chapter 1 ict in today's world.pdf

7/25/2019 Chapter 1 ICT in Today's World.pdf

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What you will learn in this section

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Just for a moment imagine a world without information and communi-cation technology. What would your life be like without ICT? You wouldhave no mobile phone, no MP3 player, no television, no internet for emailand web browsing, no computer games no computers at all! All these youcould probably live without, even if you were miserable and bored butthink also about all the ICT in use around us we rely on ICT to provideus with power for lighting and transport and as a way of managing carengines, and keeping airlines, buses and trains running to time withoutwhich our life would, as we know it, be impossible. There are places andpeople in the world today that manage quite well without all the infor-mation and communication technology that we take for granted but they

would find it impossible to run many aspects of their lives the way we do.Our modern societies would not be as pleasant and may not survive as weknow it without ICT. ICT is all around us, in our homes, in our schools and businesses andin the infrastructure that allows our society to work and function. In thissection you will find the ICT systems in todays world that you need toknow about.

ICT systemsWhat is a computer?A computer is a programmable machine that follows a set of instructions.Early computers were mechanical with levers and cogs such as CharlesBabbages Difference Engine which was an automated, mechanical calculator,large enough to fill a small room! Babbages Analytical Engine was designedto be a general purpose computer but was never built, some believe, becausethe technology of the day was either not good enough or too expensive.Babbage was still working on the design when he died in 1871. A workingmodel was built in 1992 and can be seen in the Science Museum in London.

What you will learn in this chapter The different types of ICT system and their uses The difference between hardware and software The hardware components of ICT systems The software used in ICT systems

ICT in Todays World1

ACTIVITY 1Make a list of threeitems that you ownor use regularly apart from your

laptop or PC thatuse ICT and that youthink you could notdo without, and thenwrite down whatyour life would belike without them.

Charles BabbagesDifference Engine


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1: ICT in Todays World 3

Analogue computersAnalogue computers existed long before digital computers were invented.Guns were targeted using mechanical analogue computers during WorldWar I and the Korean War by the United States Army Air Force.

Digital computersModern computers are not mechanical but are electronic and, while someanalogue computers are used in universities for research, most computersnow are digital. Computers can follow or execute a set of prewritten or recorded

instructions, called a program, and respond to commands entered by a user. All computers used today have the same basic structure, although theway the components are arranged in the structure differs depending on theuse to which the computer will be put. The photos show some examples ofmodern computers:

Charles BabbagesAnalytical Engine

WEBLINKS

http://oro.open.ac.uk/5795/1/bletchley_paper.pdf#

http://dcoward.best.vwh.net/analog/

These have explanations and documents about analogue computers

KEY WORDSAnalogueAnalogue signals arecontinually variableand even smallfluctuations in thesignal are important.Analogue systemsuse continuousranges of valuesto representinformation.

DigitalDigital signals havediscrete values suchas on/off, 1 or 0. In-between values arenot used.

WEBLINKS

http://en.wikipedia.org/wiki/Analog_signalhttp://en.wikipedia.org/wiki/Digital

These have explanations of analogue and digital signals.

Desktop PC Laptop Netbook


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4 Unit 1 OCR ICT FOR GCSE

Personal computersYou will be most familiar with the personal computers that you use inschools and at home that you use for tasks such as writing reports or lettersin a word-processor, doing calculations or data modelling in spreadsheets,photo and video editing or playing games. These personal computers areoften connected together on a network and the internet which also allowsthem to be used for searching the World Wide Web, sending and receivingemail messages, accessing chat rooms or instant messaging, writing blogsand using social networking sites. Personal computers include netbooks, laptops, notebook computers,palmtops, desktop computers, tablet computers, PDAs and handheld

computers. Modern mobile telephones can also carry out many of the tasksnormally associated with personal computers with the added advantagesof being able to keep in contact with friends by text message or telephone,having an inbuilt camera and playing music or video files or using applica-tions when out and about away from home. Personal computers are often found in businesses and are used forgeneral tasks such as running database management systems, businessspreadsheets and for specialised business purposes such as computer-aideddesign and computer-aided manufacture such as making cars or televisions.Also, personal computers can be used for capturing and monitoring datareceived from sensors such as for recording temperatures and pressures ofthe weather.

PDA Mobile phone Mainframe computer

WEBLINK

http://en.wikipedia.org/wiki/Computer

This describesdigital computers.


