On Fri, 25 Mar 2005, Vintage Computer Festival wrote:
First, the basics: I know my controller can handle FM
because I was able
to successfully copy all the files off an old 160K PC disk in my 1.2M
5.25" drive.
Sorry, but 160K MS-DOS diskettes are NOT FM.
They are MFM with a 250K data transfer rate at 300 RPM,
or a 300K data transfer rate at 360 RPM.
Second, the 8" drive can successfully
format/read/write an 8" drive when I
have the BIOS configured for a 5.25" 1.2M drive. My drive is a Tandon TM
848-02. Someone e-mailed me a link to the manual they scanned, and now I
can't find that person's e-mail nor remember who it was (I'm so sorry!)
But at any rate, of the 3 measley links that come back from Google, I see
that this drive is DSDD. Still don't know if it can do FM however.
The 848 CAN do FM. Whether or not your disk controller can remains to be
seen.
BUT,...
I don't remember whether the 848 can read "normal" 8" single sided.
Look at the index hole position of a SS and a DS 8" diskette.
Does the 848 have one, or two, index sensors?
'course if the diskettes that you formatted as 1.2M are the
same type of diskettes, then that has already been confirmed.
I have some 8" disks in both CP/M and DOS 2.11
format from my NEC APC.
They both read fine on the NEC APC.
APC CP/M diskettes could be SSSD, OR DSDD.
The MS-DOS 2.11 from the APC should be DSDD.
I'm trying to read targeted sectors using debug.
With the CP/M disk, I try to L 0 0 0 1 (Load at address 0, drive 0, sector
0, 1 sector) and get:
Not ready reading drive A
Ok, so I try L 0 0 1 1 and after a longer pause get:
General failure reading drive A
Hmm, I'm still new to this, but this seems like a density issue.
"General Failure" (wasn't he in 'Nam?) does usually mean a density
issue.
It is usually caused by an error #2 (address mark not found) from the
BIOS, although it literally means "none of the above" - an error occurred
that was not in the list of errors that DOS understands.
BUT,...
DEBUG's L... command is really only for reading MS-DOS diskettes; it will
attempt to determine WHICH MS-DOS format it is looking at first, and will
give incorrect error messages for anything else, although it will
SOMETIMES correctly say "Probable Non-DOS diskette".
"General Failure" is usually density, recording method, or blank disk.
"Sector Not Found" means right density and MFM, but the expected sector
number isn't there.
"Not Ready" USUALLY means it didn't see enough index pulses.
Good luck,
--
Grumpy Ol' Fred cisin at
xenosoft.com