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

From: Hoffmann-Vetter, Martin <>
Date: Wed, 10 Aug 2011 22:10:42 +0200
Message-ID: <008e01cc5799$9578b370$>

> I don't know how relevant it is to CBM floppy drives, but it seems to
> have something to do with chip select lines?

That's one problem when you change an 2332 (rom) to a 2532 or 2732 (eprom).
The 23xx series has many chip select (cs) signals that can be programmed in
the polarity. So the standard 2332 for the PET is non inverted chip select
(cs1) at pin 21 and inverted chip select (cs2) at pin 20. You have the same
problem with some dos roms eg. 901887-01 and 901888-01. That's a 2364 with
one non inverted chip select at pin 20!

Back to the 2332. This rom has two chip select inputs. The 2532 has only
ohne chip select input. The 2732 has one chip select and one output enable
input. So the 2732 is a better replacement for the 2332. It's used on the
adapter boards for the sfd 1001 and the 8250lp by commodore.



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Received on 2011-08-10 21:00:04

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