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Other types of computer systemLarge organisations such as banks, insurance firms and utility companies(these supply gas, electricity and water) may use mainframe computers.Mainframe computers are computers which work not as a single computerbut as if they were many, often dozens or hundreds, of computers eachrunning their own operating systems and carrying out many tasks at once.The term mainframe is now somewhat out of date but it originally referredto the construction of mainframe computers on a set of frames or racksthat held the component parts. Mainframe computers are used where largeamounts of data needs to be processed in bulk, e.g. the processing of bankstatements, utility bills or stock control.

Supercomputers and mainframesSupercomputers are the fastest computers that exist in terms of the speed of

calculation and are used, for instance, in university research departmentswhere fast and complex calculations need to be carried out. This includesthe complex calculations needed for simulations or modelling scenariossuch as those needed for modelling climate changes. Here large amounts ofdata collected from many areas will need to be used to try and predict whatwill happen to the climate. The distinction between mainframe computer and supercomputer isoften not that clear today but supercomputers are usually one of a kind,built for a particular purpose, although supercomputers often contain thesame components as other computers just more of them!

ACTIVITY 2For each of the different types of computer shown, write down some typical tasks that it would be mostsuitable for.

Desktop computer Smart mobile phoneLaptop computer Personal DigitalAssistant (PDA)

Cray or IBMsupercomputer


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Embedded computersAt the other end of the scale, embedded computer systems are foundin everyday devices and carry out only one or two tasks so they do notneed to be as flexible as a personal computer. An embedded computersystem controlling traffic lights at a road junction does not need to doanything else. Music players, mobile phones, microwave ovens, washingmachines, digital watches and calculators all contain embedded systems.The components and software in these devices only have to carry out theirdesigned function and no other; for instance, in an iPod there is only aneed for software to organise and play music and videos. A mobile phonewill contain software that controls the connection, address lists and textmessages but will not usually have to do much else. Of course, as the devicesuch as an iPhone becomes more complicated and able to carry out morefunctions, the embedded software has to be added to, but simple devices

like a washing machine will probably only ever be required to wash clothes.

Microwave ovenMusic player

Digital watch

Calculator Washing machine

KEY WORDS

Type of computer

Personalcomputer

These include netbooks, laptops, notebookcomputers, palmtops, desktop computers,tablet computers, PDAs and handheld

computers. Used for web searching, email,running applications, e.g. word-processing,spreadsheets, databases, and many othersoftware applications in homes and offices

Mainframecomputer

Large computers used in banks, insurance firmswhere very large amounts of data have to beprocessed quickly

Supercomputer Very fast computers used in universities andother areas where complex calculations areneeded and speed of calculation is important


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Hardware and softwareThe physical components of a computer system are called the hardware

and the instructions that make the system work and which the systemfollows are called software. Hardware is all of the physical components that can be touched, held andseen. Software is used to program the computer system which means tocreate a set of instructions, usually stored or saved for later use, that thecomputer will follow. Different types of software are used for different tasks,e.g. the software that controls the hardware and allows a user to interactwith a computer system is the operating system while software that enablesusers to carry out tasks is called application software or simply applica-tions. Other types of software include utility software that does a specific

task such as checking a disk drive for errors, and drivers that allow theoperating system to communicate with, e.g. a printer. Today, many utilitiesand drivers are included in the operating system and are already presentafter the operating system has been installed but if new hardware is addedthen new drivers may have to be installed.

HardwareWhatever the type of computer, it will always have the same basic hardwarestructure. The table on page 8 shows the hardware and what it is for.

There will also be all the components, nuts, bolts, screws, wiring andconnectors, etc. to allow all the other components to work together but essen-tially a computer system consists of INPUTS, OUTPUTS, PROCESSINGand STORAGE devices and data flows around the computer system fromone to another as shown in the following diagram.

WEBLINKS

http://www.teach-ict.com/gcse/hardware/types/teacher/types_theory.htm

http://computer.howstuffworks.com/10-types-of-computers.htm

http://en.wikipedia.org/wiki/Personal_computerhttp://www.webopedia.com/TERM/P/personal_computer.html

http://www.historylearningsite.co.uk/personal_computer.htm

These provide explanations and descriptions of different types ofcomputers.

ACTIVITY 3Use the internetto find out whatis meant by

microcomputerand write downthe names of twofamous makes ofmicrocomputer.


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Depending upon the type of computer system in which they are fitted,the hardware components will look different and be larger or smaller in sizebut will perform the same function.

