Path: utzoo!attcan!uunet!cs.utexas.edu!rice!uw-beaver!ubc-cs!alberta!calgary!xenlink!blender!root
From: root@blender.UUCP (Herb Peyerl)
Newsgroups: comp.unix.aix
Subject: Re: AIX PS/2 boot from hard disk
Keywords: AIX PS/2 1.1, boot, harddisk
Message-ID: <37@blender.UUCP>
Date: 13 Nov 89 08:26:04 GMT
References: <971@dutrun.UUCP> <112500001@uxe.cso.uiuc.edu> <976@dutrun.UUCP> <21941@gryphon.COM> <979@dutrun.UUCP> <1686@agora.UUCP>
Lines: 54

merwin@agora.UUCP (Ralph Merwin) writes:

>Rumor has it that OS/2 has its own style of boot record (i.e. screwed-up),
>and that another OS is not supposed to mess with it.  This leaves you with
>the options of asking OS/2 to remove itself (another rumor says that this is
>possible), or having to (at least) start the format operation, which should
>clear the boot record.  Note that I am only the messenger: I haven't had
>the misfortune of ever seeing OS/2 in operation.

 Reading this tweaked a memory in my mind about something I'd read about
 OS/2 and Dos4.0 altering the boot record such that other operating 
 systems wouldn't recognize the boot track.. Anyways, I dug through my
 notes and found the article in question...

 This was written in "PC TECH JOURNAL" but I don't have the date of
 the article.  It may or may not be applicable, however they say that
 DOS and OS/2 both place the characters "IBM" in the 8 bytes beginning
 at offset 3 of the boot record.  Apparently this block used to be
 informative only, however, now DOS and OS/2 examine this field to
 make sure that it starts with the characters "IBM".  Also they mention
 that besides DOS and OS/2 sold by IBM, Compaq also places "IBM" in
 the boot record for their versions of DOS and OS/2 whereas other versions
 of DOS and OS/2 from other vendors merely write "MSDOS" and "OS2" in 
 the boot record.

  Anyways, the article provides a cure for this, I'll cite the relevant
  information:

DEBUG
L CS:100 2 0 1
E CS:103 'IBM '
W CS:100 2 0 1
Q

These instructions assume that you are patching drive C:.  If not change
the drive number in the L and W commands (0=A, 1=B, and so on). Also
note that in the "E" command, there must be a space after "IBM" and
before the closing quote.

Reboot the system; if this fails, the reboot from a diskette and 
transfer the system (using SYS) to the drive with the same version
of the operating system that was on it originally.  If this does not
work, reformat it and restore it from your backup.

    I take no responsibility for the reliability of this information,
    but provide it merely as a guide in the hopes that it will help
    someone.


-- 
---------------------------------------------------------------------
UUCP: herb@blender.UUCP   ||  ...calgary!xenlink!blender!{herb||root}
ICBM: 51 03 N / 114 05 W  || Apollo Sys_admin, Novatel Communications
"The other day, I...... No wait..... That wasn't me!" <Steven Wright>