1.1.5 HARDWARE & SOFTWARE

Hardware

Def:

  The physical, tangible parts of the computer are known as the hardware.

Hardware can be broadly categorized into four:

a)      Input Devices

b)     Processor Devices

c)      Output Devices

d)     Storage Devices

Input Devices:

1.      Keyboard:   It is the main Input Device attached to our system to instruct the computer to what to do and also used for typing purpose.

 Fig 06: Keyboard

Its typing alphabets are similar to that of type writer but it has some optional keys which are

F Functional Keys

F Cursor Control Keys

F Numeric Key Pad

F Shift Keys

F Enter, Pause, Tab, Esc, Print Screen, Delete, Back Space etc.

2.      Mouse: A mouse is a hand held pointing Device that allow user to control computer System without typing any command or Instruction from the Keyboard.  It has three main parts

F Left Click

F Right Click

F Scroll Bar

 

                     Fig 07:  Mouse

3.      Scanners:   A scanner is a device that can transfer an image of a photograph or written information to the computer. It acts like a photocopy machine. Just Instead of making another copy of it on to the paper, it stores it in the computer. Scanner can scan typed, handwritten text, graphs, diagrams and photographs.

Fig 08: Scanner.

Processor Device:

C.P.U. (Central Process Unit) :

It is regarded as brain of Computer. The CPU provides the fundamental commands and instructions for the environment of the Computer.

The major components of CPU are

F Arithmetic Logic Unit (ALU)

F Control Unit (CU)

F Memory Unit.

Fig 09: Block Diagram

1. Arithmetic Logic Unit:  The Arithmetic logic unit performs arithmetic operations such as Addition, Subtraction, Multiplication and Division etc and some logical operations like comparison of Values.
2. Control Unit  Control Unit directs and coordinates the activities of the entire computer which include controlling the Input/Output units, the operations of ALU and transfer the data from the main memory
3. Memory Unit: The data and Instruction that are entered into the system has to be stored inside the computer before the actual processing takes place. Similarly the final result produced by the computer also has to be stored before they passed to the output unit.

Output Devices:

1.      V.D.U. (Visual Display Unit):  It is also called Monitor. It works like a Television, displaying text characters and graphics in color. The image that we see at the screen of Monitor is made up of Tiny Dots called Pixels. It is made up of C.R.T. (Cathode Ray Tube) is similar to Picture tube in Television Sets. Modern Monitors are made up of L.C.D. (Liquid Crystal Display) screen.

2.      Printers:  A hardware device that produce text or graphics output. Printers are grouped broadly into either Impact or Non-Impact printers

F Impact Printers: A printer that has direct mechanical contact with the print medium (Paper) to create an image. Example:  Dot Matrix, Daisy Wheel

F Non-Impact Printers: The printer that does not have direct contact with the print medium falls under this category. Example: Inkjet Printers, Laser Printers

Storage Device:

1.      Floppy disk:   A floppy disk is used to store data permanently. It has a flexible disk coated with magnetic material and is enclosed in a plastic cover. Floppy disks of 3 ½ inch diameter have a storage capacity of 1.44MB. The FDD (floppy disk drive) has a read/write head which reads/writes data on to the disk. The disk rotates at 360rpm while reading or writing on to it. Figure below shows the floppy disk.   
              Data are stored in a floppy disk in concentric circles known as tracks. Tracks are divided into many storage locations called sectors. Tracks and sectors on a disk are identified by the disk drive through formatting. Formatting is a process by which the operating system program controls the disk drives by removing the old data and sets up each track and sector. The root directory will be created in the disk during formatting and the users create other directories. Information is stored in the form of files. A file allocation table (FAT) is used by the operating system to identify the files stored in the disk.

 Fig 10: Floppy disk

2.      Hard Disk: Hard disk is a reliable and permanent storage disk. It has a set of metal disks coated with magnetic material and are mounted on a central spindle which rotates at 7200 rpm. The HDD has a set of read/write heads which are mounted on an arm. Latest hard disks are available with a storage capacity of more than 40GB.  A hard disk has a collection of several (say 6 or 7) hard disk platters staked one above another to have a high storage capacity.

          A collection of tracks across all the disks is called cylinder. In order to read a specified file, the access mechanism with the head moves to the specified cylinder.

         The advantages of a hard disk are high storage capacity, high speed of operation and reliable media mainly in personal computers. External disturbances to the drive may lead to the damage of disk surface or read/write head. This is a major disadvantage in a hard disk.     

Fig 11: Hard disk

3.      CD ROM: Compact Disk (CD) is an optical disk used to store data permanently. It is the most reliable storage media available today. Data stored on a compact disk cannot be erased. The CD drives commonly available are read only. Read/Write CD drives are also available but are expensive. Storage capacity of CD is 700MB. Figure shows a CD-ROM.

      In the optical disk, a high power laser beam is used to record data by burning tiny pits in the surface of the hard plastic disk. To read the data, a low power laser beam is used to scan the disk surface. When the laser beam reflects from the smooth surface of the disk it is interpreted as a 1 bit and when the beam enters the tiny pits it is interpreted as a 0 bit.

     The major advantages of the optical disk are high storage capacity and high quality recording of graphical images and sound. These are used commonly nowadays. CAD and structural drawings used by architects and engineers are generally stored in compact disks. It is also used in high quality music recording, multimedia and educational applications.

 Fig 12: CD-ROM

 

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Components of a personal computer:

A personal computer commonly available  today comprises a processor (like Pentium IV), a keyboard, a mouse, a floppy disk drive(FDD), a hard disk drive(HDD), a compact disk drive (CDD) a color monitor, RAM(Random Access Memory) and ROM(Read Only Memory). The microprocessor/CPU, RAM, ROM and other supporting circuitry are interconnected on a single board called mother board.

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Software:

Def:

  The set or series of instructions given by user, called program, used to run the hardware, is known as software.  

The following are the two major categories of software under which different types of computer programs can be classified:

·         System software

·         Application software

Fig 13: Layered Architecture

The figure shows a layered architecture, which represents different components of a computer such as hardware, system software, application software, and user in a hierarchical manner.

System Software

Ø  System software refers to a computer program that manages and controls hardware components of a computer system.

Ø  The system software is also responsible for the proper functioning of the application software on a computer system.

Ø  The system software includes general programs, which are written to provide an environment for developing new application software using programming languages.

Ø  The following are the various functions of system software:

o   Process management

o   Memory management

o   Secondary storage management

o   I/O system management

o   File management

Application Software

Ø  Application software is a computer program that is executed on the system software.

Ø  It is designed and developed for performing specific tasks and is also known as end-user program.

Ø  There are six basic types of application softwares:

o   Business software: word processors, spreadsheets, database programs

o   Communication software: allows computers to communicate with other computers like fax software, Novell Netware, AOL, Modem software

o   Graphics software: software that allows users to create and manipulate graphics like Photoshop, Print Shop, etc.

o   Education and Reference software: programs that help teach new material and ideas, and programs that can be used to find information like Encarta, Wordbook Encyclopedia, Jumpstart Kindergarden,etc.

o   Entertainment and Leisure software: like War craft, Age of Empires, Barbie Design Center, Packman, Solitaire, etc.

o   Integrated software: combines several types of software into one program or package like Quicken(Spreadsheet/database/communication/reference) or PrintShop(Graphics/Word processor)