Hardware Function

Inputdevices

Components to allow users to enter data such asinstructions

Processor Component for deciding what the instructions mean andwhat to do this is the processing of the instructions or data

Outputdevices

Components for showing the results of the processing tothe user data such as instructions

Internalor mainmemory

Components to storethe data and/or instructions that areabout to be, are being, or have been, processed

Backingstorage

Components to storethe data and/or instructions when thecomputer is switched off so the computer system or a usercan come back to them later

INPUT OUTPUTPROCESSING

MAIN orINTERNALMEMORY

BACKINGSTORAGE

KEY WORDS

InputEntering data into acomputer system isinput.

ProcessingData is convertedit from one form toanother. This is doneby following a setof instructions andcommands.

OutputWhen the resultsof processingare shown, this isoutput.

StorageData is kept orrecorded whilewaiting to be usedor for future use.

Data, such as instructions and commands or information to be used forcalculations, is entered using the INPUT devices, worked on (processed),and OUTPUT so the user can see the results. If you are typing a memo, theinput would be the keystrokes on a keyboard for the letters, the processingwould be where the letters should go and the output would be the memoon a monitor. If you decide to stop and leave the memo for later, the memocould be stored on a flash memory device or hard disk.


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More componentsOften, other devices may be present such as the components needed toconnect the computer systems to others on a network. Other devices could be the communication devices such as modems,network interface cards, routers and hubs. Other connection systems mayalso be present, e.g. USB interfaces.

Network interface card

ACTIVITY 4Imagine that you have a list of your friends and want to keep it on yourlaptop. You carry out three tasks: typing in the list, sorting the list intoalphabetical order of name and printing yourself a list to keep at home.

Identify which of the three tasks is input, output and processing.

Router

CPU

Hub

ModemUSB Flash memory stick


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Communication devicesThe function of these devices is shown here:

Device Function

Modem This device encodes digital information on to ananalogue signal. Often used to send digital data

along ordinary telephone lines

Network interfacecards

This device is often just called a network card or NIC;these provide the electronic circuitry for computersto communicate on a network

Hub This device connects different networks sections

Routers andswitches

These devices connect different networks and canbe used to control where the data is sent. They areoften found in homes and used for connecting to theinternet

USB interface This is used to connect a computer with anotherdevice such as a flash memory device

Processing dataThe processing in computer systems is carried out by the Central ProcessingUnit or CPU for short. The CPU is a collection of electronic circuits that carryout, orexecute, the instructions either in a program or which are enteredby the user and which make decisions using the instructions. How these

KEY WORDS

NetworkWhen computers are connected together so that they can share data anddevices such as printers, they are said to be in a computer network.

InterfaceThis is where data is transferred between computer devices or betweenpeople and computers.

USB interfaceThe Universal Serial Bus interface was designed for use on personalcomputers to connect peripheral devices such as printers, keyboards andflash drives. It is now commonly used to connect other devices such ascameras. USB connections are also now found on many other devices suchas PDAs, mobile phones and can also be used to charge batteries.

Peripheral deviceAny device that is not actually part of the computer but is attached to

a computer is called a peripheral device. Peripheral devices are seen asexpanding the system and include scanners and printers.

ACTIVITY 5Find out what a userinterface is andwhat it is for.


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instructions are executed is not important here but the instructions have tobe entered into the computer, stored in the computers main memory, or insome special memory actually inside the CPU itself, and the results outputfrom the computer for every task that the computer is asked to perform.

If the computer is switched off, then the data that users need to carry onwith their work when it is switched back on and all the instructions neededto start and operate the computer have to be kept on a storage device. If thisdata was not stored safely, the users would have to redo all of their workevery time they switched off and restarted the computer; if the instructionsto start the computer were not stored, then it wouldnt restart! The components used for input include not only the familiar devices suchas the mouse and keyboard found in personal computer systems but alsomore specialised input devices such as microphones designed to capturesounds, suck and puff switches used by those people unable to use their handsto manipulate a keyboard or mouse and the input devices used in computer

games (such as wireless games controllers) and at supermarket terminals.

