jc58+@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.