X-Authentication-Warning: delorie.com: mail set sender to opendos-bounces using -f Date: Thu, 17 Jun 2004 12:16:32 +0200 From: Matthias Paul Subject: Re: Random Lockups with DR-DOS 7.03 To: opendos AT delorie DOT com Message-id: <001f01c45454$3f7d9f80$c03dfea9@atlantis> Organization: Aachen University of Technology (RWTH), Germany MIME-version: 1.0 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 X-Mailer: Microsoft Outlook Express 6.00.2800.1409 Content-type: text/plain; charset=iso-8859-1 Content-transfer-encoding: 7BIT X-Priority: 3 X-MSMail-priority: Normal References: <40CF0305 DOT 10732 DOT 9898147 AT localhost> <40CF5940 DOT 32064 DOT 21C57E AT localhost> Reply-To: opendos AT delorie DOT com 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 -- ; http://www.uni-bonn.de/~uzs180/mpdokeng.html; http://mpaul.drdos.org "Programs are poems for computers."