Input devicesSome examples of input devices are shown here:

Input device Typical use

Mouse Choosing options from an on-screen menuand selecting icons

Keyboard Entering characters when typing a letter

Joystick/game controller Moving on-screen objects in a computergame

CPU


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Scanner Importing a printed image into a computersystem

Barcode reader Reading the data stored in a barcode

Chip and PIN reader Reading the data stored in a chip on a bankor ID card

Magnetic stripe reader Reading the data stored in a magnetic stripeon a bank or ID card

Keypad Entering numbers at a supermarket checkout


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Webcam Capturing still or moving images

Microphone Capturing sounds

Sensors Capturing data about physical conditionssuch as temperature, light and pressuresensors

Remote control units Sending the users decisions to, e.g. a TV

Puff-suck switch A mouth-operated switch for use by those

who are physically impaired


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Foot mouse A foot-operated switch with mouse functionsfor use by those who are physically impaired

Braille keyboard A specialised keyboard for use by those whoare visually impaired

Touch screen For entering data by touching, e.g. an imageof the item at a supermarket or fast foodcheckout; this device is also an output device

Other devices that could be considered to be input devices are digital stilland video cameras as these can be directly connected to computer systemsand the images passed directly to the computer system. Digital camerasusually capture images and store the images on internal storage devicesbefore these are downloaded to the computer system so, strictly speaking,they are not input devices when used on their own and then the imagesdownloaded.

ACTIVITY 6Persons withphysical disabilitiesoften have

difficulties usingcomputers in schoolsto do their work. Find out aboutthe specialisedequipment andsoftware that canhelp those people touse computers.

WEBLINK

http://schools.becta.org.uk/index.php?section=tl&catcode=ss_tl_inc_ac_03&rid=9813

This gives a description of the use of ICT for assisting with disabilities.

Output devicesOutput devices are needed so that a user can find out the results ofprocessing the input. Some output devices and their uses are shown here:

Digital camera

Digital video camera


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Output device Typical use

Monitor This is the screen or display found on most computersystems and used to see the results of processing.

Monitors are now nearly all LCD with flat screens,and the older-style vacuum tube displays are nolonger used. They are found in all shapes and sizes butwidescreen monitors are best for viewing movies

Printer Printers produce copies of the results on paper this ishardcopy

Speakers/headphones

These produce sounds

Actuators These produce movement, e.g. motors to move a

barrier or door

Storage devicesThe storage of data and instructions is important because the CPU needs tobe able to access the data or instructions quickly and easily and a user needs

to be able to store their work for future use. A computer system has twotypes of storage for its data: the main memory (also called internal memory),where the data that is being used, is about to be used or has just been usedby the CPU is kept, and a backing storage for longer-term storage of data.

Storage Function

Main (internal) memory Holds the data that is currently in use

Backing storage Holds data for long-term storage

ACTIVITY 7During one schoolweek, make a list of

each different inputdevice that you use,why you use it andhow many times youuse it.


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Computer memoryThe main, internal memory consists of two types:

Read Only Memory (ROM) which is used to store data or instructionsthat do not need to be changed such as the instructions needed when thecomputer is first switched on. When a computer is first switched on, theCPU does not know what to do so there are a few instructions stored in

ROM that tell it where and how to find the instructions to get started. ROM is a type of memory from which data can be read but which cannotusually be changed or erased such as the data that a computer needs whenstarting up or the instructions in a washing machine. Users must not beable, or have any need, to alter these instructions because if they do thenthe machines would not work. Also, ROM does not lose its data when the electrical power is switchedoff. It is said to be nonvolatile, i.e. keeps its data without the need forelectrical power. Special types of ROM can have the data changed, e.g. anEEPROM (Electrically Erasable Programmable Read Only Memory) canbe erased and reprogrammed and there are other types that are used for

specialised purposes such as storing the configuration details of a router.Sometimes, the initial startup instructions of a computer (called the BIOS)are stored in EEPROMs so that they can be updated in the future.

Random Access Memory (RAM)makes up the bulk of the memory foundin computer systems. RAM does not keep any data if its power supplyis switched off (it is said to be volatile) but, usually, data in RAM can beaccessed much faster than in ROM. More importantly, the data in RAM canbe accessed quickly wherever it happens to be stored. Data stored on tapes and hard disks is accessed much more slowly,although data stored on flash memory, such as memory sticks, can be

accessed more quickly. RAM is used to store the data and instructions such as the operatingsystem that the CPU is currently using, and the data and software applica-tions being used by the user. A typical laptop computer would have some internal memory (ROMand RAM) and a hard disk. When it is switched on, the instructions storedin its ROM will be used to start it and load the operating system from thehard disk into its RAM. When it is ready for use, a user may start an appli-cation like a web browser and this will also be loaded from the hard diskinto RAM ready for use.

