Re: Real 82S100 in C64

From: Julian Perry <>
Date: Sun, 2 Sep 2012 09:53:56 +1000
Message-ID: <>
My old, personal, original C64 (July 1983) used the 82S100, and
despite years of heavy use and abuse, the PLA is still going strong.
I replaced it's keyboard, both CIA  chips, the SID chip, and BASIC
ROM. The RAM was replaced with 256 kbit RAM as part of a (never
completed) expansion project, and there were various other mods done
to it over the years, but the 82S100(N) is still chugging along fine,
despite the original PSU going overvoltage (I measured it at 7.5V when
it failed!!), and chuggs along fine with an EasyFlash3 cartridge!

There's a photo of the poor long-suffering board, complete with

Having said that,
now the bugger will smoke the next time I turn it on :D !!


Hello Silverdr,

Sunday, September 2, 2012, 8:54:13 AM, you wrote:

>>>> On Sun, Jul 29, 2012 at 06:48:19PM +0200, Gerrit Heitsch wrote:
>>>>> The funny thing is... Did Commodore ever use the 82S100 in production C64 systems? So far I have only seen the 93459PC made by Fairchild in any of them.

>>> On Jul 29, 2012, at 1:43 PM, Marko Mäkelä wrote:
>>>> I seem to remember that my oldest C64 (serial number 34727) contains a 82S100. Can anyone confirm?

>> On Jul 30, 2012, at 19:10, raycomp <> wrote:
>>> I have repaired perhaps a dozen of the older C64's which have had the 82S100 chip (some of them had failed).

> On 2012-07-31, at 02:14, Justin wrote:
>> I agree, all of mine failed also.

> This thread can possibly explain to me the difference between what
> everyone kept saying for years (that the main failure cause for a 64
> was a dead PLA chip) and my own experience from repairing literally
> hundreds of them back in the days. From my experience PLA was
> responsible for a really tiny percentage of the failures. But I
> recall only few (one or two - memory doesn't serve so good - of the
> very oldest boards) having the actual 82S100 loaded.

> Might it be that the 82S100 was failing like hell and the Fairchild chips were much more robust?

Best regards,

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Received on 2012-09-02 00:00:04

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