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COMPUTER FUNDAMENTALS

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Introduction to Computers

The word “computer” comes from the word “compute", which means, “to calculate”.

Thereby, a computer is a electronics device that can perform arithmetic operations at high speed.

A computer is also called a “data processor” because it can store ,process & retrieve data whenever required.

Introduction to Computers

Software - Word, PowerPoint, Excel, etc. Fun stuff - Games, Photos, etc. Operating Systems – Microsoft, Unix

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Data Processing

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Characteristics of Computer

Automatic

Characteristics

Speed Accuracy No IQ Diligence

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Basic operation of Comp. System

INPUTTING STORING

PROCESSING

OUTPUTTING CONTROLLING

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Basic organization of a computer system

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Input Unit

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Output Unit

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Storage Unit

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Types of Storage

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Central Processing Unit

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Memory Units

Memory is divided into storage locations called memory cells.Associated with each memory location are: 1. Address - position of a cell in memory

2. Contents - info stored

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Memory Units

Everything is manipulated as 0s and 1s stored using two-state devices:

switches, transistors, vacuum tubes.

On/Off states easily compare to the binary numbering system, Base 2.

On = 1, Off = 0 Binary Digit = Bit

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Memory Units

Bits are grouped into bytes ( 8 bits = 1 byte)

Each Memory Cell is 1 byte

Bytes are grouped into words (length is dependent on the machine)

The computer handles data in multiples of bit chunks (bytes)

Data stored in 1 byte

Memory Units

MAIN MEMORY UNIT:

Also called as Primary Memory unit. 2 most important are: RAM ROM They work in different ways and perform

distinct functions.

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RAM (Random Access Memory)

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ROM (Read Only Memory)

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Types of ROM

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Types of ROM

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Cache Memory

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Classification of Computers

Computers Generations

“Generation" in computer talk is a step in technology. It provides a framework for the growth of computer industry.

Till today there are five computer generations:

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Electronics Devices

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Input Devices Also known as Peripheral devices. Used to enter data from the outside world into

primary storage.

For e.g.: Keyboard Mouse Electronic Pen Joystick Scanner ,etc

Keyboard

Mouse

Mouse is a point-and-draw device. Move in all directions.

Electronic Pen Point-and-draw device Used to directly pt with it on the screen to

select icons or to draw graphics on screen. Can write with it on a special pad for direct I/P

of written information to a system.

Joystick

Pointing Device. Moved forward,backward,left & right. Button on the top is provided for selection.

USES:

Commonly used for video games,for controlling industrial robots.

Scanner

,etc.

OCR (Optical Character reader)

l Used to recognize alphanumeric characters.l Reflected light converts into binary no.l Dark area absorb the light whereas light is

reflected by lighted areas.l Reflected light falls on Photocells which

provide binary data corresponding to dark and light areas.

l A B C D E………………………….z

0 1 2…………………………………………...9

‘ - { } % ? etc.

Monitor Printer Speaker Screen image projector ,etc

Monitors are the most popular o/p device used for producing soft-copy of the o/p.

Types of Monitor: CRT Monitor LCD Screens

CRT Monitors

This acronym stands for “Cathode Ray Tube” Very widespread Cheap Good performance

CRT Monitors

The Shadow Mask

Working method of CRT monitor

The back of the tube has a negatively charged cathode, so called electron gun. The electron gun shoots electrons down the tube and onto a positively charged screen. The screen is coated with a pattern of red, green and blue phosphor dots that will glow when struck by the electron stream. The three dots together make up a pixel.

LCD Screens

LCD means Liquid Crystal display

Good quality

How LCD works?

There is a thin liquid cristal layer between a horizontal and a vertical filter. Thanks to an appropriate voltage liquid cristals get arranged and light can pass the filters. This light will appear on the screen.

In color LCDs each individual pixel is divided into three cells, or subpixels, which are colored red, green, and blue. Each subpixel can be controlled independently to yield thousands or millions of possible colors for each pixel.

Printers A computer printer is a device that

produces a hard copy of documents stored, usually on physical print media such as paper.

Main types of PrintersDot matrix

Inkjet

Laser

Drum ,etc.

