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Path: utzoo!watmath!clyde!caip!think!husc6!uwvax!astroatc!nicmad!brown
From: brown@nicmad.UUCP
Newsgroups: net.micro,net.micro.pc
Subject: Re: Hard disk problems
Message-ID: <895@nicmad.UUCP>
Date: Tue, 14-Oct-86 10:54:45 EDT
Article-I.D.: nicmad.895
Posted: Tue Oct 14 10:54:45 1986
Date-Received: Fri, 17-Oct-86 20:08:05 EDT
References: <239@rayssd.UUCP>
Reply-To: brown@nicmad.UUCP (Mr. Video)
Distribution: net
Organization: Nicolet Instrument Corp. Madison WI
Lines: 34
Xref: watmath net.micro:15762 net.micro.pc:10439

In article <239@rayssd.UUCP> wjr@rayssd.UUCP (Bill) writes:
>I'm running an XT-Turbo with a 10M harddisk and am getting divide overflow
>errors when trying to boot up from the hard disk. ...
>...         I am running with MS-DOS 3.1 and going through all the procedures
>to make the disk bootable. I have managed to use PC-DOS to format the disk
>and get the disk to boot before the disk "dies" trying to access other
>programs.  Has anybody had this problem before or could I have a bad hard disk,
>bad MS-DOS, or just a crappy BIOS ROM?

We ran into that problem while making an operating system make DOS compatible
floppy diskettes.  The result was that the first three bytes of the boot
sector were wrong.  Apparently when the machine boots, a check is made.  Now,
in our case is was floppies that were were using, so the boot track on the
floppy wasn't really used, or needed.  So we thought.  When doing a DIR of the
floppy, the divide overflow error came up.  Without the first three bytes
being correct, the floppy was unusable.

For PC-DOS the requirements are:
	2.10 - 3 byte near JUMP (E9h)
	3.xx - 2 byte short JUMP (EBh) followed by a NOP (90h)

The destination of the jump is the code within that boot sector.

I hope this helps a little bit.  As I said, it is the experience that we
had with floppies, not hard disks.  Use a program, after booting from floppy,
like Norton's Utilities and look at the boot sector of the hard disk.

Mike Brown
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