UNIT -2

COMPUTER SOFTWARE

INTRODUCTION• SOFTWARE• HARDWARE• DIFFERENCE BETWEEN THE S/W

AND H/W

TYPES OF SOFTWARE

APPLICATIONSYSTEM

SOFTWARE

SOFTWARE

• Application software

-Easy-to-use programs designed to perform specific tasks.

• System software-Set of programs designed to operate and control the computer.

OPERATING SYSTEM

• It is a collection of programs that controls and manages the computer

• ExamplesWindows, Unix, MSDOS

Functions Of OS• It provide an interface between the hardware

and the user.• It controls and co-ordinate the entire computer

system.• It controls the allocation and use of various

resource by various user and task.• It controls the various application programs.• Scheduling the jobs.• Process management, Memory management,

Device management etc,.

TYPES OF OS

• Single user/ single tasking OS

• Single user/ multi tasking OS

• Multi user/ multi tasking OS

• Time sharing OS

• Virtual storage OS

• Real time system

Single user/Single tasking OS

• One user works on the system

• Performs one task at a time

• Take up little space on disk

• Run on inexpensive computers

• Example MS-DOS

Single user/Multitasking OS

• User performs many tasks at once

• Most common form of OS

• Require expensive computers

• Tend to be complex

• Example: Windows XP

Multi user/Multitasking OS

• Many users connect to one computer

• Each user has a unique session

• Maintenance can be easy

• Requires a powerful computer

• Example: UNIX, Linux, etc,.

Time sharing OS

• It handles multiple jobs at a time.

• It switches the CPU among various jobs that are running on the computer whenever there is a program break or a fixed time has expired.

Virtual storage OS

• It uses the technique Demand paging. i.e. whenever the program size is larger than the main memory it splits the program into many pages.

• Only the needed page is loaded to the main memory for execution.

Real-time operating system

• It gets data from an on going event.

• Respond quickly to user input.

• Example: Reservation system

LOGICAL SYSTEM ARCHITECTURE

HARDWARE

• The physical components present in the computer is called Hardware.

• Example: Keyboard, Monitor etc,.

SOFTWARE

• It is a collection of programs which, performs some task.

• System s/w

• Application s/w

System S/W

• It is collection of programs that controls and manage the computer.

• Types:OS,Language processor etc,.

TYPES OF SOFTWARE

APPLICATIONSYSTEM

SOFTWARE

Example:Operating system,Device drivers,Language Processor,System utilities etc,.

Example:Ms-Office,Reservation system,Payroll processing systemHospital management system etc,.

GENERALCUSTOMISED

OS

• It is a collection of programs that controls and manages all the components present in the computer

Device drivers• It is set of programs, which act as an

interface between the computer and the device.

• It is responsible for the proper functioning of the device.

COMPUTER

DRIVERS

DEVICE 1

DEVICE 2

DEVICE n

Language Processor

• It is a system s/w that translates the programs written in High level language to Machine language.

• Machine language: 0’s and 1’s.

• High level language: C, C++, Java etc,.

Example: Compiler, Interpreter, Assembler

Compiler

• It converts the programs written in high level language to machine language i.e. it translates the source code to object code.

HIGH LEVEL LANGUAGE

COMPILER

MACHINE LANGUAGE

Interpreter

• It converts the programs written in high level language to machine language.

• It executes the source code in line-by-line manner. I

NTERPRETRE

HIGH LEVEL LANGUAGE

MACHINE LANGUAGE

Assembler

• It converts the programs written in Assembly language to machine language.

ASSEMBLER

ASSEMBLY LANGUAGE

MACHINE LANGUAGE

System Utilities

• These programs performs tasks related to the maintenance of computer– Example: Disk clean-up.

APPLICATION SOFTWARE

• It is collection of programs that performs a specific task.

– Customised

– General

APPLICATION SOFTWARE (Cont)

• Customised Application s/w It is developed to meet the requirements of

limited user.

• General Application s/w It is developed to meet the requirements of

many user.

S/W Terminologies• Firmware

It is a software, which is permanently stored on the memory

Eg: BIOS• Open source

• It is software developed by some programmers and released for public use

• The programming code is available so that the user can modify it.

S/W Terminologies (Cont)• Freeware

• It is a copyrighted software which is given away free by the owner.

