Computer Concept Lecturer : PRAGYA DIXIT

TextbookE. Balagurusamy, Fundamentals of Computers, Mc Graw Hill.

Whats a Computer?A computer is an electronic machine that takes input from the user, processes the given input and generates output in the form of useful information.

Whats a Computer?Input: data, programs, user replyData: the raw details that need to be processed to generate some useful information. Programs: the set of instructions that can be executed by the computer in sequential or non-sequential manner.User reply: the input provided by the user in response to a question asked by the computer.

Computers Have Two Main PartsComputer Hardware

Computer Software

What is Computer Hardware?Computer Hardware is the physical part of the computer system, the machinery and equipment.

Parts of the computer you can see

Examples of Computer HardwareMonitor: T.V. like screen used to show pictures and wordsCPU: Central Processing Unit this is where most of the computers calculations take place. In terms of computing power, the CPU is the most important element of a computing systemKeyboard: This device is used to type information into the computer and contains the numbers 0-9.

More Computer HardwareMouse: a small device, which you move across the top of the desk to move the pointer or cursor on the screen.

Printer: used to make a paper copy of the information into the computer.

Image Scanner: an electronic device that generates a digital representation of an image for data input to a computer

What is Computer Software?Computer Software are programs that tell the computer what to do.

ExamplesMicrosoft Word-word processing programMicrosoft PowerPoint-presentation programMicrosoft Excel-work book program used to track, calculate, and analyze numeric data

Computer Input DevicesInput is any data entered into the computers memory.Computer Devices that input information in the computer

ExamplesKey BoardMouseScannerDigital Camera

Computer Output DevicesComputer Devices that output information from the computer.

ExamplesMonitorPrinter

General Understanding of how your computer works!Motherboard It is the main circuit board inside the CPU case. It holds the microprocessor, memory and other crucial circuits and components that control the operation of the Personal Computer. Every device inside or connected to a Personal Computer finds it's way to this board.

MemoryThe mother board takes the input you give it like mouse clicks, and produces output for you like displaying or printing a file.

It can't do this without memory. The PC operating system used by the PC is copied from storage to memory at power up.The OS copy in memory then runs the PC.

Memory is volatile which means that when your PC is turned off the contents of memory are lost. It is completely blank and must reloaded each time the PC is powered up.

Storage Storage is non-volatile which means it retains information even when it is powered off. It stores programs which run the PC as well as data, which is a digital form of everything you use like documents, music, pictures, etc

Input Devices The keyboard and mouse are the main input devices you use to control your PC.

Storage Devices

Primary storage: is the storage provided by memory in a computer system e.g. ROM/RAM. Secondary storage: is storage provided by peripheral devices other than memory

Secondary storage: is required in a computersystem for three reasonsStorage Devices The content of memory is usually volatile, which means that if power is disconnected the data is lost.2. The capacity in megabytes of memory is limited.3. Memory is more expensive than secondary storage.

Storage Devices Several types of disks may be used for Secondary storage.Floppy disks

Hard disks

Optical disks (including CD-ROM, writeable CD, DVD

Backup Storage Devices e.g. tape

Floppy Disk

A floppy disk is a low capacity disk which may be removed from the computer. Data may be written to and read from a floppy. A small notch can be used to make the disk read-onlyThey are small lightweight and easy to transport.

Ideal for backups of small amounts of data or fortransfer of data from one machine to another.

Floppy Drives are common to most if not all computers.

Hard Disk

A hard disk is a higher capacity medium, with up to hundreds of gigabytes.They are usually non-removable, but removable hard disks are becoming more common. They can be both read from and written to, and are the standard medium for storage on computer systems today.Hard disks are much faster than floppy disks and can store much larger amounts of data.

Optical disks

CD ROM = Compact Disk Read Only Memory, is an ideal device for storing large quantities of data and information such as large software packages.The CD drive uses laser technology to read the disk contents and therefore both access and transfer are extremely fast.

CD ROM as the name suggests is Read Only Writable CDs allow for large amounts of data to be written to a CD as well as read from it. They are sometimes know as CD-RW.

DVDDVD or Digital Versatile Disk is a higher capacity version of a CD and DVD drives have a higher transfer rate.DVD disks provide high quality playback of films and audio and are increasingly found as standard on the home PC.DVDs may be read only or read/write. They are sometimes know as DVD-ROM and DVD-RAM.

