Re: 1551 Repair - 28 pin 6523 Wanted

From: Gerrit Heitsch <>
Date: Sun, 09 Mar 2014 15:05:48 +0100
Message-ID: <>
On 03/09/2014 02:51 PM, smf wrote:
>> If it's the normal 6525 die
> If not found anything that says whether the 6525 has internal pull ups
> either.
>> (and I doubt Commodore made a new die just for that, much easier just
>> use a different package),
> commodore were always making one off dies and doing one off runs for
> unimaginable reasons.

Only if the runs where high enough and they couldn't just use an 
existing die and just bond it out differently. I'm certain, the 6510T in 
the 1551 is just a differently bonded 6510 that passed a test for 2 MHz. 
Putting the pinouts side by side is very suggestive.

Same if you do it for the 6525A and the 6523T.

>> Should be easy enough to check by someone with a working 6523T.
> Yes, checking it is the easiest way. Getting one de-capped and imaged
> would also be interesting too.

No one will part with a working 6523T, you'd need to get your hands on a 
defective one.

> OT: The differences between the static ram 6566 and dram 6567 are also
> interesting, you can see how they hacked multiplexed address lines into
> the non multiplexed design (the static ram version was finished first
> because dram was too expensive and they would be able to ship the Max
> sooner).

Yes, unfortunatly. Would have been nicer to keep the static design when 
it comes to address lines and run everything through the multiplexers as 
well (as was done with TED later). But I think the 6567 doesn't have 
enough Pins to do that since you'd still need _RAS and _CAS.


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Received on 2014-03-09 15:00:02

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