16 Jun
2006
16 Jun
'06
4:52 p.m.
Subject: Re: Floppy stepping problem
DOS (actually the BIOS) uses a table with an entry for
each drive to
indicate several things like specify bytes (which sets stepping rates).
Later 5.25" drives tend to step at 6 ms per cylinder, although some older
drives (e.g. SA400) require longer than that. 3.5" drives typically can
step at 3-4 msec. per track.
It doesn't hurt a drive to step it more slowly than the manufacturer
specifies, but it does tend to increase the noise level. As a quick fix,
you may simply want to slow everything down.
Years ago I experimented with the MicroSolutions Compaticard 4. The
documentation included some tables showing how to change the stepping rate.
This was especially important for 8" drives, as I recall.
The experiments were made a necessity, as I had to read some funny CP/M
disks, and it showed that the BIOS's embedded in newer systems (I'm now
speaking of 486/50's etc) could not read 180 KB and 160 KB disks anymore,
not to speak of 8" disks.
The compaticard solved my problems; I could even generate a bootable 8" disk
for DOS 3.20
Nico