information & communication technology–it also accesses and uses the main memory (ram - random...

Information & Communication

Technology

Data & Information

• Data can be defined as a raw of facts

– Represented with the help of characters like alphabets (A-Z,a-z), digits (0-9) or special characters(+,-,/,*,<,>,= etc..)

• Information is the processed data on which decisions and actions are based.

– Information has some meaningful values to the receiver.

• Data & Information are relative to the source

10/23/2018 Information Technology Center, University of Peradeniya 2

How to store data in a computer

• Computer stores data in the form of bit (0 or 1) both 0 and 1 represents voltage levels.

• In human readable way it can be referred as files• Many file types or formats• A file format is a standard way that information is encoded for storage in a

computer fileEx: Text files - doc, docx, txt, rtf, wpd

Data files - csv, dat, xmlAudio files - aif, m3u, mp3, wavVideo files - wmv, mp4, rm, flvImage files - bmp, jpg, png, tiff


Computing

• What is Computing– Any goal-oriented activity with data are called computing.

• designing ,building, processing, structuring, managing various kinds of information

• What is computer

– A computer is an electronic device that manipulates information, or dataaccording to set of instructions.

– Set of instructions are called program.

– That is computer has the ability to retrieve,

process(manipulate) and store data.

10/23/2018 4Information Technology Center, University of Peradeniya

Computer System

Computer System

Hardware Software Liveware


Hardware

• Physical components of your computersuch as the system unit (computer),mouse, keyboard, monitor etc…

• Basically, hardware means what istangible

– i.e., Something that can be touched and felt.


Software

• Collection of executable programs with proper documentation and configuration files

• That makes the computer work.

• Held secondary storages (Hard disk, CD-ROM, DVD or on Floppy disk)

• Loaded (i.e. copied) into the RAM (Random Access Memory), as and when executing time.

• Intangible (cannot be touched and felt) as opposed to hardware.


liveware

• People using (attached to) computers.

• Based on the need for a human, or liveware, to operate the system using hardware and software.


Information & Communication Technology (ICT)

• Use of computer systems for storing, retrieving, and sending information.


Main Parts of a Computer


Architecture of CPU


Central Processing Unit

• The CPU is the brain inside the computer.

• Main components of CPU

– Control Unit

• Directs operation of the processor.

• Controls communication and co-ordination between input/output devices

– Arithmetic Logic Unit

• Digital circuit that performs integer arithmetic and logical operations


Central Processing Unit…

• Registers

– Small amount of memory associated with the CPU

– It uses to store data to be operated.

– It also accesses and uses the main memory (RAM - Random Access Memory) within your computer.

• CPU and Main Memory are linked together by Buses.

– Buses contains sets of parallel electrical conducting lines


System Bus

According to von-neuman architecture there are three buses are used to communicate between CPU and devices those are Control bus Address bus Data bus


Types of Computers

• Mainframe Computers

• Supercomputers

• Personal Computers

• Laptop and Palmtop Computers

• Embedded Computers (Systems)


Mainframe Computers

• Very big computers which we had several decades ago.

• They are powerful, expensive computers used in the background by most large organizations.


Supercomputers

– An extremely fast computer which can perform hundreds of millions of instructions per second

– Used extensively by the military, astronomy, space travel, whether forecasting etc.

• Basic idea of supercomputing is computation by many processors on a common task.

– similar to situation where many people co-operate to accomplish a task, which is impossible for one person to do.


Personal Computers

• A small, relatively inexpensive computer designed for an individual user.

• IBM invented the PC (Personal Computer) way back in 1981.


Laptop and Palmtop Computers

• Small and Portable

• Can run on batteries as well as mains power.

• They use special screens, rather than the traditional bulky VDUs (Visual Display Units).

• Palmtop computers are even smaller than laptop computers.


Embedded Computers (Systems)

• Computers that are dedicated to perform a specific task.

• IT may be a washing machine, micro processor based vehicle, or even a mobile phone.


Computer Storages

Memory Unit

• Amount of data that can be stored in the storage unit.

• The storage capacity are expressed in terms of Bytes.

BIT

• A Binary digIT is logical 0 & 1

• Representing a passive or an active state of a component in an electric circuit.

