Basic of Operating System

What is Operating System ?

Operating system is an interface between user and the computer hardware. The hardware of the

computer cannot understand the human readable language as it works on binaries i.e. 0's and 1's. Also it

is very tough for humans to understand the binary language, in such case we need an interface which

can translate human language to hardware and vice-versa for effective communication.

Types of Operating System:

 Single User - Single Tasking Operating System

 Single User - Multitasking Operating System

 Multi User - Multitasking Operating System

Single User - Single Tasking Operating System

In this type of operating system only one user can log into system and can perform only one task at a

time.

E.g.: MS-DOS

Single User - Multi tasking operating System

This type of O/S supports only one user to log into the system but a user can perform multiple tasks at a

time, browsing internet while playing songs etc.

E.g.: Windows -98,Xp,vista,Seven etc.

Multi User - Multi Tasking Operating System

These type of O/S provides multiple users to log into the system and also each user can perform various

tasks at a time. In a broader term multiple users can logged in to system and share the resources of the

system at the same time.

E.g.: UNIX, LINUX etc.

UNIX Principles

 Everything is a file:- UNIX system have many powerful utilities designed to create and

manipulate files. The UNIX security model is based around the security of files. By

treating everything as a file, you can secure access to hardware in the same way as you

secure access to a document.

 Configuration data stored in text: - Storing configuration in text allows an administrator

to move a configuration from one machine to another easily, provide the ability to roll

back a system configuration to a particular date and time.

 Small, Single-Purpose Programs: - UNIX provides many utilities.

 Avoid captive user interfaces:-

 Ability to chain programs together to perform complex tasks:- A core design feature of

UNIX is that output of one program can be the input for another. This gives the user the

flexibility to combine many small programs together to perform a larger, more complex

task.

Examples of Operating Systems are – 

• Windows (GUI-based, PC)
• GNU/Linux (Personal, Workstations, ISP, File and print server, Three-tier client/Server)
• macOS (Macintosh), used for Apple’s personal computers and workstations (MacBook, iMac).
• Android (Google’s Operating System for smartphones/tablets/smartwatches)
• iOS (Apple’s OS for iPhone, iPad, and iPod Touch)