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Computer Fundamentals

Updated: Dec 29, 2023


Computer Fundamentals

Definition of a Computer:

• A computer is an electronic device that operates under the control of a set of instructions that is stored in its memory unit.

• A computer is a collection of hardware and software components that help you complete many different tasks.

• A computer can be more accurately defined as an electronic device that takes data as input, stores, and processes it, and displays the output according to the given instructions.

Data Processing Concept

I-P-O Cycle

The cycle of activities performed by a computer is referred to as the Input- Process-Output cycle or the I-P-O cycle. A computer consists of several components. Each component participates in either one of the inputs, process, or Output phases


A computer usually accepts input in the form of data. Data is the raw material. Data refers to numerical (1,2,3,4,5,6,7,8,9,0), alphabetical (A,B,C,D ……Z) and special characters (e.g., @,#,$,%,^,&,!). A set of numbers could be examples of data. OR Data is a word of Latin used to describe a collection of natural phenomena like numbers, characters, images, or symbols, in a very broad sense.


Information is the finished product (manipulation of raw facts). Information refers to data in a particular context, which helps us understand facts. Example- +91(011) 2555-1212 is a telephone no. of a directory. It includes country code 91, an area code 011, a telephone exchange 2555, and a number within the exchange 1212.



Definition of a Computer:

A computer is an electronic device that operates under the control of a set of instructions that is stored in its memory unit. A computer is a collection of hardware and software components that help you complete many different tasks. A computer can be more accurately defined as an electronic device that takes data as input, stores, and processes it, and displays the output according to the given instructions.

Characteristics of computer

Computers of all sizes have common characteristics:


• It works at very high speeds and can much faster than humans.

• It is equivalent to one million mathematicians working 24 hours a day.


• Computers are extremely reliable as well. Most errors are caused by humans, not computers.

• Computers are capable of storing enormous amounts of data that must be located and retrieved very quickly.


• Modern computers can perform multiple tasks at once. i.e. they can perform a set of works simultaneously.

• Example – at the same time it can play a game & printing your document.


• Unlike a human, a computer simply does not get bored or tired.

• Repetitive work does not affect the computer.


• Computers rarely make mistakes.

• Most computer errors are caused by human faults

Storage capacity

• It stores a huge amount of data/information

Classification of Computers

On The Basis Of Purpose

1. General Purpose Computers

These are designed to perform a range of tasks. They have the ability to store numerous programs, but lack in speed and efficiency comparatively.

2. Special Purpose Computers

Specific purpose computers are designed to handle a specific problem or to perform a specific task. A set of instructions is built into the machine.

On The Basis Of Size

1. Microcomputers

• Microcomputers are connected to networks of other computers.

• The price of a microcomputer varies from each other depending on the capacity and features of the computer.

• Microcomputers make up the vast majority of computers.

• A single user can interact with this computer at a time.

• It is a small and general-purpose computer.

2. Mini Computer

• Mini Computer is a small and general-purpose computer.

• It is more expensive than a microcomputer.

• It has more storage capacity and speed.

• It designed to simultaneously handle the needs of multiple users.

3. Mainframe Computer

• Large computers are called Mainframes.

• Mainframe computers process data at very high rates of speed, measured in the millions of instructions per second.

• They are very expensive than the microcomputer and minicomputers.

• Mainframes are designed for multiple users and process vast amounts of data quickly.

• Examples: Banks, insurance companies, manufacturers, mailorder companies, and airlines are typical users.

4. Super Computers

• The largest computers are Super Computers.

• They are the most powerful, the most expensive, and the fastest.

• They are capable of processing trillions of instructions per second.

On The Basis Of Functionality/ Data Handling

1. Analog Computers

• An Analog Computer is a form of computer that uses continuous physical phenomena such as electrical, hydraulic, or mechanical quantities to model the problem being solved.

• They work on the principles of measuring in which the measurements obtained are translated into data.

