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Introduction to computer IT-101Lecture #1System Def #1:A set of detailed methods, procedures, and routines established or formulated to carry out a specific activity, perform a duty, or solve a problem.Def #2: A group of interacting, interrelated, or interdependent elements forming a complex whole.Sub-system A major part of a system which itself has the characteristics of a system, usually consisting of several components.

Computer System A complete, working system. Computer systems will include the computer along with any software and peripheral devices that are necessary to make the computer function. Every computer system, for example, requires an operating system.Computer System

Why we use Computers ?Why we need IT ?Introduction to ComputerAn electronic device designed to accept data, perform prescribed mathematical and logical operations at high speed, and display the results of these operations.


It helps you automate various tasks that you cannot do manually.It helps you organize your data and information in a better way. It has much more computing and calculating power then an ordinary human. It may help your work to be a lot easier. It may be the storage of your important data and files. AdvantagesIt may be your handy book. It may help you solve problems faster than an ordinary human being can do. It has speed, storage, reliability, consistency and communications.It helps you to find useful information using the Internet. It helps in businesses, factories, offices, schools and homes.

Disadvantage It destroys your social life and interactions with humans if you do not maintain the balance. It may effect to the destruction of your eye sight due to radiation. It may cause pimples and wrinkles. It may damage your studies and life. Too much time in front of monitor may adverse effect your eye sight and can also make you fat.

Disadvantage The way it distracts and can deviate our thoughts and activities towards unproductive activities.It could cause violation of privacy, impact on labor force, health risks, impact on environment, distraction from work, and possible antisocial influences. Getting away from their real life and getting into bad lines.

Types of Computer Computer types can be divided into 3 categories according to electronic nature.Analog Computer Digital Computer Hybrid Computer

Analogue ComputerAnalogue types of Computer uses what is known as analogue signals that are represented by a continuous set of varying voltages and are used in scientific research centers.

Digital Computer A computer that stores data in terms of digits (numbers) and proceeds in discrete steps from one state to the next. The states of a digital computer typically involve binary digits which may take the form of the presence or absence of magnetic markers in a storage medium. In digital computers, even letters, words and whole texts are represented digitally.

Hybrid ComputersHybrid computers are the form of computers which had been designed to display the features and characteristics of both computers which are the analog and the digital computers. When the hybrid computers are used in the form of digital computers then they are deigned to act as the controller for the operations carried out in the system. When analog is taken into account then in that case the computer acts as a solution provider for different problems that exit and thus by depicting both the feature, it is found to be a beneficial computer.Classification of ComputerThere are two types of classesClasses by size Classes by Functions

Classes by size

Microcomputers (Personal computers)Minicomputers (Midrange computers)Mainframe computersSupercomputer

Classes by functions ServersWorkstationsInformation appliancesEmbedded computers

MicrocomputersMicrocomputers are the most common type of computers used by people today, whether in a workplace, at school or on the desk at home. E.g.:Desktop computersGame consoles LaptopsNotebook computersPalmtop computersTablet PCProgrammable calculatorMinicomputers (Midrange computers)A minicomputer is a class of multi-user computers that lies in the middle range of the computing variety, in between the smallest multi-user systems (mainframe computers) and the largest single-user systems (microcomputers or personal computers ). Minicomputers (Midrange computers)Computer that possesses the same components as large mainframes but has reduced memory and slower processing speeds.Contemporary term for this class of system is midrange computer, such as the higher-end SPARC, POWER and Itanium -based systems from Sun Microsystems, IBM and Hewlett-Packard.

Mainframe Computers& Supercomputer

A very large and expensive computer capable of supporting hundreds, or even thousands, of users simultaneously. In the hierarchy that starts with a simple microprocessor (in watches, for example) at the bottom and moves to supercomputers at the top, mainframes are just below supercomputers.In some ways, mainframes are more powerful than supercomputers because they support more simultaneous programs. But supercomputers can execute a single program faster than a mainframe. The distinction between small mainframes and minicomputers is vague, depending really on how the manufacturer wants to market its machines. Servers

Server is a physical computer (a hardware system) dedicated to running one or more such services (as a host) to serve the needs of users of the other computers on the network. Depending on the computing service that it offers it could be a database server, file server, mail server, print server, web servers, or other.Workstations

In networking, workstation refers to any computer connected to a local-area network. It could be a workstation or a personal computer.

Information ApplianceIn information appliance or information device is any machine or device that is usable for the purposes of computing, telecommunicating, reproducing, and presenting encoded information in myriad forms and applications.Information ApplianceInformation Appliance" (IA) is more specific an appliance that is specially designed to perform a specificuser-friendlyfunction such asplaying music,photography, orediting text.Smart PhonesPersonal Digital Assistants(PDAs)

Embedded Computers

Embedded computers can be compared to "computers on a chip". All in one so to speak. You will find them in all kind of appliances that surround us. Washing machines, ticket machines at the subway, camera's, cars, motors, sewing machines, clocks. Everywhere needing something to regulate, control of check something.