Configure Windows NT boot manager for dual-boot

By default when installing Windows NT on top of an existing Windows operating system, then Windows NT will adjust its boot manger during the install to include the previous operating system.

If wanting a dual-boot or multi-boot system, then the easy way is to install the oldest operating system first, and then install the newer version on top of the old one.

If already having a newer version of Windows installed, and want to dual boot with an older version of Windows, then there are two paths:

  • Install the older version of Windows on the same hard disk partition as the current install, and then use the recovery console command fixboot to restore the newer version of the Windows NT boot manager. Then use the recovery console command bootcfg to configure the boot manager to include the older version of Windows.
  • Install the older version of Windows on a new primary partition, and then change the active partition back to the hard disk partition containing the newer version of Windows with the recovery console command fixboot. Then use the recovery console command bootcfg to configure the boot manager to include the older version of Windows on the other partition.

Microsoft has created several dual boot articles:

Credits labmice.net