24 Nov
2015
24 Nov
'15
10:19 p.m.
On Nov 24, 2015, at 22:11, Glen Slick <glen.slick
at gmail.com> wrote:
I did some support work for a product that used a 3.5-inch 20MB
Miniscribe drive back in the mid-80's which had a failure mode where
the track zero flag would rotate slightly out of position on the
shaft. [...]
Very interesting!
I have the drive spinning up happily, though track alignment is still a crap shoot.
I've tried dumping it with the MFM Reader/Emulator, and its software could not make
sense of the track format or CRC. I dumped a raw MFM transitions file for more analysis,
since the Xebec controller might just use a track format that the emulator software
doesn't currently support. I tried analyzing the disk on several cylinders, in case
the tracks line up with steps but the track zero sensing is offset by some number of
tracks.
I think I'll try reading the drive with its original controller next, but first I need
to do some work on the chassis. There's lots of electrical tape falling off of sloppy
wire splices in there, as well as signs of rodent nibbling on some wires. I don't know
if its power supply works yet, and I'll do some repair work on the chassis wiring
before I try smoke testing it.
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/