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Introduction to Computer

Introduction – A Computer is an electronic device that manipulates information, or data. It has the ability to store, retrieve, and process data. You probably already know that you can use a computer to type documents, send email, play , and browse the Web. You can also use it to edit or create spreadsheet, presentations, and even videos.

Or

Computer is an electronic device that takes raw data as from the user and processes it under the control of set of instructions (called program), gives the result (output), and saves it for the future use.

Charles Babbage is called the “Grand Father” of the computer. The First mechanical computer designed by Charles Babbage was called Analytical Engine. It uses read-only memory in the form of punch cards.

What is Data?

“Data is a Collection of Facts, Figures and numbers which is used to Input into computer for processing.”

Data can be defined as a representation of facts, concept or instructions in a formalized manner which should be suitable for , interpretation, or processing by human or electronic .

Data is represented with the help of characters like alphabets (A-Z, a-z), digits (0-9) or special characters (+,-,*,/,<,>,=,etc).

What is Information?

“After being processed data is known as information”

Information is organized or classified data which has some meaningful values for the receiver. Information is the processed data on which decisions and actions are based. For the decisions to be meaningful, the processed data must qualify for the following characteristics:

Timely – Information should be available when required. Accuracy – Information should be accurate. Completeness – Information should be complete.

Advantage of Computer

Following list demonstrates the advantages of in today’s arena. 1. High Speed - Computer is very fast device. - It is capable of performing calculation of very large amount of data. - The computer has units of speed in microsecond, nanosecond, and even the picoseconds.

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2. Accuracy - In addition to being very fast, computers are very accurate. - The calculations are 100% error free. - Computers perform all jobs with 100% accuracy provided that correct input has been given. 3. Storage Capability - Memory is a very important characteristic of computers. - A computer has much more storage capacity than human beings. - It can store large amount of data. - It can store any type of data such as images, videos, text, audio, and many others. 4. Diligence - Unlike human beings, a computer is free monotony, tiredness and lack of concentration. - It can work continuously without any error and boredom. - It can do repeated work with same speed and accurate. 5. Versatility - A computer is very fast versatile machine. - A computer is very flexible in performing the jobs to be done. - This machine can be used to solve the problems related to various fields. - At one instance, it may be solving a complex scientific problem and the very next moment it may be playing a card games. 6. Reliability - A computer is a reliable machine. - Modern electronic components have long lives. - Computers are designed to make maintenance easy. 7. Automation - Computer is an automatic machine. - Automation means ability to perform the given task automatically. - Once a program is given to computer i.e, stored in , the program and instruction can control the program execution without human interaction. 8. Reduction in Paper Work - The use of computers for data processing in an organization leads to reduction in paper work and results in speeding up a process. - As data in electronic files can be retrieved as and when required, the problem of maintenance of large number of paper files gets reduced. 9. Reduction in Paper Work - Though the initial investment for installing a computer is high but it substantially reduces the cost of each of its transaction.

Disadvantages of Computer

Following list demonstrates the disadvantages of computers in today’s arena. 1. No.1 Q - A computer is a machine that has no intelligence to perform any task. - Each instruction has to be given to computer. - A computer cannot take any decision on its own.

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2. Dependency - It functions as per a user’s instruction, so it is fully dependent on human begin. 3. Environment - The operating environment of computer should be dust free and suitable. 4. No Feeling - Computers have no feelings or emotions. - It cannot make judgment based on feeling, taste, experience, and knowledge.

Computer Applications

1. Business – A computer has high speed of calculation, diligence, accuracy, reliability, or versatility which made it an integrated part in all business organizations.

Computer is used in business organizations for:  Payroll Calculations  Budgeting  Sales Analysis  Financial Forecasting  Managing Employees Database  Maintenance of Stocks Etc. 2. Banking – Today banking is almost totally dependent on computer.

Banks provides following facilities:  Banks provide online accounting facility, which includes current balances, deposits overdraft, interest charges, shares, and trustee records.  ATM are making it even easier for customers to deal with banks. 3. Education – The computer has provided a lot of facilities in the education system.  The computer provides a tool in the education system known as CBE (Computer Based Education).  CBE involves control, delivery, and evaluation of learning.  The computer education is rapidly increasing the graph of number of computer students.  There are number of methods in which educational institutes can use computer to educate the students.  It is used to prepare a database about performance of a student and analysis is carried out on this basis. 4. Communication – Communication means to convey a message, an idea, a picture or speech that is received and understood clearly and correctly by the person for whom it is meant for. Some main areas in this category are:  Email  Chatting  Usenet  FTP  Telnet  Video-Conferencing

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5. Government – Computes play an important role in government.

Some major fields in this category are:  Budgets  Sale Tax Department  Income Tax Department  Male / Female Ratio  Computerization of Voters Lists  Computerization of Driving Licensing System  Computerization of PAN Card  Weather Forecasting

6. Airlines and Railways Ticket Reservation – Indian Railways have computerized ticket reservation in almost all important railways stations. The computer stores all necessary information required for ticket processing such as train number, stations, distance between stations, number of seats available in each train for each class, train fare, etc. The computer can also give information regarding train timings, fares, etc. On telephone enquiry.

7. Marketing – In Marketing uses of computer are following:  Advertising – With computers, advertising professionals create art and graphic, write and revise copy, and print and disseminate ads with the goal of selling more products.  At Home Shopping – Home Shopping has some made possible through use of computerized catalogues that provide access to product information and permit direct entry of orders to be filled by the customers.

8. Accounting and Investment Analysis – A Spreadsheet program is a software package through which you can analysis investment, inventory control, preparation if budget etc. Specialized software packages such as Tally are available to handle accounts in medium sized companies. Accounting Programs are used for data entry, Billing, Inventory Control, Sales Analysis. Many companies issue shares, debenture, etc. Software packages for such analysis are available at small price, like MS-Office Suits supported by Corporation.

9. Computers in Graphics and Animation – Computers can be used to make , graphics and movies. CorelDRAW, Illustrator, Visio 2000 and FreeLancePlus for Windows are some such software packages, which can help you to increasing your capability.

10. Engineering Design – Computers are widely used in Engineering Purpose. One of major areas is CAD (Computer Aided Design). That provides creation and modification of images. Some fields are:  Structural Engineering – Requires stress and strain analysis for design of Ships, Buildings, Budgets, Airplanes, Etc.  Industrial Engineering – Computers deal with design, implementations and improvement of integrated systems of people, materials and equipment’s.  Architectural Engineering – Computers helps in planning towns, designing buildings, determining a range of buildings on a site using both 2D and 3D drawings.

