13 Dec
2005
13 Dec
'05
9:14 p.m.
The
"official", "standardized" support of 3.5" 720K in 3.20 was with
use
of DRIVER.SYS and/or DRIVPARM. DRIVPARM was incompatible with IBM's BIOS,
and therefore was undocumented in PC-DOS.
Do you remember the details of the problem with
DRIVPARM?
I never researched the actual causes.
Data (from about 1986 on) :
MS-DOS with DRIVPARM worked properly, as documented, with half a dozen
generic 286 ATs
Although undocumented in the PC-DOS manual, PC-DOS with DRIVPARM worked
properly in the same machines.
Both MS-DOS with DRIVPARM and PC-DOS with DRIVPARM, used with some real
IBM PC/ATs and PS/2 (model 50?) gave "unrecognized command in CONFIG.SYS"
(an error message that probably resulted from incorrect handling of the
problem)
A couple of generic 286 ATs that worked with DRIVPARM ceased working with
DRIVPARM when the BIOS ROMs were successfully replaced with EPROM copies
of IBM's AT BIOS.
Conclusions, subject to further analysis and experimentation:
DRIVPARM exists in both PC-DOS and MS-DOS, although undocumented in
PC-DOS.
Behavior of PC-DOS and MS-DOS appears to be the same.
Neither will work with some real IBM computers.
Change of BIOS altered whether DRIVPARM would work.
Therefore, it appears to be a BIOS related issue, rather than motherboard,
or brand of OS.
I have found the discussions of DRIVPARM on the web quite amusing.
Particularly the one that Scott Stevens referenced, where nobody
questioned the FDC, and one fellow insisted that there needed to be a path
for DRIVPARM!, and that said path (to an internal config.sys option) could
be set by AUTOEXEC.BAT (which is processed AFTER CONFIG.SYS).