Installing MS-DOS on Qemu

MS-DOS is a great 'little' OS for bootstrapping other operating systems. If you are going to install Windows 95, Windows 98 or Windows Me, Novell Netware, Windows NT 3.1/3.5/3.51/4.0 or even setup a dual boot OS/2 VM it's best to start here.

First MS-DOS 5.0 & 6.0 (6.1/6.2/6.22) are the 'best' versions to load as they can support a hard disk up to 2GB in size. MS-DOS 4.0 can only use 32MB partitions, however it can use extended partitions.. So you can have LOTS of 32MB partitions. MS-DOS 3.x can only use a single 32MB partition.. I wouldn't waste time with MS-DOS 1, as it has no support for hard disks, and early 2.0 doesn't have support for directories.

In this example I'm going to install MS-DOS 6.22. It's very straight forward.

Create a hard disk

The first step is to create a hard disk image. I'm going to create a 2GB one, so the syntax is:

qemu-img create -f qcow msdos.disk 2G

Installing MS-DOS

MS-DOS uses the BIOS for all IO so the ISA/PCI thing doesn't matter. Also the installation, and all files will run on 8088/8086 or higher so you don't have to worry about any cpu flags. MS-DOS himem.sys will only see a maximum of 64MB of ram. So there is no point in letting qemu grab 128mb of ram.

qemu-system-i386 -hda msdos.disk -m 64 -L . -fda dos622_1.img -boot a

On the first boot, MS-DOS will partition the disk & slap down a MBR.. Let it have the whole disk, you just hit enter a few times, then qemu will reboot, then it will format the disk & then prompt for disk two. Remember it's control+alt+2 to get to the qemu console to change the floppy to dos622_2.img, then control+alt+1 to get back to the display to hit enter. You only have to do this twice, then MS-DOS is installed. Once it is installed, you can close Qemu.

Running MS-DOS

You can now start Qemu like this:

qemu-system-i386 -hda msdos.disk -m 64 -L . 

And you are good to go.

Sound

Qemu has various sound options, but for MS-DOS the best is to enable the PC-speaker, Adlib and SoundBlaster cards.

-soundhw sb16,adlib,pcspk

For reference, the BLASTER environment variable should be set to the following:

BLASTER=A220 I5 D1 H5 P330 T5

Where to go from here

Well MS-DOS by itself isn't that useful, you may want to investigate network clients (ones that use TCP/IP are better!), sound settings and of course CD-ROM access. I'll update these topics in the future.