• Modern Analog Computers usually employ electrical parameters such as voltages, resistances or currents to represent the quantities being manipulated.

• They measure continuous physical magnitudes

2. Digital Computers

• A computer that performs calculations and logical operations with quantities represented as digits, usually in the binary number system.

• They process data into a digital value (0s and 1s).

• They give results with more accuracy at a faster rate.

3. Hybrid Computers

• A combination of computers, those who are capable of inputting and outputting in both digital and analog signals.

• A Hybrid computer system set up offers a cost-effective method of performing complex simulations.

• They incorporate the measuring feature of an analog computer and counting feature of a digital computer.

• For computational purposes, these computers use analog components and store digital memories are used.

Limitations of Computer

The computer cannot operate without the instructions given by humans. It is programmed to work effectively, fast, and accurately. The computer cannot think by itself and does not have common sense. It is totally dependent on humans.

• Depend on the user’s input.

• The computer has no imagination.

• Cannot detect an error in logic. • An only an expert user can work on it.

• Cannot take its own decisions.

Some of the limitations of the computer are as follows:

• No Self-Intelligence

The computer does not have an intelligence of its own to complete the tasks. They give wrong output if the input given by humans is wrong. It works according to the instructions given to it by the user.

• No Thinking and Decision-Making Power

The computer cannot think of itself. The concept of artificial intelligence shows that a computer can think. But still, this concept is dependent on a set of instructions. It cannot take any decision. It can only perform the tasks that are instructed by the users.

• No Feeling

Lack of feeling is another limitation of the computer. A computer cannot feel like us. It does not have emotions, feelings, knowledge etc. It does not get tiring and keep on doing its tasks. It can do very risky works that are not capable of human beings.

• No Learning Power

The computer has no learning power. The computer cannot perform the tasks without instructions. It cannot read the same instructions time and again. Once the instructions are given it will work for one time. It can solve the problems but it cannot learn the problems. It can only work according to the instructions given.



Components of a Computer

A computer system consists of both hardware and information stored on the hardware. Information stored on computer hardware is often called software.

The hardware components of a computer system are the electronic and mechanical parts

The software components of a computer system are the data and computer programs.

The major hardware components of a computer system are:

1. Processor

2. Main memory

3. Secondary memory

4. Input devices

5. Output devices

The below section describes briefly all the computer components in a computer system –

Input Unit

The input unit is used for transfering raw data and control signals into the information processing system by the user before processing and computation. All the input unit devices provide the instructions and data are transformed into binary codes that are the primary memory acceptable format.

Example of Input unit devices:

keyboard, mouse, scanner, joystick, MICR, Punched cards, Punched paper tape, Magnetic tape, etc.

Memory or Storage

Unit Memory or Storage unit is used for storing Data during before and after processing. The capacity of storage is expressed in terms of Bytes. The two terms Memory or Storage unit are used interchangeably, so it is important to understand what is the difference between memory and storage?


This unit retains temporary results until further processing, For example, Random Access Memory (RAM). This memory is volatile, which means data disappear when the power is lost.


The storage or “secondary storage” is used to retain digital data after processing for permanently. For example, hard drive. The Storage is non-volatile in nature. CPU does not access directly to secondary storage memories, instead, they accessed via the input-output unit. The contents of secondary storage memories are first transferred to the main memory (RAM) and then CPU access it.

Output Unit

The output unit receives information from the CPU and then delivers it to the external storage or device in the soft or hard processed form. The devices which are used to display output to the user are called output devices. The Monitor or printer is a common output device.

Central Processing Unit

The main chip in a computer is the microprocessor chip, which is also known as the CPU (central processing unit). The CPU is mounted on a printed circuit board called the mainboard or motherboard. This chip is considered to be the controlling chip of a computer system since it controls the activities of other chips as well as outside devices connected to the computer, such as to monitor and printer. In addition, it can also perform logical and computational tasks. Microprocessors work on a parallel system. The figure shows a typical structure of one of the first-generation microprocessors. The recent ones possess greater complexity, although the basic design concept has not changed much.

