[rescue] Anybody remember MFM? (Durango Poppy II problem)
walter+rescue at belgers.com
Tue Aug 5 12:09:40 CDT 2003
Mike Hebel wrote:
> > Now the problem: although the Micropolis 1325 71MB MFM drive spins up,
> > I
> > cannot read/write it, I get an error on the first block. I do have the
> > correct /dev entry: the HD drive LED goes on. I tried inserting another
> > (21MB) MFM drive with the same problem.
> Inserting another drive probably won't work. You might want to look at
> some low-level formatting routines. Some of the older cards you had to
> use a command in DOS debug to get to the low-level routines: c800:g
> Depends entirely on the card.
The 21MB disc was DOS-formatted (with MS-DOS installed, I took it out of
a 80286). So I don't think low-level formatting would help (besides,
since I cannot boot DOS, also not from floppy, I have no way to perform
a low-level format). The system has no interactive BIOS AFAIK.
> > The drive is connected to a board from 'Molecular Systems' which has 3
> > connectors: 2 for the MFM drive and a 50 pin connector. I am hesitant
> > to
> > try out if it's SCSI. Were combined MFM/SCSI cards normal in the old
> > days?
> Umm...not that I can recall but it _might_ be SCSI-1. If it is you'll
> probably not find a drive that will run on that connector.
Why not? SCSI-2 drives should work on a SCSI-1 controller?
> > Also, there are two potentiometers (is that English? variable
> > resistors)
> > that are next to the MFM connectors. Would fiddling with those improve
> > my chances of getting this thing to work?
> Don't mess with those! If you're having a problem _now_ then you could
> very well put yourself totally out of the picture because you'll never
> get them back into the original adjustment. IIRC they had something to
> do with sync. Data or motor I can't recall but either way they aren't
> easily adjusted properly without the original signal specs from the
> board manufacturer.
Then again, these may cause the problem..
Walter Belgers "Si hoc signum legere potes, operis boni in rebus
walter at belgers.com Latinis alacribus et fructuosis potiri potes!"
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