1st Year Computer Notes CH#08 Computer Network

Computer Network

In connection with the information technology and computers a network is a way to connect computers together so that they can communicate, exchange information and pool resources or a network is a communicating system connecting two or more computers. Network connects people as close as the next office and as for as halfway around the world.

In business networks have revolutionized the use of computer technology. Many businesses that used to relay on a centralized system with mainframe and a collection of terminals now use computer networks in which every employee who needs a computer has personal computer connected to the network. In education, schools, colleges and universities have also shifted to strategies built around networked personal computers.


Configurations or Topologies Networks

A network can be arranged or configured in several different ways. This arrangements is called the network's topology. The four principal network topologies are

1. Star Network

2. Bus Network

3. Ring Network

4. Hierarchical Network


1. Star Network

In a star network small computers or peripheral devices are linked to a central unit. This central unit may be a host computer or a file server. All the communications pass through this central unit. Control is maintained by polling. Each device is in turn allowed to send the message.

One particular advantage of the star form of network is that it can be used to provide a time-sharing system. i.e several users can share resources (time) on a central computer. The star is a common arrangement for linking several microcomputers to a mainframe that allows access to an organizations database.


2. Bus Network

In a bus network each device in the network handles its own communication control. There is no host computer. All communications control travel along a common connecting cable called a bus. As the information passes along the bus it is examined by each device to see if the information is intended for it.

The bus network is typically used when only a few microcomputers are to be linked together. The bus network is not as efficient as the star network for sharing common resources. However it is less expensive and is in very common use.

3. Ring Network

In a ring network, each device is connected with two other devices forming a ring. There is no central file server or computer. Messages are passed around the ring until they reach correct destination. With microcomputers ring network is the least frequently used arrangement. However it is often used to link mainframes specially over wide geographical areas.

A ring network is useful in a decentralized organization because it makes possible a distributed data processing system i.e. computers can perform processing tasks at their own dispersed locations.


4. Hierarchical Network

This type of networks are also called hybrid network. It consist of several computers linked to a central host computer just like a star network. However these computers are also hosts to other smaller computers or to peripheral devices. The host at the top of the hierarchical network could be mainframe. The computers below the mainframe could be minicomputers and those below microcomputers. This network allows various computers to share database processing programs and different output devices. It is useful in a centralized organizations.


Strategies of Networks

Every network has a strategy or a way of coordinating the sharing of the information and resource. The most common network strategies are terminal, peer-to-peer and client/server systems, terminal network system. In this system processing power is centralized in one large computer, usually the mainframe. The nodes (a node is any device connected to network) connected to this host computer are terminals (a terminal is a input or output device) with little or no processing capability. Most airline reservation systems are terminal systems.


Peer-to-Peer Network System

In a peer-to-peer network, nodes can act both as servers and clients. There are several advantages of using this type of strategy. The networks as inexpensive and easy to install and they usually work well for smaller systems with less than ten nodes. As the number of nodes increases, however the performance of the network declines.


Client/Server Network System

Client/Server network system uses to coordinate and supply services to all other nodes on the network. The server provides access to centralized resources such as databases, applications software and hardware. This strategy is based on specialization. Server nodes coordinate and supply specialized services and client nodes request services.

One advantage of client/server network system is its ability to handle very large networks efficiently. Another advantage is the powerful management software that monitors and controls networks activities. The major disadvantage of it is the high cost of installation and maintenance.


Advantages of Network

Networks provide tremendous benefits. The most compelling advantages of network are as follows.

1. Networks allow users simultaneous access to shared programs and data.

2. Network also allows users to share peripheral devices such as printers and hard disks.

3. Network usually includes the capacity to send e-mail and many e-mail systems let users to attach files to their messages.

4. Connecting computers to form a network makes it easier to perform backups of the data on all the network hard disks.


Types of Networks

Communications differ in geographical size. Three important types are LANs, MANs, WANs.