ACTIVITY 8The size or capacity of storage devices is measured in bytes.(a)Find out what is meant by a byte.(b)Find out how many bytes make up a kilobyte (Kb), a megabyte (Mb) and

a gigabyte (Gb).

WEBLINKS

http://www.hardware.

windowsreinstall.com/memory.htm

http://www.computersecuritynews.org/computer_memory_explained.htm

This provides anexplanation ofcomputer memory.


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Losing all your work when the power supply is switched off is veryannoying, so computer systems have backing storage, such as a hard disk,

where users can store or save their work. Backing storage is used to keepthe instructions that the CPU needs to function the operating system and the instructions that a user will need to carry out a task the softwareapplications and any data needed or used by a user of the system. Modernapplications provide an automatic backup of a users work so, in the event ofa power failure or other disaster such as a program crash, most of the workcan be recovered easily. Hard disks are commonly found in modern computers and, as the namesuggests, are made of metal disks, inside a sealed casing, on which data isstored by magnetising the surface of the disk. The correct term for the harddisk device is hard disk drive or hard disk device. The actual data is stored

on the metal disks which are the medium. It is important to use the correct terms in ICT or computing so a deviceor drive is the physical mechanism that is used to hold the medium (themetal disks in the hard disk example above) on which the data is stored. Atape drive uses magnetic tape as a medium and a USB memory stick usesflash memory as the medium and the now rather outdated floppy disk driveis the device and the floppy disk is the medium.

KEY WORDS

ROMRead Only Memory is a permanent storage area of memory that does notlose its data when power is turned off it is said to be nonvolatile. Datacan only be read from ROM, not written to it.

RAMRandom Access Memory loses its data when power is turned off it is saidto be volatile but can be written to as well as read from.

BIOSThe Basic In Out System that is needed to tell the computer what to do onstartup.

Hard disk drive

Tape drive


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Some backing storage devices, e.g. DVD drives, have a removablemedium, e.g. a DVD-R, so that when one is fully used another disk can besubstituted or the disk can be taken to another computer which can readthe data using its DVD drive.

Flash memoryFlash memory is becoming more commonly used as the technologybecomes easier and cheaper to manufacture. Flash memory is similar toROM in that it retains its data when the power to the computer is switchedoff (it is nonvolatile) but it is like RAM in that it can be erased and usedover and over again. Flash memory is a very specialised type of EEPROM that can be erasedand rewritten to many times over and is used in memory cards (such asthose used in mobile phones and digital cameras) and USB flash drives.

Because flash memory needs no power to keep its data intact, allowsfast access times to its data and is not easily damaged, many people storeimportant data on their USB key sticks instead of on their hard drive. Some computer manufacturers are now using flash memory insteadof hard disks in their smaller computer systems. Flash memory is usedin systems such as mobile phones, music players, PDAs, game consolesand digital cameras. Digital video cameras now use flash memory to storeimages as flash memory is more reliable and can hold more data than theconventional video tapes that were used previously. One disadvantageof flash memory is that the devices that use it, e.g. USB key sticks, aresmall and easily lost! However, they do appear to be resistant to damage,surviving being dropped or put through washing machines cycles when leftin pockets!

Removable storage mediaSome storage devices can have the medium removed so that the data can betransported to another computer or stored safely and securely away fromthe computer system. Flash memory (in USB sticks) is removable, andDVD and CD are commonly used for storing video and music. Moderncomputers no longer use floppy disks and do not usually have a floppy

disk drive but there are still a few uses for the floppy disk. Invented in themid-1970s by IBM, the floppy disk was once the most common form ofbacking storage. Billions of floppy disks were made before they were super-seded by flash memory in USB drives, or CDs and DVDs. Most peopleno longer use floppy disks, although there are older industrial computersystems for automatic control of drilling and manufacturing equipment(oddly, some of these are used to make the printed circuit boards that arefound in modern computers!) that still have them. But even here flashmemory devices are being made to replace the floppy disks, giving theequipment a new lease of life.

USB memory stick


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DVD and CD are optical storage systems. Both disk formats can hold largamounts of data but the technology is always advancing so more and more datacan be stored. Blu-ray technology, using a disk the same size as DVD, allows adisk the size of a DVD to store over ten times the amount of data compared to a

DVD. Blu-ray, DVD and CD drives read and/or write the data to a disk. Optical storage systems use lasers to read and write data to the removablmedium in specially sealed devices or drives.

