Where does computer stores the Operating System info

Question

If i have three partitions on computer. On every drive i have three OS installed.

Now where does the Computer store that OS information which tells which partition has which OS.

Because e,g My computer got virus infected and it didn't boot. I had the image of Cdrive with Vista OS.

Now when i restore that drive, will computer also shows other OS on stratup or not

Answer 1

There's the master boot record (MBR) and then there are various possibilities, depending on the boot manager your's using (Windows Boot Loader, GRUB/LILO or some 3rd party product).

If you restore the C: drive from a drive image, the original boot loader will be restored and the other operating systems will be still bootable.

Edit: you can use EasyBCD to edit the Vista Bootloader and fix problems.

Answer 2

The partition table information is stored in the MBR. The BIOS passes control to this 512 byte sector which is read and executed (also called the stage 1 bootloader) and eventually passes control to the stage 2 bootloader (GRUB, Windows bootloader, LILO, etc) which will in turn pass control to the operating system's kernel. This process is called bootstrapping. Each partition on the disk has a boot record, and there can only be 1 active partition per disk.

If you restore a complete drive image, the MBR information should be restored as well.

Answer 3

The information about partitions in stored in the 'partiton table' which is not really part of any OS.

It's information which describes the disk itself, not the operating systems you might have installed.

When the computer boots (probably from a bootloader) it goes to whichever partition you select and finds the information there, to boot the OS on that partition.

It's unlikely that a Windows virus would have touched the other partitions, but you'll have to try it out.