• Smallest measuring size is Bit8 bits = 1 Byte

1024 Bytes = 1 Kilo Byte1024 KB = 1 Mega Byte1024 MB = 1 Giga Byte1024 GB = 1 Tera Byte1024 TB = 1 Peta Byte


Hierarchy of storage

• Primary storage• Directly accessible to the CPU

• Ex: RAM

• Secondary storage• It is not directly accessible by the CPU

• Ex: Hard disk

• Tertiary storage• It involves a robotic mechanism which will mount (insert)

and dismount removable mass storage• Off-line storage


Characteristics of Memory

• Volatile Memory• Requires constant power to maintain the stored information• Loose its data when the power of the computer is turned off• The fastest memory technologies of today are volatile ones

• Ex: RAM

• Non-Volatile Memory• Will retain the stored information even if it is not constantly supplied with

electric power.• It is suitable for long-term storage of information.

• Ex : Hard Disk


Random Access Memory (RAM)

• RAM is the main 'working' memory of the computer.

• When booting computer, operating system (OS) is loaded from the Hard disk to the RAM.


ROM (Read Only Memory )

• Special type of memory chip from which existing software can be read but not written to. – Ex: ROM-BIOS chip, which contains read-only software.

• ROM chip is programmed during manufacture time

• Network cards and video cards also contain ROM chips.

• The ROM contains the program containing the basic functions that a computer should execute when the computer is started


RAM vs ROM

RAM ROM

Temporary memory Permanent memory

Volatile memory-contents are lost when power is off

Non-volatile memory-contents are not erased when power is off

Read and Write memory Read only memory

Working memory Used to store startup instructions-booting instructions


Video (graphics) memory

• The picture that you see on your screen is a form of data and this data has to be stored somewhere.

• The on-screen pictures are held in special memory chips called video memory chips.

• These chips are usually located on the video card.

• A modern computer will be supplied with several Megabytes of video memory.


Peripheral device

• External object that provides input and output for the computer

• There are three different types of peripherals

• Input

• Output

• Storage


Secondary Storage Devices

Secondary Storage Devices

Magnetic Optical Flash

memoryOnline

and cloudPaper

storage

• Floppy Disk• Hard Disk• Magnetic strip• SuperDisk• Tape cassette• Zip diskette

• Flash• Memory card• Memory stick• SSD

• Blu-ray disc• CD-ROM disc• CD-R and CD-

RW disc• DVD(-R,+R, -

RW,+RW) disc

• Cloud storage• Network

media

• OMR• Punch card


Floppy Disk

• Thin magnetic-coated disk contained in a flexible or semi-rigid protective jacket.

• Data is stored in tracks and sectors.

• Double sided high density 3.5" disks can hold 1.44 Mb of data.

• Once data is stored on a floppy disk it can be 'write protected' by clicking a tab onthe disk.– This prevents any new data being stored or any old data being erased.


Hard Disk

• Concentric circles on the magnetized surface of the magnetic disks are known as Tracks

• The tracks on the disk surface are divided into invisible segments known as Sectors

• Each sector stores a fixed amount of user-accessible data

• 512 bytes for hard drives2048 bytes for CD & DVD ROMs


Solid state drive(SSD) VS hard drives(HDD)

• SSD hard drive has no moving parts– less chance of breakage

• SSD hard drive uses flash memory can store and access data much faster.

• less power consumption

• Easy to install


Magnetic tape

• A magnetically thin coated piece of plastic wrapped aroundwheels capable of storing data.

• Tape is much less expensive than other storage mediums

• it is a much slower solution that was typically only used forbackup


Optical Disk• Metallic disk that uses a laser beam for reading and writing. • There are Four kinds of Optical Disk:

1. CD-ROM (compact disc read-only memory) • Cannot be written on or erased by user (read-only).

2. CD-R (CD-recordable) or WORM (write once, read many) • Can be written to one time only• After writing to the disk it cannot be erased by users but can be

read many times without deterioration. 3. Erasable optical disks

Can be written and erased and reused. Two basic types:

a. CD-RW (compact disk re-writeable)b. MO (magnetic optical).

4. DVD(digital versatile disk) similar to CDs. Have a greater capacity of 4.7 gigabytes.

5. Blue Ray DiskBlu-ray beat out HD DVD in the high-definition disc format


Pen Drives(flash drives)

• Very high capacity portable devices

• It can be plugged directly into the USB port

• Present day pen drives which are about thumb size have gigabytes of memory


Memory card

• Alternatively referred to as a flash memory card.

• Used to store photos, videos, or other data in electronic devices


Cloud computing

• Services provided over a network by a collection of remote servers.

• This abstract "cloud" of computers provides massive, distributed storage and processing power

– Can be accessed by any Internet-connected device running a web browser.


Network Storage Media

Media is any audio, video, images or text, used on a computer network, like the Internet.

