Sunday, July 31, 2011

What are Dual Devices or Both Input/ Output Devices

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The devices that can be used to perform both functions -input and output- are called Dual Devices. These devices are also called Dual Purpose Devices or Both Input/Output Devices. With the help of a dual purpose device, we can enter data into computer as well as we can output data from the computer to outside world.  For example, Dual devices include:  Touch Screen Monitor, Modem, Network Interface Card, Sound card, Hard disk drive, Floppy disk Drive, Magnetic Tape Drive CD-Writer and DVD-Writer etc. These are also called Input/output devices, because they perform both functions.
  • Touch Screen Monitor

Touch Screen Monitor is an input/output device. It uses a special touch sensitive screen. The User can enter data by touching icons or menus on the screen. As soon as the user selects a command from menu, output is displayed on screen. Commonly touch screen monitors use sensors to detect touch of finger.
  • Modem
Internal modem

External modem

Modem stands for Modulator / Demodulator. Modem is a communication device.  It performs two functions: Modulation (converting digital signal into digital signal) and Demodulation(converting analog signal to digital signal). It makes possible receiving data from internet into our computer (input) and sending data from our computer to another computer on internet(output). Modem sends and receives data from one computer to another through telephone lines. It links your personal computer to the Internet through your ISP (Internet Service Provider). A telephone line supports only analog signals, whereas computer accepts only digital signals. So when a computer wants to send data to another computer, digital data is converted into analog data before placing on telephone line. The process of converting digital signal into analog signal is called Modulation. Similarly, on the receiving computer, modem converts analog data (from telephone line) into digital data, before it is entered into receiving computer. The process of converting analog signal into digital signal is called Demodulation.  
  • NIC - Network Interface Card
NIC or LAN card

NIC stands for Network Interface Card. It is used to link network computers for transmitting data. With the help of NIC our computer can receive  data, instructions and information from another computer (input). NIC will also be helpful to send data from our computer to another computer on the network (output). NIC is also called a LAN card, local area network card or LAN adapter.

  • Sound Card
Sound card or audio card

A sound card is a computer component that facilitates the input and output of audio signals to and from a computer. A speaker produces audio output with the help of sound card. In addition we use microphone to input our voice into computer with the help of sound card. 
  •     Hard disk Drive

Hard disk drive is an input/output device. It has read/write heads to read data from hard disk(input) and to write data to hard disk(output).
  • Floppy disk Drive

Floppy disk drive is an input/output device. It has read/write heads to read data from floppy disk(input) and to write data to floppy disk(output).   
  • Magnetic Tape Drive

Magnetic Tape drive is an input/output device. It has read/write heads to read data from magnetic tape(input) and to write data to magnetic tape(output).
  • CD-Writer / CD-Recorder
CD-Writer is an input/output device. It is used to store data on CD. It is used to read data from CD(input) and to write data to CD(output).
  • DVD-Writer / DVD-Recorder

DVD-Writer is an input/output device. It is used to store data on DVD. It is used to read data from DVD(input) and to write data to DVD(output).

Monday, July 25, 2011

Explain Parts of CPU and its Working

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CENTRAL PROCESSING UNIT / CPU / Microprocessor / Processor

Central processing unit is the brain of computer. It is also called CPU or processor. Processor is used to process data according to given instructions. It performs arithmetic and logical operations on data. It controls all activities of different parts of a computer. As brain in human body controls all other parts of body and takes decisions, CPU controls all other parts of the computer and their working. A CPU has three basic parts: Arithmetic Logic unit, Control unit and Registers.
Figure: Microprocessor or Processor or CPU or Central Processing Unit


ALU performs data processing according to given instructions. All computations are done in this unit. ALU is the real place in computer where actual execution of instructions takes place. ALU may be further categorized into two sections according to their function:
ARITHMETIC SECTION of ALU performs arithmetic operations like addition, subtraction, multiplication and division on data.
LOGIC SECTION of ALU performs logical operations like comparison between two values. For example, 10>5 will give TRUE answer. And 5<1 will give FALSE answer. Control unit sends data and instruction to perform calculation on the data to the ALU. ALU then performs this calculation. 


Control unit controls all over operations of different parts of computer. For example it takes data and instructions from input unit and stores it into memory. It sends data to ALU for processing. It takes results from ALU and sends it to output device. It can also store results in memory. Control unit performs all these functions by giving commands to relevant part of the computer.
Control unit performs following four functions for executing instructions of a computer program.

  1.  Fetching: obtaining instruction from memory
  2.  Decoding: understanding this instruction
  3.  Data Fetching: If needed, obtaining data from memory
  4.  Executing: Control unit sends the instruction and data to ALU for taking suitable action on the instruction


A register is a very small and temporary memory area in ALU. It holds instruction and data as long as it is being processed by CPU. When instruction and data is fetched from memory then it is stored in a register. ALU contains a number of registers for example AX, BX, CX, DX etc. A Register may be of 8 bits, 16 bits, 32 bits or more.

