Cambridge IGCSE Information and Communication Technology PDF

The Cambridge IGCSE™ Information and Communication Technology series consists of a Student’s Book, Boost eBook, Workbooks and Teacher’s Guide with Boost Subscription. Cambridge Cambridge Cambridge Cambridge Cambridge IGCSE™ IGCSE™ IGCSE™ IGCSE™ IGCSE™ Information and Information and Information and Information and Information and Communication Communication Communication Communication Communication Technology Third Technology Boost Technology Technology Technology Edition eBook Practical Theory Workbook Teacher’s Guide 9781398318540 9781398320932 Workbook Second Second Edition with Boost Edition 9781398318564 Subscription 9781398318519 9781398318533 To explore the entire series, visit www.hoddereducation.com/cambridge-igcse-IT Cambridge IGCSE™ Information and Communication Technology Teacher’s Guide with Boost Subscription Created with teachers and students in schools across the globe, Boost is the next generation in digital learning for schools and colleges, bringing quality content and new technology together in one interactive website. The Teacher’s Guide includes a print handbook and a subscription to Boost, where you will find a range of online resources to support your teaching. Confidently deliver the revised syllabus with schemes of work, answers for all Student’s Book exercises and exam-style questions, electronic solutions for practical activities in the Student’s Book and answers for both Workbooks. Aid understanding with vocabulary flashcards to offer support to ESL learners. To purchase Cambridge IGCSE™ Information and Communication Technology Teacher’s Guide with Boost subscription, visit www.hoddereducation.com/ cambridge-igcse-IT Cambridge IGCSE™ Information and Communication Technology Third Edition Graham Brown David Watson 318540_FM_CAM_IGCSE ICT_i_xii.indd 1 19/02/21 2:39 PM Cambridge International copyright material in this publication is reproduced under licence and remains the intellectual property of Cambridge Assessment International Education. Cambridge Assessment International Education bears no responsibility for the example answers to questions taken from its past question papers which are contained in this publication. Exam-style questions and sample answers have been written by the authors. In examinations, the way marks are awarded may be different. References to assessment and/or assessment preparation are the publisher’s interpretation of the syllabus requirements and may not fully reflect the approach of Cambridge Assessment International Education. Third-party websites and resources referred to in this publication have not been endorsed by Cambridge Assessment International Education. The Publishers would like to thank the following for permission to reproduce copyright material. 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T. Willett/Alamy Stock Photo; p.251 © Funtap/stock.adobe.com; p.287 t, p.290 t, c and b, p.294 cr, p.295 t © Alexey Kljatov/stock.adobe.com t = top, b = bottom, l = left, r = right, c = centre Acknowledgements Every effort has been made to trace all copyright holders, but if any have been inadvertently overlooked, the Publishers will be pleased to make the necessary arrangements at the first opportunity. Although every effort has been made to ensure that website addresses are correct at time of going to press, Hodder Education cannot be held responsible for the content of any website mentioned in this book. It is sometimes possible to find a relocated web page by typing in the address of the home page for a website in the URL window of your browser. Hachette UK’s policy is to use papers that are natural, renewable and recyclable products and made from wood grown in well-managed forests and other controlled sources. 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Printed in Slovenia A catalogue record for this title is available from the British Library. 