bios-"Master boot Record (MBR)-" Startup file-"operating system

The BIOS has self-test and bootstrap program, after the machine power up, the CPU automatically calls the program in the BIOS, the system hardware initialization and hardware failure check, including the various boards. After checking, the BIOS transfers control to the hard drive master boot record (MBR), the BIOS transfer control is very simple, because the MBR on the hard disk fixed track fixed position, as long as the hard disk on the location of the 512 bytes loaded into memory and call it, so that control is given to the master boot record, The master boot Record is also the program, which then find the boot file on the hard disk, For example, the 98 system is Msdos.sys and Io.sys, found after they read into the memory and transfer control to them, Msdos.sys and Io.sys will go to execute Command.com and win.com,win.com 98 system loaded into memory, 98 started up.

It is not difficult to understand why the start disk to use Sys.com to pass Msdos.sys and io.sys the two boot files to the target disk, and just copy the two files to the target disk is not used, because sys.com can write these two files to a specific location on the disk, or the master boot record cannot find them then the system hangs.

In addition, the master boot record can be modified, it is a program, you can modify it not to find Msdos.sys and io.sys two files to find other files, such as nt/2000 startup file is NTLDR, install the two systems when the installation program will modify the master boot record, and set the master boot record to find NTLDR this file when booting the system. It's not hard to understand how multiple operating systems coexist.

There is no device driver in the Ps:bios, but it provides control of the various hardware in the computer, which is programmable, simply can be modified, such as upgrading the BIOS, the control method provided to the operating system such as 98, the operating system through the hardware control provided by the BIOS to achieve the operation of the hardware , the usual driver is built on the basis of a higher level of control.

bios-"Master boot Record (MBR)-" Startup file-"operating system