I sent this before, but it didn't show up on the list;
Part 1;
Which versions of DOS let you boot off B: ?
Obviously, NO command that you run in DOS (which would be after it has
booted), will change the boot sequence, which is before DOS is present.
Nor will such a change last through a boot (although MICROS~1 could have
included a tepid/partial boot, if they had wanted to.)
DRIVER.SYS achieved prominence in DOS 3.20. PC-DOS 3.20 was the first time
that IBM supported a 3.5" ("720K") drive. Several other companies, other than
IBM, already used 3.5" drives for laptops, such as Data General, Gavilan, etc.
with their own drivers in MS-DOS, particularly version 2.11, which was similar
to 2.10, but used by OEMs that needed to customize MS- DOS. In many cases,
the 3.5" disk formats that those companies created were different from what is
supported in DOS 3.20 http://www.xenosoft.com/fmts.html
IBM PC/JX was an IBM machine with 5.25" "720K" drives, but was never sold in
USA.
Because IBM's 5170, and most already existing 286 machines, did not include
"720K" as any of the options in the "CMOS Setup" for identifying what kind of
drive each physical drive was, DRIVER.SYS permitted creating a
logical/virtual/shadow drive that would share a physical drive, as E:, F:,
etc.
LASTDRIVE was also needed if you already had more than two floppy drives and a
HDD, to permit assigning drive letters past D:
Another alternative was DRIVPARM ! It was a CONFIG.SYS command to alter the
parameters of floppy drives, WITHOUT creating any new logical drives or drive
letters! DOS 3.20 and onwards.
Something that has always confused me:
DRIVPARM is documented in MS-DOS 3.20, but is not mentioned in the PC-DOS 3.20
documantation.
I used MS-DOS with DRIVPARM on a generic 286 machine, and it worked!
I used PC-DOS with DRIVPARM on a generic 286 machine, and it worked!
I used MS-DOS with DRIVPARM on a genuine 5170, and it failed, with a "BAD
CONFIG.SYS COMMAND" message (possibly mistaken on the exact wording)
I used PC-DOS with DRIVPARM on a genuine 5170, and it failed, with a "BAD
CONFIG.SYS COMMAND" message (possibly mistaken on the exact wording)
I used MS-DOS with DRIVPARM on a generic 286, with copy of the 5170 BIOS, and
it failed, with a "BAD CONFIG.SYS COMMAND" message (possibly mistaken on the
exact wording)
I used PC-DOS with DRIVPARM on a generic 286, with copy of the 5170 BIOS, and
it failed, with a "BAD CONFIG.SYS COMMAND" message (possibly mistaken on the
exact wording)
So, therefore, I concluded that DRIVPARM was incompatible with the IBM 5170
BIOS. But present in both MS-DOS 3.20 and PC-DOS 3.20, although it is
UNDOCUMENTED in PC-DOS.
Chuck has mentioned that if you insert 3 Ctrl-A characters, it will work
on most;
DRIVPARM ^A^A^A B: /F:2
--
Grumpy Ol' Fred [email protected]
