Mail Archives: opendos/2004/06/17/06:23:16
On 2004-06-17, Paul O. Bartlett wrote:
> I went into CONFIG.SYS and commented out the line SHELL=
> specifying NDOS and uncommented the line for SHELL=C:\COMMAND.COM.
> Unfortunately, perhaps, through a lack of attention, I forgot to
> comment out of AUTOEXEC.BAT any lines that would have required NDOS
> to be loaded as the command processor.
>
> When I booted, once it got to the command prompt the system went
> berserk. Black screen with a cursor racing madly everywhere across
> the screen. Then the printer (HP laser on the parallel port) started
> spitting out pages with nothing but C:> about every twenty lines or
> so.
Well, since you use a dual-boot system, are you sure the DR-DOS
visible command processor C:\COMMAND.COM is actually the DR-DOS
COMMAND.COM? I'm asking because if it's the Windows 98 equivalent,
the system is known to crash (for some explanation from a different
point of view, see the description of why F5 mode still scans
for SHELL= in my other post).
Background: In all MS-DOS versions prior to Windows 95, Microsoft
used a COM style COMMAND.COM file which has a special signature
at the start of the file (which is queried by the MS-DOS BIOS
before it loads the shell, but not by the DR-DOS BIOS). However,
their COMMAND.COM would also check that it is running on the
"correct" DOS version, so if you would load their COMMAND.COM
under DR-DOS, you would receive a "Bad version" error message
and their COMMAND.COM would exit, so DR-DOS would either fall
back to its own COMMAND.COM prompt (in case you tried to load
the MS-DOS COMMAND.COM from the DR-DOS COMMAND.COM) or display
an error message "Bad or missing command interpreter" (if DR-DOS
was trying to load the SHELL= command processor after having
finished CONFIG.SYS processing). In this case, you could enter
the path to a valid DR-DOS COMMAND.COM (C:\DRDOS\COMMAND.COM)
and everything was fine.
Now, things have changed since MS-DOS 7.0 (Windows 95). Their
COMMAND.COM has internally become an EXE style file, so there
is no magic "COMMAND.COM signature" to check for at the start
of the file any more - thus no way for DR-DOS to rule out an
incompatible COMMAND.COM. Further, their COMMAND.COM no longer
does any version checks, but for unknown reasons still does
not work under DR-DOS, instead it just crashes under DR-DOS
(interestingly, the PC DOS COMMAND.COM works fine under
DR-DOS, BTW).
Since you changed the SHELL= line to point to C:\COMMAND.COM
which - in a normal multi-boot scenario with Windows 98 - is
likely to be the MS-DOS COMMAND.COM - it could well be, that
this is the reason why you see it crashing. If it is, make sure
you have a copy of the DR-DOS COMMAND.COM in the C:\DRDOS\
directory and then change the SHELL= line into something like:
SHELL=c:\drdos\command.com c:\drdos\ /E:512 /P:autodos7.bat
In fact, the only reason why I am not completely /sure/ you are
seeing exactly this problem is that you have installed Windows 98
into a separate primary partition, so you don't normally see
the DR-DOS drive C: while you are under Windows 98 and vice versa.
However, it would still be possible for Windows 98 to mount the
DR-DOS partition as drive E: (or higher).
> Booted into Win98 and fired up Partition Magic (v5.0). Partition
> Magic will let me unhide it, but just before I tell it to do so, it
> comes up with a dire warning, "OS/2 and Windows 95/98 do not support
> multiple visible primary partitions. If you unhide this partition and
> then boot OS/2 or Windows 95/98, data loss can occur." So I chickened
> out.
You can ignore this warning. Not sure about OS/2, but Windows 9x does
support multiple primary FAT partitions (it just does not normally
allow you create them under this OS). There can be only one active
primary partition, but being active/inactive is a completely different
quality than being visible/hidden.
However, as said above, in some cases, recent issues of MS-DOS will
log-in sub-sequent primary FAT partitions after having logged in all
active primary partitions and all logical drives in extended partitions
on all hard disks, so it is possible that your DR-DOS drive C: shows
up as drive E: (or higher) under Windows.
Well, you have decided to switch the active flag in order to switch between
the two operation systems. While this has some known advantages, it
also has a number of inconveniences and risks.
Personally, if I set up a multi-boot system with Windows 9x and DR-DOS,
I use a different approach, which I have found to work more reliable
and be more convenient (at least for me):
I install both operating systems into the same FAT16 primary partition,
if required, first an old MS-DOS or PC DOS, then Windows 9x, then DR-DOS.
This way, you can use the Windows 9x dual-boot feature to switch between
the old MS-DOS/PC DOS and Windows 9x, and the DR-DOS LOADER to switch
between DR-DOS and Windows 9x. You won't have to allow permanent write
access to the MBR once you have finished the setup, so you can eliminate
the risk to get infected by a MBR virus.
Windows' dual-boot feature will maintain two sets of configuration
files for the optional old MS-DOS/PC DOS and Windows 9x, and you
can utilize DR-DOS' feature to look for DCONFIG.SYS to have another
separate set of configuration files for DR-DOS (mind, that the SHELL=
line in this DCONFIG.SYS file can point to a different batchfile
than AUTOEXEC.BAT, for example /P:AUTODOS7.BAT). If you install
DR-DOS after Windows 9x, the setup program will automatically do
this for you.
If application setup programs attempt to change configuration files,
they will only touch the MS-DOS/Windows files (that is CONFIG.SYS and
AUTOEXEC.BAT), not the DR-DOS ones, which I will edit manually.
This way, DR-DOS works as a reliable fall-back platform even if some
setup program has (once again) messed up the MS-DOS/Windows files.
If you want to hide some Windows stuff from DR-DOS (prior to 7.04),
you can put that into a FAT32 partition, if you want to hide some
DR-DOS visible stuff from Windows/MS-DOS/PC DOS, you can put that
into a DR-DOS secured partition. (There is a way to set up a pseudo-
secured partition without activating DR-DOS system security. It
works by creating two extended partitions, the first one of type
C5h (rather than 05h), the second of type 0Fh - see the list archives
for more detailed descriptions of this trick. Sometimes this can be
very handy in case you need to hide stuff from Windows, but don't
want to install system security. However, it requires the use of
a disk editor or a similar tool.)
Hope it helps,
Matthias
--
<mailto:Matthias DOT Paul AT post DOT rwth-aachen DOT de>; <mailto:mpaul AT drdos DOT org>
http://www.uni-bonn.de/~uzs180/mpdokeng.html; http://mpaul.drdos.org
"Programs are poems for computers."
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