• Commercial s/w

• It is developed by business organizations to earn profit

SYSTEM DEVELOPMENT LIFE CYCLE

Steps:

• Requirement analysis

• Design

• Coding

• Testing

• Implementation & maintenance

SDLCRequirement

Analysis

Impl & Maintenance

Testing

Coding

Design

Requirement analysis

• It produce the Software requirement document (SRS),which specifies all requirements of the customer.

Design

• It is the process of designing how the requirements to be implemented.

Coding

• It is the process of developing code for the software.

Testing

• It is the process of executing the software with sample data to verify whether it has errors or not.

Implementation & maintenance

• It involves installation of the s/w, giving training to the customer etc,.

ASSIGNMENT

DECIMAL ↔ BINARY

• 29

• 68

• 116

• 202

• 423

DECIMAL ↔ OCTAL

• 27

• 171

• 262

• 726

• 3731

DECIMAL ↔ HEXA

• 83

• 796

• 2947

• 4321

• 8239

DECIMAL ↔ OTHER

• 85 ↔ BASE4

• 76 ↔ BASE3

• 317 ↔ BASE6

• 186 ↔ BASE7

• 251 ↔ BASE8

BINARY ↔ OCTAL,HEXA

• 1110111

• 1100001001

• 10010101101011

• 101011110001

• 10110101011

OCTAL ↔ HEXA

• 567

• 649

• 814

• 2457

• 4948

• 61.62510 BASE2

• 427.2910 OCTAL

• 759.3710 HEXA

INTERNET

• Network of networks i.e. interconnection of networks.

EVOLUTION OF INTERNET

• In 1960 US Dept of Defense created a network called ARPANET (Advanced Research Project Agency Network).It is the forerunner of today’s Internet.

• By 1970’s ARPA helped in the development of TCP/IP (Transmission Control Protocol/Internet Protocol) which is used for transferring of data between networks.

• In 1980’s National Science Foundation (NSF) created the NSFNET.

• In 1980’s e-mail was introduced.

• In 1990’s the world wide web was introduced.

Internet Terminology

• Webpage – It is an electronic document which contains information.

• Website – It is a collection of related WebPages.

• Homepage – It is starting point or doorway to the website. It is also known as the index page.

Internet Terminology (Cont)

• Web Browser or Browser – It is a program that enables the user to access the Webpage and displays the webpage on the computer screen.

• Uniform Resource Locator (URL) –It is the unique Address of the Webpage, which is used to identifies its location on the internet.

Internet Terminology (Cont)

• Hypertext – It refers to the text that connects other documents.

• Internet Service Provider (ISP) - It provides access to the internet to user.

• Web Server – It is a computer that services the requests from the clients i.e. web browser

Internet Terminology (Cont)

• Download - It is the process of receiving data from a remote computer to the local computer.

• Upload – It is process of sending data from local computer to remote computer.

Getting connected to the Internet

Requirements

• Modem

• A Connection with the ISP

IP Address

• The Internet Protocol Address is used for identifying the computer.

• It can be expressed in dotted decimal form or binary form.

• It has four octets i.e. it has four 8 bit number Eg: 175.192.0.110101111.11000000.00000000.00000001

DNS

• Domain Name System

• It is used to maps the text to the IP Address.

URL

• Uniform Resource Locator.

• It contains the protocol name, domain name etc,.

• Eg: http://www.microsoft.com

Internet Application

• World Wide Web

It is a collection of information or collection websites.

• e-mail

It is used to send electronic message to anyone.

Internet Application (Cont)

• Chatting

• It is online Conversation.

• It is used to send message back and forth to anyone.

• Remote Access

• It is the process of accessing information present in a remote computer.

Internet Application (Cont)

• File Sharing

• It enables a group of user to share information.

• The information has been placed on a shared location and the user access the information.

Internet Application (Cont)

• IRC

• Internet Relay Chat.

• It is designed for group communication.

• Video Conferencing

• It allows two or more user to interact via video and audio transmission.

Internet Application (Cont)

• FTP

• File Transfer Protocol

• It is used to transfer data from one computer to another computer.

• TelNet

• Telecommunication Network

• This protocol is used to get services from the server.

Internet Application (Cont)

• VOIP

• Voice Over Internet Protocol.

• It sends voice over the internet protocol.

SYSTEM DEVELOPMENT LIFE CYCLE

Requirements – defines needed information, function, behavior, performance and interfaces.Design – data structures, software architecture, interface representations, algorithmic details.Implementation – source code, database, user documentation, testing.