🚀 go-pugleaf

In article <1990Sep5.171921.14940@cbnewsh.att.com> europa@cbnewsh.att.com (r.j.capik) writes:
>
>	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.

   Microsoft is one of those companies that knows a buck when they see it,
and will do almost anything to sell their operating system, including
allowing the hardware manufacturer to tailor the operating system to
the hardware, instead of doing it all in the BIOS.   (there are some
arguements in favor of this sort of thing, but i don't want to get into
that.

   Something that is quite common is mapping the interrupts physically 
differentthan in the original ibm, and rerouting the interrupts in the
operating system so that everything works fine as long as you use that
custom version of dos in that machine.   i don't understand there to be
any technical advantage to doing this, but some manufacturers want to be
different.   (not invented here syndrome.)   zenith is very good about
doing this.

   compaq modified dos so that you could have hard drives larger than
32 megabytes.  handy for those with 300 megabytes drives who don't want
drive designators spanning from a: to l:, but creates its own incompatibilities
when that one piece of software that comes down the pike does something the
designers at compaq never dreamed of.

   others have modified DOS so you would have more than 640k TPA, only to
find that such mods would create havoc when the machine it was running on
was upgraded to VGA.

   and of course there are those companies that some time ago marketed semi-
compatible machines, like DEC's Rainbow, which i consider to be one of the
"left feild" orphans.   not only is the interrupt structure screwy, or the
floppy disk format screwy, or the bios screwy (IT HAS NONE!!!), but it
runs a funny version of the operating system as well.  (a bastard mod of
dos 3.1, which packs along its own bios on disk.)   I really shouldn't slam the
rainbow as much as i do (i'm using one to write this) because it does have
its good points.   (when chkdsk reports 800k ram free, i still snicker at
those stuck with less that 600k free.)

>	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...

   when dos jumped from 2.xx to 3.xx, some stuff was added to the hard
disk format in such way that 2.xx could find what it needed, but no
provision was made in 3.xx to read the 2.xx format.   the guys at
microsoft probably never anticipated that happenning, and so saved a 
few bytes leaving it out.  (in other words, 3.xx needs information from
the disk that 2.xx never wrote and as such thinks it's an error in the
media.

>	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.

   dos 4.xx is still too buggy for many uses.  it changed a considerable
amount of things in the hard disk format (to allow drives greater than
32 megs) which makes it a necessity to reformat your hard disk. even then,
i know people who wish they never heard of 4.xx because a bunch of their
software wouldn't coexist with it.

>	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).

   different versions of lotus??  perhaps the creator used a lotus
lookalike??

-- 
fzsitvay@techbook.COM - one of these days i'll get it right...

Version 2 of anything is usually the version that works.