UNIT -2COMPUTER SOFTWARE

INTRODUCTIONSOFTWAREHARDWAREDIFFERENCE BETWEEN THE S/W AND H/W

TYPES OF SOFTWAREAPPLICATIONSYSTEMSOFTWARE

SOFTWAREApplication 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 OSIt 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 OSSingle user/ single tasking OSSingle user/ multi tasking OSMulti user/ multi tasking OSTime sharing OSVirtual storage OSReal time system

Single user/Single tasking OSOne user works on the systemPerforms one task at a timeTake up little space on diskRun on inexpensive computersExample MS-DOS

Single user/Multitasking OSUser performs many tasks at onceMost common form of OSRequire expensive computersTend to be complexExample: Windows XP

Multi user/Multitasking OSMany users connect to one computerEach user has a unique sessionMaintenance can be easyRequires a powerful computerExample: UNIX, Linux, etc,.

Time sharing OSIt 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 OSIt 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 systemIt gets data from an on going event.Respond quickly to user input.Example: Reservation system

LOGICAL SYSTEM ARCHITECTURE

HARDWAREThe physical components present in the computer is called Hardware.

Example: Keyboard, Monitor etc,.

SOFTWAREIt is a collection of programs which, performs some task.System s/wApplication s/w

System S/WIt is collection of programs that controls and manage the computer.Types:OS,Language processor etc,.

TYPES OF SOFTWAREAPPLICATIONSYSTEMSOFTWAREExample:Operating system,Device drivers,Language Processor,System utilities etc,.Example:Ms-Office,Reservation system,Payroll processing systemHospital management system etc,.GENERALCUSTOMISED

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

Device driversIt 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.

COMPUTERDRIVERSDEVICE 1DEVICE 2DEVICE n

Language ProcessorIt is a system s/w that translates the programs written in High level language to Machine language.Machine language: 0s and 1s.High level language: C, C++, Java etc,. Example: Compiler, Interpreter, Assembler

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

HIGH LEVEL LANGUAGECOMPILERMACHINE LANGUAGE

InterpreterIt converts the programs written in high level language to machine language.It executes the source code in line-by-line manner.

INTERPRETREHIGH LEVEL LANGUAGEMACHINE LANGUAGE

AssemblerIt converts the programs written in Assembly language to machine language.

ASSEMBLERASSEMBLY LANGUAGEMACHINE LANGUAGE

System UtilitiesThese programs performs tasks related to the maintenance of computerExample: Disk clean-up.

APPLICATION SOFTWAREIt 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 TerminologiesFirmware It is a software, which is permanently stored on the memoryEg: BIOSOpen sourceIt is software developed by some programmers and released for public useThe 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/wIt is developed by business organizations to earn profit

SYSTEM DEVELOPMENT LIFE CYCLESteps:Requirement analysisDesignCodingTestingImplementation & maintenance

SDLCRequirementAnalysisImpl & MaintenanceTestingCodingDesign

Requirement analysisIt 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.

CodingIt is the process of developing code for the software.

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

Implementation & maintenanceIt involves installation of the s/w, giving training to the customer etc,.

ASSIGNMENT

DECIMAL BINARY2968116202423

DECIMAL OCTAL271712627263731

DECIMAL HEXA83796294743218239

DECIMAL OTHER85 BASE476 BASE3317 BASE6186 BASE7251 BASE8

BINARY OCTAL,HEXA111011111000010011001010110101110101111000110110101011

OCTAL HEXA56764981424574948

61.62510 BASE2427.2910 OCTAL759.3710 HEXA

INTERNETNetwork of networks i.e. interconnection of networks.

EVOLUTION OF INTERNETIn 1960 US Dept of Defense created a network called ARPANET (Advanced Research Project Agency Network).It is the forerunner of todays Internet.By 1970s ARPA helped in the development of TCP/IP (Transmission Control Protocol/Internet Protocol) which is used for transferring of data between networks.

In 1980s National Science Foundation (NSF) created the NSFNET.In 1980s e-mail was introduced.In 1990s the world wide web was introduced.

Internet TerminologyWebpage 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 RequirementsModemA Connection with the ISP

IP AddressThe 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

DNSDomain Name SystemIt is used to maps the text to the IP Address.

URLUniform Resource Locator.It contains the protocol name, domain name etc,.Eg: http://www.microsoft.com

Internet ApplicationWorld Wide Web It is a collection of information or collection websites.e-mailIt is used to send electronic message to anyone.

Internet Application (Cont)ChattingIt is online Conversation.It is used to send message back and forth to anyone.Remote AccessIt is the process of accessing information present in a remote computer.

Internet Application (Cont)File SharingIt 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)IRCInternet Relay Chat.It is designed for group communication.Video ConferencingIt allows two or more user to interact via video and audio transmission.

Internet Application (Cont)FTPFile Transfer ProtocolIt is used to transfer data from one computer to another computer.TelNetTelecommunication NetworkThis protocol is used to get services from the server.

Internet Application (Cont)VOIPVoice Over Internet Protocol.It sends voice over the internet protocol.

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