On Sat, Jan 7, 2023 at 2:11 PM Rhialto <rhialto_at_falu.nl> wrote: > > On Fri 06 Jan 2023 at 22:06:42 +0100, Francesco Messineo wrote: > > Now, the really puzzling part is: why I can't read the disks formatted > > on the other 8250? All I get is 20 READ ERROR 39 0 > > Things that I've checked: > > DS0/1 start at 1/1 then change at tracks 40, 54, 65 > > The GCR rom has the correct dump. > > I've written a program that leaves the motor on, and can step in or > > out by pressing a key on the PET, it seems the disks formatted on the > > other 8250 have lower signal (as if alignment isn't really spot-on) > > but the analog signal isn't too bad to justify a read error anyway. > > Sync is clearly recognized or I would get a 21 and not a 20. > > Just a silly idea. I think you can probably see this with your scope. Is > the disk you're trying actually formatted in 8250 format and not 4040? > The bit speeds would be different, but maybe (just maybe) an incorrect > speed SYNC might just be recognized? nope, I'm sure my friend used his other 8250 (non-LP) since we worked remotely to make that one work before. Regards FrankReceived on 2023-01-07 15:03:45
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