Categories of Computer

Categories of Computer

              Normally, computers are categorized on the basis of size, speed, processing power and price. However, categorizing computers is not very straight-forward. The distinction between these categories is sometimes not very clear. Some characteristics overlap different categories. Computers can be divided into the following categories:

1 Personal Computers / Micro Computers

             Personal computer is a type of computer that performs input, output, processing and storage activities by itself. It was introduced in 1970. It contains a processor, memory and one or more input, output and storage devices. It generally has one processor. However, some personal computers may have multiple processors. It is designed to be used by one person at a time. Most commonly used personal computers are PC and Apple Macintosh. The price of personal computer is from $500 to $5000.

                  Personal computers have different processors and operating system. PC and its compatible computers use windows operating system. Apple Macintosh and compatible computers use Macintosh operating system also called MAC OS.

          Pc and its compatible computers follow the specifications of the original IBM personal computer. Some PC compatible computers include Compaq, Dell and Toshiba. Following are different types of personal computers:

1.1 Desktop Computers

Desktop computers are the most common type of personal computer. It is designed in a way that all its components fit on a desk or a table and monitor is placed on system unit. In another model, called tower model, both monitor and system unit are placed on the table. The system unit in tower model is placed vertically.

          Different desktop computers are as follows:

·         All-in-One computer: It is less expensive computer. In this computer, monitor and system unit are combined into single device.

·         Workstation Computer:  It was introduced in early 1980s. It is more expensive and powerful personal computer. It is used for calculations and graphics work. A workstation can tackle task that require a lot of processing speed. It is mostly used by engineers, graphics artists and architects. Architecture uses a workstation to view and create maps. A graphics artist uses a workstation to create computer-animate special effects for full-length motion picture and video games.

·          Server computer: It is a computer that manages the resources of a network. It controls access to the software, hardware of the network. It also provides centralized area to store date, information and software.

1.1.2 Notebook Computers

Notebook computer is also called laptop computer. Laptop computer is small in size and can be placed easily on lap. Only one user can use them at a time. It uses less power. It can be used using batteries. A laptop computer can perform the same basic functions as a personal computer. The computing power of modern notebook computers are nearly equivalent to personal computers.

                A notebook computer contains CPU, memory capacity and disk drives. The keyboard and touchpad in notebook computer are placed on the top of system unit.

          Notebook computers can be brought anywhere easily because of lightweight. Its weight is generally around 2KG. They are easy to carry and can be used outdoors in airports and in classrooms without the need for nearby electrical outlet. Laptop computers are more expensive than desktop computers. The cost of these computers is from $1000 to $2500.

.11.3 Tablet PC

Tablet PC was introduced in 2002. It is a special type of notebook that works with digital pen. The user gives instructions with digital pen. It can also use keyboard for input. It also supports voice input. Many Tablet PCs have built-in microphone. Tablet PC is used to take notes in lectures, meetings, conferences etc. The price of tablet PC is high and it typically costs $2000 to $2500. Two basic design of Tablet PC are as follows:

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Generations of Computer

Generations of Computer

            The development of electronic computers can be divided into generations depending upon the technologies used. The generations of computers are as follows:

·         First generation                    (Vacuum tube)                            1942-1955

·         Second generation              (Transistor)                                  1955-1964

·         Third generate                     (Integrated Circuits)                   1964-1975

·         Fourth generation               (Microprocessor)                        1975-Present

·         Fifth generation                  (Artificial intelligence)                Present and Beyond

1 First Generation Computer (1942-1955)

The beginning of commercial computer age is from UNIVAC (Universal Automatic Computer). It was developed by two scientists MAUCHLY and ECHERT at the Census Department of United States in 1947.

        First generation computers were used during 1942-1955. They were based on vacuum tubes. Examples of first generation computers are ENIVAC and UNIVAC-I etc.

Advantages

·         Vacuum tubes were the only electronic component available during those days.

·         Vacuum tubes technology made possible to make electronic digital computers.

·         These computers could calculate data in millisecond.