StorageDevice

Medium Full name Typical use

CD CD-ROMCD-RCD-RWmini-CD

CompactDisk

This disk was the originaldigital disk used forstoring music and replacedvinyl LP discs. Later, CD-drives for computers that

could read and write datato the disks were madeavailable. CDs can storeabout 700 mb of datawhich is about 80 mins ofmusic. Computer gamesare often sold on CD-ROMas these cannot be erased.Most people refer to theCD-ROMs that carry musicsimply as CDs

DVD DVD-ROMDVD-RDVD-RWDVDRDVDRWDVD-DLmini-DVD

(There aretwo typesof DVDavailablefor use

the plusor minusvarietiesare twocompetingstandardsbut domuch thesame thing)

DigitalVersatileDisk

This is used mainly forvideos and movies. It hasa large capacity whichdepends on the type ofDVD disk used but single-sided DVDs can store4.7 gb and double-sidedaround 9 gb.DVD-ROM is used to storecomputer software forsale. Most people refer tothe DVD-ROMs that carrymovies simply as DVDs

The correct spellingof the media usedby computers isdisk but often thespelling disc isused in names.

The storage capacityof storage mediais measured inmegabytes (mb),

gigabytes (gb) andterabytes (tb).


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StorageDevice

Medium Full name Typical use

Blu-ray BD-R

BD-REmini-BDdisk

(BD-REis thereusableversion)

The name

comes fromthe typeof laserused ithas a shortwavelengthin theblue-violetpart of thespectrum

This is used to store very

large amounts of data andis used for high-definitionaudio and video

Multilayerdisks

BD These havebeen madewith up toeight layersfor storage.

These are enhancementsand developments of theBlu-ray disks and may have100 to 200 gb capacity.The disks will need newtypes of drives to usethem but the capacityshould allow ten hours ormore of high definitionvideo to be stored on onedisk

Floppy disk drive CD/DVD drive A flash memory card Blu-ray player

In all the optical disk formats shown above, the medium can be disks thatare used once only (shown by an R) and those that can be reused (RW) the RW disks are often much more expensive than the cheap use-once onlydisks! As with all technology, the advances in storage devices and mediamean that the list above will be added to as time goes by. The increasedcapacity of the latest Blu-ray disks will mean that the amount of user data


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that can be stored on a single disk will be huge, making them ideal forbackups. These disks will also allow many hours of high-definition videoand multichannel sound to be easily stored. Each of the backing storage devices and media used by computer

systems has its use and its advantages and disadvantages. For example,flash memory is easy to carry around but can be easily lost or stolen, DVDscan be used to store vast amounts of computer data but can be damagedby scratches. Some advantages and disadvantages of the different storagemedia are shown here:

Storagemedium

Advantage Disadvantage

CD Write once, i.e. CD-R arecheap to buy so cheap

that most people use CD-Rinstead of CD-RW and CD-RWs can be written tomore than once all modern computers canuse them

CD-ROM cannot be written to after manufacture small capacity compared to DVD, Blu-ray, flash

memory easily damaged by, e.g. scratches

DVD Write once are cheap tobuy all modern computers canuse them large storage capacity

rewritable DVD-RWs are expensive double-layer DVDs are expensive some devices cannot use both the plus and minustype of DVD cannot be used on the CD drives of older computers easily damaged by, e.g. scratches

Blu-ray very large storage capacity devices and media are expensive but prices will fall asmore people buy them not usable by DVD or CD drives so a new opticaldrive is needed easily damaged by, e.g. scratches

Floppydisk

easily transported all older computers can usethem not as easily damaged ashard disks

not commonly used in modern computers very small storage capacity easily lost or stolen can be damaged by magnetic fields, or mishandling

Harddisk

very large storage capacity relatively cheap forlarge storage capacitiescompared to removabledevices/media

easily damaged by knocks, heat, magnetic fields not as suitable for removable devices as flashmemory as hard disk should not be moved especiallywhen in use

Flashmemory

all modern computers canuse flash memory via USB large storage capacity not easily damaged

very expensive for the very large storage capacitiesneeded to replace hard disks slower access to data than hard disks they can only be reliably used about 10,000 or so times easily lost or stolen when used as removable USB sticks


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It is possible to attach any or all of the storage devices to a computer systemvia USB so a large hard disk can become a removable device. Often, harddisks attached in this way are used for storing private files or backups asthey can be locked away from the computers.