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FUNDAMENTAL OF COMPUTER

System Unit

The system unit is the most important part of a computer system. It resembles a rectangular box containing some buttons and disk drives at the front side, and sockets of different shapes and sizes at the back side. All devices, such as keyboard, mouse, monitor, , and speakers, are linked to the system unit through cables, which are plugged into the back of the system unit. The core devices of the computer system are kept safely inside the system unit. The core devices include , CPU, Basic Input Output System (BIOS), RAM, hard disk, and switched-mode power supply (SMPS) to regulate the flow of electric current in the computer system.

Front Side of the System Unit

Lets us now view the front visible portion of the system unit. The various components seen in the front side of a system unit and their functions are as follows:

 Power Switch: Helps you to turn ON or OFF the PC.  Reset : Helps you to restart your computer without disconnecting the power supply.  Lights: Indicates whether the hard disk, , or CD-ROM is being read or written.  Floppy Disk Drive: Helps you to read the information stored in the floppy disks (also called a diskette).  CD/DVD Drive: Allows you to read data from CDs and . Apart from reading data from the CDs and DVDs.

Back Side of the System Unit

The back side of a system unit contains various connection points of different shapes. These connection points are known as ports. Generally, PCs have three types of ports, namely, , , and Universal Serial (USB).

 Serial Port: Refers to a general-purpose interface utilized for most of the device, such as modems, mouse, and keyboard. Most PCs have two serial ports.  Parallel Port: Connects the computer to a printer. It is also referred to as the printer port.  USB Port: Refers to a plug-and-play port with which you can attach various devices, such as audio, players, , keyboards, telephones, scanners, and printers, to the computer. You can add new devices to your computer without adding additional hardware or turning the computer off by USB. A single USB port can be used to connect up to 127 devices.  Power Socket: Supplies electricity to your computer. A power cable is plugged into the power socket, which carries the power from the electrical outlet to the system unit and from the system unit to your monitor.  Fan: Works similar to an exhaust fan. When you work on a computer, its machinery produces a lot of heat. It this heat is not moved out of the system unit. It can cause havoc to the computer machinery.

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Inside the System Unit

The system unit of a computer is a complex machine, which contains several devices and chains of colored electronic wires running from one end to another. If you look inside the system unit, you can find green boards with mysterious circuit paths and soldering joints. These boards play an essential role in running your computer as they control the flow of data and operating electricity for all primary components, such as CPU, , and Graphics in a computer.

 Motherboard – A motherboard is a component that contains the computer’s basic circuits and other components, such as sockets and chipsets of the computer. An electronic circuitry us printed or fixed on the surface of the mother board, and this task is done at the time of manufacturing the motherboard. A motherboard also contains the connectors that are used to attach additional boards to the computer. Typically, a mother contains the controls the controllers for all standard devices, such as the display screen, keyboard, and disk drive.

 Basic Input Output System – BIOS is a built-in software, which kept track of all devices, such as keyboard, monitor, and disk drives attached to a computer and provides an intercommunication channel between them. Older computers contained read-only BIOS that could not be altered. This means that the new components could not be added to the computer because the BIOS would be unable to communicate with them. This limited the user’s ability to upgrade their computers. This problem was solved with the introduction of flash BIOS. Now, when a new component is installed in the computer, the flash BIOS can be electronically upgraded so that it can recognize and communicate with the new devices. BIOS is typically placed in a ROM chip, which loads and starts an OS (it is often called a ROM BIOS).

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Computer Hardware and Software

Computer Hardware –

This equipment that processes data to create information is called hardware. Hardware for a microcomputer system consists of a variety of devices. Hardware represents the physical and tangible components of a computer i.e the components that can be seen and touched. These may be divided into four basic categories: Input, Processing, Output, Storage and Communication. While input devices converts what we can understand into what the system unit can process, output, device convert what the system unit has processed into a form that we can understand. Output devices translate machine language into letters, numbers, sounds and images that people can understand.

Hardware represents the physical and tangible components of a computer i.e. the components that can be seen and touched.

Examples of Hardware are Following:

: Keyboard, Mouse, Etc.  Processing Device: CPU, Etc.  : Monitor, Printer, Etc.  Secondary Storage Device: Hard Disk, CD, DVD, Etc.  Internal Components: Mother Board, RAM, Etc.

Mother Board– The motherboard serves as a single platform to connect all of the parts of a computer together. A motherboard connects CPU, memory, hard drives, optical drives, , sound card, and other ports and expansion cards directly or via cables. It can be considered as the backbone of a computer.

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Popular Manufactures

 Intel  Asus  Gigabyte Biostar

Port –

 Is a physical docking point using which an external device can be connected to the computer.  Can also be programmatic docking point through which information flows from a program to computer or over the internet.

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Types of Ports

Following are few important type of ports: Serial Port

 Used for external modems and older  Two versions : 9 pin, 25 pin model  Data travels at 115 kilobits per second

Parallel Port

 Used for scanners and printers  Also called printer port  25 pin model  Also known as IEEE 1284-compliant Centronics port

PS/2 Port

 Used for old computer keyboard and mouse  Also called mouse port  Most of the old computers provide two PS/2 port, each for mouse and keyboard  Also known as IEEE 1284-compliant Centronics port

Universal Serial Bus (USB) Port

 It can connect all kinds of external USB devices such as external hard disk, printer, scanner, mouse, keyboard, etc.  It was introduced in 1997.  Most of the computers provide two ports as minimum.  Data travels at 12 megabits per seconds  USB compliant devices can get power from a USB port.

Video Graphic Array Port

 Connects monitor to a computer’s video card.  Has 15 Holes.  Similar to serial port connector but serial port connector has pins, it has holes.

Power Connector

 Three-pronged plug  Connects to the computer’s power cable that plugs into a power bar or wall socket.

Firewire Port

 Transfer large amount of data at very fast speed.  Connects camcorders and video equipment’s to the computer.  Data travels at 400 to 800 megabits per seconds.  Invented by Apple

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 Three variants: 4-Pin FireWire 400 connector, 6-Pin FireWire 400 connector, and 9-Pin FireWire 800 connector.

Modem Port

 Connects a PC’s modem to the telephone network.

Ethernet Port

 Connects to a network and high speed Internet.  Connect network cable to a computer.  This port resides on an Card.  Data travels at 10 megabits to 1000 megabits per seconds depending upon the network band width.

Game Port

 Connects a to a PC.  Now Replaced by USB.

Digital Video Interface, DVI Port

 Connects Flat panel LCD monitor to the computer’s high end and video graphic cards.  Very popular among video card manufacturers.  Connects , speakers to sound card of the computer.

Computer Software –

Software is a set of programs, which is designed to perform a well-defined function. A program is a sequence of instructions written to solve a particular problem.

