Operating system Overview and boot

A computer system consists of three layers: an interface that is provided by the operating system when the upper-level application wants to use hardware.

Universal Turing Works, "Set control action" is equivalent to the application.

From Turing machine to computer: first put the program in memory, use IP to point to it, take the finger, execute. Each instruction corresponds to the logic in "set control Actions".

After power on the computer (take X86 pc as an example): Disk 0 Track 0 sector is the boot sector of the operating system.

The following is the code for the boot sector: This code moves the 256-byte code at 7C00 to 90000 (to make room).

Jmpi indirect jump, ip=go,cs=initseg.

Bootsect continue reading into the following, first read the setup

After reading into the Setup module

。 So, after power on, the computer's job is to play the logo, read setup, read the rest of the operating system.

Operating system Overview and boot