Starting over with 8" drive on PC

[Vintage Computer Festival]

Ok, starting over here since there's been a long hiatus since the last
time I messed around with this.

I'm experimenting with different 8" disks trying to figure out what's
going on.

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.

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.

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.

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.

Tried on the DOS 2.11 disk and got the exact same errors on both read
attempts.

I formatted an 8" disk under DOS, then tried L 0 0 0 1 from debug and
successfully load the sector into memory.

What's interesting is if I try to read sector 0 from the NEC DOS disk and
get the "Not ready reading drive A (Abort, Retry, Fail)" error, then
immediately put in my known readable formatted DOS disk and hit R)etry, I
get the same error ("Not ready reading drive A").  If I abort and then
retry, it works fine.  Or if I wait at the Abort, Retry, Fail prompt for a
little while then retry, it also works.

Hmmm....

-- 

Sellam Ismail                                        Vintage Computer Festival
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International Man of Intrigue and Danger                http://www.vintage.org

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