The Software of a computer system refers to the organized sets of instructions that control the working of the computer’s operations. The purpose of software is to convert data (unprocessed facts) into information (processed facts). Some programs are used by the computer to control its own tasks and devices.

There are two types of Software:

Software

System Application Software Software

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System Software –

The system software is collection of programs designed to operate, control, and extend the processing capabilities of the computer itself. System software are generally prepared by computer manufactures. These software products comprise of programs written in low-level languages which interact with the hardware at a very basic level. System software serves as the interface between hardware and the end users.

Some examples of system software are , Compilers, Interpreter, Assemblers, Etc.

Application Software –

Application software products are designed to satisfy a particular need of a particular environment. All software applications prepared in the computer lab can come under the category of Application software. Basic applications are those programs which most computer competent person are familiar with such as browsers, word processors, spreadsheets and database management systems. These are used to create software for billing systems, accounting software or software that enables the creation and storage of documents.

Application software may consists of a single program, such as a Microsoft’s notepad for writing and editing simple text. It may also consists of a collection of programs, often called a software package, which together to accomplish a task, such as a spreadsheet package.

Examples of Application software are following:

 Payroll Software  Student Record Software  Inventory Tax Software  Railways Reservation Software  Suite Software  Microsoft Office Word  Microsoft Office Excel  Microsoft PowerPoint

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Input Process and Output Devices

Introduction – There are lot of devices that are attached to the computer. Some of them are input devices, processing devices, and while other are output devices. These devices are collectively referred to as peripheral devices.

Computer Devices

Processing Output Input Devices Devices Devices

Input Devices- An input device is a hardware device that sends data into the computer system. These devices are used to input (or enter) data and instructions into the computer system. All instructions are accepted by the CPU through electrical pulses from various kinds of input devices.

Some of the input devices are explained as following: 1. Keyboard – The keyboard is one of the main input devices used in a computer. It is used to enter text and numeric data in a computer system. It is the most commonly used an input device which uses an arrangement of buttons and keys to. Both data and program can be entered into the computer through the keyboard. It is an essential device for interactive processing because the user can easily issue commands to receive the data response immediately on the computer screen.

Keyboard is basically divided into two parts: 1. AT-XT Keyboard (83-84) Keys. 2. Multimedia Keyboard (101-More) Keys.

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Types of Keys on Keyboard Sl. No. Keys Description All of the letters and numbers 1 Alpha Numeric Keys on the keyboard are A-Z and 0- 9. Such as Comma, Period, 2 Punctuation Keys Semicolon, Brackets, Parenthesis and so on. Such as Arrow Key, Caps Lock 3 Special Keys Key, Delete Key, Alt Key, , Etc. Keys labeled F1 to F12. These 4 Function Keys keys have different meaning depends o running program. Such as Control Keys, Insert, 5 Control Keys Home, End, Page Up, Page Down. Esc – Use for Abort the Current Action.

Tab – Move Cursor Point Default 8 Bit.

Caps Lock – Turn ON or OFF for Capital Letters.

Shift – Turn ON or OFF Keyboard Upper and Lower.

Ctrl – To Activate Special Function Action.

Fn – To Access Function Button.

Window – To Access the Start Button.

Alt – To Activate the Function Keys and Special Buttons.

Space – Fill the Blank Space.

Right – To Active Right Mouse .

Enter – To Move the Cursor Next Line.

Backspace – To Move the Cursor One Character Back.

Scroll Lock – To Lock the Scroll of Screen.

Print Screen – To Print the Screen.

Pause Break – To Break the Continues Action.

Insert – To Insert a Character on Specific Position.

Num Lock – To Turn ON or OFF the .

2. Mouse – The mouse is a that allows to control the movement of pointer (also known as mouse pointer) on screen. Mouse is most popular pointing device. It is very famous

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FUNDAMENTAL OF COMPUTER cursor control device having a small palm size box with a round ball at its base which senses the movement of mouse and sends corresponding signals to CPU when the mouse buttons are pressed.

Types of Keys on Mouse:  Primary Button (Left Click)   Secondary Button (Right Click) 3. Joystick – The joystick is also pointing device like the mouse. The joystick can be moved in all four directions. Commonly joysticks are used for playing computer games.

4. Light – A is a pointing device which is similar to a pen and connected to a Visual Display Unit (VDU). It is used to select a displayed menu item or draw pictures on the monitor screen.

5. Track Ball – Track Ball is an input device that is mostly used in notebook or computer, instead of a mouse. This is a ball which is moving fingers on ball, pointer can be moved.

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6. Scanner – Scanner is an input device which works more like a photocopy machine. It is used when some information is available on a paper and it is to be transferred to the hard disc of the computer for further manipulation. Scanner captures images from the source which are then converted into the digital form that can be stored on the disc. These images can be editing before they are printed. It is mainly used to convert a scanned document in a digital format.

Types of Scanner – The common types of scanners we see today are flatbed scanners, handheld scanners, and sheet fed scanners.

(i) Handheld Scanners – They are very small which can be held in a hand. These are less expensive and less wide. Hence, in order to scan a single page image, multiple passes are required. But their handlines is a major advantage of hand-held scanner.

(ii) Flatbed Scanners – They are large and more expensive scanners that create higher quality images. These scanners have a flat surface on which the printed image to be scanned, is placed. (Similar to the way a page is placed on a photocopier). Flatbed scanners can scan a page in a single pass.

(iii) Drum Scanners – They are medium size scanners with a rolling drum. The sheet is fed through the scanners so that the drum rolls over the entire sheet to be scanned (Just as the sheet is fed in a fax machine).

7. – A graphics tablets is an input device that consists of an electronic writing area and a special pen that works with it. It allows artists to create hand-made images and graphical images with motion and action, similar to the way a person draws images with and paper. The pen of the graphical tablet is pressure sensitive, so pressing harder or softer can result in brush strokes of different width. When user draws anything on the tablet with the special pen, the drawing

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FUNDAMENTAL OF COMPUTER appears on the screen. The tablet and pen can also be used like a mouse to move the cursor and click. Graphics tablet may also be used to capture data or handwritten signature.

8. Touch Screen – It is an electronic visual display that can detect the presence and location of a touch with in the display area. The term touch screen generally refers to touching the display of the device with a figure or hand. The touch screen sends a signal to the computer. This signal gives the location on the screen, which has been touched. Touch screen is quick and simple to use. Generally, ’s have a high-resolution capacitive touch screen.