The various activities that a microprocessor performs, such as storing data, doing arithmetic calculations (addition, subtraction, multiplication, division, etc.), are the result of instructions given to the CPU in the form of sequences of 0s and 1s. Microprocessors are designed to carry out a large number of instructions and all the instructions may be represented by different sequences of 0s and 1s. Each instruction is represented by a unique set of 0s and 1s.

The internal structure of a typical CPU consists of circuits which form a number of registers (the typical number is 16), an arithmetic unit for carrying out arithmetic operations, a logic unit, and a control unit.

Arithmetic logic unit (ALU)

Arithmetic Logical Unit is used for processing data after inputting data is stored in the primary unit. The major operations of the Arithmetic Logical Unit are addition, subtraction, multiplication, division, logic, and comparison.

Control unit (CU)

It is like a supervisor, that checks ordaining operations or check sequence in which instructions are executed.

Generations of Computers

First Generation

• Basic component – Vacuum Tubes 1940-1956

• Processing Speed – Slow & Unreliable Machine

• Heat Generation – Huge amount of Heat generated

• Size – Bulky & Non – Portable Machine • Instructions – Only Machine Language was used

• User Friendly – Very Difficult to operate

• Cost – Production & Maintenance costs were very High

• Example – ENIAC, UNIVAC, ENIAC = (Electronic Numerical Integrator and Calculator, UNIVAC = (Universal Automatic Computer)

Second Generation

• Basic component – Transistors & Diodes

• Processing Speed – More reliable than 1st one

• Heat Generation – Less amount of Heat generated

• Size – Reduced size but still Bulky

• Instructions – High-level Language was used (Like COBOL, FORTRAN)

• User Friendly – Easy to operate from 1st one • Cost – Production & Maintenance costs was < 1st

• Example – IBM 7090, NCR 304

Third Generation

• Basic component –Integrated Circuits 1964-1971

• Processing Speed – More reliable than 1st & 2nd Machine

• Heat Generation – The lesser amount of Heat generated

• Size – Smaller than older computer

• Instructions –Expensive use of High-level Language

• User Friendly – General-purpose Machine used in commercial Application

• Cost – Production & Maintenance costs were Cheaper than the older one

• Example – IBM 360, CDC 7600

Fourth Generation

• Basic component –: Microprocessors 1971-Present

• 8842Thousands of integrated circuits were built onto a single silicon chip.

• Processing Speed – Most reliable than older computer

• Heat Generation – Virtually no Heat generated

• Size – Smallest in size making them easily portable

• Instructions –Very sophisticated programs & Languages use

• User Friendly –Easiest to operate

• Cost – Production & Maintenance costs were Cheapest than the older one

• Example – IBM 3090, VAX

Fifth Generation

• Fifth Generation – Present and Beyond: (Artificial Intelligence)

• Fifth-generation computing devices, based on artificial intelligence, are still in development.

Computer’s Primary and Secondary Storage

Storage Device/Media

Data needs to be stored for later use on storage media. The two types of storage media are:

• Primary storage media

• Secondary storage media

Primary storage media

1. Random Access Memory (RAM)

• It is the internal storage area of the machine.

• This is the memory that the computer uses for storing the programs and their data while working on them.

• Data within the RAM can be read or modified, i.e. you can either read from the RAM or write onto it.

2. ROM (Read Only Memory)

• It is an internal permanent storage memory.

• ROM contains permanently recorded instructions that are vital for starting the computer.

• One set of instruction in ROM is called the ROM-BIOS

• All machine-level instructions are stored in the ROM.