Dot Matrix Printer

Inkjet Printers

Inkjet Printers

Inkjet Printers

Laser Printers

Laser Printers

Drum Printers They are Line printer coz it print one line at

a time. Have a solid cylindrical drum with

characters embossed on its surface in the form of a circular bands.

Set of hammer mounted in front of the drum in such a manner that an inked ribbon & paper can b placed b/w the hammer & drum.

Drum Printers

It can only print a pre-defined set of characters in a pre-defined style that is embossed on the drum.

The drum would have to complete one full revolution to print each line.

Drum printers are impact printers,hence they can b used to produce multiple copies by using carbon paper.

Drum Printers

Screen Image Projector

Magnetic Tape

Magnetic Tape

Advantages of Magnetic Tape

Limitation of Magnetic Tape

Magnetic Disk

Magnetic Disk

Magnetic Disk

Magnetic Disk

Magnetic Disk Access Time

Magnetic Disk

Floppy Disk

Floppy Disk• Data is recorded on

disk in concentric circular bands called tracks

• Each track is divided into pie-shaped wedges called sectors.Two or more sectors combine to form a cluster.

Floppy Disk Most computers

maintain on the disk a table with the sector and track locations of data. This table, the file allocation table (FAT), enables the computer to locate data easily.

Hard Disk

Zip/Bernoulli Disk

Disk Pack

Winchester Disk

Optical Disks

Optical Disks Storage organization

Types of Optical Disks

CD-R (WORM)

CD-RW

DVD

Optical Disks CD-ROMs: Compact Disc Read-Only

Memory can store up to 6 Mega Bytes

CD-R: Compact Recordable holds the same storage, it is recordable once.

CD-RW: Compact Disc Re-Writeable are read and writable, but does not have the same capacity, because it uses some magnetic technology.

DVDs: Digital Versatile Disc can hold up to 17 Giga Bytes. Used by the contents industries.

OPERATING SYSTEM

A program that acts as an intermediary between a user of a computer and the computer hardware.

Operating system goals: Execute user programs and make solving

user problems easier. Make the computer system convenient to

use. Use the computer hardware in an efficient

manner.

OPERATING SYSTEM

OS is a resource allocator Manages all resources Decides between conflicting requests for

efficient and fair resource use OS is a control program

Controls execution of programs to prevent errors and improper use of the computer

OPERATING SYSTEM

Logical Architecture of a Computer System

This operating system layers hides the details of the hardware from the programmer

Provides the programmer with convenient interface.

Parameters for measuring system performance

Functions of OS

Process Management

Memory Management

File Management

Security

Command Interpretation

Process Management

A process (also called job) is a program in execution.

Process Management manages the processes submitted to a system in a manner to minimize idle time of processors (CPUs,I/O processors,etc.)

Process Management mechanism in early computers

Multiprogramming

Uniprogramming

Multiprogramming System

Process state in multiprogramming

Multitasking

Interleaved execution of multiple jobs (often referred to as task of same user)in a single-user system.

Computer system used for multitasking is uniprocessor systems(having only one CPU)

Multiprocessing

Multiprocessing System

Time-Sharing

Simultaneously interactive use of a computer system.

Short period during which a user process gets to use CPU is known as TIME SLICE,TIME SLOT or QUANTUM.

CPU is taken away from a running process when the allotted time slice expires.

Process State Diagram of Time-Sharing System

Advantages of Time-Sharing

l Reduces CPU idle time.l Provides advantages of quick response time.

Memory Management

l Keeps track of parts of memory in use and parts not in use.

l Allocates memory to processes as needed and deallocates when no longer needed.

Uniprogramming Memory Model

l Used in systems that process one job only at a time.

Multiprogramming Memory Model

Multiprogramming with fixed no. of memory partition

Multiprogramming with variable no. of memory partition

Multiprogramming with variable no. of memory partition

Virtual Memory

Virtual Memory Realization

File Management

File access Method

File Operation

File Extensions

l .c c source program file.l .txt general text file.l .doc microsoft world document file.l .xls microsoft excel spreedsheet file.

Security

l Deals with destruction and unauthorized access.

Types of Security:l External Security : Deals with fire,floods etc.l Internal Security : Deals with user

authentication, access control, cryptography mechanism.

Security

Command Interpretation

Command Interpretation