Booting three different operating systems: RedHat Linux 5.2, SCO Openserver 5.0.5 and Windows NT 4.0

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UNIX Basics

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original in es Edgar Hernández Zúñiga

es to en Manuel Dominguez

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This document explains how the three operating systems RedHat Linux 5.2, SCO Openserver 5.0.5 and Windows NT 4.0 (or alike) can be installed and booted on the same computer from the same hard drive. All this is done with Lilo as the boot loader. My article bases on the above operating system versions but it will not be much different for another configuration.

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I have decided to write this document to provide the the Linux community with documentaiton on how to setup such a tripple boot system. In our Computer Science Lab at University we had to find a solution to NT during a SCO Openserver installation. Courses in the Computer Lab are taught in all three operating systems as part of the course flow for the Computer Science degree.


The situation: NT uses its NTFS, SCO runs HTFS file system, and Linux uses a ext2 and its swap partition. This was a problem, since SCO did not recognize the NTFS partition created during NT installation, and was getting the whole hard drive space, a totally unwanted effect. We had to make some experiments and at least two NT and SCO installation were needed to arrive at this solution.

Installing SCO Openserver 5.0.5

It was a surprise to me how a Unix system, in this case SCO, was not able to integrate with NT, thus the first step is the SCO Openserver installation.

Insert your SCO boot disk. If you do not have one, you can create it with rawrite. This is the simplest solution.
On a machine with Windows or DOS run:

It asks for the source: d:\images\boot\N00
And the target drive: a:\

With this disk, a SCO kernel image will be loaded and installation can proceed. Accept, choose the option fresh installation and install SCO Openserver.

Reboot and you will see something like this:

Installing Windows NT

Let us go to the next step. The machine, an IBM 300GL, allows booting from the CD-ROM, thus we insert the NT installation disk and the file copy process will start...

The complex NT installation is now left in your hands, until rebooting the system and...

You will find that SCO has dissapeared, logically, since each operating system takes possesion of the hard drive MBR (Master Boot Record). So, I was wondering how to recover SCO. I wanted also to keep the NTFS under NT for security reasons. The problem was now how to boot again SCO.

During the installation process a message appeared similar to "if you wish to use your other operating system, you will have to reactivate the partition and make it bootable". This looked like the solution for my problem. You have to go to Administration Tools, select Disk Administration and you will see a Unix type partition. Select and activate it: SCO is back!

You will see:

If you type Enter the system will boot with SCO Openserver, but how am I going to boot NT again?. I knew LiLo and it is the best loader (together with the OS/2 Loader), but how can Lilo work together with the SCO loader?.

It's simple: given that SCO knows how to differentiate between filesystems like NTFS, HPFS and so on, you must use the following initial command:
Boot: bootos os2

You will see NT booting. Although this step is not required when finally installing also Linux it seemed interesting to me. Furthermore, it took more than 1/2 hour of investigation. You might have known this, but if it is not the case...

Installing RedHat Linux

Until now, about 1 1/2 hrs. have passed on a decent machine, let's say a Pentium MMX/233/32RAM. Now the best part: Install Linux and control everything from there.

I have previously mentioned a RedHat Linux distribution but nowadays any distribution can be booted just from CD-rom if your CD-rom drive is capable to do so. Thus, you have arrive at the screen where you can decide how to install Lilo. Choose Master Boot Record, go on and label each bootable partition with a different name. There should be three:

Finish the installation process and reboot. You must be able to boot NT with:
LILO: nt
SCO with:
LILO: sco
and Linux will be the default boot system. If you wish to make other systems the default boot, it can be made with:
lilo -D <lable>


As some of you may have noticed, in general, the installation of two Unix-like systems in the same machine is unusual. That is the main reason that motivated this document and I hope it will be useful to you. Any doubts, comment or suggestion are always welcome...


I suggest reading  the Multiboot HOWTO and the LILO man page. For SCO,  the SCO Openserver Handbook was a help.