Secondary storage media

Compact Disk (CD ROM) Floppy Disk Cartridge Tape Magneto-Optical Disk USB drive / Pen Drive Memory Stick Hard Disk

About Memory Size

1 Nibble = 4 bits

1Byte = 8 bits

1 Kilobyte (KB) = 1024 Bytes

1 Megabyte (MB) = 1024 KB

1 Gigabyte (GB) = 1024 MB

1 Terabyte (TB) = 1024 GB

1 Petabyte (PB) = 1024 TB

1 Exabyte (EB) = 1024 PB

1 Zettabyte = 1024 EB

Data Entry Devices/ Input Devices

Input devices are necessary to convert our information or data into a form that can be understood by the computer. A good input device should provide timely, accurate, and useful data to the main memory of the computer for processing. The following are the most useful input devices.


This is the standard input device attached to all computers. The layout of the keyboard is just like the traditional typewriter of the type QWERTY. It also contains some extra command keys and function keys. It contains a total of 101 to 104 keys. A typical keyboard used in a computer you have to press the correct combination of keys to input data. The computer can recognize the electrical signals corresponding to the correct key combination and processing is done accordingly.


The mouse is an input device that is used with your personal computer. It rolls on a small ball and has two or three buttons on the top. When you roll the mouse across a flat surface the screen censors the mouse in the direction of mouse movement. The cursor moves very fast with mouse giving you more freedom to work in any direction. It is easier and faster to move through a mouse

Types of Mouse:

Trackball Mouse: In this, the ball is rolled at one place rolling the mouse on the tabletop.

Optical Mouse: It uses a light beam to detect movement.

Wireless Mouse: It is a mouse without a cable. This mouse works up to one and a half meters away from the computer.

Light Pen Mouse: It uses a light-sensitive detector, requiring you to hold a pen and point it at the screen.

Joystick Mouse: It usually includes two upright sticks which are moved with the hand and the button is pressed on either stick.


The keyboard can input only text through keys provided in it. If we want to input a picture the keyboard cannot do that. The scanner is an optical device that can input any graphical matter and display it back.

The common optical scanner devices are:

Magnetic Ink Character Recognition (MICR): This is widely used by banks to process large volumes of cheques and drafts. Cheques are put inside the MICR. As they enter the reading unit the cheques pass through the magnetic field which causes the read head to recognize the character of the cheques.

Optical Mark Reader (OMR): This technique is used when students have appeared in objective type tests and they had to mark their answer by darkening a square or circular space by pencil. These answer sheets are directly fed to a computer for grading where OMR is used.

Optical Character Recognition (OCR): This technique unites the direct reading of any printed character. Suppose you have a set of handwritten characters on a piece of paper. You put it inside the scanner of the computer. This pattern is compared with a site of patterns stored inside the computer. Whichever pattern is matched is called a character read. Patterns that cannot be identified are rejected. OCRs are expensive though better the MICR.

Barcode Reader (BCR): A barcode reader is an electronic device for reading printed barcodes. Like a flatbed scanner, it consists of a light source, a lens and a light sensor translating optical impulses into electrical ones. Additionally, nearly all barcode readers contain decoder circuitry analysing the barcode’s image data provided by the sensor and sending the barcode’s content to the scanner’s output port.

Data Output Devices

Visual Display Unit

The most popular input/output device is the Visual Display Unit (VDU). It is also called the monitor. A Keyboard is used to input data and a Monitor is used to display the input data and to receive messages from the computer. A monitor has its own box which is separated from the main computer system and is connected to the computer by cable. In some systems, it is compact with the system unit. It can be colour or monochrome. Currently, there are two types of visual display units (VDU) available. These help in displaying what we have entered into the computer, as well as the output that is derived from the computer after a process.

CRT – Cathode Ray Tube, which comes in monochrome, soft white, and color forms. These are normally used with Desktop computers.

LCD – Liquid Crystal Display, also in soft white and colour. These are sleek and mostly used in portable computers, viz. palm-tops, and laptops. On the same lines, there are LCD overhead projectors, which when interfaced with the computer the output could be projected on to a screen in a larger form for convenient viewing in meetings, demonstrations, and presentations.


