TYPES OF COMPUTER

There are three types of computer:

• Analog Computer
• Digital Computer
• Hybrid Computer

Analog Computer:

                            Analog Computer use electronic or mechanical phenomena to model the problem being solved by using one kind of physical quantity to represent another. The analog computer excels in solving dynamic problems and simulating  complex physical  systems. It has no way for man_machine interaction, recording and graphic display High_speed computing elements, used to simulate mathematical functions, physical system, and dynamic processes, are arranged in as  much the same pattern as the physical system they represent. Early special_purpose analog computers were the slide rule, the curvimeter and plainmeter, and the harmonic analyzer. In world  war 2, analog computing mechanisms were of great importance for gunfire control on warships. General-purpose analog computers were first built in 1930s.
Digital Computer:
                           Digital Computers process data in numerical form using digital circuits. The digital computers perform arithmetic and logic operations with discrete values. Digital  computers are good at solving algebraic equations and even better  manipulating numbers. Its is unbeatable for high-speed  precision in arithmetic operations, data storage, and documentation. It   can perform only one calculation at a time.The result can be obtained in a variety of forms, such as printed tables, magnetic tape, and the familiar punched cards,While properly used in high_accuracy, high-volume numerical calculations, the digital computers are extremely good. In early 1940, Aiken built the first general-purpose digital computer called Mark-1. With the invention of digital computer are widely being used in business, educational institutes, hospitals  etc.for various purposes. Examples of digital computers are IBM PC, Apple"s Macintosh computers etc.
Hybrid Computer:
                             Hybrid Computers are the combination of analog and digital computers.Hybrid computers use analog-to-digital conversion and digital-to-analog conversion, and may input or output either analog or digital data. Dynamic problems that once took too long or were too difficult to handle can be solved in a reasonable period of time.The computers can produce highly accurate and precise results. These types of computers are used in a robotics, medical labs etc.

DISK DRIVE

Disk drive is a machine that reads data from and write onto a disk. Disk drive rotates the disk with precise timing and has one or more read/write heads that read  and write  data. The data is read by the read/write head and  transferred to the computer's  main memory for further processing. There are different types  of disk drives  for different types of disks e.g. a hard disk drive (HDD) reads and writes hard disks, and  a floppy disk drive (FDD) accesses  floppy disks, and an optical disk drive reads  optical disk. Disk drive can be either internal ( house within the computer) or external (house in a separate box that connects to the computer.

MICROPHONE

Microphone is an input device used to digitally record audio data , such as the human voice. It can be plugged into a computer or recorder. Many productivity applications can accept input via a microphone, enabling the user to dictate text  or issue  commands orally. Software in the computer converts the sound  impulses into  digital form. It is then stored in memory and processed when  required.

SCANNER

A Scanner is an input devices which is capable  of reading the image present on a piece paper and transferring the information into a computer where  a program can store and interpret it. The information is an the from  of a graphic image or picture and not in the  form of text. Even if the paper  contains text, the information transferred is not text but a picture of text. Optical character recognition(OCR) software is necessary  to read this image and convert it to actual text  data and this software  varies widely in its ability to do so. Scanners  rang from  monochrome (2 color) scanners to flatbed  scanning a whole page at once and costing  several  thousand rupees.

JOYSTICK

Joystick is an input device used for games, computer aided designs or simulations. It is like a lever that moves in all directions and controls the movement of a pointer or some  other display symbol. A joystick is similar to a mouse, except that with a mouse the cursor stops moving as soon as you stop moving the mouse. With a joystick, the pointer continues moving in the direction the joystick is pointing. To stop  the pointer, you must return the joystick ti its neutral position. Most joysticks include two buttons called triggers.

TRACKBALL

A Trackball is a pointing  device that works like a mouse. Trackball contains a ball exposed on its surface. To move the pointer on the screen, you roll the ball with your thumb, fingers, or the palm of your  hand. There are usually one to three buttons next to the ball, which you use just like mouse buttons.The advantage of  trackball over mouse is that the trackball is stationary so it dose note require much space for use. In  additions, you can place a trackball on any type of surface. For both these reasons, trackball are popular pointing devices for portable computer.

MOUSE

  MOUSE:-

A Mouse is an input device that rolls around on a flat surface and controls the pointer on a display screen.The pointer is an on_screen object _ usually an arrow _ that is use to select text; access menus: and interact with programs, files or data appear on screen. As you move the mouse, the pointer on the display screen moves in the same direction. A typical mouse has to buttons, which perform different functions depending on what application is running.Some mouse also include a scroll wheel for scrolling through long documents.
Optical mouse is getting popular nowadays: instead of having a roller ball it uses light reflection to control the movement of pointer on the screen.
 MOUSE EVENTS:
                               Mouse event refers to the activity that can be performed by using the mouse.
A typical mouse can perform the following events:

• Left Click
• Right Click
• Drag 

Left click:

                 Left click is used to select a graphical object such as a file icon and apiece of text in a document etc., or to press a button such as  the start  button and closing, opening or minimizing a window etc.

Right Click:

                    Right click is used to view the properties  of  an object such as  file, folder,desktop etc.

Drag:

          Drag event triggers when you keep on pressing the left mouse button while moving the mouse.This event is used to select more than one items at a time, a to drop an object into another application.

                  

USB

USB stand for universal serial bus is a plug and play hardware interface for peripherals such as the keyboard, joystick,scanner,printer and modem. USB has a maximum bandwidth of 12 M bits/sec and up to 127 devices can be attached. with usb, a new device can be added to the computer without having to add an adapter card. 

CPU

CPU   stand for central processing unit. The central processing unit is generally referred to as the brain of the computer. The primary work of cpu is to convert data from intput,process the data and output in useful infomation that can be use by either user or other  computer program.Central processing unit(CPU) is a highly complex set of electronic circuitry that executes program instructions. It is like a really fast calculator that has the ability to recall numbers from various locations in memory, perform arithmetic and logical operations with them, such as addition or multiplication, and then store the results.

HARDWARE

The Physical Part of computer that you can touch and feel are know as COMPUTER HARDWARE in a broader sense a computer can be divided into following units:                                               

1.INTPUT UNIT

2.OUTPUT UNIT

3.SYSTEM UNIT

COMPUTER SOFTWARE

COMPUTER SOFTWARE

Computer Software is a term used for organized collections of computer data and instructions. Computer programs are also usually referred to us computer software. A computer program is a set of instructions given to the computer to solve a particular problem. Computer program specify a sequence of operations that computer will perform.

             Computer Software is further divided into two major categories

•  System Software
• Application Software

SYSTEM SOFTWARE

                         System Software refers to the programs that are responsible for controlling and managing the actual operations of the computer hardware. Generally system software consists of any operating system and some fundamental utilities such as disk formatters, file managers, display managers, user authentication (login)  and network control software.

APPLICATION SOFTWARE

                          Application software is used to accomplish tasks specified by the user. Application  software may consist of a single program, such as an image viewer or a collection of programs (called software package) that work together to accomplish a task. e.g. Word Processor, Spreadsheet, database etc.
                                         

COMPUTER

COMPUTER is a device that accepts data and processes its for some result based  on a sequence of instructions. The sequence of instruction given to computer for manipulating data is know as a program. Computers also include the means for storing data and the program on internal memory. The process of performing arithmetic and logic operations with   the help of  computer is know as electronic data processing(EDP).