There are different types of touch screens available with electronic devices like –  Capacitive Touch Screen.  Resistive Touch Screen.  Gorilla Glass Touch Screen. 9. Touch Pad – It is a specialized surface that can translate the motion and position is a user’s figure to a relative position on the screen. This is a common feature of laptop computers and also used as a substitute of a computer mouse, where disk space is scarce. The sensors of only react through fingertip and not a pencil or other object. There are usually two buttons next to the touchpad which works as left and right button of the mouse.

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10. Web Camera – is a attached to computers and can be used for video conferencing or online chatting, etc. It is a video capture device. are able to capture full motion videos as well. A webcam connected to a computer allows the user view either a still picture or motion video of a user or other object. Now-a-days, webcams are either embedded into the display with or connected via USB or firewire port or Wi-Fi to the computer system. After connecting webcam to a computer, you need to install required software or drivers.

11. Digital Camera – It is a device that stores the pictures or videos in an electronic format instead of film. There are several features that makes digital camera a popular choice, when compared to film cameras.

12. Biometric Sensor – It is an input device which recognizes physical or behavioral traits of the individual. Biometric sensors are mainly used marking attendance of employees / studentsin organizations / institutions. Biometric sensors are working with accuracy, so these can be widely used in security purpose.

13. Magnetic Character Recognition (MICR) – It is a character recognition which is primarily used by the banking industry to facilities the processing of cheques. This technology allows the computers to read information (such as account numbers) on printed documents. Characters are printed in special typefaces with a magnetic ink (that contains Iron Oxide). MICR can

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FUNDAMENTAL OF COMPUTER read up to 2400 documents/min. The MICR coding system contains 14 characters (four special symbols and 10 decimal digits). So, it can recognize these 14 characters only. The type font E-13 B, a standard typographical style, it used to print the characters or identification marks.

14. Optical Character Recognition (OCR) – It is used to translate scanned images of handwritten, type-written, printed text or special type font printed on conventional paper with conventional ink into machine-encoded text. It is widely used to convert books and documents into electronic files, to computerize a record-keeping system in an office or to publish the text on a website. An optical reader user photoelectric device to scan the characters begin read and convert the reflected light patterns of the data into binary data suitable for computer input. The normal speed of an OCR is 1500 to 3000 characters per second. The technology is begin developed for greater accurate recognition and is also known as Intelligent Character Recognition (ICR).

15. Optical Mark Reader (OMR) – It is used to capture human marked data from document from such as surveys and tests. One of the most families application of optical mark reader is the checking of optical answer sheets in multiple choice question. It uses high intensity to read the marks or symbols.

16. Bar Code Reader (BCR) – It is an input device used for reading printed bar codes (Universal Product Code) available on product to be sold. A bar code reader emits a beam of light, which reflects of the bar code image. A light sensitive detector in the barcode reader identifies the bar code image by recognizing special bars at both the ends of the image. Once code is identified, it is converted into numeric code. A perfect example of a barcode reader is its use in a super market

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FUNDAMENTAL OF COMPUTER where barcode scanner reads the price of a product. Software like Wasp, Bar Code are used for scanning and printing barcodes. A barcode is a machine readable representation of information in the form of stripes of dark and light ink.

17. Microphone – We can send sound to the computer though a special manual input device called microphone or mic. A mic converts the received sound into computer’s format, which is called Digitized Sound or Digital Audio. To convert a voice into digital form, an additional hardware is always needed which is known as Sound Card.

18. Speech Recognition System (SRS) – Speech Recognition converts spoken words to machine- readable input. Speech reorganization is a board term which means it can recognize almost any body’s voice. Such as a Call Center System designed to recognize many voices.

Processing Devices – The (CPU) is the part of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical logical and input/output operations of the system. The CPU is also known as the brain of the computer. The speed of CPU depends upon the type of used and it is measured in Mega Hertz (MHz).

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Three typical components of a CPU are the (ALU), Memory Unit (MU) and Control Unit (CU):

Arithmetic Logic Unit– In computing, an arithmetic logic unit (ALU) is a digital circuit that performs arithmetic and logical operations. The ALU is a fundamental building block of the central processing unit of a computer. An ALU loads data from input registers and control unit tells the ALU that which operation is to be performed on that data and then the ALU stores its result into an output register.

Most ALU’s can perform the following operations: 1. Logical Operations – (AND, NOT, OR, XOR). 2. Arithmetic Operations – (Addition, Subtraction, Multiplication and Division). 3. Bit-Shifting Operations – (Shifting or Rotating a word by a specified number of bits to the left or right, with or without sign extension). 4. Comparison – (=,<,<=,>,>=).

Memory or Storage Unit – This unit can store instructions, data and intermediate results. This unit supplies information to the other units of the computer when needed. It is also known as internal storage unit or main memory or primary storage or Random Access Memory (RAM).

Its size affects speed, power and capability. Primary memory and secondary memory are two types of memories in the computer. Functions of memory unit are:

 It stores all the data and the instructions required for processing.  It stores intermediate results of processing.  It stores that result of processing before these results are released to an output device.  All inputs and outputs are transmitted through main memory.

Control Unit – The control unit coordinates the input and output devices of a computer system. It fetches the instructions which are given in the form of micro-programs. It directs the operation of the other units by providing timing and control signals. In general, a control unit is a central part of the machinery that controls its operation and entire processing. E.g. in the automation industry, the control unit helps to maintain various functions of a motor . The control unit is the circuits that controls the flow of data through the and coordinates the activities of the other units within it. Control units acts like human nerves system, which does not process data but behaves as a central unit for other data manipulating components.

Output Devices– An output device is a part of computer hardware equipment, used to communicate the results of data processing which are carried out by an information processing system (such as a computer), to the outside world. Output devices carry the results of various operations performed by the user. Some of the devices, which are used to display the processed result or output are as follows -

1. Monitor – The most commonly used output device is monitor, that display all work done and images on its screen. It is also called Visual Display Unit (VDU). A monitor (called a visual display unit) is an electronic visual device used to display the output. The rectangular area of the monitor, its refresh rate and dot pitch, all directly affect the resolution of the display. It can support 256 colors at a time. A VDU normal contains 25 Rows and 80 Columns.

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Resolution – Resolution refers to the clarity of screen and measured by the number of individual tiny colored dots (knows as ), scattered on the screen. Resolution indicates the number of . The smaller the dots pitch is the better the resolution will be.

Types of Monitors

 Cathode Ray Tube (CRT) – The CRT works in the same way as a television. It contains an electron gun at the back of the glass tube. This gun fires electrons in a group of phosphor dots, which is coated inside the screen. When the electron strikes the phosphor dots they glow to give the glass tube.

 Liquid Crystal Display (LCD) – These screens are used in laptops and notebook sized PCs. A special type of liquid is sandwiched between two plates. It is a thin, flat and light weight screen made up of any number of colors or monochrome pixels arranged in front of a light source.

