What & How & Why

Operation System

An operating system (OS) is system software that manages computer hardware and software resources and provides common services for computer programs.


If people try to use the early computer, they need write driver and corresponding software for each device individually to make computer work. That means they have to rewrite driver and software again and again when they switched to another type of computer(hardware,driver,software will not match). To solve this problem, people developed a special program which includes drivers and corresponding management softwares. This is Operating System. The Kernel, as the core of OS, is mainly focus on dealing with hardware.

System Call

In computing, a system call is the programmatic way in which a computer program requests a service from the kernel of the operating system it is executed on. This may include hardware-related services (for example, accessing a hard disk drive), creation and execution of new processes, and communication with integral kernel services such as process scheduling. System calls provide an essential interface between a process and the operating system. The main functions that System Call has:

  1. Process Control
  2. File management
  3. Device Management
  4. Information Maintenance
  5. Communication