[vcf-midatlantic] Workshop this weekend - Thoughts?

[Rob Clarke]

Hi Jonathan, take a read of this. The PLA has been exhaustively investigated and read using a top max programmer.

ftp://www.zimmers.net/pub/cbm/firmware/computers/c64/C64_PLA_Dissected.pdf


On 31 January 2016 17:24:26 EST, Jonathan Gevaryahu via vcf-midatlantic <vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
>Not that I am aware of. The BP-1600 programmer I use uses built-in 
>functionality of the PLA to dump the raw original fusemap.
>
>On 1/31/2016 3:36 PM, Douglas Crawford via vcf-midatlantic wrote:
>> Another question related to this:
>>>>> If anyone has an older 'breadbox' c64 (not c64c) with the
>signetics 
>>>>> 82s100
>>>>> PLA in it (only used for the first year or so before being
>replaced 
>>>>> with
>>>>> the MOS PLA) let me know, I'd like to try to read the fusemap out 
>>>>> with an
>>>>> 82s100 programmer. There exists a reverse engineered fusemap of
>the 
>>>>> 82s100,
>>>>> but it was done "by hand" using an eprom programmer to probe all 
>>>>> the inputs
>>>>> and look at outputs like a giant truth table, and based on an 
>>>>> interview
>>>>> with Bil Herd a few years ago, I now know that this will not 
>>>>> produce an
>>>>> accurate dump of the chip, because the engineeres at commodore 
>>>>> played some
>>>>> tricks by adding extra/unnecessary gates to certain outputs to
>>>>> intentionally 'slow down' the edges of certain signals to prevent 
>>>>> glitches.
>>
>>
>> Any real risks to the PLA in reading in this fashion?
>>
>
>
>-- 
>Jonathan Gevaryahu
>jgevaryahu at gmail.com
>jgevaryahu at hotmail.com

-- 
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