Connecting computers together and networkingMany ICT systems are connected together so that data can be sharedbetween them. The hardware needed to do this is not essential to theworking of the system but many ICT systems have the components alreadybuilt in by the manufacturer. Laptops, PDAs and mobile phones have thecomponents already fitted to allow them to connect to other devices viawireless networks and often by more conventional wired networks. Theseallow the users to communicate with each other and to share data easily. If the ICT system is to be able to communicate with other systems, ithas to have a network interface card which can use wires or radio waves(wireless connections) to communicate with other devices on a network ornetworks. Often these are already installed in the ICT system, e.g. all laptopshave these built in and a mobile telephone would be useless without one! In the network itself there are the physical connectors, i.e. the wires orradio (wireless) connections, and additional hardware to connect the systemtogether. Such hardware components are routers, hubs and repeaters. A router is used to connect two networks together or to connect to theinternet. Often in the home, a router is called the modem as it is used toconnect home computers or networks to the internet but it really is justa router. This device consists of hardware and software that directs datafrom one network to another one of the networks could be the internet

which is one very large network! Routers have a number of connec-tions called ports and can be programmed to direct data to whicheverport the user wishes. Users can also program the router not to send datato particular ports and this can be used to make networks secure. Oftena router will have a wireless port and this can be used to share a singleinternet connection between multiple computers. The wireless connectionis separately programmable as wireless connections are less secure thanwired connections. Hubs and repeaters are similar to routers but they are much simplerthan routers as they cannot be programmed and just forward all the data

WEBLINKS

http://www.computerhope.com/

jargon/s/stordevi.htm

http://en.wikipedia.org/wiki/Data_storage_device

http://www.howstuffworks.com/flash-memory.htm

http://www.manifest-tech.com/media_dvd/dvd_hd_multi_layer.htm

These providedescriptions andexplanations ofstorage devices.

CD disk Floppy disk Multi-layer disks


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they receive. Most hubs have multiple connection ports and all the datafrom one port will be sent to all the other ports. They are used to share onenetwork wire between a number of computers.

SoftwareSoftware is the set of instructions that the computer follows. The softwarethat controls the whole system is called the operating system and this has anumber of specific functions such as:

manages the CPU usage by hardware and software

managing the hardware including peripherals such as printers using,e.g. device drivers

provides an environment for software applications to run

provides a suitable user interface manages software on the computer system

provide a multitasking environment that allows a user to carry morethan one task at once

manages inputs and outputs

manages memory resources.

Operating systems and utility softwareOperating systems on most computers today use windows, icons, menus

and pointing devices for the user to access the facilities but other operatingsystems exist, the most common being a command line interface.

WEBLINK

http://www.didcotgirls.oxon.sch.uk/depts/it/gcse/notes/hardware/index.htm

This providesexplanations ofhardware.

A window is an area of the screen used to interact with a softwareapplication. An icon is a small image used to represent an element of theinterface or application. A menu is a list of items to choose from and apointer is the on-screen icon or image that is used for selection.

A Graphical User Interface (GUI) has advantages over a command lineinterface in that the user does not need to be highly skilled in ICT or evenknow how to use the software in any detail to get started. There is helpavailable from menus if the user needs it. Using a GUI means that the userdoes not need to access all the features of the operating system or softwareto carry out tasks. A command line interface requires the user to know theexact commands needed to use it and to have some experience of usingcomputers. A command line interface usually allows full access to all aspectsof an operating system or software application but can be quite difficult forinexperienced users.


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Operating systems often have utility software included but occasionallythese are extras and have functions such as:

managing the hard disk to keep it working at its best, e.g. defrag-menting the files

compressing files so that they become smaller

encrypting files for security

scanning for viruses.

Utility software is used by users to fine tune their computer system and tokeep it running efficiently. Utility software usually is designed to performonly a single task.

Applications software

Users of ICT systems often do not seem to notice the operating system atall especially if it is really easy to use and performs well but are morefamiliar with the applications that allow them to carry out tasks such aswriting a letter or creating a video. This software is called applicationsoftware. Application software includes:

applications for creating and managing data and information:

word-processors

desktop publishing software

spreadsheet

database management software

multimedia software

slideshow software

web authoring software

applications for creating and managing still, moving and video images:

photo-editing software

animation software

video-editing software

graphics manipulation software

applications for communicating with others:

web browsing software

communications software, e.g. social networking software, e.g. chat,instant messaging, web browsers, file transfer and email clients

gaming software

and more.


