Software Concept

A computer consist of two parts Hardware & Software. In previous unit we know about hardware peripherals quite in details. This unit will know us about software concept in term of computer. Without software our computer behaves like a car without petrol. Software is used to control the hardware devices, we see in previous unit.

A software is set of programs, which are the set of instructions. These instructions are written in a special computer language that computer can understand. These languages are known as Programming Languages.

A computer can nither think nor make any decision its own. Also it is impossible for any computer to independently analyse a given data and follow its own method of solution. It need a program to tell it what to do with data.

A computer software is classified in two parts-

System software:- A system software consist of many programs for controlling many Input/Output operation. A operating system is example of system software. A system software is further classified in three parts

Language Translator:- A program that convert programming source code to machine readable codes are known as language translator. There are three types of language translator
1. Interpreter:- This is a program that convert high level language to machine level language i.e. Machine level language. The basic property of Interpreter is that it first scan one line of a program or source code, if this is error free then it executes either it will stop the execution. So a interpreter will check a program line by line and execute it, if it is error free. This process takes more time in execution of any program.
2. Compiler:- A compiler is a program used to covert high-level language into machine level. The basic property of compiler is that it first scan all file at a time and check for any error, if no error found then change the program to machine level either show all the errors present in the program. So it takes very less time for execution.
3. Assembler:- An assembler is a program written to convert assembly level language to machine level language.
Operating system:-An operating system is the system software which is used to operate the computer. An operating system manages a computer resources very efficiently, takes care of scheduling of multiple jobs for execution and manages the flow of data, instructions between input/output unit and the main memory. Windows, Unix, Linux, Macintosh etc. are few widely used operating systems. An operating system are classified in different categories with there performance.
1. Single user operating system:- A single user operating system give the permission to run or execute one application or program at a time. That is one user can work at a time. e.g.- MS-DOS.
2. Multi-user Operating system:- A multi-user operating system give the permission to many users work at same time. A transaction process system such as railway reservation system need of hundred of terminals under a single program is example of multi-user operating system. e.g. Unix, Linux etc.
3. Network operating system:- A network operating system is a collection of software's which allow a set of computers which are interconnected by a computer network to be used together in a convenient and cost effective manner. In a network operating system the users are aware of existence of multiple computers and can log into remote machine and copy files from one location to another. Like Unix, Windows-NT, Linux etc.
4. The Graphical User Interface (GUI) operating system:- A GUI uses graphical components like small images, pictures to represent a program, so that instead of typing it we just select it using pointing devices like Mouse etc. Ex. Windows 3.1, Windows-95/98/2000/ME/XP, Linux etc.
Utilities:- Utility program are the programs which are often used by application program. These utility programs are created by the manufacturer. Ex. Text Editors, Sorting, Formatting etc.

Application Software:- Application software are written to enable the computer to solve a specific data processing task. It is used for solving our various works. A program written for specific purpose could be termed as Application software. Example- Word processor, Database management system's software, accounting software's etc. Application softwares can be classified in different classes like

Database Management Software:- Database management softwares are used for maintaining data, queries and reports. These softwares provides the facility for ease creation of databases of Invoice, order and contact files. some examples of database softwares are Dbase, FoxPro, Oracle, SQL etc.
Accounting Packages:- The accounting packages are one of most important package for an office. These are few facilities available in a accounting package like in Tally, Tata EX etc.
- Tax Planner facility
- Facility for producing charts and graphs.
- finding accounts payable
- Payroll function . etc.
Desktop Publishing Packages:- Desktop publishing packages are getting more popular in India. These are used for built formats such as broachers, newsletters, flyers etc. some example of this packages are PageMaker, Corel Draw, Microsoft Publisher etc.
Word Processor:- It is a software package that help to create and edit a document. Editing a document involves correcting the spelling mistakes, if any and deleting the words, sentences, paragraphs. Example:- WordStar, Microsoft Word, Word perfect etc.
Spread sheet:- A worksheet that provide a number or rows and columns for numeric data entry. They are widely used in accounting, scientific and business fields. Example Lotus 1-2-3, Microsoft Excel etc.
Designing & Architecture:- Auto-CAD ( Auto desk Computer Added Designing) is a package is useful in engineering design offices. Using AutoCAD we can perform drawing and store them in magnetic form. We can recall the drawing an plot them using the plotter. AutoCAD allows us to view a drawing in a solid modeling form like three dimensional object.

Computer Languages

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So far we understand that a software is collection of programs, and each programs are written in a specific language. We can use any language to write a program, but computer can execute it after changing these codes to binary format ( i.e. 0 or 1) with the help of language translator.

The languages used for writing programs are as follows:-

Machine Language

This is the sequence of instructions written in binary numbers consisting of 0 or 1. Computer can read this code directly, we not need to use any language translator. This language is also known as first generation language. Writing program in this language is difficult to understand. A user cannot communicate with computer when he doesn't know this language. Ex. 0010001001.

Assembly Language

In machine language it was difficult to debug any program by external user. In Assembly language special symbols uses for operation part and for instructions codes. This language is known as second generation language. Writing a program in Assembly language is more convenient than machine language. It is written in the form of symbolic instructions. But it is specific for particular machine. The codes written for any application on any computer can't run to another computer if it is architecturally different. Ex.

LDA, 7

LDB, 10

ADD A, B

LDC, A

HALT

High level language

It is a programming language that uses grammatical and mathematical notations similar to everyday language. Writing program in this language is quite easier than Assembly or Machine language. For converting this language to machine readable format we need a compiler or Interpreter as we have read in previous unit. High level languages are also known as third generation language. Example

BASIC:- Bigness All purpose Symbolic Instruction Code - used for general purpose language. Its programming structure is like this-

10   LET    A = 10

20   LET    B = 30

30   LET   SUM = A + B

40   PRINT   SUM

50   END

FORTRAN:- FORmula TRANslation- used for scientific purpose.

COBOL:- COmmon Business Oriented Language- used for business oriented programs.

C- It is a high level language. It runs on DOS and Unix operating system. Now a days it is most widely used in preparing Operating Systems.

Fourth generation language (4GLs)

This language is mainly database oriented language. In this generation language programmer need not to write much amount of codes. Most people feel that a fourth generation language is a high level language that requires fewer instructions for a particular task than a third generation language. Fourth generation languages are mostly machine independent. Usually they can be used on more than one type of computer. They are mostly used for office automation or business, but not for scientific program.