From: M H Stein <dm561 at torfree.net>
Interestingly, Andrew Lynch apparently got a different
version of the GFR
(-149 IIRC) to work on his Vector with HS disks, whereas my -159 never
goes ready at all with HS disks.
I was trying to oversimplify a bit on my reply; Teac drives across
any single product line have a tremendous potential for variability.
The last thing in the world I wanted was for someone to hunt down a
set of FD-55GFR drives and report back that they didn't work. The
same variability is present in 3.5" Teac drives--the 235HFs come in
many varieties; some offer many options; others offer next to none.
Undocumented jumpers and pads on drive PCBs are even wilder in
assortment and presence/absence.
I've had pretty good luck with Mitsubishi and NEC floppy drives
manufactured for the Japanese market (PC9801-style systems). As the
floppy format is based on an 8" model and doesn't change much across
physical formats, the drives themselves tend to behave when pressed
into use in 8" applications. They can be tough to find on this side
of the Pacific, however.
Generally, the later a drive is manufactured, the more "smarts" are
used in its drive control logic--and the less it will be suited for
non-PC use. I was surprised to find that there's a Toshiba 3.5"
floppy (ca. 1996) that senses the data rate on HD diskettes and
automatically changes its spindle speed. You can read, write and
format 1440 KB on it and read and write 1232 KB, much like many USB
and IDE floppy drives. The idea probably was that there were still a
lot of DOS-V format floppies hanging around Japan and wouldn't it be
nice to be able to read and write them on a "generic" PC...
Heaven only knows what the drive would do with some nonstandard data
rate or modulation.
Hope this helps,
Chuck