It is a very popular interactive input-output unit. It can be divided into two types: hard copy terminals and soft copy terminals. A hard copy terminal provides a printout on paper whereas soft copy terminals provide a visual copy on the monitor. A terminal when connected to a CPU sends instructions directly to the computer. Terminals are also classified as dumb terminals or intelligent terminals depending upon the work situation.


It is an important output device that can be used to get a printed copy of the processed text or result on paper. There are different types of printers that are designed for different types of applications. Depending on their speed and approach of printing, printers are classified as impact and non-impact printers. Impact printers use the familiar typewriter approach of hammering a typeface against the paper and inked ribbon. Dot-matrix printers are of this type. Non-impact printers do not hit or impact a ribbon to print. They use electrostatic chemicals and ink-jet technologies. Laser printers and Ink-jet printers are of this type. This type of printer can produce colour printing and elaborate graphics. A computer printer is a computer peripheral device that produces a hard copy (permanent human-readable text and/or graphics, usually on paper) from data stored in a computer connected to it. The world’s first computer printer was a 19th-century mechanically driven apparatus invented by Charles Babbage for his Difference Engine.

Non-impact printers: In these printers, the print head does not physically touch the paper; but makes impression on the paper by different techniques viz. heat, light and liquid. All these are versatile, high-speed letter-quality printers that work almost silently. Monochrome, colour, and photo printers – A monochrome printer can only produce an image consisting of one colour, usually black. A monochrome printer may also be able to produce gradations of the tone of that colour, such as a scale. A colour printer can produce images of multiple colours.

Toner-based printers: Laser printers refer to the method used to adhere toner to the media. The advent of cost-effective, precision lasers has made them the dominant toner-based monochrome printer type for home and office applications. Another toner-based printer is the LED printer which uses an array of LEDs instead of a laser to cause toner adhesion.

Inkjet printers: Inkjet printers spray very small, precise amounts of ink onto the media. For colour applications including photo printing, inkjet methods are dominant. Inkjet printers or bubblejet printers are one of the most commonly used printers. They consist of nozzles that produce very small ink bubbles that turn into tiny droplets of ink. The dots formed are the size of tiny pixels. Ink-jet printers can print high-quality text and graphics. They are also almost silent in operation. They are cheaper than laser printers but are expensive to run as their cartridges need to be frequently replaced.

Impact printers: These printers physically touch the paper and make the impression on it; hence these are called impact printers. These are very noisy printers. Impact printers rely on a forcible impact to transfer ink to the media, similar to typewriters, that are typically limited to reproducing text. A daisy wheel printer is a specific type of impact printer where the type is moulded around the edge of a wheel. A golf ball typewriter is similar to the daisy wheel type but has the characters distributed over the face of the globe shape.

Dot-matrix printers: In the general sense many printers rely on a matrix of pixels, or dots, that together form the larger image. However, the term dot matrix printer is specifically used for impact printers that use a matrix of small pins to create precise dots. The advantage of dot-matrix over other impact printers is that they can produce graphical images in addition to text; however, the text is generally of poorer quality than impact printers that use letterforms. Dot-matrix printers can either be character-based or line-based (that is, a single horizontal series of pixels across the page), referring to the configuration of the print head. At one-time Dot-matrix printers were one of the more common types of printers used for general use – such as for home and small office use. Such printers would have either 9 or 24 pins on the print head. 24 pin print heads were able to print at a higher quality.

Line printers: Line printers, as the name implies, print an entire line of text at a time. Two principle designs existed. In drum printers, a drum carries the entire character set of the printer repeated in each column that is to be printed. In chain printers (also known as train printers), the character set is arranged multiple times around a chain that travels horizontally past the print line. In either case, to print a line, precisely timed hammers to strike against the back of the paper at the exact moment that the correct character to be printed is passing in front of the paper. The paper presses forward against a ribbon which then presses against the character form and the impression of the character form is printed onto the paper. These printers were the fastest of all impact printers and were used for bulk printing in large computer centres. They were virtually never used with personal computers and have now been partly replaced by high-speed laser printers.