It almost always requires

a computer to send and receive

a community of people to create and consume the content.


OMR(Optical Mark Reading )

• Process of gathering information from human beings by recognizing marks on a document.

• Accomplished by using a hardware device (scanner) that detects a reflection or limited light transmittance on or through piece of paper.


Punch card

• Punch card containing several punched holes that were punched by hand or machine to represent data.

• These cards allowed to store and access information by entering the card into the computer.


Memory Hierarchy


Input Devices

Mouse

• A Mouse is a palm-sized device

• Used to control the movement of an object on the computer screen called a mouse Cursor, or pointer.


Touch pad

• Device for pointing (controlling input positioning) on a computer display screen.

• Alternative to the Mouse.

• Originally incorporated in laptop computers,

• Also being made for use with desktop computers.

• Works by sensing the user's finger movement and downward pressure


Keyboard

• The most common way of entering information into a computer.

• Number of different types of keyboards, including those specially designed to use with Microsoft Windows.

• Normally we use “QWERTY” keyboard.

• "The name "QWERTY" for our computer keyboard comes from the first six letters in the top alphabet row.


Typing(alphanumeric) keysFunction Keys

Control keys

Scanner

• A scanner is a device that can read text or images printed on paper and translate the information into a form the computer can use.


Digital Camera vs Web Camera

• Digital camera –– Stores images digitally.

– Once a picture has been taken, • it can be transfer to a computer system

• then edit with a graphics program and printed.

• Web Camera– A video camera, usually attached directly to a computer

– Takes digital images and transmits them over the Internet.

– Widely use for chat trough internet.


Microphone

• Converts sound into an electrical voltage wave or signals.


Output Devices

Monitor

• Monitor is visually interface with the computer

• Mainly there are two types of Monitors

– CRT Monitor

– LCD Monitor

– LED Monitor

• Visual Display Units(VDU) display images and text

• Those are made up of small blocks of coloured light called pixels.

• The resolution of the screen improves as the number of pixels is increased.


CRT Monitors

CRT stands for Cathode Ray Tube.

The monitor tube is a glass vacuum tube

one end having an electron gun

Electron gun projects three beams(red, green, and blue)

Display surface coated with phosphors.

When the electron beam strike the coating it glows with the particular color


LCD Monitors

• LCD stands for Liquid Crystal Display

• Used in digital watches and many portable computers.

• Low power consumption when considering to the CRT monitors.

• Also it has excellent text contrast than CRT.


LED Monitors

• An LED display is a flat panel display,

• Uses an array of light-emitting diodes as pixels for a video display.

• capable of providing general illumination in addition to visual display.


Ink-jets (bubble-jets) printers

• Tiny drops of ink onto a page to create an image.

• Capable of producing high quality print which almost matches the quality of a laser printer.

• Has a resolution of 300 dots per inch


Laser printers

• Print very fast, and the supply cartridges work long time.

• Color laser printers use the same toner-based printing as ( B/W) laser

printers,

– But that they combine four different toner colors.

• Color laser printers can also be used as a regular black and white laser

printer.


Impact (Dot-matrix) printers

• Use a set of closely spaced pins and a ribbon to printing.

• Impact the page to print a character, much like a typewriter.

– Commonly used for printing invoices, purchase orders, shipping forms, labels, and other multi-part forms.


Thermal Printers

• Print more quietly and usually faster than impact dot matrix

printers.

• They are also smaller, lighter and consume less power, making

them ideal for portable and retail applications.

Commercial applications • filling station pumps

• point of sale systems

• voucher printers in slot machines


Plotters

Large-scale printers that are very accurate at reproducing line drawings.

Commonly used for technical drawings such as engineering drawings or architectural blueprints.


Headphone

• A pair of small loudspeakers, or less commonly a single speaker,

• Held close to a user's ears and connected to a signal source

– such as an audio amplifier, radio, CD player or portable media player.

• They are also known as stereophones and headsets.


Speakers

• Output of Sounds


Multimedia Projector

• At its most basic, a multimedia projector simply projects an image on a screen.

• Multimedia projectors can be configured to project a

• Computer's video signal

• Outputs from DVD players

• Direct connections from cable and satellite systems.

• Designed for almost every application, level of quality, and size of audience.