Local Area Networks (LANs)

Network with computers and peripherals devices in close proximity within the same building are called local area networks (LANs).

The figure shows an example of a LAN. This type of arrangement has two benefits.

1. People can share different equipment, which lowers the cos of equipment.

2. LAN also features a network gateway. i.e. a LAN may be linked to other LANs or to large networks in this manner.


Metropolitan Area Network (MANs)

These network are used as links between office buildings in a city. Cellular phone systems expand the flexibility of MANs by allowing links to car phones and portable phones.


Wide Area Network (WANs)

Wide area networks are countrywide and worldwide networks. Among other kinds of channels they use microwave relays and satellites to reach users over long distances. One of the most widely used WANs is Internet. Which allows users to connect to other users and facilities worldwide.


Uses of Internet

The most common uses of Internet are


1. Communicating

Sending and receiving e-mail is the most popular internet activity. You can send and receive e-mail to and from you friends and family located almost anywhere in the world. You can join an listen to discussions and debates on a wide variety of special interest topics.


2. Shopping

One of the fastest growing applications of Interest is electronic commerce. You can visit a cyber mall for making purchases.


3. Researching

Internet provides you to have one of the world's largest libraries available from home.


4. Entertainment

Do you like music, the moves and reading or playing computer games? You can find them all on Internet waiting for you to locate and enjoy.

1st Year Computer Notes CH#07 Data Presentation

Data Presentation


The set of symbols to express quantities as the basis of counting is referred to be a number system. There has been various number systems under human use for the purpose of counting and measurement. For instance decimal number system, octal number system, binary number system and hexadecimal number system have been most popular number systems which human beings have been utilizing for the purpose of counting and measurement.

Though a computer can process only binary numbers i.e. only 0 and 1, we give a brief account of each of the number system mentioned above. Inter conversion of these number systems would also be discussed in this chapter.



Decimal Number System

This is the most commonly used number system and which is very natural to man, hence very easy to use and remember. It consists of ten digits, i.e. from 0 to 9. As the total number of digits used in a number system is called its base or radix, hence base of radix of decimal number system is said to be ten.


Binary Number System

The base or radix of binary number is two, implying that there are only two digits 0 and 1 used in binary number system. This number system has become most popular system because of its use by the computers for processing data.


Octal Number System

This number system is consist of eight i.e. 0,1,2,3,4,5,6 and 7. Hence the base or the radix of octal number system is eight. Actually this number is a short hand version of binary numbers, Hence one octal represents three binary digits.


Hexadecimal Number System

Hexadecimal numbers are extensively used in microcomputers. As they are much shorter than binary numbers, hence easy to write and remember. They are also a short hand version of binary numbers. The hexadecimal also called Hex is equivalent to four binary digits. This number system consists of 0,1,2,3,4,5,6,7,8,9, A,B,C,D,E and F. The base of this number system is 16. The symbol A........F stand respectively for 10.....15.


Binary to Decimal Conversion

All the number system may be easily converted into other number systems. In order to convert binary numbers into decimal numbers we multiply each bit of a particular binary number with (n-1) power of 2.

Add all the resultant multiplied bits.


Example No. 1

To convert the binary number 10010 to a decimal number we proceed as follows:

100102 = (1 x 24) + (1 x 23) + (1 x 22) + (1 x 21) + (1 x 20)

= (1 x 16) + (0 x 8) + (0 x 4) + (1 x 2) + (0 x 1)

= 16 + 0 + 2 + 0

= 18

It should be kept in the mind that any number raised to the power 0 equals 1.


