The MBR is the very first code launched in the boot process by the BIOS. Its one and only job is to launch the bootsector code written to the active partition of your boot disk, which in turn is responsible for actually searching for and running your bootloader.

When to update the MBR and Bootsector

There are many cases wherein the MBR and sometimes the bootsector are modified against your will, resulting in a system that doesn’t work the way you want it to. In these cases, you’ll want to use EasyBCD’s bootloader installation components to update the MBR and bootsector to a compatible version, or else you’ll find yourself unable to view EasyBCD’s boot selection menu.

Some cases where you might need to update the MBR and bootsector with EasyBCD:

  • Upon installing legacy versions of Windows (DOS, 9x, XP, etc) after an existing Vista/7 installation
  • When installing Linux and forgetting to untick the MBR installation option
  • After a virus infection that targets the bootloader

Picking a Bootloader

This section of the EasyBCD Bootloader Management page allows the user to choose which bootloader resides in the MBR. Two options available are:

  • Windows Vista/7 “BCD” Bootloader
  • Legacy Windows NTLDR Bootloader

Please note: Using this page will overwrite any existing MBR! If you are using a 3rd party MBR like Grub or Darwin, don’t worry, EasyBCD can be used instead. However, if you are using any software that customizes the MBR, such as Roxio GoBack, Acronis TrueImage, or TrueCrypt, the post-boot interface for these applications will no longer be available. You’ll need to reinstall their boot-time helpers after configuring EasyBCD.

The New BCD Bootloader

The new Windows bootmgr/bcd bootloader is installed to your first-boot hard drive’s MBR the first time you install a “BCD OS” – Windows 8, Windows 7, Windows Vista, and Windows Server 2008 – and every time thereafter it is updated or rewritten depending on its status. In order to boot into newer versions of Windows, the new BCD bootloader must be the currently installed MBR script! The new Windows boot menu supports booting into Windows Vista, Windows 7, and Windows Server 2008 out-of-the-box. With EasyBCD, this feature-set is expanded to include older versions of Windows along with Linux, Mac OS X, BSD and many more.

EasyBCD can be used regardless of whether or not the BCD bootloader is installed to the MBR, but in order for any of the settings visible in EasyBCD to take place upon reboot, the MBR must be configured to use the BCD.

The Legacy Windows Bootloader

The Legacy Windows Bootloader, or NTLDR, is used to boot legacy versions of Windows. NTLDR cannot be used to boot into Windows Vista or 7 — to do that you must install the new BCD bootloader. Generally speaking, the only time you’d want to install this bootloader to the MBR is if/when you want to completely remove Windows Vista/7 from your system. The Windows Vista/7 bootloader — when supercharged with EasyBCD — can load any operating system that NTLDR can boot and then some; making it almost entirely pointless to install NTLDR to your MBR.

Writing the MBR

Launch EasyBCD and go to the BCD Deployment page, paying attention to the “MBR Configuration Options” section at the bottom of the screen:

Once you’ve picked the bootloader you’d like to use, you can proceed and press the “Write MBR” button.

Please pay careful attention to the following: Writing the MBR is a very delicate process that requires direct access to the hard drive. This feature shouldn’t be used through a virtualization layer or under custom filesystem drivers. Writing the MBR will may result in some rather unexpected behavior!

  • Disrupted I/O access to the hard drive.
  • Loss of data in the process of being saved to the hard drive.

None of these are fatal and EasyBCD takes extra precaution to protect your hard drive. Under almost no circumstances will this result in problems, however, you might want to do the following before writing the MBR:

  • Stop any running torrents – They might become corrupted.
  • Finish burning CDs or DVDs – If you don’t, the CD will be corrupt and unfixable.
  • Save any open documents – And wait for the save to finish.
  • Disconnect from network shares – Make sure no one is remotely using critcal data from your hard drive.

If you followed these steps you should be OK to hit that button. Once the process is complete, you may go back to whatever you were doing.