DEO Lesson 1

What Is A Computer?

Computer is a device that transforms data into meaningful information. Data can be anything like marks obtained by you in various subjects.

Functions Of A Computer

A computer can i) accept data, ii) store data, iii) process data as desired, and iv) retrieve the stored data as and when required and v) print the result in desired format.

Major Characteristics Of A Computer

The major characteristics of a computer are high speed, accuracy, diligence, versatility and storage.

Input

This is the process of entering data and programs into the computer system.

Control Unit

The process of input, output, processing and storage is performed under the supervision of a unit called 'Control Unit'. It decides when to start receiving data, when to stop it, where to store data, etc. It takes care of step-by-step processing of all operations in side the computer.

Memory Unit

The part of the computer that is used to store data and instructions.

Arithmetic Logic Unit

The major operations performed by the ALU are addition, subtraction, multiplication, division, logic and comparison.

Output

This is the process of producing results from the data for getting useful information.

Central Processing Unit

The ALU and the CU of a computer system are jointly known as the central processing unit (CPU). The CPU acts as the brain of any computer system.

Peripheral Devices

Peripheral devices are connected to the computer externally. These devices are used for performing some specific functions.

Input Devices

Input devices accept data and instructions from the user.

Keyboard

A keyboard is the most common input device. Several kinds of keyboards are available, but they resemble each other with minor variations. The keyboard in most common use is the QWERTY board. Generally standard keyboard has 104 keys. In these keyboards, the cursor control keys are duplicated to allow easier use of the numeric pad.

Mouse

An electro-mechanical, hand-held pointing device used to select commands, move icons, resize windows, and start programs.

Light Pen

An input device that utilizes a light-sensitive detector to select objects on a display screen. A light pen is similar to a mouse, except that with a light pen you can move the pointer and select objects on the display screen by directly pointing to the objects with the pen.

Optical Scanner

Devices for automatic data collection that eliminate manual data entry, such as bar-code readers and image scanners that convert printed images into electronic formats.

Touch Screen

Touch panel displays and pads are now being offered as alternatives to keyboard. Here the input can be given through the computer screen, that accepts the input through monitor; users touch electronic buttons displayed on the screen or they may use light pen.

Microphone

Microphone is an input device, which takes voice as input. The voice communication is more error-prone than information through keyboard.

Track Ball

Trackball, a pointing device, is a mouse lying on its back. To move the pointer, you rotate the ball with your thumb, your 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.

Output Devices

Output devices return processed data, that is information, back to the user.

Monitor

The monitor is the primary output device, displaying computer information visually via a video adapter, similar to how a TV presents cable service content.

Cathode Ray Tube Monitor

CRT or Cathode Ray Tube Monitor is the typical monitor that you see on a desktop computer. It looks a lot like a television screen, and works the same way. This type uses a large vacuum tube, called cathode ray tube (CRT).

Liquid Crystal Displays

This type of monitors are also known as flat panel monitor. Most of these employ liquid crystal displays (LCDs) to render images. These days LCD monitor are very popular.

Monitor Resolution

Most monitors have a resolution of at least 800 x 600 pixels. High-end monitors can have resolutions of 1024 x 768 pixels or even 1280 x 1024 pixels. Thus monitors are available either in low resolution or in high resolution.

Printer

After a document is created on the computer, it can be sent to a printer for a hard copy, or printout. Some printers offer special features such as colored and large page formats.

Laser Printer

A laser printer produces high-quality prints quickly and quietly, with easy operation and automatic paper loading. The fastest printer prints up to 200 pages per minute in monochrome and 100 pages per minute in color.

Dot Matrix Printer

The dot matrix printer is a versatile, inexpensive output device that prints by striking the paper through a ribbon to create text/images using dots. It is slower, louder, and produces lower quality but is cost-effective.

Line Printer

A line printer is a high-speed printer used with large computer systems to produce text-based reports, typically printing 100 to 3800 lines per minute. While earlier models had lower print quality, modern technology has improved it. These printers usually cost several lakhs of rupees.

Plotter

A plotter is an output device that produces large drawings, such as blueprints, by drawing lines on paper. It uses a robotic arm with colored pens, following coordinate instructions from a computer to create images, including curves made from short straight lines.

Flat Bed Plotter

Plotters of small size to be kept on table with restriction of paper size.

Drum Plotter

These plotters are of big size using rolls of paper of unlimited length.

Speaker

Speakers are another type of output device, which allow you to listen to voice like music, and conversation with people.

Software

A computer cannot operate on its own, it requires user instructions. These instructions, given in a specific sequence, are called programs. Software is a collection of such programs that directs hardware to perform tasks in an organized manner.

System Software

System softwares are sets of programs, responsible for running the computer, controlling various operations of computer systems and management of computer resources.

Operating System

An operating system is a system software that provides an interface for a user to communicate with the computer, manages hardware devices, manages and maintains disk file systems and supports application programs.

Utilities

These are programs that bridge the gap between the functionality of an OS and the needs of users. Utility programs are a broad category of software such as compress (zip)/uncompress (unzip) files software, anti virus software, split and join files software, etc.

Application Software

Application software is a set of programs, which are written to perform specific tasks.

Generalised Packages

These are user friendly softwares written to cater to user’s very general needs. It is a group of programs that provide general purpose tools to solve specific problems.

Customised Packages

These are the applications that are customised (or developed) to meet the specific requirements of an organization/institution. These packages are developed using high-level computer language.

Computer Language

Communication with computers is carried out through a language. This language is understood both by user and the machine. Every computer language is bound by rules known as SYNTAX of that computer language. The user is bound by that syntax while communicating with the computer system.

Low Level Language

The term low level means closeness to the way in which machine understand.

Machine Language

This is the language (in the form of 0’s and 1’s, called binary numbers) understood directly by the computer. It is machine dependent. It is difficult to learn and even more difficult to write programs.

Assembly Language

Assembly language replaces binary code with mnemonic symbols, making programs easier to write, understand, and debug than machine language. However, it is machine-dependent and requires knowledge of the target system.

High Level Language

High level language uses normal English like, easy to understand statements to solve any problem. Higher level languages are computer independent and programming becomes quite easy and simple.

Beginners All Purpose Symbolic Instruction Code

It is widely used, easy to learn general purpose language. Mainly used in microcomputers in earlier days.

Common Business Oriented Language

A standardized language used for commercial applications.

Formula Translation

Developed for solving mathematical and scientific problems. One of the most popular languages among scientific community.

C

Structured Programming Language used for all purpose such as scientific application, commercial application, developing games etc.

C++

Popular object oriented programming language, used for general purpose.

Compiler

The software (set of programs) that reads a program written in high level language and translates it into an equivalent program in machine language is called as Compiler.

Assembler

The software (set of programs) that reads a program written in assembly language and translates it into an equivalent program in machine language is called as Assembler.