Boot process with boot manager in MBR
When the boot manager of Boot-US is installed in the
MBR, the boot manager
becomes active in an initial stage of the boot process. When the
computer is restarted the MBR of the first hard disk is loaded and executed.
This procedure is still identical to the standard boot process.
However the boot loader code of the MBR now does not contain the usual boot loader
but the first part (LOADR-US) of the boot manager Boot-US.
When executed, LOADR-US loads the main part of the boot manager (BMGR-US) und starts
this main part (BMGR-US).
From this moment the boot process is identical to the boot process where
the boot manager is installed on a primary partition.
Thus the user
selects one of the configured partitions and the boot manager loads
and executes the boot sector of this partition. This will boot the
corresponding operating system.