Disadvantages

·         These computers were very large in size

·         They consumed a large amount of energy

·         They heated very soon due to thousand of vacuum tubes

·         They were not very reliable

·         Air conditioning was required

·         Constant maintenance was required

·         Non-portable

·         Costly commercial production

·         Limited commercial use

·         Quite slow speed

·         Limited programming capabilities

·         Used Machine language only

·         Used magnetic drums which provide very less facility of data storage

·         Punch cards for input

·         Not versatile

·         Very faulty

2 Second Generation Computers (1955-1964)

The second generation computers used transistors. The scientists of Bell Laboratories developed transistor in 1947. These scientists include John Bardeen, William Brattain and William Shockley. The size of computer was decreased be replacing vacuum tubes by transistors. The examples of second-generation computers are IBM 7094 series, IBM 1400 series and CDC 164 etc.

Advantages  

·         Smaller in size as compared to first generation computers

·         More reliable

·         More energy-efficient

·         Used less energy and were not heated

·         Wider commercial use

·         Better portability

·         Better speed, could calculate data in microsecond

·         Used faster peripherals like tape drives, magnetic disks, printer etc

·         Used Assembly language instead of Machine language

·         Accuracy improved

Disadvantages

·         Air conditioning was required

·         Constant maintenance was required

·         Commercial production was difficult

·         Only used for specific purposes

·         Costly

·         Not versatile

·         Punch cards were used for input

3 Third Generation Computers (1964-1975)

           The third generation computers used integrated circuits (IC). Jack Kilby developed the concept of integrated circuit in 1958. It was an important invention in computer field. The first IC was invented and used in 1961. The size of an IC is about ¼ square inch. A single IC chip may contain thousands of transistors. The computer became smaller in size, faster, more reliable and less expensive. The examples of third-generation computers are IBM 370, IBM System/360, UNIVAC 1108 and UNIVAC 9000 etc.

Advantages   

·         Smaller in size as compared to previous generation

·         More reliable

·         Less energy used.

·         Produced less heat as compared to previous generation computers

·         More good speed, could calculate data in nine seconds.

·         Used fan for heat discharge to prevent damage.

·         Maintenance cost was low because hardware failure is rare.

·         Totally general purpose

·         Could be used for high-level languages

·         Good storage

·         Versatile too an extent

·         Less expensive

·         Better accuracy

·         Commercial production increased

·         Used mouse, Keyboard for input

Disadvantages

·         Air conditioning was required

·         High sophisticated technology required for the manufacturing of IC Chips.

4 Fourth Generation Computers (1975-Present)

              The fourth generation computers started with the invention of microprocessor. The microprocessor contains thousands of ICs. Ted Hoff produced the first microprocessor in 1971 for Intel. It was known as Intel 4004. The technology of integrated circuits improved rapidly. The LSI (Large Scale Integration) circuit and VLSI (Very Large Scale Integration) circuit were designed.

                         Microprocessor revolutionized the computer world. It greatly reduced the size of computer. The size of modern microprocessors is usually one square inch. It can contain millions of electronic circuits. The examples of fourth generation computers are Apple Macintosh and IBM PC.

Advantages 

·         Very small in size

·         Less power consumption

·         Less heat generated

·         Fan for heat discharging and this to keep cold

·         No air conditioning is required

·         Best speed to read instructions i.e. one billionth per second

·         Reliable and Powerful

·         Totally general purpose

·         Commercial of repairing

·         Cheapest among all generations

·         All types of high-level languages can be used in this type of computers

Disadvantages

·         High sophisticated technology required for manufacturing microprocessors

5 Fifth Generation (Present and Beyond)

                  Scientists are now working on the 5^th generation computers using recent engineering advances. It is based on the technique of artificial intelligence (AI). Computers can understand spoken words instructions and imitate human reasoning. The ability to translate a foreign language is also moderately possible with fifth generation computer.

         Scientists are working to increase the speed of the computer. They are trying to create a computer with real IQ with the help of advanced programming and technologies. The advancement in modern technologies will revolutionize the computer in future.

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Boot Order Enter BIOS Keys

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History of Computer

History of Computer

Computer was invented because “necessity is the mother of invention”. Man always searched for a fast calculating device. It took a long time to invent the digital computer. A brief history behind the invention of computer is as follows: 

Abacus

             Abacus was first computing device. It was developed 5000 years ago. It was used to perform simple addition and subtraction. Abacus was a wooden rack. It contained horizontal wires with beads strung in them. The beads could move easily. All simple arithmetic calculations were performed by moving these beads according to programming rules.

John Napier’s Bone

               John Napier was a Scottish mathematician. He created logarithm tables to facilitate calculations. He also created a device known as Napier’s Bones. The device used rods to perform arithmetic calculations. It was designed in the early 17^th century. The device was widely used by accountants and bookkeepers.

