europa@cbnewsh.att.com (r.j.capik) (09/06/90)
Here is a question that I can't seem to find an answer for
and don't even have a clue where (else) to look. The question:
What is the difference between DOS? To be a bit more specific,
what do vendors do to DOS and how can one evaluate the
differences.
I've encountered an unreasonable number of odd problems that
can for the most part be traced to some *magic* that a vendor
has added to their DOS. However, even without added magic
different DOS versions seem to have unpredictable results.
In one upgrade; hard disk #0 (normaly drive C:) became drive
D: and disk #1 became C: (with a read error). FDISK showed no
DOS Partitions on disk #1. Re-boot (same versio, different
vendor) and both disks are back, but now I get interupt errors
that I didn't have before.
I did an upgrade on another system (DOS 2.2 to DOS 3.0)
where I backed every thing to another hard disk. I upgrade the
1st disk only to find that I can no longer read the 2nd disk
(the one with my full backup). It turns out that the new version
can't read the old hard disk format, BUT, the old version can
read both the old and the NEW format. So go figure...
I did another upgrade on another computer (DOS 3.3 to DOS
4.0, and a tape backup). Install the new DOS, OK. Down load the
old files, OK. Use some programs, OK. Edit a file: ERROR can't
find ROOT directory! Copy some files to another directory: ERROR
can't find ROOT directory! I run CHKDSK, Norton, Mace, etc. and
everything is fine, no errors found. Re-install DOS 3.3, and
every thing is back to normal.
I got a data disk from a friend (Lotus123 WKS files) where
the files were created on a HP machine. All my DOS machines can
read the disk fine, but Lotus gives me a file error, and once
more CHKDSK shows no errors. Then magic of magic, I try the disk
on a Macintosh with a DOS reader, and all the data is there just
like it should be (but I have no idea how to move it from the
Mac to a normal computer).
These are just a few of the problems I've encountered. I
won't even go into the extended/expanded memory problems, or the
low level format problems. So stands the question: What's the
difference between DOS? [ PC-DOS, MS-DOS, Zenith DOS, HP DOS,
AST DOS, ATT(MS)DOS, etc. ]
Ron Capik
AT&T Bell Labs, Holmdel, N.J.
cbnewsh.europa@ATT.COMjc58+@andrew.cmu.edu (Johnny J. Chin) (09/11/90)
Various vendors of DOS add so called "enhancements" to their DOSes. The noted
vendors that I know of are Wyse, Compaq, AST, Epson and Zenith.
Most of them make modifications on how their version of DOS can access specific
information in the CMOS of their computers (ie. user defined drive types).
Also, DOS 2.x, 3.x0, 3.x1, and 4.x are *NOT* always compatible. I strongly
recommend that you backup *ALL* drives *BEFORE* you do any DOS upgrades.
Some DOS versions use different drive partition descriptors, thus you won't
be able to read the old partitions (whereas the older DOS may recognize
the new partition). I guess the DOS writers put more contraints on the
descriptors in the newer versions.
I hope this helps ...
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Computer Dr.
Disclaimer: The views expressed herein are STRICTLY my own, and not CMU's.