Evolution of ComputersManual Computing Devices: Sand table, Abacus, Automated Computing Devices: difference engine, analytical engine, Colossus, Charles Babbage: A professor of mathematics a the Cambridge University is considered to be the father of modern computer.

Generations of ComputersFirst Generation ComputersEmployed during the period 1940-1956Used the vacuum tubes technology for calculation as well as for storage and control purpose.Advantages: (1) Fastest computing devices of their time; (2) These computers were able to execute complex mathematical problems in an efficient manner.

Generations of ComputersDisadvantages:(1) The functioning of these computers depended on the machine language.(2) There were generally designed as special-purpose computers. (3) The use of vacuum tube technology make these computers very large and bulky. (4) They were not easily transferable from one place to another due to their huge size and also required to be placed in cool places.(5) They were single tasking because they could execute only one program at a time.(6) The generated huge amount of heat and hence were prone to hardware faults.

Generations of ComputersSecond Generation ComputersEmployed during the period 1956-1963Use transistors in place of vacuum tubes in building the basic logic circuits.Advantages: (1) Fastest computing devices of their time; (2) Easy to program because of the use assembly language; (3) Could be transferred from one place to other very easily because they were small and light; (4) Require very less power in carrying out their operations; (5) More reliable, did not require maintenance at regular intervals of time.

Generations of ComputersDisadvantages: (1)The input and output media were not improved to a considerable extent(2) Required to be placed in air-conditioned places(3) The cost of these computers was very high and they were beyond the reach of home users(4) Special-purpose computers and could execute only specific applications

Generations of ComputersThird Generation ComputersEmployed during the period 1964-1975Use of Integrated CircuitsAdvantages: (1) Fastest computing devices; (2) Very productive; (3) Easily transportable from one place to another because of their small size; (4) Use high-level languages; (5) Could be installed very easily and required less space; (6) Can execute any type of application. (7) More reliable and require less frequent maintenance schedules.

Generations of ComputersDisadvantages:(1)The storage capacity of these computers was still very small;(2) The performance of these computers degraded while executing large applications, involving complex computations because of the small storage capacity;(3) The cost of these computers was very high;(4) They were still required to be placed in air-conditioned places.

Generations of ComputersFourth Generation ComputersEmployed during 1975-1989Use of Large Scale Integration technology and Very Large Scale Integration technologyThe term Personal Computer (PC) became known to the people during this era.

Generations of ComputersAdvantages: (1) Very powerful in terms of their processing speed and access time; (2) Storage capacity was very large and faster;(3) Highly reliable and required very less maintenance;(4) User-friendly environment; (5) Programs written on these computers were highly portable; (6) Versatile and suitable for every type of applications;(7) Require very less power to operate.

Generations of ComputersDisadvantages: (1) The soldering of LSI and VLSI chips on the wiring board was not an easy task and required complicated technologies to bind these chips on the wiring board;(2) The working of these computers is still dependent on the instructions given by the programmer.

Generations of ComputersFifth Generation ComputersThe different types of modern digital computers come under this category. Use Ultra Large Scale Integration technology that allows almost ten million electronic components to be fabricated on one small chip.

Generations of ComputersAdvantages: (1) Fastest and powerful computers till date; (2) Being able to execute a large number of applications at the same time and that too at a very high speed; (3) Decreasing the size of these computers to a large extent; (4)The users of these computers find it very comfortable to use them because of the several additional multimedia features; (5) They are versatile for communications and resource sharing.

Classification of ComputersWe can classify the computers according to the following three criteria:(1) Based on operating principles(2) Based on applications(3) Based on size and capability

Classification of Computers(1) Based on operating principles:Analog computers: represent data in the form of continuous electrical signals having a specific magnitudeDigital computers: store and process data in the digital form.Hybrid computers: a combination of analog computer and digital computer because it encompasses the best features of both.

Classification of Computers(2) Based on applications:General purpose computers: can work in all environments.

Special purpose computers: can perform only a specified task.

Classification of Computers(3) Based on size and capabilityMicrocomputers: Designed to be used by individuals.Mini Computers: Can handle more data and more input and output than micro computers.Mainframe Computers: A very large computerSuper Computers: The fastest type of computer that can perform complex operations at a very high speed.