             The concept of logarithm was used to develop slide rule. The modern slide rule could be used to perform arithmetic calculations. It was also used to calculate squares, square roots, logs, sine and cosine etc. The slide rule was used till the middle 70’s.

Blaise Pascal

             Blaise Pascal was a French mathematician. He invented a mechanical adding machine in 1642 known as Pascaline Calculator.  The machine contained different metal wheels. Each wheel displayed the digit 0 to 9. It could only add and subtract numbers. Division and multiplication was performed by repeated addition and subtraction. It was not a commercial success because it could not provide sufficient precision for practical use.

Von Leibnitz

                Von Leibnitz was German scientist. He developed a calculating machine in 1694. It was the first calculator that could multiply and divide also. It was similar to Pascal’s calculator but it was more reliable and accurate.

Charles Xavier

                    A French scientist Charles Xavier developed a machine that could perform addition, subtraction, multiplication and division.

Punched Board

                 A French engineer Joseph developed punchboard system for power looms. It was used to create specific weaving pattern on cloths. Later on, the system was used in computing devices.

Charles Babbage

              In 1822, a mathematician Charles Babbage invented a difference engine for mathematical calculations. In 1842, he developed Analytical Engine that was automatic. This engine could perform 60 additions per minute.

Herman Hollerith

                     In 1889, Herman applied the idea of punchboards in computers. He used punch cards in computers for input and output.

Atanasoff

         Atanasoff was a professor at Lowa University. He invented an electronic computer. He applied Boolean algebra to computer circuitry.

George Boole

           George Boole simplified binary system of algebra. His rule states that any mathematical equation can be stated simply as either true of false.

The Mark I Computer (1937-44)

           It is also known as Automatic Sequence Controlled calculator. It was first fully automatic calculating machine. It was designed by Howard A. Aiken of Harvard University. It was very reliable but huge in size.

The ENIAC (1943-46)

               ENIAC stands for Electronic Numerical Integrator and Calculator. It was invented by J. P. Eckert and John Mauchly in 1946. It was the first electronic computer. It was very heavy and large in size. It consumed 140 Kilo Watts of power. It could perform 5000 additions per second.

The EDVAC (1946-52)

            EDVAC stands for Electronic Discrete Variable Automatic Calculator. It was developed by Dr. John Von Neumann. It could store instructions and data.

The UNIVAC (1951)

                UNIVAC stands for Universal Automatic Computer. Eckert and Mauchly formed Eckert-Mauchly Computer Corporation in 1947 to manufacture computers commercially. They manufactured the first successful computer UNIVAC. It was the first computer for scientific and commercial applications. 

Commercial Computers

                  The first commercial computer was 701. It was introduced by IBM (International Business Machines).

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Characteristics of Computer

Following are the important characteristics of a computer:

1.       Speed

               Computers work at a very high speed and are much faster than humans. A second is very large time period time for computer. A computer can perform billions of calculations in a second. The time used by a computer to perform an operation is called the processing speed. Computer speed is measured in Mega Hertz (MHz) or Giga Hertz (GHz). 

2.       Storage

              A computer can store large amounts of data permanently. Users can use this data at any time. We can store any type of data in a computer. Text, graphics, pictures, audio and video files can be stored easily. The storage capacity of the computer is increasing rapidly.

3.       Processing

               A computer can process the given instructions. It can perform different types of processing like addition, subtraction, multiplication and division. It can also perform logical functions like comparing two numbers to decide which one is the bigger etc.

4.       Accuracy

             Accuracy means to provide result without any errors. Computer can process large amount of data and generate error-free results. A modern computer performs millions of operations in one second without any error.

5.       Recalling

            A computer can recall the stored data and information as and when required. The data stored in the computer can be used at a later time. The computer can recall the required data in a few seconds.

6.       Control Sequence

                  A computer works strictly according to the given instructions. It follows the same sequence of execution that is given in a program.

7.       Consistency

              Computer works in a consistent way. It does not lose concentration due to heavy work. It does not become tired or bored. Computer performs all jobs with equal attention.

8.       Communication

                Most computers today have the capability of communicating with other computers. We can connect two or more computers by a communications device such as modem. These computers can be share data, instructions, and information. The connected computers are called network. We can communicate with other people in the world using network like Internet.

