[vcf-midatlantic] Workshop this weekend - Thoughts?

[Jonathan Gevaryahu]

Yes, I believe so.

On 1/31/2016 9:46 AM, Jeffrey Brace via vcf-midatlantic wrote:
> Would I simply look on the PLA chip and find 82s100 on the top imprinted
> there?
>
> On Sat, Jan 30, 2016 at 6:27 PM, Jonathan Gevaryahu via vcf-midatlantic <
> vcf-midatlantic at lists.vintagecomputerfederation.org> 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.
>>
>>
>> On 1/29/2016 5:49 PM, Jeffrey Brace via vcf-midatlantic wrote:
>>
>>> Chris,
>>>
>>> I was wondering the same thing. I would say from experience with repairing
>>> Commodore 64s at the workshop, I would bring 5-10. Some you would use for
>>> parts, but I would expect at least 5 can get fixed. But this workshop is
>>> unusual because we got a lot of people that know their stuff coming to
>>> help
>>> and lots of people working on fixing. If you want to bring 20, that is
>>> great. I wouldn't expect all to get fixed, but there is a great
>>> possibility
>>> that they can. For myself I will bring 5 working drives, and 10 non
>>> working
>>> drives. Some of them I have labeled as to the dysfunction with a post-it
>>> note. I don't have a lot of experience fixing them, I have tried cleaning
>>> some and they remained unfixed. My gut tells me that a smaller percentage
>>> can be fixed with cleaning them 10%, a bigger percentage could have chip
>>> issues like 25%, maybe 50% have component issues (capacitor, resister
>>> etc.), another 15 percent are disk head or speed issues. What does
>>> everyone
>>> else think?
>>>
>>> Jeff
>>>
>>>
>>>
>>> On Fri, Jan 29, 2016 at 12:15 PM, Chris Fala via vcf-midatlantic <
>>> vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
>>>
>>> I have been really looking forward to an opportunity to get some
>>>> experienced assistance repairing 1541 drives. I acquired several on eBay
>>>> and other sources over the last couple years. Some were functional, some
>>>> worked after the heads were cleaned, and some are still malfunctioning
>>>> for
>>>> unknown reasons. I haven't had the time to dig deeper and diagnose the
>>>> problems on these. I hope that I can learn more about these this weekend
>>>> and get at least some of this last category working.
>>>>
>>>> Practically speaking, how many drives should I bring this weekend? Is 20
>>>> too many or is it possible to actually work on that many in a day? Are
>>>> there common problems that can be addressed quickly, or is it more likely
>>>> that each drive will require unique troubleshooting?
>>>>
>>>> .
>>>
>> --
>> Jonathan Gevaryahu
>> jgevaryahu at gmail.com
>> jgevaryahu at hotmail.com
>>
>>


-- 
Jonathan Gevaryahu
jgevaryahu at gmail.com
jgevaryahu at hotmail.com