Re: PLA equations for the 1551 drive's cart

From: Gerrit Heitsch <gerrit_at_laosinh.s.bawue.de>
Date: Sat, 22 Feb 2025 19:59:31 +0100
Message-ID: <191cfaa2-fba1-4b45-a546-ef8ae3b7f79a_at_laosinh.s.bawue.de>
On 2/22/25 19:29, Uffe Jakobsen wrote:
> Gerrit Heitsch writes:
>> On 2/22/25 18:28, Francesco Messineo wrote:
>>>
>>> I've never seen a good 8501 in my whole life so far. I have made a
>>> replacement for it with a 6502 and 2 x ATF1502 CPLDs, this is barely
>>> larger than the 8501 itself. But I only have one C16 that was donated
>>> many years ago by a friend.
>>
>> The 8501R4 or 8501 without R-Number seem to last. I have a few of 
>> them, a few years ago a number popped up on ebay for a low price.
>>
>> I still have working 8501R1 too.
>>
>> My 7501R1 failed though.
>>
> 
> 
> So maybe the 7501/8501's aren't as that bad as their reputation - it 
> just comes down to them being used in a "bad" design...
> 
> Any thoughts about this theory ?

Yes.. That 7501R1 was on a spare board that I never connected to 
anything. Just hooked it up to a monitor and power supply for testing 
every few months. And one day it just didn't start. Replacing the 7501R1 
with a known working 8501R1 fixed the issue. So the CPU just died.

  Gerrit
Received on 2025-02-22 20:00:19

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