9.       Versatile

            A computer can perform different types of task. We can use a computer in hospital, bank or at home. We can use it for calculating our budget or can play games. A variety of facilities are available through computers.

10.   Cost Reductions

                We can perform a difficult task in less time and less cost. For example, we may have to hire many people to handle an office. The same work can be performed by single person with the help of computer. It reduces the cost.

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Software and Hardware

          Software is a set of instructions that tells a computer what to do. A computer works according to the given instructions in the software.

                 The physical parts of a computer are called hardware. The user can see and touch hardware. Keyboard and mouse are examples of hardware.

Relationship of Software and Hardware

                 Software is a set of instructions that tells computer hardware what to do. The hardware cannot perform any task without software. The software cannot be executed without hardware. A computer becomes useful only when hardware and software are combined.  

Difference between Software & Hardware

          Following is a brief difference between software and hardware:

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Definetion of C.P.U.

 Define C.P.U.

C.P.U

           C.P.U stands for Central Processing Unit.

C.P.U is a highly complex set of electrical circuits that executes stored program instructions.

It is also known as brain of computer.

C.P.U can be divided into two main parts.

      Control Unit

      Arithmetic and Logical Unit

How many types of computer are there uses?

There are following types of computers.

1.     Personal Computers (PCs)

       Types of PCs

·         Desktop PCs

·         Tower PCs

·         Laptop PCs

2.     Mini Computer

3.     Main Frame Computer

4. Super Computer

DEFINE BASIC MEMORY UNIT OF THE COMPUTER

                  Bit is the basic memory unit of the computer. Bit stands for Binary Integer.

                            8 bits = 1 byte

                           1024 Bytes = 1 Kilo Bytes

                           1024 Kilo Bytes = 1 Mega Bytes

                           1024 Mega Bytes = 1 Giga Bytes

                           1024 Giga Bytes = 1 Tetra Bytes

Computer Memory

                        A component of a computer in which instructions and data stored is called computer memory.

TYPES OF MEMORY

           

There are two main types of memory of a computer.

1)      Random Access Memory (RAM)

                                    Ram is used to execute programs in computer system.

      It is called primary memory or main memory.

      Data is disappear or lost when computer is shutdown or off.

      The computer uses RAM as a temporary memory.

2)      READ ONLY MEMORY (ROM)

                               The instructions written in ROM can be read but cannot be changed or deleted.

ROM stored data permanently.

STORAGE DEVICES

HARD DISK DRIVE (HDD)

                                               Hard Disk Drive is the secondary storage device of the computer.

        HDD store data permanently but you can change data according to requirements.

H.D provides large storage capacity. It is primary media for storing data and programs.

WHAT DO YOU MEAN BY CD-ROM AND DVD-ROM?

CD-ROM

                Stands for Compact Disk Read Only Memory.

 The data on the CD-ROM can be read but cannot be changed or deleted.

It has storage capacity up to 680 MB.

It is used for storing large amount of data and application programs.

DVD-ROM

                    Stands for Digital Video Disk Read Only Memory.

  The DVD looks like CD but its storage capacity is seven to fourteen times than that of the CD. It can store 17GB of data.

DVD drives can play CDs

MOTHER BOARD

                                It is a circuit board that contains the microprocessor, electronic circuit for handling tasks as input / output signals from peripheral devices and memory chip.

DEFINE WINDOWS OPERATING SYSTEM AND WINDOWS DESKTOP.

WINDOWS OPERATING SYSTEM

                                                            Windows operating system is GUI we can open several applications at the same time and easily moved data from one application to another.

WINDOWS DESKTOP

                                     The background area of the windows screen is called desktop.

                                     You can customize the desktop by adding shortcut to your favorite programs and documents.

ICONS

            Icons are small graphic representation of programs, drives, folders and documents.

MY DOCUMENTS

                             My document icon is a shortcut to a folder that is used to save your document.

MY COMPUTER

                            My computer is used to see everything on your computer and access to the computer resources such as hard disk and floppy disk.

MY NETWORK PLASES

                                         My network places provide an easy way to connect to other computers on your networks.

RECYCLE BIN

                          When items are deleted they are first moved to the recycle bin. You can restore file from recycle bin.

INTERNET EXPLORER

                                        The internet explorer icon launches the internet explorer browser.

TASK BAR

                    Task bar appears at the bottom of the windows desktop.

Taskbar contains start menu, Quick Launch, system tray and running applications. 

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