Daisy wheel / Golf ball printer: A small Daisy-like structure/golf ball-like structure the fonts forming characters is embossed. The wheel/ball rotates at a speed and a hammer hits the wheel or ball, based on the instruction from the computer when a particular character is on the side of the paper, which in turn hits a ribbon which makes the character print on the paper. The print out is called a letter-quality printout, since complete characters are printed, unlike dots in a dot matrix printer. These cannot print graphs etc.



The system software is a type of computer program that is designed to run a computer’s hardware and application programs. If we think of the computer system as a layered model, the system software is the interface between the hardware and user applications. The operating system (OS) is the best-known example of system software. The OS manages all the other programs on a computer. Besides the application software, there is another software called system software. The system software is the operating system. This is very important for the working of the PC.

Example – Windows 98, Windows 95, Windows XP, Solaris, Linux, Unix, Vista, etc.

When a user wants to store any data or program, the data or the program is stored at a location that is known only to the operating system. Therefore, the operating system performs the task of storage management.

Other examples of system software include:

• The BIOS (basic input/output system) gets the computer system started after you turn it on and manages the data flow between the operating system and attached devices such as the hard disk, video adapter, keyboard, mouse, and printer.

• The boot program loads the operating system into the computer’s main memory or random-access memory (RAM).

• An assembler takes basic computer instructions and converts them into a pattern of bits that the computer’s processor can use to perform its basic operations.

• A device driver controls a particular type of device that is attached to your computers, such as a keyboard or a mouse. The driver program converts the more general input/output instructions of the operating system to messages that the device type can understand.

Additionally, system software can also include system utilities, such as the disk defragmenter and System Restore, and development tools, such as compilers and debuggers.

System software and application programs are the two main types of computer software. Unlike system software, an application program (often just called an application or app) performs a particular function for the user. Examples include browsers, email clients, word processors, and spreadsheets.

Application Software

Application software is a program or group of programs designed for end-users. These programs are divided into two classes: system software and application software. While system software consists of low-level programs that interact with computers at a basic level, application software resides above system software and includes applications such as database programs, word processors, and spreadsheets. Application software may be bundled with system software or published alone.

Application software may simply be referred to as an application. Different types of application software include:

Application Suite: Have multiple applications bundled together. Related functions, features, and user interfaces interact with each other.

Enterprise Software: Addresses an organization’s needs and data flow in a huge distributed environment

Enterprise Infrastructure Software: Provides capabilities required to support enterprise software systems

Information Worker Software: Addresses individual needs required to manage and create information for individual projects within departments

Content Access Software: Used to access content and addresses a desire for published digital content and entertainment

Educational Software: Provides content intended for use by students

Media Development Software: Addresses individual needs to generate and print electronic media for others to consume

Types of Computer Language

Low-Level Languages: A language that corresponds directly to a specific machine

High-Level Languages: Any language that is independent of the machine

There are also other types of languages, which include;

System languages: These are designed for low-level tasks, like memory and process management

Scripting languages: These tend to be high-level and very powerful

Domain-specific languages: These are only used in very specific contexts

Visual languages: Languages that are not text-based

Esoteric languages: Languages that are jokes or are not intended for serious use

Language is a means of communication. Normally people interact with each other through communication. On the same pattern, communication with computers is carried out through a language. The language is understood both by the user and the machine. Normally every language has its grammatical rules; similarly, every computer language is bound by rules known as the SYNTAX of the language.

Programming language

A programming language is an artificial language that can be used to write programs that control the behaviour of a machine, particularly a computer. Programming languages are defined by rules which describe their structure and meaning respectively. Many programming languages have some form of written specification of their syntax. There are two levels of language.

