1. Operating Systems

1. Operating Systems
	Chapter 1. Introduction

Operating Systems
- Hardware:
  - 1 or more processors
  - Main Memory
  - Clocks
  - Discs
  - Bus
- Software:
  - Application programs
  - System programs
    Compilers
    Editors
    Linkers
    Command Interpreter(shell)
OS Responsibilities
- Control all computer's resources
- Build a necessary base for application programs
- Create a Virtual Machine easier to understand and use.
  Figure 1.1. Computing Layers
OS Basic Concepts
System Calls are OS provide instruction extensions. They given to user OS kernel access.
There are 2 system calls classes in UNIX:
1. Process system calls
2. File System system calls
Process:
A process is a running program.