manually installing MSDOS...

Roy J. Tellason rtellason at
Mon Mar 13 17:04:04 CST 2006

On Monday 13 March 2006 05:35 pm, Jules Richardson wrote:
> Another DOS question! :)
> I've got a laptop that currently has Win2k and Debian Linux on it, along
> with a small FAT partition (it's actually FAT32 currently, but I can change
> that easily enough)
> I want to put MSDOS on the FAT partition and triple-boot the machine - but
> the laptop has no floppy drive on it, so I can't just boot from a DOS
> floppy and run SYS that way.
> So is there a way of putting the necessary files on there from either
> Windows or Linux such that DOS will boot? Can't remember how MSDOS does
> it's boot process now, but I assume that certain files (io.sys for one)
> need to be in certain locations on the FAT partition or something?

DOS needs three files to boot,,  io.sys,  and msdos.sys.  Those 
last two are given different names if we're talking about IBM's version.  In 
earlier versions of dos they needed to be the first files on the drive,  but 
I think that this requirement went  away at some point,  though I couldn't 
say for sure when that happened.

> At one point I would have known how to do this, but the info's long since
> fallen out of my brain...

I know what you mean.  :-)

> (Currently I'm booting Debian / Win2k from Grub - it should handle booting
> MSDOS too though).
> Before I shoot myself in the foot, are there any other gotchas (like MSDOS
> needing to be the first partition on the drive or anything nuts like that)?
> The FAT partition is about 2GB into the disk - I seem to recall that a FAT
> partition can't be more than 2GB in size, but presumably providing the BIOS
> can see the whole disk DOS won't care about the offset to the start of the
> partition?

That sounds reasonable to me,  but that doesn't necessarily mean much.  :-)  
Most of what I did under dos back when was on way smaller drives...

> (All I actually want to do is put Slackware Linux on the machine there in
> place of Debian, but the CDROM drive's too flakey to boot from. If I can
> get MSDOS on there by copying from a remote machine then I can boot the
> Slackware installer from MSDOS and then install the rest of Slackware
> across the network - talk about complicated!!)

Hmm.  There oughta be some easier way.  Ever played with tomsrtbt?  Worth a 
try,  anyhow.

Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
Information is more dangerous than cannon to a society ruled by lies. --James 
M Dakin

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