• Making a CD that is bootable on most computers requires that certain files exist on the CD. The files required depend on the operating system that you intend to run. It also requires that BIOS (basic in-out system) be set up to boot from an optical drive. To boot Windows XP on most computers there are three files that are crucial, however, some computers may require more.
  
  

Ntldr

• Ntldr is the boot loader for many versions of windows including Windows XP. It exists simply as "ntldr" on the hard drive or other bootable disc with no file extensions. No device will boot into Windows XP without a usable ntldr file. If multiple operating systems are installed, ntldr can provide the user with the choice of what operating system to boot. For instance, if you have both Windows 2000 and Windows MCE installed, ntdlr will provide a text menu upon system boot asking you which operating system to load.
  
  

Ntdetect.com

• Once ntldr has been loaded into memory, it calls ntdetect.com. Ntdetect is a program that detects most of your basic hardware, such as a keyboard or mouse, and reports it to the operating system to be loaded. Each device needs system resources, and ntdetect.com is the program responsible for delegating the responsibility of assigning of these resources. If ACPI (advanced configuration and power interface) is absent on the computer, ntdetect.com will have BIOS assign system resources. If ACPI is present on the computer, then ntdetect.com will let Windows assign system resources to the hardware.
  
  

Boot.ini

• Boot.ini contains some of the variables that are used to boot an operating system. If two or more operating systems are present, ntldr gives the user the option of which one to boot. Boot.ini is the file that controls this interface. Boot.ini lists and names the operating systems available and controls the amount of time that user has to choose an operating system. Variables in boot.ini control both the disk and partition to use to boot the operating systems installed. Boot.ini also controls multiple variables that affect the way the boot process continues.
  
  

Ntbootdd.sys

• Small/Simple Computer System Interface (SCSI) hard drives use an interface protocol that is not native to Windows. In order to boot Windows XP from a SCSI device ntbootdd.sys needs to be present. This is a device driver for SCSI devices. If no SCSI devices exist, this file is not needed.
  
  

Bootsect.sys

• If you have multiple operating systems installed, bootsect.sys needs to be present on your bootable CD. Bootsect.sys is a copy of the boot sector that was originally on the drive before Windows was installed. This file is usually made automatically.