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

Martin,

I sent you a couple of emails a while back re: 8296 HSG Emulator board roms... 
got no reply. Hoping you can help!

Steve



----- Original Message ----
> From: "Hoffmann-Vetter, Martin" <martinHV@arcor.de>
> To: cbm-hackers@musoftware.de
> Sent: Wed, August 10, 2011 4:10:42 PM
> Subject: RE: Repairing a SFD-1001 (8250/LP, 8050, 4040, 3040, 2040)
> 
> Hello,
> 
> > 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.
> 
> Greetings
> 
> Martin
> 
> 
> 
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