Input Output ports and connectors

• Ports- used to connect external devices to the computer

• Connectors- cable used to connect the external device to the computer through the port


Types of ports

• Serial

• Parallel

• Universal Serial Bus

• PS-2

• Infrared

• Bluetooth


Serial ports

• Transfer data serially a bit in or out one at a time

• Takes longer time

• Necessary to send a start bit before each byte of data and stop bit after each byte of data

• Often known as communication(COM) port or RS232C port

• Come in the form of 9-pin or 25-pin male connector

• Used to plug devices like Keyboard, Mouse or modem


Parallel port

• Can send or receive 8-bits at a time

• Transmits data parallel

• Comes with 25-pin female connector

• Used to connect Printers, CD writers, Hard Disks


USB port

• Generally used for flash drives, scanners, cameras

• Now even for mouse, keyboard, printers, etc..


PS2 port

• Generally used for mouse, keyboard, printers, etc..


Infrared Port (IR Port)

• Sends and receives IR signals

• Involves a transceiver- transmitter & receiver

• Short distance

• Used in TV remotes, Music systems, etc..


Bluetooth

• Wireless protocol used to exchange data from fixed and mobile devices

• Uses radio frequency


Types of Software

Software

• Collection of executable programs with proper documentation and configuration files

Software

System SoftwareApplication

Software

Packaged Software

Custom-Made Software

Utility Software


Types of Software

• System Software– Controls the operations of a computer and the other types of software

that runs on the computer. • Ex: operating system, device drivers, programming languages, compilers,

assemblers ,translators and editors, and debuggers

• Application Software – Type of program that you use once the operating system has been

loaded. – Programs designed to perform specific tasks – Application software may be of two types.

• Packaged Software• Custom-madeSoftware


Application software

• Packaged Software– Programs prewritten by professional programmers that are typically

offered for sale.• Word-processing applications

• Spreadsheet applications

• Database applications

• Presentation applications

• Custom-made software– Programs written for a specific purpose and for a specific organization

• Banking system

• Student Registration System


Utility Software

– Carries out all the day to day tasks in maintaining a computer system and its data files.– Ex: screensaver, virus checker, and system tools like disk defragmenter.

– Certain utility programs are usually bundled along with the operating system.


What is an operating System?

• Software program that enables the computer hardware to communicate and operate with other software.


• It is loaded into the main memory when the computer is switched on.

HD

RAM

OS

LOAD OS TO RAM

Operating Systems….



• The operating system does the followings on a computer:

– Controls a Computer’s Hardware

– Runs a Computer’s Programs

– Organizes Files


• A part of the OS remains in the main memory until the computer is turned off.

RAMOS



Types of User Interfaces

• User interfaces let user communicate with the computer.

• There are two types of them,

– Command Line Interface (CLI)

– Graphical User Interface (GUI)


An Example of a CLI


Operating System….

• Command Line Interface(CLI).

– Users have to use keyboard commands to use the OS.

– The user has to remember the commands.

– At the beginning all the OS were running in CLI mode.

– Even today some OSs give CLI as a part of their system tools.

– Examples : MS DOS, Linux, UNIX, etc.


An

Exa

mp

le o

f a

GU

I



• Graphical User Interface (GUI).– Contains graphics and icons and is commonly navigated by using a

computer mouse and can be used to invoke commands.

– The GUI was first used on Apple Macintosh Computers

– The GUI is very easy to learn and use i.e. user friendly.

– Many of the modern operating systems come with GUIs

Example :

Windows 3.1 , windows 95 , windows 98, windows ME , windows NT, Windows 2000, Windows XP(Home/Professional),Windows-8, Windows-10



• Some operating systems support both GUI and CLI.

• Example : linux


Hardware

OS

Applications


Data Backup and Computer Viruses

Data Backup

• What is Data backup ?

– Important files are usually replicated (saved) in several places.

• Why is it needed?

– To minimize the bad effects of

• Hardware or software failures

• Virus infections

• Power failures

• Unauthorized changes to data


Data Backup…

• Backup software are used for backup data

– Windows XP (Start->Programs->Accessories->System Tools->Backup)

• The backup program will skip currently using files.

• Backed up data should be restored to be of any use again.

– This can generally be done using the same software that is used for backing up.

• Backup files with extension “.bkf”


Backup Media

• Widely used backup media

– Physically separate IDE of SCSI drives

– Floppy disks

– ZIP disks

– Compact disks (Writable or Rewritable)

– Tapes


Computer Viruses

• Viruses are small programs that

hide themselves in your disks.

• Different viruses are activated in different ways.

• The worst thing is that they can spread from one computer to another

– over a computer network or portable storages

• It is better to use antivirus software and update regularly.


information & communication technology–it also accesses and uses the main memory (ram - random...

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