Multiple OSs for One PC

PCQ Bureau
New Update

The days of running only one operating system on a PC are over. At least that’s what we felt after receiving a deluge of mail on how to run Linux simultaneously with other operating systems like NT and Win 9x. 


To boot multiple operating systems off one hard disk, you need a small program called a boot-loader. This lets you select one of the operating systems at startup. A boot-loader resides in the Master Boot Record (MBR) of the hard disk and loads the first piece of operating system code that starts up your PC.

This process is known as booting. To add a bit of interesting history, “boot” comes from the word

“bootstrap”. In olden times, the bootstrap was a strap attached to the top of your boot that you had to pull to help pull up your boot. Once loaded, the boot-loader gives you a choice of operating systems to boot into. Two common examples of boot-loaders are the Win NT boot-loader (, and the Linux loader–better known as LILO. You can use either of the two for multibooting. We’ll concentrate on LILO in this article. If you want more information about the NT boot-loader, check



Here, we’ll explain how to load 

Win 98, NT, and Linux off the same hard disk using LILO. The method of installing multiple operating systems would vary depending on whether you’re doing it on a blank hard disk, or you already have an operating system installed. We’ll cover both methods. 

Starting with a blank hard drive

You’ll need at least a 4.3 GB hard drive for loading Win 9x, NT, and Linux on it. There will be four partitions on it–one for each operating system, and the fourth for Linux swap space. 64 MB is all right for Linux swap. You can partition the remaining hard disk into 1 GB partitions. 

Before you start, ensure that you have a bootable floppy with Fdisk, Format, and Sys. We’ll use the first of these to partition your drive. The second will format the partitions to the FAT16 file system, while the third will make your hard drive bootable. 


Before we proceed, let’s look at how DOS deals with partitions. DOS recognizes two types of partitions–primary and extended. The primary partition must be set as active if you intend to boot from the hard disk. The extended partition can have up to 23 logical partitions or drives out of a maximum of 26–the remaining three being reserved for the two floppy drives and the primary partition.

Use the DOS or Windows Fdisk utility to create the partitions on the hard disk. When you run the utility, it’ll ask you whether you want to enable support for large hard disk. Type “N” for no, otherwise it’ll create FAT32 partitions, and you can’t have Win NT run simultaneously with Win 9x on a FAT32 partition. Create the primary partition and mark it active to make the system boot from it. Then create a secondary partition and define two logical partitions in it. After defining all your partitions, format them. 

The primary partition is where you’ll install Win 9x. Once you’ve done this, install NT in the second partition. To do this, run the NT installation through

Win 98, and select the second partition when prompted. You can also install it in the same partition as the primary, but you won’t be able to convert it to NTFS in that case. So, plan beforehand what you want. If you don’t want NTFS, then you need just three partitions, where the first will be for Win 9x and NT, and the last two will be for Linux and swap partition.


After you’ve installed NT, the NT loader program takes over during bootup. It’ll give you the choice of booting either in Win 9x or NT. Ensure that you’re able to boot in both operating systems.

The next step is to set up partitions for Linux. Linux doesn’t run on the regular FAT file system, and requires its own native partition. You can create it before starting the Linux installation using a utility called FIPS. You’ll find this on every PCQ Linux CD—the last one was in November 1999. Alternatively, you can use Disk Druid. This is GUI-based and is therefore easier to work with. Using this utility, delete the last logical partition you created and split it into two. Change the first one to Linux native, and the second to Linux swap. 

During the last stage of installation, Linux will add the LILO on the hard drive’s master boot record. When you reboot the computer, you’ll get a LILO prompt first. Type Linux at the LILO prompt and press “Enter” to load Linux. To get into the other two operating systems, type DOS and press “Enter”. The NT Loader will start and from there you can choose whether to boot into Win 9x or NT. 


A preloaded operating system

If you’re using a system that already has Win 9x installed on a FAT32 partition, you won’t be able to load NT on it, because Win NT 4 doesn’t support FAT32 partition. When NT installs, it loads the NT boot loader in the primary partition, which takes over from the previous version of Windows. That’s why if it’s FAT32, it won’t work. 

If the file system is FAT16, first back up all your important data. If the whole hard disk has been allotted to Windows, ensure that you have sufficient disk space for the other two operating systems. You must also defragment your hard drive and use a non-destructive disk partitioning utility such as FIPS. Be sure to use ver-sion 2 as it also supports FAT32. This will repartition your hard disk space without destroying any data. 

Boot into DOS mode and run FIPS. It’ll ask you to save your existing partition to a floppy disk. It’s advisable to do so because you can always restore it later if the re-partitioning doesn’t go properly. After this, FIPS will present you with a screen. Here, you can adjust the amount of space that you want to assign to your new partition by moving your cursor keys to the left or right. 


Now, you have the option to run FDISK again, and create two logical partitions in the extended partition. You can then install NT in the secondary partition, and Linux in the third. Alternatively, you can leave the secondary partition intact for Linux (if you don’t have enough hard drive space), and install NT on the primary partition over the previous Windows. The procedure in either case would be the same, as described in the previous section.


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