Date: Mon, 20 Nov 2000 17:37:39 +0200 (SAST) From: Robert Nordier <rnordier@nordier.com> To: stable@FreeBSD.org Subject: Re: Dedicated disks (was: Dangerously Dedicated) Message-ID: <200011201537.RAA25621@siri.nordier.com> In-Reply-To: <20001120192044.Q58333@echunga.lemis.com> from "Greg Lehey" at Nov 20, 2000 07:20:44 PM
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Greg Lehey wrote:
> > Why do you *insist* on calling it a "Microsoft partition table"??
>
> Hmm. I was going to say "Because it was introduced with Microsoft
> 2.0", but I'm no longer so sure. Reading the MS-DOS 2.11 source code,
> it seems that they didn't have a partition table at the time.
Of course they had a partition table at the time, and of course
MS-DOS 2.11 used it:
[io.sys]
1431 8d9fbe01 lea bx,[bx+0x1be]
1435 8b4740 mov ax,[bx+0x40]
1438 3d55aa cmp ax,0xaa55
143b 7539 jnz 0x1476
143d b90400 mov cx,0x4
1440 807f0401 cmp byte [bx+0x4],0x1
1444 7407 jz 0x144d
1446 83c310 add bx,byte +0x10
1449 e2f5 loop 0x1440
144b eb29 jmp short 0x1476
> Can anybody remember when it was introduced?
In March 1983, with the release of PC-DOS 2.0.
> Anyway, it's needed for "modern" Microsoft offerings, and not really
> for much else. It's also not a UNIX partition table.
Actually, the immediate reason for its introduction was in order to
support dual-booting XENIX (Early SCO/Microsoft UNIX) on PCs. This is
why the partition type numbering starts
1 DOS
2 XENIX
3 XENIX
--
Robert Nordier
rnordier@nordier.com
rnordier@FreeBSD.org
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