INTRODUCTION TO COMPUTERS
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INTRODUCTION TO COMPUTERS
What is a Computer
A computer is a programmable machine. The word “computer” comes from the word “compute”, which means to calculate. A computer may be defined as a device, which operates upon data (Bio-data of various applicants when the computer is used for recruiting personnel)
Data & Information
The input to computers is data. Data means facts, the raw material for information. Data are represented by symbols, but they are not information except in a limited sense. Information is data arranged in an understandable form, that is useful to the people who receive it.
Input-Process-Output Cycle
Every activity follows the pattern of Input-Process-Output. For every activity, there is an input, a process and output.
(Data) Calculating, Sorting, (Information)Merging, RetrievingCommunicating data
Input-Process-Output Cycle
INPUT PROCESS OUTPUT
• Collecting data from various sources• Converting data into machine readable form• Reading data into Computer• Converting data into human readable form• Distributing data to actual users.
COMPUTER PROCESSING OPERATIONS
Essential activities of a data processor :
• Automatic • Speed• Accuracy• Diligence• Versatility• Power of Remembering• No I.Q.• No Feelings
CHARACTERISTICS OF COMPUTER
• Computer Hardware
(Computer equipment that is mechanical,
electrical and electronic parts)• Computer Software
(Programs that instruct a computer how to
process the data and generate reqd infn)• Computer Heart ware
People who prepares data for computerized
input, write computer programs, monitors
computer operations & distribute the output.
Anatomy of Computer
Block Diagram of Computer
INPUTUNIT
CPU• ALU• CU
OUTPUTUNIT
Program Information& Data (Results)
Memory• Primary• Secondary
• ALU• CU CPU components• Memory Unit
Output UnitInput Unit
Secondary Storage
Primary Storage
Control Unit
Arithmetic Logic Unit
Storage Unit
Information Result
Program &
Data
Block Diagram of Computer
Functional Components of Computer
• CPU (Central Processing Unit) Is the brain of the computer system. Responsible for activating & controlling operations of the computer System. The CPU functions in a fetch- execute cycle.
Hardware of any Computer System can be classified into :-
• Peripheral Devices Input Devices Output Devices Data Storage Devices
CPU performs :
1. Arithmetic Operations 2. Input-Output Operations3. Internal data movements4. Data Manipulation (accepting data, sorting it, processing it, generating the results)
CPU has various components :
• Arithmetic-logic Unit (ALU)
• Control Unit (CU)
• Memory Unit
ALU : Calculations (+, -,/, x,<, >, =, positive, negative & zero). The output from ALU is fetched by the Control Unit and sent to various parts of the computer.
Control Unit :
Coordinates the operations of hardware & flow & execution of data and instructions that are fed into the memory via CPU.
Memory Unit : Also known as the primary storage or main memory - is a part of the microcomputer that holds data for processing, instructions for processing the data (the program) and instructions (processed data).It can be divided into primary & secondary memory.
There are several types of memory :
• RAM• ROM
RAM (Random Access Memory)
(a) This is volatile memory. (b) Its consists of some Integrated circuits chips (IC
Chips) on the motherboard. (c) Motherboard is designed in such a manner that
its memory capacity can be easily increased by
adding more memory chips in empty memory slots on the motherboard.
ROM (Read only memory) (a) Non-volatile memory chip.(b) Data is stored permanently and cannot be altered by the programmer. (c) The data stored in ROM chip can be read and used but cannot be changed. (d) Essential functions that computer performs when the computer is switched on, special programs are written to perform them, called as microprogram (system boot program)
Peripheral Devices
It can be classified as :
• Input Devices
• Output Devices
• Data Storage Devices
Input Devices
It can be classified as :
• Keyboard Devices
• Mouse
• Scanner
Output Devices
It can be classified as :
• Monitors
• Printers
• Screen Image Projector
• 1ST Mechanical machine was invented
by Blaise Pascal in 1642.
• Charles Babbage is considered the
father of modern digital computers.
(19th Century)
Evolution of Computer
• The Mark I Computer (1937-44).• The Atanasoff-Berry Computer (1939-42)• The ENIAC (Electronic Numerical Integrator and Calculator) (1943-46)• The EDVAC Electronic Discrete Variable Automatic Computer (1946-52)• The EDSAC (Electronic Delay Storage Automatic Calculator) (1947-49)• The UNIVAC I (Universal Automatic Computer) (1951)
Well Known Early Computers
Mini , Micro , Mainframe computers & their features
Classification of computers
• On the basis of size & capabilities
Mini computer
Micro computer
Mainframe computer
Micro Computer• Smallest type of computer , least expensive of all type• Known as Personal computer• Introduced by IBM• Low cost of development• Arithmetic & control unit combined• Uses : by single person for single activity• Microcomputer can be grouped in five categories Workstation, Desktop, Server , Laptop , Notebooks
• Desktop : used by business people for Word processing ,spreadsheeting & physically placed on desk.
Mini Computer• First introduced in 1960’s• Faster than micro computer• More storage space & more input & output devices • Smaller than mainframe computer• More expensive
But in general, a minicomputer is a multiprocessing system capable of supporting from 4 to about 200 users simultaneously. (they r also used as servers in LANS).
• Business use : Large supermarket
Mainframe computer
• More powerful
• More access to input & output device.
