Hi I was just Reading the article from http://www.comptechdoc.org/os/linux/howlinuxworks/linux_hlbootproc.html in the article before the system can boot the BIOS detect the first available IDE device, on this device is the MBR which contain the boot loader and partition tables
now suppose i have Two OS install -- debian Etch and the centos ...and grub is the default boot loader ( and grub file is located in /etc/grub.conf ..which has instruction / menu screen for booting the various OS ) but i don't seem to understand one thing - How is /etc/grub.conf made available to the boot loader even before a OS is selected ( explanation not very clear in the article )