1. Unit# 3: Operating System

2. Learning Objectives Operating Systems introduction Main functions
In this unit you will be learn about:
Operating Systems introduction
Main functions
Process and Memory Management
Introduction to Windows
Unix and Linux
Basic components of windows

3. Introduction to operating System
An operating system is the most important and major program that runs on a system (computer).
Every computer system must have an operating system in order to run different programs.
An operating system performs several tasks such as:
Recognize input from a keyboard
Send output to a display screen (monitor)
Keep track of files as well as directories on a disk
Control various peripheral devices like hard drive, printer, video or sound card etc.

4. Introduction to operating System
Integrated set of programs that controls the resources
(the CPU, memory, I/O devices, etc.) of a computer system
Provides its users with an interface or virtual machine that is more convenient to use than the bare machine.
Two primary objectives of an OS are:
1. Making a computer system convenient to use
2. Managing the resources of a computer system

5. Introduction to operating System

6. Types of Operating System
There are two types of operating system:
Graphical User Interface (GUI) Operating- System
Command Line Operating-System

7. Types of Operating System
Graphical User Interface (GUI) Operating-System:
A GUI operating-system basically provides a graphical-user-interface to its users in order to communicate with system/computer.
The users of GUI operating systems don't need to memorize different commands while interacting with computer.

8. Graphical User Interface (GUI)

9. Types of Operating System
Command Line Operating-System:
A command line operating-system basically provides a command-prompt in order to type different commands.
Users use these commands while their interaction with computer.
Examples of command line operating-system include:
DOS
Unix
The features of command line operating-system may include:
It is faster than GUI operating system.
It provides a powerful and significant scripting facility.
It provides full/complete access to computer-resources.

10. Command Line Operating-System
Drawbacks of the command line operating-system:
Not very easy to learn
Not very simple to use
Few command line operating-systems provide the facility of multi­tasking (but it is very difficult to implement).

11. Main functions of Operating System
Manage Resources
Memory Management
Applications/Multitasking
Support for Built-In Utility Programs
Control Computer Hardware
System Performance Measures
Process Management

12. Functions of Operating System
Manage Resources:
To manage the different resources of a computer which include mouse, keyboard, monitor, printer, storage devices or memory
Operating system usually creates a file- structure on a hard drive. Once a file is stored, the operating system saves it, names it and also remembers it for future use.
Organized storage
Long file names
Folders can be created and nested
All storage devices work consistently

13. Functions of Operating System
Memory Management:
Memory is important resource of a computer system that must be properly managed for the overall system performance
Memory management module:
Keeps track of parts of memory in use and parts not in use
Allocates memory to processes as needed and deallocates when no longer needed

14. Functions of Operating System
Run Applications/Multitasking:
Operating systems support “multi-tasking”. The term multi­tasking means that an ability to run two or more applications/programs at a time. As soon as a user sends a request for a program, an operating system suddenly locates that application & loads it into a RAM (Random Access Memory).

15. Functions of Operating System
Support for Built-In Utility Programs:
When unexpected things happen such as hard disk crash, virus attacks or slow operations etc. then function of the utility programs start.
Operating systems have built-in utility programs for common purposes.
Utility programs are commonly known as “System Tools”
Utility tools may include:
Format
Scan Disk
Disk Cleanup
Disk Defragmenter and
Anti-Virus

16. Functions of Operating System
Control Computer Hardware:
Operating system lies between the two main things, Programs and BIOS (Basic Input Output System).
BIOS controls the computer hardware(s).
Operating system access hardware resources through BIOS or device drivers.

17. System Performance Measures
Throughput: Amount of work that the system is able to do per unit time Turnaround time: Interval from the time of submission of a job to the system for processing to the time of completion of the job Response time: Interval from the time of submission of a job to the system for processing to the time the first response for the job is produced by the system

18. Process Management
A process (also called job) is a program in execution
Process management manages the processes submitted to a system in a manner to minimize idle time of processors (CPUs, I/O processors, etc.) of the system
A program in execution-mode (as mentioned above) is called a process.
A compiler (time-shared user program) can also be referred as a process.
A word-processing program which is being run through an individual user (on a PC) is also known as a process.