Example No. 2

Similarly in order to convert the binary number 110111 to a decimal number we may proceed as follows:

1101112 = (1 x 25) + (1 x 24) + (1 x 23) + (1 x 22) + (1 x 21) + (1 x 20)

= (1 x 32) + (1 x 16) + (1 x 8) + (1 x 4) + (1 x 2) + (1 x 1)

= 32 + 16 + 0 + 0 + 4 + 2 + 1

= 56

Example No. 3

If there is a period (.) in the binary number e.g. (1011.10). Then the conversion of such binary number can be illustrated as follows:

(10112) = (1 x 23) + (1 x 22) + (1 x 21) + (1 x 20)

= (1 x 8) + (0 x 4) + (1 x 2) + (1 x 1)

= 8 + 0 + 2 + 1

= 11

AND

(.102) = (1 x 2-4) + (1 x 2-2)

= (1 x 1/2) + (1 x 1/4)

= 1/2 + 0 = 0.5

Hence (1011.102) = 11.5


Decimal to Binary Conversion

A decimal number can easily be converted to a binary number. For this purpose we take following steps.

1. Divide the decimal number by 2 and note down the remainder.

2. Take the quotient and again divide by 2, then note down the remainder again.

3. Repeat the 2nd step unit you get 1 as the quotient.

4. The remainders in the reverse order would be our required binary number.


Example No. 4

For example in order to convert decimal number 15 to binary number. we may proceed as follows.

15/2 = 7 and the remainder is 1

7/2 = 3 and the remainder is 1

3/2 = 1 and the remainder is 1

1/2 = 0 and the remainder is 1

Hence the required binary number is 1111


Converting Decimal Fractions to Binary Numbers

The most simple method of converting fractional decimal numbers to binary number is repeated multiplication by two. In this method numbers to the right of the decimal point are repeatedly multiplied by 2 till we get a whole number. The product in fractions is assigned as 0 bit while in whole number it is assigned as 1 bit.

The process of converting a fractional decimal number to binary number would be explained by the following example.


Example No. 5

Let us suppose the we want to convert 0.125 in a binary numbers then proceed as follow.

0.125 x 2 = 0.250 it carries 0

0.250 x 2 = 0.500 it carries 0

0.500 x 2 = 1.00 it carries 1

Hence we can conclude that (0.125)10 = (0.001)2


Addition to Binary Numbers

In order to add binary number below given table should be kept in mind

0 + 0 = 0

0 + 1 + 1

1 = 0 = 1

1 + 1 = 0 with a carry of 1

The following example will illustrate the addition of binary numbers.


Example No.6

Add 1001 and 1010

1001 + 1010 = 11011


Subtraction of Binary Numbers

In order to subtract a binary number from another binary number you must keep the following table in your mind.

0 - 0 = 0

1 - 0 = 1

1 - 1 = 0

0 - 1 = 1 with a barrow of 1

The process of binary subtraction an be illustrated with the help of example given below


Example No. 7

For subtracting binary number 101 from 1001 we proceed as follows

1001 - 100.1 = 1.11


Octal to Decimal Conversion

For converting an octal number to a decimal number we use the same sort of polynomial as was used in the binary case. However in octal to decimal conversion the base or radix is 8 instead of 2.

The process of converting an octal number into a decimal number would be clarified with the help of following example.


Example No. 9

The Octal number 2134 can be converted into decimal number by proceeding as follows

(2134)8 = (2 x 83) + (2 x 82) + (2 x 81) + (2 x 80)

= (2 x 512) + (1 x 64) + (3 x 8) + (4 x 1)

= 1024 + 64 + 24 + 4

= 1116

Hence (2134)8 = (1116)10


Example No. 10

The octal number 1.123 can be converted to decimal number as follows

(1.123)8 = (1 x 80) + (1 x 8-1) + (1 x 8-2) + (1 x 8-3)

= (1 x 1) + (1 x 1/8) + (1 x 1/64) + (3 x 1/512)

= 1 + 1/8 + 2/64 + 3/512

= 1 83/512


Decimal to Octal Conversion

For converting decimal number to octal number. we apply a method of repeatedly dividing decimal by 8 and use each reminder as a digit in the octal number. The process of converting decimal to octal number may be illustrated by the following example.


