Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!watmath!mks!alex
From: alex@mks.UUCP (Alex White)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Running OS/2 and MS-DOS on same computer
Keywords: OS/2, booting, fdisk, partition
Message-ID: <1480@mks.UUCP>
Date: 23 Aug 89 17:44:15 GMT
References: <55045@peregrine.peregrine.com> <3486@asylum.SF.CA.US>
Reply-To: alex@mks.UUCP (Alex White)
Organization: Mortice Kern Systems, Waterloo, Ontario, Canada
Lines: 61

In article <3486@asylum.SF.CA.US> sharon@asylum.UUCP (Sharon Fisher) writes:
>In article <55045@peregrine.peregrine.com> chris@peregrine.peregrine.com (Chris Cole) writes:
>>Is it possible to install and run both MS-DOS and OS/2 on the same
>>computer?  I am trying to use devices (e.g., CD-ROMs and large
>As I recall, some versions of OS/2 allow you to have DOS, and some do
>not.  IBM's doesn't, for example, while some third parties' versions
MS-DOS and OS/2 have no problem in co-existing on the same computer,
indeed, the same partitions.
If you bought the SDK, then release 1.05 specifically included dual-boot;
i.e. it would boot, from the active partition, either dos or os/2.
[SDK by the way, stands for software development kit; i.e. you paid
microsoft lots of money and they shipped you manuals hot from the press
and beta software, and windows, and presentation manager, and lan manager,
and C compiler, and assembler, and then shipped it all again, and then
again, and then again...]

The next release of the SDK was 1.06.  It was supposed to be IDENTICAL
to the shipped release from IBM of OS/2 1.1.
It gave the IBM logo and things; as I recall some things only differed from 1.05
in the copyright notice being IBM or Microsoft.
This release did not offer dual-boot.  The IBM installation program DELETED
the dos system binaries from my hard disk.
However, I did run on that system for many months where when I wanted os/2
I booted from disk; when I wanted dos I booted from floppy (just the
ibmbio.com, ibmdos.com and config.sys files; my config.sys ran MKS
init with the C: as the root drive and picked up init itself from the
hard drive).
So that release wasn't as easy to use, but both would run.

The next release of the SDK was 1.1.  This was supposed to be the same
as the IBM 1.1, only the microsoft version of it.  In other words, it
was supposed to run on more hardware versions, and support more drivers,
and have Microsoft copyrights.  It also supported dual-boot, ie.
a screen comes up at the beginning and you can request os2 or dos.
[You can select a default, and a timeout, i.e. if nobody types anything
for 30 seconds, then boot dos].
Dual boot works by the boot block booting the file dbmon.com
which asks the questions.
It then renames config.sys, command.com, autoexec.bat
such that the currently booting system is named with those names.
The alternate system would be renamed
	config.os2, command.os2 and autoexec.os2
if you were selecting dos,
	config.dos, command.dos and autoexec.dos
if you were selecting os2.
It then would boot either ibmbio/ibmdos or os2ldr files depending on
the system.

This dual-boot by the way worked fine with 1.06, i.e. the IBM version.
There was a letter somewhere in the various versions pointing out
that dual-boot was provided by microsoft, it was up to the individual
OEM vendor whether or not to provide it; IBM had decided not to provide
it.

Alternatively, I have seen adds for a product called Multi-boot from
BOLT systems: 1-301-656-7133, $49.95
I have only seen the adds and know nothing else about it.

Alternatively again, I have no idea which at this point, but one of the
mags that publishes source code sometime within the last year published
code for a dual-boot.