 Liquid/Light Emitted Diode (LED) – LED is an electronic device that emits light when electrical current is passed through it. LEDs usually produces red light, but today’s LEDs can produce RGB (Red, Green, and Blue) light and white light as well.

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 3-D Monitor– 3-D Monitor is a television that conveys depth perception to the viewer. 3-D describes an image that provides that perception of length. When 3-D images are made interactive, user fells involved with the scene and this experience is called .

2. Printer – A Printer is an output device, which produces a hard copy of documents that are stored in an electronic form on physical print media such as paper or transparencies. So printers are the primary output devices used to prepare permanent documents. The speed of a printer is normally rated either by Pages Per Minute (PPM) or by Character per Second (CPS).

Printers can be classified into two broad categories: 1. Impact Printers 2. Non – Impact Printers

Impact Printers – Impact printers rely on a forcible impact to transfer ink to the print media, similar to the action of a typewriter. There is a mechanical contact between the paper and the print head.

The main types of Impact Printer’s are as follows:

 Line Printer – There are impact shaped character printers which capable of printing an entire line at one instead of one or more character at a time. Print quality of line printer is not high.

 Drum Printer – It is an old line printer technology that is used to formed character images around a cylindrical drum as its printing mechanism. When the desired character for the selected position rotated around the hummer line, the hammer hit the paper from behind and pushed it into the ribbon and onto the character.

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 Daisy Wheel Printer – It can print one character at a time. In daisy wheel printer, round disk extends a portion of the wheel making contact with ink ribbon that makes contact with paper for creating the character. This procedure is repeated for each key when it is pressed. These printers are fitted with unchangeable print heads called daisy wheels. To print each character, the wheel is rotated and the appropriate stoke struck against inked ribbon. Daisy wheel printers cannot produce high quality print graphics. The speed of daisy wheel printer is about 100 CPS.

 Dot Matrix Printer – The term dot matrix refers to the process of placing dots to form an image. It uses print heads to shoot ink or strike an ink ribbon to place hundreds to thousands of little dots to form text or images. It prints one character at a time. The speed of dot matrix printer lies between 200 to 600 CPS. The quality of the image is determined by the dots per inch. These printers are slow, noisy and are not commonly used for personal computers. They can print multi-layer forms, which neither inkjet nor printers can print. It can print special characters and graphics. Dot matrix printers do not have fixed character fonts.

Non-Impact Printers – Non-Impact printers are much quiter than impact printers as their printing heads do not strike the paper. Most non-impact printers produce dot-matrix printers. There is no mechanical contact between the paper and the print head. These printers are comparatively faster and produce high quality output. They can be used for printing text and graphics both in black and white and colored.

The main types of Non-Impact Printer’sare as follows:

 Electromagnetic Printer – Electrographic or electro-photographic printers are very fast printers and they fall under the category of page printers. They can produce documents at a speed of over 20000 lines per minute i.e more than 250 pages per minute. The electrographic technology has developed from the paper copier technology.

 Thermal Printer – Thermal Printer paper tends to darken over time due to exposure of sunlight or heat. The standard of print produces poor. Thermal printers are widely used in battery powered equipment such as portable calculators.

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 Electrostatic Printers – Electrostatic Printers are generally used for large format printing. They are favored by large printing shops because of their ability to print fast, making low cost.

 Laser Printers – Laser Printer, the methods of printing is based on principle of electro photography and use a beam of laser light as a photocopy machine. The powered ink (i.e. toner) is transferred to paper to form a text/image pattern and then fixed by heat or pressure. When used to print bulk of papers, the laser printer produces the cheapest cost per printout.

 Inkjet Printer – An inkjet printer fires extremely small droplets of ink onto the paper to create impression of text or image. The printhead of inkjet printers, known as print cartridge, containstiny nozzles (50 or more) through which different colored can be sprayed onto the paper to form the characters or graphic image. Color inkjet printers provide an inexpensive way to print fully colored documents.

3. – It is a output device similar to printer that uses a pen, pencil, marker or other writing tool to make a design. are generally used to generate the map of building and shopping malls. A plotter is a computer printing device for printing vector graphics. In the past, plotters were widely used in applications such as Computer Aided Design (CAD) and other print jobs. Through they have generally been replaced with wide-format conventional printers.

There are two basic types of plotters those that used and those that do not. Drum plotters and flatbed plotters use pens but electrostatic plotters do not use the same.

 Drum Plotter – A drum plotter contains a long cylinder and a pen carriage. The output paper is placed over the drum. The pen is mounted horizontally on the carriage. Both the pen and drum move under the computer’s control to produce the design drawing.

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 Flatbed Plotter – A flatbed plotter consists of a stationary horizontal alt surface on which paper or any other medium is fixed. The pen is mounted on a carriage that can move along the horizontal and vertical axis.  – It mark paper with electrostatic charges and run it through a developing system to create an image. They produce high-quality images and are used by graphic and commercial artists.

4. Speaker – Speaker is an output device that receives the sound in the form of electric current form the sound card and converts it into sound format. Speakers are used for listening to music. (multimedia speakers) are the speakers, which are attached internally or externally to a computer system.

5. Headphones – Headphones are a pair of small or less commonly a single speaker, held close to a user’s ears and connected to a single source such as an audio amplifier, , CD player or portable media player. They are also known as stereo phones, headsets or cans.

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6. Projector – It is an output device, which is used to project information from a computer onto a large screen, so it can be viewed by a large group of people simultaneously. Projectors are widely used for classroom training or conference holes with a large audience. It provides a temporary output display.

7. Speech Synthesizer – Speech synthesizer is used to produce sound from a text and can be implemented in software and hardware. A text-to-speech system converts normal language text into speech.

Computer Memory

The computer memory is one of the most important elements in a computer system. It is the internal or external storage area, which holds the data and instructions during processing in the form of binary numbers. It also relates to many devices and components that are responsible for storing data and applications on a temporary or a permanent basis. Computer memory can be classified into two types:

Memory

Primary Secondary Memory Memory

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 Primary Memory / Main Memory / Temporary Memory  Secondary Memory / Storage Device / Permanent Memory

Primary Memory – It is also known as Main memory. It is the internal storage memory used by computer to holds data and instructions. The primary memory has limited storage capacity. Primary memory holds the data and programs needed at that instant by CPU. Primary memory is volatile in nature i.e it requires constant power supply to motion the current information.