Example No. 11

To convert the decimal number 429 to octal number we process as follows

429/8 = 53 Reminder is 5

53/8 = 6 Reminder is 5

6/8 = 0 Reminder is 6

Hence (429)8 = (655)10


Octal to Binary Conversion

As we have mentioned earlier that octal number system is a short hand version of binary numbers and one octal represents three binary digits as shown by the following table

Equivalent Octal and Binary Number

Octal 0

1

2

3

4

5

6

7


Binary

000

001

010

011

100

101

110

111

In order to convert an octal number to a binary number we just replace each octal digit with the appropriate three bits. This produce an be explained with the help of following example


Example No. 12

(25)8 = (010101)2

Because (2)8 = (010)2 and (5)8 = (101)2 as shown by the above table.

1st Year Computer Notes CH#06 Computer Software and Programming Languages

Computer Software and Programming Languages


An information system has five parts. People, procedures, software, hardware and data. Software which is one of the most important part of an information system. Is an other name for a program or programs. Program is the step by step instructions that tell the computer how to do its work. The purpose of a software is to convert data (unprocessed facts) into information (processed facts). In most cases, words software and programs and interchangeable.

There are two major kinds of software-application software and system software.

Application software are the software the users of the computer use. Whereas system software are used by the computers.




Application Software

Application software may be describe as end-user software. They perform useful work on general-purpose tasks such as word processing and cost estimating.

Application software may be

1. Packaged

2. Custom Made


1. Packaged Software

Packaged Software are the programs prewritten by professional programmers that are typically offered for sale.


2. Custom-Made Software

Custom-Made or Custom programs are the programs written for a specific purpose and for a specific organization. Using computer languages, programmers create this software to instruct the company's computer to perform whatever tasks the organization wants.

There are certain general purpose programs which are called "basic applications" The most popular basic tools are


Word Processing Programs used to prepare written document.

Spreadsheets Programs used to analyse and summarize numerical data.

Database Manageers used to organize and manage data and information.

Presentation Graphic Programswhich are used to communicate a message.

Personal Information Management Programs used to organize and schedule activities.

Integrate Programs which combine some or all of these applications in one program.


Summary of Basic Application Software

The summary of the basic application software mentioned above has been given below. Which shows various software designed by well known software publishers. Microsoft, Lotus and Corel.


Basic Applications

Word Processors = Microsoft Word, Lotus, Word Pro, Corel WordPerfect

Spreadsheets = Microsoft Excel, Corel Quattro Pro, Lotus-2-3

Database Managers = Microsoft Access, Corel Paradox, Lotus Approach

Presentation Graphics = Microsoft PowerPoint, Corel Presentation

Personal Information managers Microsoft Outlook, Lotus Organizer

Integrated Packages = Microsoft Work, Lotus Works.

Software Suites = Microsoft Office 97, Corel Office 97


Common Features of Basic Application

As all the above mentioned categories of software are designed to be used by many people to perform most common kinds of tasks we call them basic applications. Most common application software have some common features. The most important of them are given below.


Menu

Almost all software packages have menus to present commands. Typically menus displayed in a menu bar at the top of the screen when one of the item is selected a pull down menu appears.

This is a list of commands associated with the selected menu.


Shortcut keys

Many applications also have shortcut keys for frequently used commands. Many of the shortcut keys are function keys. F1, F2 and so on. Others shortcut use key combinations typically consisting of the Alt, Ctrl or Shift key used in combination with a letter number or function key. For example in Word97 the short cut key F7 starts the spelling tools and the key combinations of shift and F7 starts the Thesaurus tools.


Toolbars

Toolbars are typically below the menu bar. They contain icons or graphic representations for commonly for commonly used commands.


Help

For most applications packages one of the menus on the menu bar is Help. This typically include a table of contents a search feature to locate reference information about specific commands and access to specific learning features such as tutorials and step-by-step instructions.


Dialog Boxes

Dialog boxes frequently appear after selecting a command from a pull down menu. These boxes are used to specify additional options.