Thursday, July 21, 2011

Explain Different Types Of Output Devices

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Output devices

Out put devices are used to display results of processing to the user. They perform the following functions:
  1.  Receive results from memory
  2.  Convert data into human readable form
  3.  Display results to the user

Examples include: Monitor, printer, plotter, speaker, and multimedia projector.

1.    Monitor
LCD Monitor

CTR Monitor

Monitor is the most commonly used output device used to display results of processing. It has a TV like shape. Pictures on monitor are formed with picture elements called PIXEL. Monitors may be Monochrome that will display results in Black & White. Color Monitors are also available. They display results in multi colors. Monitor produces soft copy output.

2.    Printers

Printers are used to produce hard copy out put. They print processing results on paper. Printers are divided into two main categories:
·    Impact Printers
·    Non Impact printers

Impact Printers.

These printers print with striking of hammers or pins on ribbon. For example Dot Matrix printer and daisy wheel printers are impact printers.

Non-Impact Printers.

These printers do not use striking mechanism for printing. They use electrostatic and laser technology. Quality and speed of these printers is better than Impact printers. For example Laser printer and Inkjet printers are non-impact printers.

3.    Speaker
Speakers for Desktop computer

Speaker produces sound output. We can listen recorded voices, sounds or music with the help of speaker. Speaker produces sound output with the help of sound card.

4.    Plotter

Plotters are used to draw different designs of buildings or internal structure of machines. Mostly Engineers and Architects use plotters.

5.    Multimedia Projector.
Multimedia Projector

Multimedia projector is used to produce computer output on a big screen. These are used in meeting rooms or in classrooms of educational institutes.

Wednesday, July 20, 2011

What are Different Types of Input Devices

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Input devices are used to enter data and instructions into computer memory from external world. Examples include: Keyboard, Mouse, Track ball, Track Pad, Joy stick, Touch Screen, Light pen, Touch Screen, Scanner, Digital Camera, Microphone, Graphics tablet. They perform three main functions

1. Receive data from user
2. Convert data into binary form [the language of 0 and 1 also called the machine language. Machine language   is the only language, a computer can understand directly.]
3. Provide converted data to computer memory for processing

1.    Key board

Keyboard is the most familiar input device. It is most widely used input device to enter data and instructions into the computer. Keyboard has a set of keys like a typewriter. It has alphabetic keys for A,B,C…Z or a,b,c,…z. It has numeric keys like 0,1,2,3,…9. It has function keys F1,F2,…F12 used to perform specific tasks.
It has other keys used for editing like Delete, Backspace, Home, End, etc.

2.    Mouse

Mouse is an input device used to control motion of pointer on screen. A mouse has two or three buttons called Left, Right and Middle button. Buttons are used to perform different functions. It has a rubber or metal ball inside its body. Mouse is rolled over a flat surface called mouse pad. The movement of ball is detected by internal circuits of mouse. These circuits convert this movement into digital signals, which are sent to computer. Mouse is used in graphical applications. It is also used for playing video games on computer.

3.    Track Ball

Track Ball is an input device like a mouse. It is used in Lap top computers to control motion of pointer on screen. It is a pointing device like upside down mouse. It has a ball on its upper side. This ball is moved by fingers or thumb and the pointer moves accordingly on screen.

4.    Track Pad

Track pad is a pointing input device. It is used in Lap top computers to control motion of pointer on screen. Track pad is a stationary input device. It has a flat surface of 1.5 to 2 square inch. Finger is moved on this surface to move pointer on screen.

5.    Joy stick

Joystick is an input device used to play games on computer. It is used to control motion of an object quickly in game with the help of a hand held stick. This stick can be moved forward, backward or side ways. This stick is mounted on a ball. When stick is moved then ball is moved and signals are sent to the computer.

6.    Light Pen

Light pen is an input device consisting of a special pen that is connected to a computer's monitor. The user points at the screen with the pen and selects items or chooses commands either by pressing a clip on the side of the light pen or by pressing the light pen against the surface of the screen (the equivalent of performing a mouse click).

7.    Microphone

Microphone is an input device used to enter sounds into the computer. We can record sounds in computer with the help of microphone and sound card.

8.    Scanner

Scanner is an input device. It is used to save pictures or text on paper into computer memory. It converts picture or text on paper in to binary form and saves it in computer memory. With the help of scanner we may save our time to type a lot of text. For example, if we have a book and wish to enter the whole text of book in to computer. It will be a long, tedious and time consuming job. But if we use a scanner, we can do this with in less time. We can scan each page of book. Editing of the scanned text is also possible. So our job will become very easy with the help of a scanner.

