Booted to DOS 5.0, on AT class machine, drive B set to
1.2MB, formats
and writes/reads disks fine. imd has been copied to HD, as well as IMD
image.
If you are booting to real/raw DOS ... does the drive work under DOS.?
Yes
Can you FORMAT
1.2M and 360k disks under DOS and read/write
them.? If not, you have a hardware problem (for DOS, make sure it is
configured correctly in BIOS - IMD doesn't use BIOS settings though).
Works
fine
When you create 360/1.2M disks by formatting on the PC - can you then
read and recreate those disks with IMD?
If yes, then likely your hardware setup is working. If no, then you may have
some compatibility issue with the mainboard controller. (IMD does direct
access to the FDC hardware)
Fred's post below also reminded me that Kay disks are 10x512 - this can
be "a bit tight" for some PC controllers. 765's and derivitives have a
"blind
spot" just after the index hole - and some versions are worse than others.
Once you try to recreate a Kay disk and it fails ... try reading the first track
back. Does it get most of the sectors. If the first or last sector is missing,
then it likely held off writing the first sector long enough that the whole track
with the "extra" sector didn't fit in the remainder of the track.
If this happens, you could try slowing the drive down slightly ... you may be
able to create a readable disk that way (I almost always have to slow my
drives by a few rpm to write Cromemco disks for example). You might also
make readable disks by reducing the gaps from the precalculated values..
a little experimentation may be in order.
IIRC you indicated that you were using a Teac 1.2M drive - it might be
jumperable for 300rpm ... if so, try that - running the controller at 250kbps
might improve the situation. I find that generally recreating DD disks can
be a little more forgiving with 300rpm drives.
Dave
--
dave13 (at) Dave Dunfield
dunfield System/Firmware development services:
www.dunfield.com
(dot) com Classic computers:
http://www.classiccmp.org/dunfield
