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Computer Fundamentals

 Computer

Computers have made great inroads in our everyday life and thinking. They are put to use for all sorts of application ranging from complex calculations in the field or frontline research, engineering simulations down to teaching, printing books and recreational games. The ease with which computers can process data, store and retrieve it painlessly has made them inevitable in office and business environment. Therefore, it is essential for every person to know computer, its strengths, its weakness and its internal structure.

What is computer?

A computer is an electronic device that can perform a variety of operations in accordance with a set of instructions called program.

Functional components of computer system

1. Input unit

2. Output unit

3. CPU

4. Memory

5. Storage devices

Input Unit

Input unit is a unit through which user communicates with the computer. It acts as a translator between the user and the computer. it converts the given data into computer acceptable form.

Functions of input devices are:

1. Accepts data and instructions from user.

2. Coverts accepted data into machine language.

3. Gives converted data and instructions to CPU for processing.

Examples of input devices are – Keyboard, Mouse, Light pen, Joystick, Magnetic ball, MICR, OCR, etc.

Output Unit

Output unit is a unit through which computer communicates with the user. It acts as a translator between the computer and the user. It converts the processed data from machine language to some natural language like English, which user can understand easily.

Functions of output devices are:

1. Accepts processed data from CPU.

2. Converts results from machine language to some natural language.

3. Displays results to user.

Examples of output devices are – Printer, Plotter, VDU, Magnetic disk drive, Speaker, Floppy disk drive, etc.

CPU (Central processing unit)

All the processing work of computer is performed by CPU. It controls all the parts of computer system and is termed as BRAIN of the computer. It has three components:

1. ALU (Arithmetic and Logic Unit)

2. CU (Control Unit)

ALU: This unit performs all arithmetic and logic operations.

CU: This unit controls and guides the interpretation, flow and manipulation of all data and information. Another important function of CU is the program execution.

Memory

It is also termed as primary memory or central memory or internal memory. It is only the memory which is in direct contact with CPU. It is quite costly and its storage capacity is small. It is used to store data and program that is being executed currently. It is of two types- RAM and ROM.

Functions of main memory are:

1. It temporarily holds the data received from input devices.

2. It holds the data being processed and the intermediate results.

3. It holds the final results and releases them to output devices when required.

4. It holds the system software and the application software in use.

Storage devices

Since computers main memory is temporary, secondary memory space is needed to store data and information permanently for later use. Some common secondary storage media are the floppy diskette, the hard disk and the CD-RWs, etc. The secondary memory devices are also known as STORAGE DEVICES.

Hardware

Hardware represents the physical and tangible components of the computer. Input devices, CPU, floppy disk, harddisk, etc are the example of computer hardware.

Software

It represents the set of programs that govern the operation of a computer system and make the hardware run.

Strengths of computer

1. Its speed is much faster as compared to human beings.

2. It has high storage capacity.

3. It can perform all the calculations and comparisons accurately.

4. Computers are more reliable than human beings.

5. Computers are versatile to repetitive jobs.

Limitations of computer

1. Computers cannot decide on their own which a great asset of human being is.

2. They have zero IQ.

EVOLUTION OF COMPUTERS

The word generation of computer refers to different hardware technologies used in computers. It provides an idea about the growth in the computer industry. Till today there are five generations of computers.

