The booting process has changed significantly with Windows Vista . Instead of using the traditional BOOT.INI to boot through an ARC path as in earlier Windows NT-based OS, Windows Vista boots to a boot manager. This boot manager allows for a more extensible and platform independent boot environment and also maintains backward compatibility for previous operating systems. The boot environment is referred to as the Boot Configuration Database (BCD).

Boot Configuration Database

The Boot Configuration Database (BCD) is a configuration and storage mechanism for describing boot applications and related settings. Conceptually, the store is an abstracted, portable and firmware independent replacement for the traditional BOOT.INI.

Boot Process in Windows Vista

BCD consists of three major components: stores, elements, and objects. Broadly, a store is a collection of objects, and an object is a collection of elements. The figure bellow shows a conceptual example of a system BCD store.

The boot process in Windows Vista now works as follows:

1. User powers on the system.
2. MBR is located on the system drive.
3. Boot Sector is located… then BOOTMGR is loaded and BOOTMGR looks for an active partition on sector 0 of the drive.
4. BOOTMGR reads the BCD file and gathers Information about operating systems installed on the machine and then displays a boot menu (if necessary).
5. If a Vista is chosen, BOOTMGR transfers control to WINLOAD.EXE and in the case of a resume operation, WINRESUME.EXE will be called.
6. If a down-level operating system( Win XP, Win 2k, etc. ) is chosen, BOOTMGR transfers control to NTLDR also called the down-level loader.
7. WINLOAD.EXE initializes memory and loads drivers set to start at boot, and then transfers control to the kernel.