Re: Burn in/Diags

From: Rob Clarke <>
Date: Sun, 05 Feb 2012 20:16:02 +0100
Message-ID: <>
On 05/02/2012 18:20, Gerrit Heitsch wrote:
> On 02/05/2012 06:14 PM, Rob Clarke wrote:
>> Hi Gerrit- I have many dead 264 series chip's. What sort of info are you
>> after?
> Type and datecode. I want to see if there is a pattern.
> From what I have seen so far, it seems to be the chips made in 1984 
> that are the problem with the 264. Back when HMOS-II was a new process 
> for MOS.
>  Gerrit
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Here's a pic of 9 dead 7501/8501's which I have. I keep all my dead MOS 
chips, perhaps in the hope that nannite technology will one day be able 
to repair them :-)

They are all from 1984, but I'm not sure that's statistically relavant 
as production of all the 264 models was ended before mid 1985 and I 
suspect the majority . I've got about 150 264 series specific chips and 
all but 3 are from late 83 or 84. The only exceptions to this are a 
318006 basic rom from 5086, a 318004-05 kernal rom from 0485 and a few 
8501's from 1490.

Certainly all the 8501's are killed by heat, they get ridiculously hot. 
Bil Herd recalled that there may have been a resistor on the chip mask 
that should not have been there which was to blame. The 1490 datecode 
8501's, which do not have a revision number and are marked CSG instead 
of MOS, run *much* cooler and only get slightly warm to the touch 
compared to the others. I always heatsink the CPU and TED in any 264 
machines which get regular use.


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Received on 2012-02-05 20:00:04

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