Computer A computer is an

electronic device, operating under the control of

instructions stored in its own memory, that can

accept data, manipulate the data according to specified rules, produce results, and store the result for future

use.

Information Technology is a general term that describe any technology that

helps to produce, manipulate, store, disseminate information. basically it is

the combination of computer &communication devices.

Importance & Uses of ComputerBusinessEducationMedicine & Health CareScienceEngineeringManufacturingGovernment

Importance & Uses of ComputerDefenceMusicTheatre, Film & TelevisionHomeInternetLegal Practices

Why Is Computer Literacy Necessary?

In most places of business a computer is a standard! For example:

Auto Repair ShopsComputers are used for diagnostic repairsInventory of parts and suppliesCustomer billingFood service industryCosmetologyBanking sector

Characteristics of ComputerSpeedStorageAccuracyVersatilityAutomationDiligenceReliability

According to functionAccording to function computers can be classified into four types. These classification of computer based on principle of operation and hardware structure.

Digital Computer Analog Computer Hybrid Computer

Digital ComputerA Digital computer works with data in term of discrete number or digit. These number are used to perform, arithmetic calculations and

also make logical decision to reach a conclusion depending on the data they receive from the user. All the expressions are coded into binary

digits (0 and 1) inside the computer and it manipulates them at very fast speed.

Analog ComputerAnalog computers actually is a measuring device. An analog computer measures continues type of data and use a physical quantity, such as electric current, speed, weight etc. Analog Computers are the first Computers being developed & provide the base for the development of modern digital computers. These computers are mainly made of electrical devices like resisters, amplifiers & transistors.

Hybrid Computer

A Hybrid computer is, which combines the analog & digital capabilities in the same computer system. Hybrid computers help the user to exploit the machine's ability to process both continuous and discrete data. These machines are generally used for scientific applications & it is also used as a controlling device in an industrial process.

Components of Computer There are four basic components of computer:Input unitOutput unitCentral Processing UnitMemory

Block Diagram of Computer

Input unitCentral

Processingunit

Output unit

Memory

1: Input DevicesKey BoardMouseVoice Data EntryJoy StickLight PenScannerSecondary Storage Devices (floppy, Magnetic

Tape etc).

2:Output DevicesMonitorPrinterSpeakerStorage Devices

3: Central Processing Unit The Central Processing Unit has three main

parts

Arithmetic Logic UnitControl UnitMain Memory

ALU

CU

Main Memory

Functions of CPUArithmetic Operations (+,-,*,/,%)Logical Decision (<,>, =)Data transmissionManipulating TasksDisplay Results/ Store in memory.

Functioning of Arithmetic Logic Unit Register A register is combination of memory storage

locations called Flip-Flops. It stores one bit. Accumulator A register called “Accumulator” when it

works for ALU.

Functioning of Arithmetic Logic Unit

Accumulator consist of two partsMemory Data Register It holds all data & instructions temporarily &

then pass to the main memory.Memory Address Register MAR contains the address of the memory

location whose data is to be transferred into MDR.

Control UnitCU also called the NERVE CENTRE of the

computer.CU has an Electronic Clock. Electronic Pulses (equal interval of time ) Speed in MHZ (10^6HZ).

Functioning of Control Unit

Instruction Cycle Consist of two partsFetch Cycle The CU fetches the instruction from MDR &

places it in the current Instruction register.Execution Cycle The CU then decodes the instruction & send

data for concerned device for the execution.

Random Access Memory (RAM) Read Only Memory (ROM) Complementary metal oxide semiconductor chip (CMOS) Flash Memory Cache Memory Virtual Memory

Random Access Memory (RAM) read/ write Volatile in naturehold software instructionsRead Only Memory (ROM) Non Volatile / Permanent in nature Less costlyHold BIOS instructions

Types of RAMDynamic RAMCheaperTransistorRefresh periodically (in 2 ms) Access Time (150ns-----200ns)

Static RAMExpensiveMore Power More space Access Time fast (80ns-------90ns)

•SDRAMIt is synchronized by the system clock and much faster then static RAM•DDR.RAMDouble Data Rate Synchronized dynamic RAMIts speed is very high measured in mega hertz used in Apple computers.•SIMM: Single in line memory chip•DIMM: Dual in line memory chip

Types of ROM1. Programmable Read Only Memory: Information once store in PROM store

permanent & can not be changed or erased. Entering the information is known as

Burning the PROM.2. Mask Read Only Memory: Information is permanently recorded by the

masking & metallization process.

Types of ROM3. Erasable Programmable Read Only

Memory: EPROM is cheap, reliable & widely available. The data will be erase when chip under the

high intensity ultraviolet light for 30 minutes. But we lost whole data.

4. Electronically Erasable Programmable Read Only Memory:

Using the electrical signals the data will be erase in chunks in milliseconds.

Complementary metal oxide semiconductor chip

It is powered by battery .that’s why it don’t lose the data as lights goes off. It has some flexible start up instruction for example time ,date .

Flash Memory It can erased data more than once and

reprogrammed. it available up to 8 gigabytes. it is used not only in computers but also in digital camera, pagers, cell phones etc

Cache Memory & its Types It temporarily stores instructions and data that

the processor is likely to use frequently. So it is used to speed up the system.

Level 1: part of microprocessor chip, also called internal cache. it operates much faster than level 2.it stores 256 kilobytes data.

Level 2:it is also called external cache. It is available up

to 2 or more giga bytes• Level 3: it is also separate from the motherboard .It

is found only on very high end computers.

Virtual Memory It is some free hard-disk space that is used to

extend the capacity of RAM.The processor searching for data in the

following order. L1L2RAM CDHard Disk

Process StatesInterleaving: It is process in which the CPU

alternates communication b/w two or more memory banks .it is used usually in large setup for server or workstation.

Bursting :It is used to provide the additional data to CPU on the basis of statistical method that address what data will be used next.

Pipelining :It is used to divide a task in to small stages . So CPU works in stages & than switch to next according to electronic clock.

Hyperthreding :Superscalar architerture means computer has the ability to solve two transaction @ per clock cycle.type of this technology is Hyperthreding

Secondary Storage DevicesMagnetic TapeFloppy DiskHard DiskCD’s & DVD’sUSB