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

[Geoffrey S. Mendelson]

Walter Belgers wrote:

> I have found something that _might_ be a low-level formatter. I also
> found a utility to read the EEPROM and it says it has a 7MB drive which
> is wrong. I cannot choose a 70MB drive which is in it. They guy who gave
> me the machine said it was operational when the system was shut off and
> no changes were made to the hardware config since. Also, the EEPROM disk
> selection utility only lists 7, 10, 20, 40MB drives. I do have a 21MB..
> does that count as 20? :)

MFM drives address their data by cylinder (aka track), head and sector.

Sector size is determined by the software  when the drive is formatted.
Standard (as in PC) format is 512 byte sectors, but I have also seen 256,
1024 and 2048 byte sectors. 

However to format the drive it must have the correct number of cylinders
and heads. If there are more cylinders than the drive is supposed to have
they will most likely be ignored. Too few and the format will fail.

If you cannot find out what the drive is supposed to have, you will have to
play around to see what it tries to write on. If the formating program has
good diagnostics, it will tell you which cylinder and head fail the format
operation. 

Since the cylinder and head layout of almost every drive every made can be
found with some intense googeling, you should be able to find a drive
with at least as many cylinders and heads as you need.

Geoff.


-- 
Geoffrey S. Mendelson gsm at mendelson.com 972-54-608-069
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Carp are bottom feeders, koi are too, and not surprisingly are ferrets.