Unit - 1

Unit - 1Basic Computer Architecture

P. Sugin Benzigar

Fundamentals of Computers

What is a Computer?

A computer is an electronic device that manipulates information, or "data." It has the ability to store, retrieve, and process data. You can use a computer to type documents, send email, and browse the internet. You can also use it to handle spreadsheets, accounting, database management, presentations, games, and more.

Computer components

there are 2 basic components

1. Hardware2. Software

how do computers work ???

Any device which can store , retrieve and process data needs something to control it.

Softwares ....

the ones that control the physical computer or (Hardware)

eg. programs running on Thermometers , Optometrist

devices , Mobile phones , computers , CARS (ESP) , Bikes (ABS).

contd......

how do computers work ???

all the data from all the peripheral devices are processed by

central processing unit

so the central processing unit is the brain of computer

the CPU is in the computer is in the mother board and often reffered as processor or core

eg.

pentium 4 , core2duo , i3 , i5 ......

more on CPU

the processors also determine the efficiency of the hardware .

every processor can do a specific amount of work in a specific amount of time.

the speed of the processor is measured in GHZ (giga hertz)

speed = frequency / second

block dia. of how processor works

hard disk/ instruction from key board/ mouse/ printer...

RAM cache memory

processor

Memory

the memory of the computer is classified into 2

1. primary - stores info. temporialy for faster access2. secondary or auxilary- for permanent use

eg of primary memory

RAM

eg of secondary memory

Hard disk

peripheral devices

what are peripheral devices

devices that cannot operate independently but will do fine with the help of a processor or an OS

or

any device that provides input to the computer and may or may not get output from the computer

eg.

printer , key board , mouse

more on peripheral devices

Inorder to make the peripheral devices communicate with the computer each peripheral device has its own driver

A driver is a software the can make a communication bridge between the device and the computing device

the drivers may vary with devices and OS

Eg. USB devices , printers , scanners , camera

more on peripheral devices

Certain devices may not need drivers

eg. mobile phones , Card readers

with the advent in OS , they can be treated as external storage devices

Block diagram of PC

INPUTUNIT

OUTPUTUNIT

PROCESS

INPUTUNIT

OUTPUTUNIT

MEMORY

CPU

INPUTUNIT

OUTPUTUNIT

CONTROL UNIT

ALU

MAIN MEMORY

SECONDARY MEMORY

MEMORY

INPUT UNIT

• Computer receives data and instructions through the Input Unit.• The input unit consists of one or more input devices.• Input devices include:

KeyboardMouseJoystickScanner

FUNCTIONS OF INPUT UNIT

• Accept the data and instructions from the outside world. • Convert it to a form that the computer can understand. • Supply the converted data to the computer system for further processing.

OUTPUT UNIT

• Computer provides information and results of computation to the outside world through the Output Unit.

• The output unit consists of one or more output devices.• Output devices include:

MonitorPrinter

FUNCTIONS OF OUTPUT UNIT

• Accept the results produced by the computer. (These are in a coded form.) • Convert it to a form that the outside world can understand. (OR, Converts it

into human readable form.) • Supply the converted results to the outside world.

CENTRAL PROCESSING UNIT CPU• It is the brain of the computer.

• The ALU and the Control Unit (CU) of a computer system are jointly known as the central processing unit.

• CPU performs actual processing of data, according to instructions from programs.

3 MAIN PARTS OF CPU

• CONTROL UNIT (CU)• ARITHMETIC LOGIC UNIT (ALU)• REGISTERS

• ( Registers are small high speed storage areas. )

Block Diagram

FUNCTIONS OF CPU

• It performs all calculations.• It takes all decisions.• It controls all units of the computer.

CONTROL UNIT

• It controls all other units in the computer.

• It is the central nervous system of the computer that controls and synchronizes its working.

FUNCTIONS OF CONTROL UNIT

• It instructs the input unit, where to store the data after receiving it from the user.

• It controls the flow of data and instructions from the storage unit to ALU.

• It also controls the flow of results from the ALU to the storage unit.

• The control unit determines the sequence in which computer programs and instructions are executed.

• The control unit is also capable of shutting down the computer when the power supply detects abnormal conditions.

ARITHMETIC LOGIC UNIT

• All calculations are performed in the Arithmetic Logic Unit (ALU) of the computer.

• Whenever calculations are required, the control unit transfers the data from memory to ALU. Once the computations are done, the results are transferred to the memory by the control unit and then it is send to the output unit for displaying results.

FUNCTIONS OF ALU

• It performs all arithmetic operations (addition, subtraction, multiplication, and division).

• It performs all logic operations (Logic operations test various conditions encountered during processing and allow for different actions to be taken based on the results. )

• It does comparison and takes decision.

STORAGE UNIT

• The storage unit of the computer holds data and instructions that are entered through the input unit, before they are processed.

•Storage devices are divided into two categories:o Primary storage or Primary memory

or Main memoryo Secondary storage or Secondary

memory

FUNCTIONS OF STORAGE UNIT

• It received the data and instructions required for processing from the input unit.

• It stores the intermediate results.• It stores the final results before these results are released to the output unit.• It saves data for later use.

Queries

In case of queries on any topics

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