Booting is the term information technology in the English language that refers to the process early turn on the computer where all the blank gives a chance processor registers, and status of the microprocessor / processor gives a chance reset. Then loaded at address 0xFFFF code segment (code segment) and instructions contained in the address 0xFFFF address is executed.
Generally, program the BIOS (Basic Input Output System), which is a basic software, called. Because the BIOS is usually located at that address. Then the BIOS will perform checks on all errors in memory devices installed / connected to the computer (such as serial ports, etc.). This is called POST (Power-On Self Test).
After a check of the system is completed, the BIOS will seek the Operating System, load it in memory and executed. By making changes in BIOS setup (especially for windows users, when you turn on the computer press and hold the delete button again until the display menu of bios out. There you can find out details about your computer such as memory in the computer, we can determine that the BIOS for Operating System into the floppy disks, hard disks, CD-ROMs, USB and others, with the order we want.
Actual BIOS does not contain a complete Operating System. He only contains one section of code that exist in the first sector (first sector, also called boot sector) on disk media, which we set earlier. Sections / fragments of the Operating System code for 512 bytes, and the second last byte of code fragments must be 0xAA55 (also known as the boot signature). If the boot signature is missing, then saying no bootable disk media, and the BIOS will seek the Operating System on the next disk media.
Fragment of code that should be on the boot sector was referred to as boot-strap loader. BIOS will load the boot-strap loader into memory starting at address 0x7C00, then run the boot-strap loader earlier. Finally now the power switch to boot-strap loader to load the Operating System and do the necessary setting in order to run the Operating System.
Source : http://id.wikipedia.org/wiki/Proses_booting