Scroll Bars

Scroll bars are usually located on the right and / or the bottom of the screen. They enable user to display additional information not currently visible on the screen.


Edit

The ability to change or edit entries is a feature common to almost all applications. The edit feature makes revising and updating easy and is one of the most valuable features.


Save and Print

Common to all applications software is the ability to save or store your work as a file on a floppy or hard disk. This allows user to open and use the file at a later time in case user wants to add or modify the document. In addition all applications allow user to a copy of his document on paper.

Word processing programs and spreadsheets program are most commonly used categories of application software hence we explain them in much more detail.


Word Processors

word processing software creates text-based documents such as letter, memos, term papers and reports. Once it was thought that only secretaries would use word processors. Now they are used extensively in managerial and professional life. Indeed, it has been found that among the basic software applications. Word processors are most important software used by common people.

Popular word processing packages include Microsoft Word. Corel WordPerfect and Lotus Word Pro as shown in the above summary of basic applications.


Important Features of Word Processors

Some important features shared by most word processors are as follows


Word Wrap and the Enter Key

One basic word processing feature is word wrap i.e. word processor automatically moves the insertion point to the next line once the current line is full. The begin a new paragraph or to leave a blank line Enter key is pressed.


Spelling and Grammar Checkers

Many word processors include a spelling checker feature that identifies typing errors. For example Word97 identifies misspelled words with a red wavy underline. Similarly grammar checkers can be run that will identify poor wording excessively long sentences and incorrect grammar.

Alignment

Text can be aligned within the margin in various way. The most common alignment is left alignment.


Formatting

Text can be enhanced in a variety of ways including adding basics formatting such as bold, under line and italics.

Besides above mentioned feature other common features of word processors are References, Search and Replace, Tables, Hyperlinks, Thesaurus, Graphics, Internet publishing and Workgroup.


Spreadsheets

Spreadsheets is an electronic worksheet used to organize and manipulate and display option for "what-if" analysis. Spreadsheets are used by financial analysts, accountants, contractors and other concerned with manipulating numeric data.

Popular spreadsheets packages include Microsoft Excel, Quattro Pro and Lotus 1-2-3 as shown by above summary.


Common feature of Spreadsheets

Like the word processors, spreadsheets designed by various software publishers share following common features.


Formulas and Functions

Formulas are the instructions for calculations. They calculate result using the numbers in reference cells. Whereas functions are prewritten formulas that perform calculations automatically.


Analysis

The recalculation feature can be used to analyze the effect of changes to the spreadsheets.


Analytical Graphs

To help visualize the data in spreadsheets user can create analytical graphs or charts.


Workgroup

One of the newest additions to spreadsheets applications is the workgroup program which allows multiple users to collaborate electromically on spreadsheet.


Linked Files

Most spreadsheets programs allow users to link cells in one worksheet file to cells in other worksheets in the same file or to other worksheet files. Whenever a charge occurs in one file the linked cells in the other worksheets are automatically updated.


Advanced Application Programs

Besides above mentioned basic application programs there are certain programs which are called "advanced applications". These are more specialized than the basic application. These programs are widely used in certain career areas. The most popular tools are:


Graphic Programs used to create professional publications and to capture and edit graphic images.

Multimedia used to integrate all kinds of information including video, audio, graphic and text into a single interactive presentation.

Web Publishers used to create interactive multimedia web page. Project management used to plan projects schedule people and control resources.


System Software

The user interact with the application software whereas system software enables the application software to interact with the computer hardware. System software is a "background" software. It includes programs that help the computer manage its internal resources.


Kinds of System Software

System software deals with the physical complexities of how the hardware works. System software consists of the following four programs.

1. Bootstrap loader

2. Diagnostic routines

3. Basic input-output system

4. Operating System


1. Bootstrap loader

The bootstrap loader is a program that is stored permanently in the computer's electronic circuitry. When computer is turned on the bootstrap loader obtains the operating system from hard disk and loads it into memory. This is called booting the system.


