Help with ESDI disk

[Clive Dawson <clive@mcc.com>]

I acquired a used Micropolis 1568 disk drive.  This is an ESDI
760 MByte unit, in theory functionally compatible with the
Maxtor 8760-E drives that Symbolics uses on the 3630's.  I was
hoping that I could hook this up as a second drive on a 3630, but
haven't been able to get it to work properly.  Before giving up,
I thought I'd check this list to see if anybody has any experience
with these drives.

[Hairy problem description follows.  Bail out now if you need to.]

Maxtor drives have a jumper which controls hard sectoring vs.
soft sectoring, and another jumper which, in hard sector mode,
controls whether the hard sector size is determined from the
jumper settings on the drive or from a command sent by the controller.
Symbolics uses the programmable hard sector size mode.  Presumably
the FEP disk code does this when the drive is formatted.

The Micropolis drive also has a jumper which controls hard vs. soft
sectoring.  In hard sector mode, there are only 3 jumpers used to
select eight (presumably commonly used) sector sizes.  If you are not
content with any of the sizes offered via the jumper settings, then
you must use programmable sector sizing, similar to the Maxtor drives.
However, there doesn't seem to be any jumper which tells the Micropolis
whether to pay attention to the jumpers or to a command from the controller.

Hoping for the best, I hooked the drive up and went through the normal
disk formatting procedure used with Maxtors.  (Set disk type XT8760,
Disk Format.)  The Lispm appeared to format all 1632 cylinders with
no problem.  The next step was to build an IFS "tape" and write it
to the newly formatted disk.  But attempts to write the disk label
on the disk resulted in Lisp stopping itself.  I've tried everything
I know, but I can't seem to get a file system out there.  The machine
either crashes or hangs.

I've had long talks with technicians at both Micropolis and Maxtor.
The biggest source of confusion has to do with the difference, if any,
between programmable sector sizing and soft sectoring.    Judging
from what Maxtor says, these are two different things.  But various
Micropolis people claim that they are really the same thing.

Unless anybody has any ideas, I'll probably just give up trying to
get a Micropolis drive to work on a Lispm.

Thanks in advance for any help,

Clive Dawson
MCC