• High degree storage
• Can process large volume of data
(More powerful processor)
• Act as host for smaller computers
• Business use : Large overseas Banks
COMPUTER HARDWARE & SOFTWARE
This includes the computer equipment that can be seen, touched (physical entity) and peripheral devices such as keyboards, monitors, printers, floppy drives, pen drives and other equipment that are connected to computer
WHAT IS HARDWARE
COMPUTER SOFTWARE
Software is a set of programs, documents, procedures associated with the operations of a computer systems.( Computer Instructions & Data)
WHAT IS SOFTWARE
Computer Software can be divided into :
• System Software
• Application Software
• It supports the development of other application software.
• Execution of other application software.
• Monitors the effective use of CPU, memory, peripheral etc.
• It helps the hardware components work together.
System Software
Functions of System Software :
• Operating systems.
• Utility Programs (Utilities)
• Compilers and Interpreters (Inbuilt programs)
• Communication software
Types of system software
OS software performs basic tasks such as :
• Recognizing input from the keyboard• Sending output to the display screen• Keeping track of files & directories on the disk
& controlling peripheral devices.
Most commonly used operating systems are
DOS, Microsoft windows, UNIX, Linux etc.
Operating systems
Operating System
Pathway between Hardware and Software
HARDWARE AND SOFTWARE
Hardware Software
A computer can not produce output/results unless hardware and software works together
These are a set of programs, which help users in system maintenance task of routine nature. For example formatting of hard disk or floppy disk, taking backup of files stored on hard disk on to a CD or floppy or pen drive, creating files. directories, folders etc.
Utilities Programs (Utilities)
Computer don’t understand our language. It only reads machine language. So the compilers and interpreters are the set of programs which converts our language into machine language and process it.
Eg. Spell check, grammar checking in a word document.
Compilers and Interpreters(Translating Programs)
In Network (where multiple computers are interconnected together) It enables to transfer the data and programs from one computer to another, to share the devices and data.
Communication software
Application software is a set of one or more programs, to do specific task, to solve specific problem and to complete the end user task as per requirement. The requirement is customized as per our need and application.
Eg. Ms-Word, Excel, Powerpoint, Paintbrush, Computer games etc.
Application Software
• Word-Processing Software
• Spreadsheet Software
• Database Software
• Graphics Software
• Personal Assistance Software
• Education Software
Most commonly application software are :
It enables us to make use of a computer system for creating, editing, viewing, formatting, storing, retrieving and printing documents.
For eg. letters, reports, books etc.
Word-Processing Software
This software is a numeric data analysis tool, it allows us to create a kind of computerized manual ledger having rows & columns, mostly used by accountants for keeping a record of financial transactions, and for preparing financial statements.
For Eg. Payroll, Mark sheet, tracking stocks & keeping records of investor by stock brokers.
Spreadsheet Software
• A database software is a collection of related data stored for information retrieval purpose. It enables us to create a database, maintain it (add, delete and update its records) organize data in desired format (sort its records alphabetically name wise)
Database Software
It enables us to use a computer system for creating, editing, viewing, storing, retrieving and printing designs, drawings, pictures, graphs and anything that can be drawn in the traditional manner.
Graphics Software
It allows us to use personal computers for sorting and retrieving our personal information and planning, scheduling, Set alarms, contacts, financial and inventory of important items.
Personal Assistance Software
It allows a computer to be used as a teaching and learning tool. For eg. Applications are those that teach young children to do mathematics, recognize alphabets and to read whole words and sentences
Education Software
It allows a computer system to be used as an entertainment tool. For eg. Video games, media player etc.
Entertainment Software
It deals with the integration of computers and graphics design packages for the purpose of automating the design and drafting process.
Computer Aided Design (CAD)
OPERATING SYSTEM
Operating System
Operating System (OS) is an integrated set ofprograms that controls the resources (the CPU,Memory, I/O devices etc.) of a computer system.
Two main objectives of an operating system are :-
• Making a computer system convenient to use. • Managing the resources of an operating System:
• Making a computer system convenient to use.
It manages all parts of the system and presents to the user with an interface or virtual machine, which is easier to program and use. It hides the details about the hardware resources from the programmer and provides the programmer with a convenient interface for using the computer system. It acts as an intermediary between the hardware and its users, providing a high level interface to low level hardware resources and making it easier for the programmer and other user to access and use those resources.
• Managing the resources of an operating System.
To manage the various resources of the computer system. It involves keeping track of who is using which resource, granting resource requests, accounting for resource usage and mediating conflicting requests from different users.
Single-User Operating System
A single-user operating system provides access to the computer system by a single user at a time. If another user needs access to the computer system, they must wait till the current user finishes what they are doing and leaves. We are all familiar with the concept of sitting down at a computer system and writing documents or performing some task such as writing a letter. In this instance there is one keyboard and one monitor that you interact with.
Multi-User Operating System
When referring to a network, a multi-usersystem is a term commonly used to define acomputer capable of allowing multiple usersto connect to a network.
When referring to a computer OperatingSystem, a multi-user system is a computerwith an Operating system that supportsmultiple users at once and/or different times.
Disk Operating System (DOS)
DOS is a Program which acts as user-interface between you, your application programs and the computer. None of the programs would work without it, because DOS controls every part of the computer system.
Disk Operating System (DOS)
DOS is a Program which acts as user-interface between you, your application programs and the computer. None of the programs would work without it, because DOS controls every part of the computer system.
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