When computer is turned on....
In short : BIOS will find the primary boot device(Hard Disk (HD) ) and loads first 512 bytes of it (MBR area)..
MBR area contains GRUB stage 1 which loads stage 1.5 ( 30kb immediately after 512b ). stage 1.5 loads stage 2...
BIOS loads first 512 bytes of HD. So what is the standard which is used by BIOS to fetch that 512 bytes.. i.e. the communication standard b/w BIOS firmware and HD..
Here comes the SCSI standard. It is a set of standards for physically connecting and transferring data between computers and peripheral devices. So the standard defines SCSI commands. The initiator ( BIOS firmware ) can read 512 bytes from HD using SCSI std commands...
A tip: wanna see MBR in ubuntu....
it is very simple.... open a terminal do the following commands....
- sudo dd if=/dev/sda of=~/mbr count=1 bs=512
- hexdump mbr -C
mbr is just a file name....