2.Diagnostic Routines

These are also programs stored in the computer's electronic circuitry. They start up when machine is turned on. They test the primary memory the central processing unit and other parts of the computer. Their purpose is to make sure the computer is running properly.


3. Basic Input-Output System

It consists of service programs stored in primary storage. These programs enable the computer to interpret keyboard characters and transmit them to monitor or to a floppy disk.


Operating System

The operating system is a collection of programs that help the computer to manage its resources. The Operating System takes care of lot of internal matters. For example it interprets the commands user gives to run programs. It manages memory data and file.

The most important system program is the operating system which interacts between the application software and the computer. The operating system handles such details as running (executing) programs, storing data and programs and processing data.

Microcomputer operating systems change as the machines themselves become more powerful and outgrow the older operating systems.

The most popular microcomputer operating systems are

DOS the original operating system for International Business Machines (IBM) and IBM compatible microcomputers.

Windows not an operating system but an environment that extends the capability of DOS.

Windows 95 a widely used operating system with the built-in internet support.

Windows 98 a new operating system with the intensive internet and multimedia support.

Windows NT a powerful operating system designed for powerful microcomputers.

OS/2 Warp the operating system developed by IBM for powerful microcomputers.

Macintosh Operating System the standard operating system for Apple Corporation's Macintosh computers.

Unix an operating system originally developed for microcomputers that can run on many of the powerful microcomputers.


Disk Operating System

DOS's original developer Microsoft Corporation sells it under the name MS-DOS. It was originally standard operating system for all microcomputers which were IBM compatible or DOS based.


Advantages

1. Even today DOS is still widely used operating system.

2. An enormous number of application programs have been written for DOS. Indeed more specialized software is available for DOS for than any other operating system.

3. DOS runs on many computers, old and new that are cheap.


Disadvantages

1. It can support very limited primary storage.

2. It can be used only for single-tasking and not for multi-tasking.

3. It uses character-based interface.


Windows 98

Windows like Windows 95, Window 98 and Windows NT is not a operating system, rather an operating environment. While Windows 95, Windows 98 and Window NT are operating systems. But Windows 98 is one of the most popular operating systems being used nowadays. It is an advanced version, designed for today's very powerful microcomputers.


Advantages

1. It is faster in many common tasks like starting up loading applications and shutting down. It includes a Tune-up wizard automatically monitors system operation and suggest ways to improve performance.

2. Windows 98 is fully integrated with Microsoft's browser, Internet Explorer, making Internet access easier and faster.

3. Plug and play capability is extended to support the newest advance in technology. Multiple views of an application or multiple applications can be viewed on separate monitors simultaneously.

4. Windows 98 has advanced audio and video capability. With a tuner card, TV on microcomputers monitor can be watched.

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Disadvantages

1. Windows 98 requires at least a Pentium Microprocessor to operate effectively. Besides more hard disk space and memory are necassary.

2. Fewer applications have been written specifically for it. It can however run most DOS, Windows and Windows 95 applications.


COMPUTER LANGUAGE

Language is a system for representation and communication of information or data. Like human beings, a language or signal is required to communicate between two persons. Similarly, we cannot obtain any result by computer without langtage. Computer does not understand directly what we are communicating with computer as English or Arabic, it understands only machine language (binary codes 0-1). Computer translates English language into machine codes through interpreter then process instructions and give us the results.

The computer languages can be divided into two main levels.

* Machine language (0-1)

* Symbolic language (A-Z)

Symbolic languages are further divide into two main levels

* High-level language

* Low-level language


MACHINE LANGUAGE

Although computers can be programmed to understand many different computer language. There is only one language understood by the computer without using a translation program. This language is called the machine language or the machine codes. Machine codes are the fundamental language of the computer and is normally written as strings of binary 0-1.


ADVANTAGES AND LIMITATIONS OF MACHINE LANGUAGE

Programs written in machine language can be executed very fast by the computer. This is mainly because machine instructions are directly understood by the CPU and no translation of program is required.

