Re: Repairing a SFD-1001 (8250/LP, 8050, 4040, 3040, 2040)

From: Anders Carlsson <>
Date: Wed, 10 Aug 2011 09:27:09 +0200
Message-ID: <8E27F66EE1FB4F3EAF45C145D6D1277D@ryds>
Jim Brain wrote:

> I'm now less concerned about demand for such an adapter,

Very nice!

As well as replacing broken chips, an adapter with programmable ROM part 
would be useful for anyone who has a working drive with an early DOS 
version. I had 2-3 drives of the 3040/4040 variety which were equipped with 
DOS 1, how odd it might sound. I found in order to upgrade, one needed to 
replace both the ROM chips and the RRIOT. We discussed this at the Vintage 
Computer Forum and came to the conclusion some adapter boards were needed, 
where I could plug in the old 6530 and a small EPROM just like it is done on 
the 8250LP.

Also it appeared 2532 EPROM's are not suitable replacements for the 2332 (?) 
ROM's in the drive. They work fine in a PET computer though, just not in the 
drive? We checked the pinout and saw some references on pinball repair sites 
about them having the same problems replacing ROM with EPROM, so perhaps 
this is a real problem and not just me failing to program them properly.

Most of this however are moot points now as I have traded away the drives to 
other people. Of course they might want to make the DOS upgrade later on, 
but then there needs to be a solution to the ROM replacement. Would Jim's 
ROM-el work or is that only for 8K chips and upwards?

Best regards

Anders Carlsson

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Received on 2011-08-10 08:00:13

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