For example, there is no 1024 cylinder problem because the concept of cyliders is not used. There is also no problem with a difference in geometry between the bios and linux because the concept of geometry is not used. We can boot from any place on the drive, up to 137gb. Like nuni, it does not use the bios, so any partition of any IDE drive can be selected. It will execute a loader that resides in the boot sector of any partition.
Selection is by name of partition.
You answer with names like hda1 or hde11, and it executes whatever loader resides there. It is self contained, so it could be carried to other computers on a floppy and boot those machines with no setup or installation. This is the boot loader. This passes some data to nuni.asm by means of 'equ' statements. This is a multi-boot selector.