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Using MS-DOS 4.01 with virtual machines is a NIGHTMARE ! 
Saturday, February 1, 2014, 03:00 PM
Posted by Administrator
This is really weird. There are some web sites offering a floppy disk image of MS-DOS 4.01, but you can't do anything with it - except with a real PC.

Meanwhile I own an IBM PC XT, and I wanted to reinstall a DOS.
The DOS I used before was IBM DOS 3.2, but this DOS version's keyboard driver was not really compatible with my 101-key keyboard from Cherry (which can be configured also to be used with a PC XT, not only with an PC AT machine).
So I had the idea to try other DOS versions.
I tested Tandon DOS 3.3, but this version was NOT really usable. You are not able to transfer the MS-DOS system itself with FORMAT /S, instead, you have to use "FXPREP". This utility from Tandon did not really format my MFM HDD correct, it doesn't recognized most of the bad blocks of the HDD (it marked it again as usable.... not really helpful).
You have to use SPINRITE (or similar software) again to correct this.

So I had the idea to use MS-DOS 4.01... and then the NIGHTMARE began.

Because the offered MS-DOS 4.01 boot floppy disk images were 720KB or 1.44MB disks, I had the idea to convert them by using a virtual machine.
I tried VMWare Player 5 (and also later some other versions), but VMWare is NOT able to boot from a MS-DOS 4.01 boot disk - this is very strange.
So I took Oracle's Virtualbox again, and booting from the floppy worked.
BUT. After transferring all DOS files to the virtual harddisk, I was NOT able to copy them back to a (virtual) floppy disk drive. Virtualbox always assumed I have a 1.44MB capacity HD floppy drive, but I needed to write them back to a 360KB formatted floppy, to use it with my IBM PC XT.
So VMWare player is NOT able to boot from it, Oracle Virtualbox is NOT able to write it back to 360KB floppies. I am really disappointed from both virtual machine solutions.

This is all related to MS-DOS 4.01, older or newer versions will work also with both VM software.

But there is hope:
You have to use WINIMAGE from Gilles Vollant, load the (bigger) disk image, delete some files to let the sum of the files not greater than the target floppy capacity, and then change the "Floppy Disk Format" itself just by selecting another capacity in WinImage's function for exact that case. After saving the new disk with another name, it will be possible to use this - in my example 360KB - floppy disk image to boot MS-DOS 4.01 with Oracle's VirtualBox or with MS Virtual PC 2007. And later on with my PC/XT also :-)

Btw. - MS Virtual PC 2007 (after editing the .VMC file for an additional floppy id in section "super_io") is the only Virtual Machine software which can run MS-DOS 4.01 also from HDD ! You have to disable almost all "modern" things in BIOS (press DEL at the very first seconds of boot process), e.g. 32Bit Access, LBA, Hardware Virtualization a.s.o. - then it really worked, even the original INSTALL process, which copies vvveeerrryyyy slowly files (be patient, don't reset, just wait). You will be rewarded with DOSSHELL ;-)

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