[rescue] Anybody remember MFM? (Durango Poppy II problem)

[Mike Hebel]

On Tuesday, August 5, 2003, at 11:10 AM, Walter Belgers 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 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.

> 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.

Mike Hebel

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