Friday, March 6, 2009

How Do I Make a Windows XP Bootup Disk?

What happens if you are unable to start your computer because the Operating System (OS) could not be loaded? This could happen when any file used for the booting process becomes corrupt or lost, or if your system has been affected by a virus.
You need a set of clean files that will allow you to load the OS and access the file system and services in case your PC is unable to boot. Keeping a backup of the files critical to this functionality on a Bootup disk is good practice.
Let us see what exactly happens when you turn on your computer - the BIOS is loaded first. Normally, the BIOS runs some tests on the system hardware at startup, after which it locates a bootable device on your computer (Floppy, CD-ROM, Hard disk) and the Master Boot Record (MBR) is loaded into the memory. The MBR locates the active partition and loads the boot sector into the memory. The boot sector has the code to start the bootstrap loader which then loads the OS (Windows, Linux, Unix, MacOS) into the memory.
In case of Windows XP, the bootstrap loader is called Ntldr. The bootstrap loader must be located in the active partition, in the root folder. In addition to this file, Windows XP also requires, boot.ini, bootsect.dos (for dual boot) and Ntbootdd.sys (needed if you plan to use SCSI devices) to be available in the same folder, on the active partition.
Ntldr uses, boot.ini, and bootsect.dos to let you choose the operating system that is to be loaded. Once Windows XP is chosen from the boot menu, Ntldr runs Ntoskrnl.exe which in turn launches Winlogon and Lsass, which then displays the welcome screen and allows you to log on.
Any Bootup floppy you create must be done on a system that has Windows XP already working on it and is free of viruses. Insert a blank floppy in the floppy drive; format it by right clicking on the floppy icon.
Once you have a formatted virus-free floppy in a virus-free system, copy Ntldr,, and the boot.ini files onto the floppy. You can either copy these files from the Windows CD-ROM or from your computer. As an added measure, the edit program available in windows could be copied on to the Bootup disk so that you can use it to edit boot.ini if necessary.

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