Introduction to Operating System

Today, everyone is familiar with the word operating system. Operating systems are used in the computer systems and in our smart phones. Different smart phones have their own operating system. For example, Android phone have operating system like KitKat, jelly bean, ice-cream sandwich, gingerbread, lollipop and latest one marshmallow. Computer have operating systems like MAC operating system, window OS X, Apple iOS, Linux and Unix.

What is Operating System?

• An operating system is a program that manages computer hardware.

• Operating system controls and coordinates the use of hardware among various application programs for various users.

• Operating system provides and interface between computer hardware and computer software.

Functions of Operating System: - An operating system consist of different functions: -

1) File Management: - In File management different files stored in our computer system memory at different locations are managed by operating system.

2) Communication: - Communication between different devices attached to computer system is handled by the operating system.

3) Information Management: - Information like user sensitive data stored in the computer system is managed by the operating system.

4) Process control and management.

5) Resource allocation.

6) Resource Utilization.

Basic terms frequently used in operating system: - Kernel and Bootstrap are the two basic terms that are used in window operating system. Kernel is the heart of the operating system. And boot strap is the initial program that runs on the computer system when system is powered on.

1) Kernel: - It is a part of OS that loads first. Kernel provides communication between software and Hardware. Kernel is a program running all the times on computer.

2) Bootstrap: - Whenever a computer powered on or rebooted, a program run on the system. This initial program is known as bootstrap program.

• Bootstrap program is stored in ROM or EEPROM.

Types of Operating System?

• There are three types of Operating System: -

1. Single Processor System

2. Multi-Processor System

3. Cluster System

Explanation: -

1) Single Processor System: - In single processor system, One CPU capable of executing general purpose instruction set.

· It also executes instructions from user processes.

· In single processor system, single instructions are executed at a time.

· Only one instruction at a time is executed.

· One processor is used.

· Single processor system is Slow

2) Multiprocessor System: - Multiprocessor system have two or more processors in close communication.

· Multiprocessor systems use computer bus and sometimes clock, memory and peripheral devices for communication purpose.

· Two or more than two processors are used.

· Faster as compare to single processor system.

3) Cluster System: - In cluster system, computer share storage.

· Computer are closely linked by a LAN.

What is a Process?

Process in operating system = Program under execution.

The difference between process and program is that process is an active entity whereas program is as passive entity. Process runs all times in the computer system. Whereas, program is dependent on user action or command for execution.

Different Process States: - A process in operating system goes through different stages. Each stage in process is executed one after another.

· When a process is executes, its state is changed.

· State of process is defined as the part of current activity of the process.

· Each process goes through following states: -

1. New

2. Ready

3. Running

4. Waiting

5. Terminated

The working of these five stages of process is given as below: -

NEW state = when process is created, it is in new state.

Running State = When instructions are being executed, it is in running state.