However, writing a program in machine language has several disadvantage.
MACHINE DEPENDENT

Because the internal design of every type of computer is different from every other type of computer and needs different electrical signals to operate. The machine language also is different from computer to computer.
DIFFICULT TO PROGRAM

Although easily used by the computer, machine language is difficult to program. It is necessary for the programmer either to memorize the dozens of code number for the commands in the machine’s instruction set or to constantly refer to a reference card.
DIFFICULT TO MODIFY

It is difficult to correct or modify machine language programs. Checking machine instructions to locate errors is difficult as writing them initially.

In short, writing a program in machine language is so difficult and time consuming.


SYMBOLIC LANGUAGES

In symbolic languages, alphabets are used (a-z). symbolic languages are further divide into two main levels.

* High level languages

* Low level languages


LOW LEVEL LANGUAGE

A language which is one step higher than machine language in human readability is called Assembly Language or a low-level language. In an assembly language binary numbers are replaced by human readable symbols called mnemonics. Thus a low-level language is better in understanding than a machine language for humans and almost has the same efficiency as machine language for computer operation. An assembly language is a combination of mnemonic, operation codes and symbolic codes for addresses. Each computer uses and has a mnemonic code for each instruction, which may vary from computer to computer. Some of the commonly used codes are given in the following table.
COMMAND NAMEMNEMONIC

Add - ADD

Subtract - SUB

Multiply - MUL

Compare Registry - CR

Compare - COMP

Branch Condition -BC

Code Register -LR

Move Characters -MVE

Store Characters -STC

Store Accumulator - STA

An assembly language is very efficient but it is difficult to work with and it requires good skills for programming. A program written in an assembly language is translated into a machine language before execution. A computer program which translates any assembly language into its equivalent machine code is known as an assembler.


HIGH – LEVEL LANGUAGE

A language is one step higher than low-level languages in human readability is called high-level language. High – level languages are easy to understand. They are also called English oriented languages in which instruction are given using words. Such as add, subtract, input, print, etc. high level language are very easy for programming, programmer prefer them for software designing that’s why these languages are also called user’s friendly languages. Every high level language must be converted into machine language before execution, therefore every high level language has its own separate translating program called compiler or interpreter. That’s why some time these languages are called compiler langauges. COBOL, BASIC, PASCAL, RPG, FORTRAN are some high level languages.


INTERPRETER

An interpreter is a set of programs which translates the high-level language into machine acceptable form. The interpreters are slow in speed as compared to compilers. The interpreter takes a single line of the source code, translates that line into object code and carries it out immediately. The process is repeated line by line until the whole program has been translated and run. If the program loops back to earlier statements, they will be translated afresh each time round. This means that both the source program and the interpreter must remain in the main memory together which may limit the space available for data. Perhaps the biggest drawback of an interpreter is the time it takes to translate and run a program including all the repetition which can be involved.


Compiler

A compiler converts the programmer's procedural language program called the source code into a machine language code which is called the object code. This object code can then be saved and run later. Example of precedural languages using compilers are standard versions of Pascal, COBOL, and FORTAN.


Pascal

Another language that is widely used on microcomputers and easy to learn is Pascal, named after Blaise Pascal, a French mathematician. This language has become quite popular in computer science educational programs.


C/C++

C is general purpose language that also works well with microcomputers. It is useful for writing operating systems, spreadsheets programs, database programs and some scientific applications. C++ is a version of C that incorporates object-oriented technologies.


COBOL

COBOL which stands for Common Business-Oriented Language is one of the most frequently used programming languages in business. Through harder to learn than BASIC its logic is easier to understand for a person who is not a trained programer.


FORTRAN

Short for FORmula TRANslation, FORTRAN is a widely used scientific and mathematical language. It is very useful for processing complex formulas. That's why many scientific and engineering programs have been written in this language.