There are two types of Primary memory:  Random Access Memory (RAM)  Read Only Memory (ROM)

RAM – RAM Stand for Random Access Memory. It is the internal memory that can be read from as well as written to. This memory is often associated with volatile types of memory. It can hold data only on temporary basis because it requires a continuous flow of electrical current. If current is interrupted, data is lost. It is an that enables you to access the stored data in a random order constantly.

The two main forms of RAM are:

 Static RAM – It is also written as SRAM. It is a computer memory that requires a constant power flow in order to hold information. SRAM is more expensive and requires more power therefore it is commonly used in cache and video card memory. It is faster than DRAM.  Dynamic RAM – It is also written as DRAM. It stores information in a cell containing a capacitor and transistor, these cells must be refreshed with electric impulses in few milliseconds. This process allows memory to keep charge and hold the data as long as needed.

ROM – ROM Stand for Read Only Memory, information once stored remain fixed, i.e. it cannot be changed. So, ROM can only be read and used. Generally, it contains a set of start-up instructions, i.e. what to do when a computer is turned ON. The contents or ROM remain stored even if power is turned OFF. This memory is often associated with non-volatile types of memory. A ROM cannot be altered once the chip has been made.

ROM is further sub divided into several types:

 PROM (Programmable Read Only Memory) – It is a computer memory chip capable of being programmed after it has been created. But once the PROM has been programmed, the information written is permanent and cannot be erased or deleted.  EPROM (Erasable Programmable Read Only Memory) – It is computer memory chip on which the written information can be changed by exposing to ultra violet light. It is just like a small glass circle that exposes the chip that can be re-programmed.  EEPROM (electrically Erasable Programmed Read Only Memory) – It is a PROM that can be erased and reprogrammed using an electrical charge.

Storage Devices / Secondary Memory– Secondary memory, also known as Secondary Storage or Auxiliary Memory, is the slower and cheaper from the memory. It is a permanent storage device. CPU does not access the secondary memory directly. The content in it must first be copied into the

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RAM to be processed. Secondary memory is nonvolatile in nature. i.e. the information does not get erased even when power is switched OFF and data will not be destructed until and unless the user erases it.

Secondary Memory Devices Include Magnetic Disks Optical Disks Solid State Floppy Disk Pen / Flash Drive Digital Versatile Disc Magnetic Tape Blue-ray Disc

Floppy Disk – Floppy Disk Drive is a computer disk drive that enables a user to save data on removable diskettes. This portable storage device is a rewriteable media and can be reused a number of times. It is made of with magnetic coating on it. It is round in shape and is covered by square plastic jacket. Floppy disks are commonly used to move files between different computers. Although 8” disk drives made available in 1971 were the first real disk drives, the first 1" 1" widely used floppy disk drives were the 4”, 5 floppy disk drives, which were later replaced with 3 4 2 floppy disk drives. However, today these drives are being replaced with CD-R and other writeable disc drives and flash drives.

ퟏ" 5 diameter-floppy has a capacity of 1.2 MB. ퟒ

ퟏ" 3 diameter-floppy has a capacity of 1.44 MB. ퟒ

Hard Disk Drive – A Hard Disk Drive (HDD) is a non-volatile, random access digital data storage devices. It is a data storage device used for storing and retrieving digital information using rotating disks (platters) coated with magnetic material. All programs of a computer are installed in hard disk with in a particular drive.

It consists of a spindle that holds non-magnetic flat circular disks, called platters, which hold the recoded data. Each platter requires two read/write heads that is used to write and read the information from a platter. All the read/write heads are attached to a single access arm so that they cannot move independently. The information is recoded in bands, each band of information is called a track. Each platter has the same number of tracks and track location that cuts across all platters is called a cylinder. The tracks are divided into pie-shaped sections known as sectors.

Magnetic Tape – It is a medium of data storage, made up of a magnetic material. It is storage medium on a large open feel or in a smaller cartridge or cassette (like a music cassette). It is used for those applications that are based on sequential data processing i.e, it is a sequential data access medium.

Due to this (sequential data access) nature, these tapes are not suitable for data files that need to be revised or updated often. They are generally used to store backup data or that type of data, which is not frequently used or to transfer data from one system to another.

Compact Disc (CD) – CD is an optical media that is used to store digital data. The compact discs are relatively cheap storage devices.

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Compact Disc (CD) are categorized into three main types:

 CD-ROM (Compact Disc – Read Only Memory) – Data is recorded permanently on the surface of the optical disk through the use of laser. The recorded content cannot be changed or erased by users. It is also called WORA (Write Once Read Many) disc. It is capable of storing large amount of data – up to 1GB, although the most common storage capacity is 700 MB.  CD-R (Computer Disc – Recordable)– Data can be written on these discs only once. The data once stored in these discs cannot be erased.  CD-RW (Compact Disk – Rewriteable) – It is an erasable disc. CD-RW is used to write data multiple times on a disc by the use of format feature.

Digital Video Disk (DVD) – Digital Video Disc (DVD) is also known as Super Density (SD) Disc. A DVD is an storage media manufactured for the first time by Philips, Sony, Toshiba and Panasonic in 1995. DVDs offer higher storage capacity than compact disc while having the same dimensions.

Depending upon the disk type, DVD can store several Gigabytes of data (4.7 GB – 17.08 GB).

DVDs are primarily used to store music or movies and can be played back on your television or on the computer too. They are not rewriteable media.

DVDs come in three varieties: 1. DVD ROM (Digital Video Disc – Read Only Memory) 2. DVD-R (DVD – Recordable) 3. DVD-RW (DVD – Rewritable)

Blue-ray Disc – Blue-ray Disc (Official Abbreviation BD) is an optical disc storage medium designed to recapture the data normally in DVD format. Blue-ray Discs contains 25 GB (23.31 GB) per layer space. The name blue-ray disc refers to the blue laser used to read the disc, which allows information to be stored at a greater density.

Blue-ray can hold 5 times more data than a single layer DVD.

The variations in the formats are as follows:  BD-ROM (Read Only) for pre-recorded content.  BD-R (Recordable) for PC data storage.  BD-RW (Rewritable) for PC data storage.  BD-RE (Rewritable) for HDTV Recoding.

Pen/Flash/Thumb Drive – A flash drive is a data storage device that consists of (USB memory / key memory) with an integrated, Universal Serial Bus (USB) interface.

USB flash drives are typically removable, rewritable and physical much smaller than a floppy disk. A USB flash drive, data stick, thumb drive and a pen drive is a portable drive that is same as the size of your thumb that connects to the computer USB port.

