So, you installed Windows 7 on your computer, and as you are looking around you notice your old friend boot.ini has gone the way of the dodo bird. You begin to wonder, how do I change my boot settings? and what else has changes in Windows 7 from Windows XP?
Well if you’re installing Windows 7 out of the box with its default settings, one of the first things you may notice is that Windows setup creates two volumes on your hard drive. The first volume is a 100 MB NTFS formatted “System Volume” as Microsoft calls it. Then you have your “Boot Volume” which is your C drive. These names can be a little confusing at first because as you will see you actually boot off of your “System Volume” and your operating system lives on your “Boot Volume”. You can see these volumes in Disk Manager.
Your System Volume contains your Master Boot Record (MBR), boot sector, and your boot loader. You remember the Windows XP boot loader NTLDR? That boot loader was replaced by BOOTMGR, the Windows 7 boot loader. Also the replacement for the Windows XP boot configuration file, BOOT.INI, has been replaced with the Boot Configuration Database (BCD), the BCD lives in the boot folder of the System Volume and can be edited with the bcdedit tool.
Your Boot volume contains your Windows operating system, and all other files, C:\Windows, C:\Program Files, etc. If you choose to create only one volume on your hard drive, these will be merged together. However if you ever plan on implementing Bit Locker drive encryption, you will be required to have a “System Volume” separate from your “Boot Volume”.
So here is how Windows 7 boots: the BIOS reads the MBR from the boot device. Your MBR loads the boot sector. Your boot sector loads BOOTMGR. BOOTMGR reads your BCD and boots Windows according to the configuration found in BCD. You then make the transition from the “System Volume” into the “Boot Volume” when BOOTMGR loads C:\Windows\System32\Winload.exe. Winload then loads the kernel (ntoskrnl) which then takes over running the system.
Hope you enjoyed this overview of the changes in the boot process from Windows XP to Windows 7.