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ProgrammingThe instructions that are found in all software have to be written byprogrammers who use specialised software to create and check their work.Programmers will create the instructions in a language that computers canfollow. This special software includes the programming software such as:

editors which programmers use to type and create the instructionswhich are known as source code; while the programmers can under-stand the source code computers systems usually cannot!

compilers which are special applications that convert the source codeinto a language that the computer can understand this is called theobject code; the code produced depends on the type and make of thecomputer it is designed for

debuggers used to find errors in code

linkers to link or join parts of the programmers code together withother code.

Some software is designed to be used on different types or makes ofcomputer and this often involves the use of interpreters so that the samecode may be understood on different computers in much the same way asinterpreters are used to make different human languages understood. Codewritten in interpreted languages is often slower but has the advantage ofworking on many different computers. This is especially important whenmany applications have to work on different computers over the internet.An example of an interpreted language is Java which is used by some

websites and has to work in many different web browsers on all sorts ofdifferent computers.

User interfacesAll software used to control or create requires a user interface. This is wherethe user tells the computer what to do or enters data that the computerwill use. The operating system of modern computers is responsible forproviding the user interface to the computer system and to the softwarebeing used and programmers creating applications have to make sure thattheir software sticks to the rules!

WEBLINKS

http://www.didcotgirls.oxon.sch.uk/depts/it/gcse/notes/software/index.htm

http://en.wikipedia.org/wiki/Computer_software

These provideexplanations of

software.

Data is raw numbers, letters or other characters. Information is the data putinto context so that it means something.


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A good user interface:

will be logical to use, e.g. all the menus and options will be in the sameplace as those in other applications

will have options and tools in logical and sensible order; they willfollow the normal reading directions of the user, e.g. left to right

will have similar colours and sizes of windows, text and images andthey will be easy to find

will have suitable colours, e.g. not too bright or contrasting or too palefor the user to see and take into account, e.g. colour vision problems

will have only a sensible amount of information on the screen at anyone time

will have any tools, e.g. buttons needed to move to a different page orscreen, in a logical place and similar for all applications.

File typesOne of the advantages of using ICT systems is that your data can be savedon a storage device and retrieved for later use. To save data for later use, ithas to be recorded on the, e.g. USB memory sticks flash memory in a file.The data is encoded in a file format. The data saved by e.g. word-processorsor video-editing software is recorded in files in a format that can be openedlater. So that the operating system knows which application made the fileand what to do with the file when the user tries to open it, extra data isalso stored in the file or as an extension to the name that tells the operating

system that the file contains data about, e.g. an image or a document thatshould be shown in a web browser. For instance the first two lines of a webpage would look something like this:

which tell the operating system that this is a web page and to send it to aweb browser. Some operating systems use extensions to the names used when savingthe files, e.g. Microsofts Windows operating systems have many file exten-sions, some of which are:

jpg, gif, tiff used for different types of image files

wav, mp3, aac used for audio files

mpeg2 and mpeg4 used for video files

doc, xls, ppt, rtf for document files.

The different file types are used to show that the files contain a particulararrangement of data and to help choose which application should be usedto open and view the file. Using the incorrect file type when saving a fileis not usually possible but sometimes a user will change the file extension

ACTIVITY 9Find out what ismeant by:(a)a command line

interface(b)a graphical user

interface (GUI)

and write down themain features ofeach.


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when renaming a file and when the file is accessed an error will be shownbecause the operating system either doesnt know what to do with it orsends it to the wrong application.

ACTIVITY 10Open a software package that you would use to manipulate images andfind out what image file types it can export. Find out why there is more thanone file type for saving images.

EXAM TYPE QUESTIONS

1Explain what is meant by hardware.

2For each of these tasks, state the most suitable input device that you

would use:(a) for typing text into a document(b) for reading the data on a chip in a credit card(c) for reading the data in a barcode(d) for recording a spoken commentary(e) for importing a printed photograph

3For each of the tasks listed below, write down the most suitable softwareapplication you would use to carry out the task:(a) view web pages(b) compress a file(c) manage memory resources(d) convert source code into object code

(e) edit an image4Imagine that you have to continue with some school work at home and

you wanted to transport a very large number of files of work from yourcomputer at school to your computer at home. You are not allowed tosend them home by email. Explain how you would take them home.

5You are going to be given a new computer as a present. You are asked ifyou want a laptop or a desktop computer and you decide that you wouldlike a laptop. Write down the difference between the two and explainwhy you would prefer to be given a laptop computer.

6What are the main functions of these types of software?(a) an operating system

(b) utility software(c) antivirus software

chapter 1 ict in today's world.pdf

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