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From: Rod Pemberton on 1 Nov 2007 05:52

"Mike Gonta" <mikegonta(a)gmail.com> wrote in message
news:1193822918.649388.159710(a)o3g2000hsb.googlegroups.com...
> On Oct 29, 6:18 am, "Rod Pemberton" <do_not_h...(a)nohavenot.cmm> wrote:
>
> > This is a serious question. Why would I want to boot a version of DOS
prior
> > to 6.22?
>
> When you format a USB flash drive in XP as FAT (FAT16) you get a
> MSDOS5.0 boot sector.
> I tried using the 6.22 system files which are not compatible, the 5.0
> files worked fine.
>

Ah... IIRC, XP/NT etc. uses a slightly modified version of MS-DOS 5.0 for
it's NTVDM. That's probably why later versions won't work.

These links mention some of the various c4 c4 sequences the patched NTVDM
uses. I've found mention of six total that look legit, plus another seven
which were in some virus. I'm not sure how many MS actually defined.
Anyway, worth a read:

http://www.reactos.org/wiki/index.php/DOS
http://research.eeye.com/html/advisories/published/AD20041012.html


Rod Pemberton

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