peter@aucs.uucp (Peter Steele) (12/07/89)
I went to do a chkdsk/f the other day and it reported that drive C
was a "probable non-DOS disk". It gave me the option of continuing
and I did and everything worked fine. What causes this error and
can it be removed. The machine is running DOS 3.3. No partitions
are set up (it's a 20 meg disk). Any info would be appreciated.
Thanks!
--
Peter Steele, Microcomputer Applications Analyst
Acadia University, Wolfville, NS, Canada B0P1X0 (902)542-2201x121
UUCP: {uunet|watmath|utai|garfield}!cs.dal.ca!aucs!Peter
BITNET: Peter@Acadia Internet: Peter@AcadiaU.CAbr0w+@andrew.cmu.edu (Bruno W. Repetto) (12/08/89)
>From: peter@aucs.uucp (Peter Steele) >Subject: What does "Probable Non-DOS disk" mean? >Date: 7 Dec 89 12:31:15 GMT > >I went to do a chkdsk/f the other day and it reported that drive C >was a "probable non-DOS disk". It gave me the option of continuing >and I did and everything worked fine. What causes this error and >can it be removed. The machine is running DOS 3.3. No partitions >are set up (it's a 20 meg disk). Any info would be appreciated. >Thanks! > > >-- >Peter Steele, Microcomputer Applications Analyst >Acadia University, Wolfville, NS, Canada B0P1X0 (902)542-2201x121 >UUCP: {uunet|watmath|utai|garfield}!cs.dal.ca!aucs!Peter >BITNET: Peter@Acadia Internet: Peter@AcadiaU.CA This means that you got garbage in the first 2 bytes of your FAT table. You should have a F8 FF sequence to indicate that it is a regular MS/PC-DOS partition. (It doesn't matter that the whole hard disk is dedicated to DOS as one physical drive; it is still one partition that covers the entire disk.) You can fix this by editting the FAT table with a binary editor (the Norton Utilities can help) and changing the first two bytes. This takes care of the annoying message from chkdsk, but leaves one wondering about what caused the error in the first place, and also worrying whether you are changing the FAT bytes correctly... In summary, not for the faint of heart. Backup first! So that's my $0.02. Bruno. Bruno Wiener Repetto Department of Operations Research Graduate School of Industrial Administration (GSIA) Carnegie-Mellon University Schenley Park Pittsburgh, PA 15213 GSIA Room 8b, x8730 [(412)CMU-8730] br0w+@andrew.cmu.edu
nfs0294@dsac.dla.mil (Glendell R. Midkiff) (12/08/89)
From article <1989Dec7.123115.13255@aucs.uucp>, by peter@aucs.uucp (Peter Steele): > I went to do a chkdsk/f the other day and it reported that drive C > was a "probable non-DOS disk". It gave me the option of continuing > and I did and everything worked fine. What causes this error and > can it be removed. The machine is running DOS 3.3. No partitions >are set up (it's a 20 meg disk). Any info would be appreciated. I also ran across this a couple weeks ago on a Epson Equity II running MS-DOS 3.3 with a Seagate ST238R/Ompti RLL controller. Everything works fine on the system, except when you try to run CHKDSK you get the "probable non-DOS disk". I would also like to know why if anyone can supply an answer. -- |-----------------------------------------------------------------------| |Glen Midkiff osu-cis!dsacg1!gmidkiff | |From the Internet: gmidkiff@dsac.dla.mil | |Phone: (614)-238-9643 @DLA, Systems Automation Center, Columbus, Oh. |
kevin@dell.dell.com (Kevin Staggs) (12/10/89)
In the one case where I have seen (been bitten by) this the "media descriptor byte" was munged. FYI: The first 8 bits of the FAT (file allocation table - kept by DOS) is the "media descriptor byte". For a hard disk this should be 0xf8. At least in my case changing this byte back to 0xf8 cured the problem (symptom?). If you don't want to write a prog to do this you could use a disk editor or a commercial disk maintence program (Norton's Disk Doctor, etc. - these guys will detect and fix such problems)..). -- Kevin Staggs Dell Computer Corp. !'s: uunet!dell!kevin 9505 Arboretum Blvd. Work: (512) 343-3518 Austin, Texas 78759 Home: (512) 338-9299
ho@fergvax.unl.edu (Tiny Bubbles...) (12/12/89)
From article <1598@dsac.dla.mil>, by nfs0294@dsac.dla.mil (Glendell R. Midkiff): > From article <1989Dec7.123115.13255@aucs.uucp>, by peter@aucs.uucp (Peter Steele): >> I went to do a chkdsk/f the other day and it reported that drive C >> was a "probable non-DOS disk". It gave me the option of continuing >> and I did and everything worked fine. What causes this error and >> can it be removed. The machine is running DOS 3.3. No partitions > > I also ran across this a couple weeks ago on a Epson Equity II running > MS-DOS 3.3 with a Seagate ST238R/Ompti RLL controller. Everything Me too. What happens is the 'media byte' in the first sector of the FAT gets clobbered. I've never quite figured out why. I have a sneaking suspicion that, since lots of other people seem to have the problem, it is a bug in DOS which occasionally corrupts the media byte under certain unusual conditions. I don't believe it's a random error, as there are just too many people who have had it happen to them. But I could be wrong! --- ... Michael Ho, University of Nebraska Internet: ho@hoss.unl.edu USnail: 115 Nebraska Union BITnet: cosx001@UNLCDC3 Lincoln, NE 68588-0461
bobmon@iuvax.cs.indiana.edu (RAMontante) (12/13/89)
ho@fergvax.unl.edu <918@unocss..unl.edu> : - -Me too. What happens is the 'media byte' in the first sector of the FAT -gets clobbered. I've never quite figured out why. - -I have a sneaking suspicion that, since lots of other people seem to have the -problem, it is a bug in DOS which occasionally corrupts the media byte under -certain unusual conditions. And me. I never figured out why, either. I use Zenith's MS-DOS v3.21. Paranoia time: It could be the smoothest virus we've (not) seen. If *I* was gonna write a virus to stroke my ego, this is exactly how it would act --- not destructive, just annoying at unexpected times. Infrequent enough that victims just fix it and keep the fix in mind "in case it happens again". Slow and deep, so nobody picks up any correlations between this or that program, and the changed media byte. Hmmm...at what point do we lose the ability to distinguish between a bug in DOS, and a virus in DOS?
darcy@druid.uucp (D'Arcy J.M. Cain) (12/13/89)
In article <918@unocss..unl.edu> ho@fergvax.unl.edu writes: > >I have a sneaking suspicion that, since lots of other people seem to have the >problem, it is a bug in DOS which occasionally corrupts the media byte under >certain unusual conditions. > I never had the problem on any system I used, built, installed or serviced with the single exception of a drive that actually wasn't a DOS disk. I'm no fan of DOS but before you condemn it for that consider the piles of garbage that passes for software these days that people load on their systems and then complain that the OS is broke. If the fault is in the oerating system I would suspect that it is that ordinary programs have access to the hardware but then we already knew that didn't we? -- D'Arcy J.M. Cain (darcy@druid) | Thank goodness we don't get all D'Arcy Cain Consulting | the government we pay for. West Hill, Ontario, Canada | No disclaimers. I agree with me |