19. File Management A file is a collection of related information
Every file has a name, its data and attributes
File’s name uniquely identifies it in the system and is used by its users to access it
File’s data is its contents
File’s attributes contain information such as date & time of its creation, date & time of last access, date & time of last update, its current size, its protection features, etc.
File management module of an operating system takes care of file-related activities such as structuring, accessing, naming, sharing, and protection of files

20. File Access Methods Two commonly supported file access methods are:
Sequential access:
accessed sequentially (in the order in which the Information stored in a file can be y are stored, starting at the beginning)
Random access: Information stored in a file can be accessed randomly irrespective of the order in which the bytes or records are stored

21. Introduction to Windows
What is Windows?
An operating system and Graphical User Interface (GUI) created by Microsoft and found on most computer systems (but not all!).
The “window” refers a program or document or other object that is open.
Developed by Microsoft to overcome limitations of MSDOS operating system
Single-user, multitasking OS
Native interface is a GUI
Designed to be not just an OS but also a complete operating environment

22. Introduction to Windows
Windows XP
Windows Vista
Windows 7
Windows 8/Windows 8.1
Windows 10

23. UNIX
UNIX is a computer operating system, a control program that works with users to
run programs,
manage resources, and
communicate with other computer systems.
Several people can use a UNIX computer at the same time; hence UNIX is called a multiuser system. Any of these users can also run multiple programs at the same time; hence UNIX is called multitasking.

24. UNIX
Developed in the early 1970s at Bell Laboratories by Ken Thompson and Dennis Ritchie
Written in C high-level language, hence, highly portable
Multi-user, time-sharing OS
Used on a wide variety of computers ranging from notebook computers to super computers
Especially prevalent on RISC workstations such as those from Sun Microsystems, Hewlett-Packard, IBM, and Silicon Graphics
Structured in three layers – kernel, shell, and utilities

25. Linux
Linux is a true 32 bit UNIX-like OS developed originally for home PCs, but now it runs on a variety of platforms. The source code for Linux is freely available to everyone. Linux was created by Linus Torvalds in 1991, and it has been developed with the help of many programmers across the Internet. Now it has evolved into a very functional, powerful and usable clone of Unix which has at least 10 million users worldwide.

26. Linux vs. Unix Linux is free, but Unix is not.
Unix is compatible with Linux at the system call level, meaning most programs written for either Unix or Linux can be recompiled to run on the other system with a minimum of work. But Linux will run faster than Unix on the same hardware.

27. Basic Features of Windows 7
1. The Taskbar reloaded: Windows 7's version of the Taskbar is less cluttered than Vista's, and it handles both running and no running apps with equal aplomb.
2. Slicker, quicker Taskbar Previews: Now they show you all of an application's open windows, all at once.
3. The convenience of Jump Lists: These context-sensitive Taskbar menus let you start accomplishing things in applications before you even open them.

28. Basic Features of Windows XP
Remote Desktop Windows XP professional OS enables user to use remote desktop connection feature means they can sit at a PC and access another PC remotely.
Device Driver Rollback: This new Windows XP feature let users uninstall installed device driver. If users install device driver that causes system instability then they can easily roll back the previous driver.
Built-in CD burner When Windows XP arrived, it came up with its own in-built CD burner feature. Now there is no longer need to install CD burning software, user can burn files directly via Windows Explorer.
Encrypted file system support multi-user: This feature is for Windows XP Professional, Encrypted file system make it possible to access encrypted files and folders by multiple users.
Device support improvement: Windows XP supports USB 2.0, Intel High Definition Audio based hardware, FireWire, & Windows Image Acquisition based scanners etc.