number (256kb *4 * 26 = 3.4MB)

I thought DRAM as well, but there is a catch, as far as I know, the 
256Kx4 DRAMs were not out in 1984 and the other datecodes on all the 
chips and the EPROM label suggest 1984 as the time this came into being.

Unless I miscounted, the 26 ICs are 20pin, there are some 20pin SRAMs. 
The 2114 is 18pin, so it would be likely 4K x 4 SRAMs.

I also see a 74LS154 on the additional board which is a 4-to-16 decoder 
but from the underside it doesn't seem to be used to the full extend.

Judging from the underside, it doesn't look like DRAMs from the way the 
EPROM and UARTs are wired into everything due to DRAMs using multiplexed 

Too bad the interesting parts are not photographed... I mean the PLA 
tower and the RAM matrix on the upper board.


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Received on 2012-05-06 08:00:21

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