 Computer Generation

Major features of first generation of computers are

1. Main component: Vacuum tubes

2. Size: Equivalent to a room

3. Speed: Few hundred instructions per second

4. Main memory: Magnetic drum

5. Secondary storage: magnetic drum and magnetic tape

6. Language: Machine and assembly language

7. Reliability: Failure of circuits in hour

8. Processing: Sequential Processing

9. Example: EDVAC, UNIVAC, Mark-1, etc.

                   ENIAC                                           UNIVAC-I

Major features of second generation of computers are

1. Main component: Transistors

2. Size: Smaller than first generation computers

3. Speed: Few thousand instructions per second

4. Main memory: Magnetic core

5. Secondary storage: magnetic drum and magnetic tape

6. Language: Assembly languages and high level languages like FORTAN, COBOL, and BASIC

7. Reliability: Failure of circuits in hour

8. Processing: Simple batch Processing

9. Example: ATLAS, LEO, PDP1, etc.

Major features of third generation of computers are

1. Main component: Integrated circuits

2. Size: Smaller than first and second generation computers

3. Speed: Million instructions per second

4. Main memory: Magnetic core

5. Secondary storage: magnetic drum and magnetic tape

6. Language: high level languages like COBOL, BASIC

7. Reliability: Failure of circuits in weeks

8. Processing: Multiple processing

9. Example: IBM-307 series, CDC 7600 series

Major features of fourth generation of computers are

1. Main component: Large scale integrated semiconductor Circuits (LSIC)

2. Size: Equal to the size of type writer

3. Speed: Billions instructions per second

4. Main memory: LSI semiconductor circuits

5. Secondary storage: magnetic disk, Floppy disk, Optical disk

6. Language: Improved High level languages like C++, SQL

7. Reliability: Failure of circuits in months

8. Example: CRAY 2, CRAY MP, IBM 3090 Series, etc.

Major features of fifth generation of computers are

1. Main component: Super/ Ultra Large scale integrated semiconductor Circuits (SLSIC)

2. Size: Equal to the size of type writer

3. Speed: Billions instructions per second

4. Main memory: VLSI superconductor circuits

5. Secondary storage: Card magnetic disk, Optical disk

6. Language: Improved High level languages like C++, SQL, RPG

7. Reliability: Failure of circuits in months

8. Example: Lap-top Computer, Palm-top Computer, Note-Book Computer, etc.

CLASSIFICATIONS OF COMPUTERS

Computers can be classified into different categories depending upon following criteria:

1. According to Purpose.

2. According to Use.

3. According to Technology Used.

4. According to Size and Storage Capacity.

Classification According to purpose

1. Special purpose computers: It is a computer used to perform a specific task only. In this type of computer, instructions are permanently stored. For example, computer used for weather forecasting.

2. General purpose computers: It is a computer used to perform variety of applications. Instructions are loaded at the time of need and are not permanently stored. For example, computer used to perform various calculations.

Classification According to Use

1. Scientific Computers: These computers have slow input/output devices but have fast processing speed. So these are quite suitable for scientific applications.

2. Business Computers: These have fast input/output devices but slow processing speed. So these are quite suitable for business applications.

Classification According to Technology used

1. Digital Computers: They convert data into binary digits (0 or 1) and then process them.

2. Analog Computers: They work on physical quantities.

3. Hybrid Computers: They are the mixture of Digital and Analog computers.

Classification According to Size and Storage capacity

1. Micro computers: They are the smallest digital computers that use a microprocessor as its CPU. These can be used as a stand alone machine and as a terminal in a multi-user environment. They are also known as Personal computers. Example – 1BM PC, APPLE Mac., etc

2. Mini computers: they are medium – scale computers. These are faster than microcomputers but slower than mainframe computers. These have large scale storage capacity and can support up to 20 terminals. Example – VAX, DP-1, etc

3. Mainframe computers: They are general purpose computers capable of handling all types of scientific as well as business problems. Example – CDC-600, VAX 8842, etc

4. Super Computers: They are big general purpose computer capable of handling all types of scientific as well as business problems. Its maximum speed is billions bytes per second. Example – CRAY3, PARAM 10000, etc.

Concept of Booting

In computing, booting (also known as booting up) is the initial set of operations that a computer system performs when electrical power is switched on. The process begins when a computer that has been turned off is re-energized, and ends when the computer is ready to perform its normal operations.

The computer term boot is short for bootstrap or bootstrap load and derives from the phrase to pull oneself up by one's bootstraps. The usage calls attention to the paradox that a computer cannot run without first loading software but some software must run before any software can be loaded.

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