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Today’s flash drivers are available in various storage capacities as 256 MB, 512 MB, 1 GB, 4 GB, 16 GB, 32 GB and 64 GB etc. Flash drives are widely used as an easy and small medium to transfer and store the information from the computers. History of Computer

The seeds of a computer were sown around 3500 years ago, when a huge stone-carved structure, spread in a circular pattern over the ground, was used to perform astronomical calculations by considering the position of sun rays. This stone-carved structure was known as Neolithic computer, and the mode of calculation was known as Stonehenge Calculation. The Neolithic computer is oldest computer found till date.

Computers were preceded by many devices developed by mankind for their computing requirements. However, many centuries elapsed before technology was adequately advanced to develop computer. The key development that took place till the first computer was developed are as follows:

The concept of computer in medieval times was limited to a machine by which some calculations or computing could be performed. Let us now explore how computer has evolved from a simple calculating machine to a multitasking device over the centuries.

Abacus – The term Abacus came form a calculating tool used in ancient days by the merchants of Asian and African continents to perform arithmetic calculations. Abacus was constructed as a bamboo frame containing beads sliding over wires.

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Pascal’s Medicinal Calculator – Blaisé Pascal, the French mathematician, laid the foundation of automatic computing blasé, Pascal used has adding machine simply for addition and subtraction. The machine consisted of gears, wheels and dials with this calculation could be performed by dialing these series of wheels carrying the number 0 to 9 numbers that each wheel has 10 segments and when a wheel completed one rotation the next wheel would move by one segment.

Charles Babbage – Charles Babbage, a professor of mathematics at Cambridge University, Invented a machine called differential engine which could evaluate accurately algebraic expression and mathematical tables, correct up 20 decimal places. Later his development, analytical machine, which can perform addition at the rate of 60 per minute. For technical limitations of that age Charles Babbage could not see his invention operational. However, and surprisingly enough, today’s computer has building blokes, similar to what as the tastier of computing with him, disciple and co- worker, Lady Lovelace is remembered with reverence the first programmer of the world.

Difference Engine – 1822 – The name is derived from the method of divided differences. It was designed to tabulate polynomial functions. This machine is capable of calculating various algebraic functions accurately near 20 places after decimal.

Analytical Engine – 1837 – First General Purpose Computer. It was a decimal machine used sign and magnitude for representation of a number.

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Mark I – In 1934, Harved Professor Howard Aiken developed an automatic calculating machine, which was called Mark-I digital computer, its internal operation was automatically controlled. The basic drawbacks of the mechanical and electromechanical computer were.

Computer Generation

The development of computers was characterized by phases of growth, which have come be called as Computer Generations. Major technology developments in each generation led to smaller, cheaper, more powerful and more efficient computers.

First Generation (1942-1955) – Vacuum Tubes: The First Generation Computers used Vacuum Tubes for circuitry and Magnetic Drums for memory and were big in size covering entire rooms. They were very expensive to operate and consumed lots of electricity. The system used to get heated very quickly which was often the cause of errors. First generation computers performed operations on machine language which is the lowest-level programming language understood by computers. They could perform only one single task at a time. Input was based on punched cards and paper tape and output was displayed on printouts. The UNIVAC and ENIAC computers are examples of First Generation Computing devices.

Second Generation (1955-1964) – Transistors: The Second Generation Computers used transistors which replaced Vacuum Tubes. The transistor was far superior to the vacuum tubes, allowing computers to become smaller, faster, cheaper, and more energy-efficient and more reliable than their first-generation predecessors. Transistors also generated a great amount of heat that exposed the computer to damage but it was a vast improvement over the vacuum tube. Second-generation computers used symbolic or assembly language, which allowed programmers to specify instructions in words. These were also the first computers that stored their instructions in their memory on core magnetic technology.

Third Generation (1964-1975) – Integrated Circuits: The Third Generation Computers were based on the Integrated Circuit (IC). This Integrated Chip became the basis of the third generation. Transistors were shrunk and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers. Users interacted with these computers through keyboards and monitors. They were interfaced with an operating system, which allowed the device to run many different applications at one time. For the first time computers become accessible to a mass audience as they were smaller and cheaper than their predecessors.

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Fourth Generation (1975-Present) – : The Fourth Generation Computers used microprocessor where thousands of integrated circuits were built onto a single silicon chip with the introduction of VLSI (Very Large Scale Integration). What in the first generation filled an entire room cloud now fit in the palm of the hand. The Intel 4004 chip which was development in 1975 contained all the components of the computer from the central processing unit and memory to input/output controls. In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the . As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet. Fourth Generation computers also saw the development of GUI’s, the mouse and handheld devices.

Fifth Generation (Present and Beyond) – Artificial Intelligence: Fifth Generation Computer devices are based on Artificial Intelligence (AI) and are still in development. These are some applications, such as voice recognition systems and robots that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. The goal of fifth- generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization. These devices will radically change the face of computers in years to come. Types of Computers: Based on Size

A system is group of integrated parts that have a common purpose of achieving an objective. Computers can be broadly classified by their speed and computing power. There are five types of computer systems: PC Personal Computers, Micro Computers, Mini Computers, Mainframe Computers and Super Computers.

Sl. No. Type Specifications It is a single computer system 1. PC () having moderately powerful microprocessor. It is also a single user computer system which is 2. similar to personal computer but have more powerful microprocessor. It is a multi-user computer system which is capable of 3. Mini Computer supporting hundreds of users simultaneously. It is a multi-user system which is capable of supporting hundreds of users 4. Main Frame simultaneously. Software technology is different from minicomputer. It is an extremely fast computer which can execute 5. Super Computer hundreds of millions of instructions per second.

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1. PC (Personal Computer) – A PC can be defined as a small, relatively inexpensive computer designed for an individual user. PCs are based on the microprocessor technology that enables manufactures to put an entire CPU on one Chip. Business use Personal Computers for word processing, accounting, desktop publishing, and for running spreadsheet and database management applications. At home, the most popular use for personal computers is playing games and surfing Internet. Although Personal Computers are designed as single-user systems, these systems are normally linked together to form a network. In terms of power, now-a-days High-end models of the Macintosh and PC offer the same computing power and graphics capability as low-end by , Hewlett-Packard, and Dell.

2. Workstation – Workstation is a computer used for engineering applications (CAD/CAM), desktop publishing, software development, and other such types of applications which require a moderate amount of computing power and relatively high quality graphics capabilities. Workstations generally come with a large, high-resolution graphics screen, large amount or RAM, inbuilt network support, and a graphical . Most workstations also have a mass storage device such as a disk drive, but a special type of workstation, called a diskless workstation, comes without a disk drive. Common operating systems for workstations are UNIX and Windows NT, Like PC, workstations are also single-user computers like PC but are typically linked together to form a local- area network, although they can be used as stand-alone systems.