9.    Graphics tablet / digitizer

A graphics tablet consists of a special pen called stylus and a flat pad. The image is created on the monitor screen as the user draws it on the pad with the help of stylus (special pen). Graphics tablet is also called a digitizer. 

10. Touch Screen

In ATM and in latest smart phones, touch screen is used to receive input from the user. The user enters data by the touch of his finger on different menu options or icons present on touch screen.

11. Digital Camera

A digital camera is one of the latest input devices. We can take pictures with he help of digital camera. These pictures are saved on digital camera's internal memory. There is no need of a film role as used in traditional cameras. Later on we can easily input these pictures with the help of a data cable into computer's memory. Latest digital cameras can take still snapshots and can record video as well.

Tuesday, July 19, 2011

What are Different Types of Hardware

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What is Hardware?
The physical parts of a computer are called hardware. Hardware can be touched or seen by us. For example, hard disk, mouse, keyboard, CD, CD-ROM Drive, Floppy Disk, Speakers, Modem and Printers - all are computer hardware.Different types of hardware components are as follows:

1.    Input devices

Input devices are used to enter data and instructions into computer. Examples of input devices are:
Keyboard, mouse, scanner, digital camera etc.



2.    The Central Processing unit
Central processing unit is the brain of the computer. It is also called CPU or Processor. Intel is the leading manufacturer of microprocessors. For example, Intel Pentium IV 3.2 MHz is an example of a cpu.
CPU or Microprocessor or simply Processor

3.    Output devices
 Output devices are used to show the results of processing to the user. For example monitor, printer, plotter, speaker and data projector are out put devices.

LCD Monitor


4.    Memory chips
Memory is a component of a computer to store data and instructions. RAM is an example of memory chip. It stands for Random Access Memory. Every program to be executed is loaded in RAM from hard disk. CPU executes the programs loaded in RAM.RAM is a temporary memory, all data and programs are lost from RAM, when computer is turned off. ROM stands for Read Only Memory. ROM is permanent memory chip; we cannot change or delete its contents. It is a non-volatile memory.
ROM shape 1


ROM shape 2

5.    Storage devices
Storage Devices are used to store large amounts of data permanently. For example: hard disk, CD, DVD etc. are storage devices. Moreover, Zip Disk and Floppy disk is also considered as storage devices.
Hard Disk


Floppy Disk

ZIP Disk

 6.    Communication devices
Communication devices are used to send and receive data from one computer to another. For example Modem, Network Interface Card, Hub, switches, routers, gateways and even networking cables are included in communication devices
Wireless PCI NIC Card

External Modem
LinkSys Router

Differentiate between Analog and Digital Computers

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The differences between analog and digital computers are as follows:

Analog Computers Work on continuous values. Digital computers Work on discrete values.

Analog Computers have low memory. Digital computers have a very large memory

Analog computers have Slow speed. Digital computers have fast speed.

Analog computers are less reliable. Digital computers are more reliable.

Analog computers used in engineering and science and medical fields. Digital computers are used in all fields of life.

Analog computers are used to calculate / measure analog quantities like speed and temperature. Digital computers are used to calculate mathematical and logical operations. It can solve addition, subtraction, division, multiplication and other mathematical and statistical operations.

Analog computers provide less accurate results. Digital computers provide 100% accurate results.
8 Normally Analog Computers are specific purpose Digital Computers are general purpose
9 Analog computers are difficult to use Digital computers are easy to use
10 Examples of Analog computers are: thermometer, analog clock, speedometer etc. Examples of digital computers are:
Personal Computer, laptops, smart phones etc.
Further Suggested Reading:

Saturday, July 16, 2011

Uses Of Computer In Industry

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Computers are used in industry in different types of systems. Computer-controlled robots are used to perform many complicated jobs in industry. Robots are computer controlled programmable machines. They can perform mechanical jobs, too, like pick and place different parts, welding or painting cars etc.
  •  Automated Production Systems
Today, computer-controlled robots are used to assemble cars. No doubt, these systems work faster than human beings. Another popular and efficient use for computer controlled robots is in the field of spray painting. The consistency and repeatability of a robot's motion have enabled near perfect quality painting while at the same time wasting no paint and leaving no place without paint.
Perhaps the most popular applications of robots are in industrial welding. The repeatability, uniformity quality, and speed of robotic welding is unmatched.
Computer controlled Robots can be found in the manufacturing industry, the military, space exploration, transportation, and medical applications.
  •   Design Systems
Computer programs are used to design the model of a product on the computer. This process is called Computer Aided Design or CAD. Due to CAD, we can test the designed product with the help of computer. When the design is completed successfully, the actual product is manufactured.
Further Suggested Reading:
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