1. High-level programming language

2. Low-level programming language

High-level programming language

These languages are normal, English-like. Easy to understand statements to pass the instruction to the computer. The languages are problem-oriented. It offers:

• Readability

• Easy Debugging

• Portability

• Easy software Development


Low-level programming language

Low-level programming languages are sometimes divided into two categories:

I. Machine Language

Machine Language is the only language that is directly understood by the computer. It does not need any translator program. We also call it machine code and it is written as strings of 1’s (one) and 0’s (zero). When this sequence of codes is fed to the computer, it recognizes the codes and converts it into electrical signals needed to run it. For example, a program instruction may look like this: 1011000111101. It is not an easy language for you to learn because of its difficult to understand. It is efficient for the computer but very inefficient for programmers. It is considered to the first-generation language. It is also difficult to debug the program written in this language.

Advantages and Limitations of Machine Languages

Programs written in machine language can be executed very fast by the computer. This is due to the fact that machine instructions are directly understood by the CPU and no translation of the program is required. But writing a program in machine language has some disadvantages which are given below:

1. Machine dependence: Since the Internal design of a computer varies from machine to machine, the machine language is different from computer to computer. Thus, a program written in machine language in one computer needs modification for its execution on another computer.

2. Difficult to the program: A machine language programmer must have thorough knowledge about the hardware structure of the computer.

3. Error-prone: For writing programs in machine language, a programmer has to remember the OPCODES and has to keep track of the storage locution of data and instructions. In the process, it becomes very difficult for him to concentrate fully on the logic of the problem and as a result, some errors may arise in programming.

4. Difficult to modify: It is very difficult to correct or modify machine language programs.

II. Assembly Language

It uses only letters and symbols. Programming is simpler and less time consuming than machine language programming. It is easy to locate and correct errors in Assembly language. It is also machinedependent. The programmer must have knowledge of the machine on which the program will run. An assembler is a program that translates an assembly language program into a machine language program.

Assembly languages have the following advantages over machine languages;

1. Easier to understand and use: Assembly languages are easier to understand and use because mnemonics are used instead of numeric op-codes and suitable names are used for data.

2. Easy to locate and correct errors: While writing programs in assembly language, fewer errors are made and those that are made arc easier to find and correct because of the use of mnemonics and symbolic names.

3. Easier to modify: Assembly language programs are easier for people to modify than machine language programs. This is mainly because they are easier to understand and hence it is easier to locate, correct, and modifies instructions as and when desired.

4. No worry about addresses: The great advantage of assembly language is that it eliminates worry about address for instructions and data.


1. Machine Dependence: Programs written in assembly language are designed for the specific make and model of the processor being used and are therefore machine-dependent.

2. Knowledge of hardware is required: Since assembly language is machine-dependent, the programmer must be aware of a particular machine’s characteristics and requirements as the program is written. Machine and assembly codes are based on the basic design of computers and are referred to as ‘low-level language’.


• Besides the application software and the system software, there is a third kind of software called the compiler software.

• A compiler is a system program that translates source code (user-written program) into object code (binary form).

• The whole source code file is compiled in one go and a complete.

• This means that the program can only be executed once the translation is complete.

• It is 5-25 times faster than an interpreter.

• Ex- C & C++ are most popular compiled language.


Translate the high-level language and execute the instruction before passing on to the next instruction.

• An Interpreter is a contrast to a compiler, analyses & executes the source code line- by – line without looking at the entire program.

• First, it translates & executes the first line then it moves to the next line of the source code & repeats the process.

• It is a slow process.

• It is used in the FORTRAN program.

• Ex- JavaScript & VBScript are interpreted language.



It translates the program line by line

It assembles the whole program

The debugging process is easy.

The debugging process is complex as it generates errors only at the end of the compilation.

The object code of the statement produced by the interpreter is not saved.

The object code produced by the compiler is permanently saved for future reference.

It is a smaller program compared to a compiler. Thus, it occupies less memory space and has a lower execution time.

It is a complicated process compared to an interpreter. Thus, it has a higher execution time and occupies larger memory space.

It is a slow process.

It is 5-25 times faster than an interpreter

It is used in the FORTRAN program.

It is used in C language program.



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