[ Thanks to An Anonymous Reader for
this link. ]
“GRUB stands for Grand Unified Bootloader and was created in
1995 by Erich Boleyn as he wanted to have a multiboot option. Intel
based motherboards must be started with a 16-bit operating system
because of a limitation to 640 kilobytes of RAM at startup. GRUB is
used to facilitate the 16-bit requirement and load the 32-bit Linux
kernel. The AMD CMOS is 64-bit so it can load the 64-bit kernel for
Linux. In order for GRUB to work it must use a three step process
on CentOS.”