3. Mini Computers – It is a midsize multi-processing system capable of supporting up to 250 users simultaneously. This is a generally purpose computer. Minicomputers are also known as Midrange Computers, are refrigerator sized machines. A typical mini system is more expensive than a PC and it has greater speed and storage capacity. This computer system is usually designed to simultaneously handle to needs of multiple users. For example, production departments use minicomputers to monitor certain manufacturing processer and assembly-line operations.

4. Mainframe – Mainframe is very large in size is an expensive computer capable of supporting hundreds or even thousands of users simultaneously. Mainframe executes many programs concurrently and supports many simultaneous executions of programs. A mainframe is another form of a computer system that is generally more powerful than a typical mini system. They are used in large organizations for large-scale jobs. For example, insurance companies use mainframes to process information about millions of policyholders.

5. Super Computer – Super Computers are one of the fastest computers currently available. Super computers are very expensive and are employed for specialized applications that requires immense amount of mathematical calculations (number crunching). For example, weather forecasting, scientific , (animated) graphics, fluid dynamic calculations, nuclear energy research, electronic design, and analysis of geological data (e.g. in petrochemical prospecting).

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Types of Computers – Working Principle / Computational Method

1. – An Analog computer is a form of computer that uses of continues physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved. Eg: Thermometer, Speedometer, Petrol Pump Indicator, Multimeter.

2. Digital Computer – A computer that performs calculations an logical operations with quantities represented as digits, usually in the binary number system.

3. Hybrid Computer – A combination of computers those are capable of inputting and outputting in both digital and analog signals. A hybrid computer system setup offers a cost effective method of performing complex simulations. The instruments used in medical science lies in this category.

Number System

Computers cannot understand what you give as input. Input is converted into a form so that computers be also to understand it. A computer can only understand positional number system. Positional number system contains few symbols called digits. Each digit is used to represent a value depending on its base and position, they appear in a number. Base is referred as total number of the digits available in a number system.

Following number system are give here:

Number System

Binary Decimal Octal Hexadecimal

Binary Number System – Binary number system consists of only two digits 0 and 1. All data is converted in the form of 0 and 1 (Combination of 0 and 1). Digital computes work on binary system. Base of binary number is 2, which plays a vital role in converting a number into binary or its actual form.

Binary Number System Characteristics of binary number system are as follows:  Uses two digits, 0 and 1.  Also called base 2 number system  Each position in a binary number represents a 0 power of the base (2). Example 20  Last position in a binary number represents a x power of the base (2). Example 2x where x represent the last position -1.

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Example

Binary Number: 101012 Calculating Decimal Equivalent: Step Binary Number Decimal Number 4 3 2 1 0 Step 1 101012 ((1X2 )+(0X2 )+(1X2 )+(0X2 )+(1X2 ))10

Step 2 101012 (16+0+4+0+1)10

Step 3 101012 2110

Note: 101012is normally written as 10101.

Decimal Number System – The number system that we use in our day-to-day life is the decimal number system. Decimal number system has base 10 as it uses 10 digits from 0 to 9. In decimal number system, the successive positions to the left of the decimal point represent units, tens, hundreds, thousands and so on.

Each position represents a specific power of the base (10). For example, the decimal number 1234 consists of the digit 4 in the units position, 3 in the tens position, 2 in the hundreds position, and 1 in the thousands position, and its value can be written as

(1X1000) + (2X100) + (3X10) + (4X1)

(1X103) + (2X102) + (3X101) + (4X100)

100 + 200 + 30 + 4

1234

As a computer programmer or an IT professional, you should understand the following number systems which are frequently used in computers.

S.N. Number System and Description Binary Number System 1 Base 2. Digits used : 0,1 Octal Number System 2 Base 8. Digits used : 0 to7 Hexa Decimal Number System 3 Base 16. Digits used: 0 to 9, Letters used: A-F Decimal Number System Characteristics of binary number system are as follows:  Uses two digits, 0 and 1.  Also called base 2 number system  Each position in a binary number represents a 0 power of the base (2). Example 20  Last position in a binary number represents a x power of the base (2). Example 2x where x represent the last position -1.

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Example

Binary Number: 101012 Calculating Decimal Equivalent:

Step Binary Number Decimal Number 4 3 2 1 0 Step 1 101012 ((1X2 )+(0X2 )+(1X2 )+(0X2 )+(1X2 ))10

Step 2 101012 (16+0+4+0+1)10

Step 3 101012 2110

Note: 101012is normally written as 10101.

Octal Number System – This number system contains 8 symbols to represent a number. So base for octal number is 8 and digits are used form 0 to 7. If any number contains other digit (like 9, 10 and 80 on) then it is not a octal number. Numbers like 129, 228 are not octal number because 9 and 8 digits does not belong to octal number.

Octal Number System Characteristics of octal number system are as follows:  Uses eight digits, 0,1,2,3,4,5,6,7.  Also called base 8 number system.  Each position in an octal number represents a 0 power of the base (8). Example 80  Last position in an octal number represents a x power of the base (8). Example 8x where x represent the last position -1.

Example

Octal Number: 125708 Calculating Decimal Equivalent:

Step Binary Number Decimal Number 4 3 2 1 0 Step 1 125708 ((1X8 )+(2X8 )+(5X8 )+(7X8 )+(0X8 ))10

Step 2 125708 (4096+1024+320+56+0)10

Step 3 125708 549610

Hexadecimal Number System – There are 16 unique digits available in this number system. These are 0 to 9 and A to F, where A denotes 10, B denotes 11, C denotes 12, D denotes 13, E denotes 14 and F denotes 15. As, this number system has 16 digits so it is called base 16 number system also. Each position of the hexadecimal number represents a successive power of 16.

Hexadecimal Number System Characteristics of hexadecimal number system are as follows:

 Uses 10 digits and 6 letters, 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F.  Letters represents numbers starting from 10.A=10.B=11,C=12,D=13,E=14,F=15.  Also called base 16 number system  Each position in a hexadecimal number represents a x power if the base (16). Example 160  Last position in a hexadecimal number represents a x power of the base (16). Example 16x where x represents the last position -1.

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Example

Hexadecimal Number: 19FDE16 Calculating Decimal Equivalent:

Step Binary Number Decimal Number 4 3 2 1 0 Step 1 19FDE16 ((1X16 )+(9X16 )+(FX16 )+(DX16 )+(EX16 ))10 4 3 2 2 0 Step 2 19FDE16 ((1X16 )+(9X16 )+(15X16 )+(13X16 )+(14x16 ))10

Step 3 19FDE16 (65536+36864+3840+208+14)10

Step 4 19FDE16 10646210

Note: 19FDE16 is normally written as 16FDE.

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