720k 5.25 disks

[Earl H. Kinmonth]

I have an ATT (Olivetti) 6310 AT clone running SCO Xenix/MSDOS 3.3. It
has one 1.2 meg drive. I regularly format 5.25 disks to 720 K. These
disks work fine under both Xenix and MSDOS on the ATT whether used with
tar (linear sector addressing) or MSDOS directories.

When I try to transfer these disks to a 286 Zenith (also running MSDOS
3.3), I encounter various problems. With MSDOS directory disks, the dir
command (also ls under MKS) will list all the files on the disk but
copies and reads fail. With tar disks, sector reads (using int 13) fail
after the first track. The absread and biosdisk functions (TURBO C)
also fail.

Question:

Is there any bullet proof way under MSDOS to read/write to a specific
head-track-sector UP TO THE PHYSICAL LIMITS OF WHAT THE MEDIA/DRIVE
WILL SUPPORT?

For extra points: in the absence of something equivalent to the **IX
inode, how does one tell under MSDOS whether an output file is also an
input file? (I've asked this twice before with ZERO responses. Either
it is (a) a very dumb question, not worthy of a response; (b) a real
bitch; (c) my posting was ignored.

PLEASE REPLY BY POSTING OR MAIL TO THE ADDRESS BELOW:

Earl H. Kinmonth
History Department
University of California, Davis
916-752-1636 (voice, fax [2300-0800 PDT])
916-752-0776 secretary

(bitnet) ehkinmonth at ucdavis.edu
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