318540_FM_CAM_IGCSE ICT_i_xii.indd 2 13/02/21 5:33 PM Contents Introduction vi SECTION 1 THEORY 1 1 Types and components of computer systems 2 1.1 Hardware and software 2 1.2 Main components of computer systems 7 1.3 Operating systems 10 1.4 Types of computer 14 1.5 Emerging technologies 20 2 Input and output devices 26 2.1 Input devices and their uses 26 2.2 Direct data entry (DDE) devices 37 2.3 Output devices and their uses 44 3 Storage devices and media 60 3.1 Magnetic media and magnetic storage devices 60 3.2 Optical media and optical storage devices 64 3.3 Solid-state media and solid-state storage devices 68 3.4 The future of storage devices 72 4 Networks and the effects of using them 76 4.1 Networks 76 4.2 Network issues and communication 87 5 The effects of using IT 99 5.1 Microprocessor-controlled devices 99 5.2 Potential health problems related to the prolonged use of ICT equipment 106 6 ICT applications 110 6.1 Communication 110 6.2 Modelling applications 118 6.3 Computer controlled systems 126 6.4 School management systems 128 6.5 Booking systems 131 6.6 Banking systems 135 6.7 Computers in medicine 140 6.8 Expert systems 143 6.9 Computers in the retail industry 148 6.10 Recognition systems 153 6.11 Satellite systems 160 iii 318540_FM_CAM_IGCSE ICT_i_xii.indd 3 13/02/21 5:33 PM 7 The systems life cycle 169 7.1 Analysis 170 7.2 Design 175 7.3 Development and testing 180 7.4 Implementation 185 7.5 Documentation 186 7.6 Evaluation 187 8 Safety and security 194 8.1 Physical security 194 8.2 E-safety 195 8.3 Security of data 200 9 Audiences 219 9.1 Audience appreciation 219 9.2 Copyright 223 10 Communication 226 10.1 Communication with other ICT users using email 226 10.2 Effective use of the internet 233 SECTION 2 PRACTICAL 251 11 File management 252 11.1 Manage files effectively 252 11.2 Reduce file sizes for storage or transmission 259 12 Images 261 12.1 Software tools 261 12.2 Edit an image 262 13 Layout 276 13.1 Create or edit a document 277 13.2 Tables 285 13.3 Headers and footers 297 14 Styles 304 14.1 Corporate house styles 304 14.2 Create, modify, update and apply consistent styles 306 15 Proofing 319 15.1 Software tools 319 15.2 Proofing techniques 325 16 Graphs and charts 328 16.1 Chart types 328 16.2 Create a chart 329 16.3 Label a chart 332 16.4 Use secondary axes 335 iv 318540_FM_CAM_IGCSE ICT_i_xii.indd 4 13/02/21 5:33 PM 17 Document production 341 17.1 Organise page layout 341 17.2 Format text 350 18 Databases 359 18.1 Create a database structure 359 18.2 Manipulate data 380 18.3 Present data 388 19 Presentations 405 19.1 Create a presentation 405 19.2 Use a master slide 407 19.3 Edit a presentation 414 19.4 Output a presentation 434 20 Spreadsheets 439 20.1 Create a data model 439 20.2 Manipulate data 462 20.3 Present data 468 21 Website authoring 480 21.1 Web development layers 481 21.2 Create a web page 482 21.3 Use stylesheets 527 Index551 v 318540_FM_CAM_IGCSE ICT_i_xii.indd 5 13/02/21 5:33 PM INTRODUCTION Introduction Aims This book has been written for students of Cambridge IGCSE® Information and Communication Technology (0417/0983) for examination from 2023. It fully covers the syllabus content, provides guidance to support you throughout the course and helps you to prepare for the examination. Assessment The information in this section is taken from the Cambridge IGCSE Information and Communication Technology 0417/0983 syllabus for examination from 2023. You should always refer to the appropriate syllabus document for the year of examination to confirm the details and for more information. The syllabus document is available on the Cambridge International website at: www.cambridgeinternational.org There are three examination papers: Paper 1 Theory Paper 2 Document Paper 3 Spreadsheets Production, Databases and Website Authoring and Presentations Duration 1 hour 30 minutes 2 hours 15 minutes 2 hours 15 minutes Marks 80 marks 70 marks 70 marks Syllabus sections 1–21 11–16, 17, 18, 19 11–16, 20, 21 examined Papers 2 and 3 assess practical skills using a range of different software applications. How to use this book Organisation The content is organised into 21 chapters, corresponding to the syllabus. The content is generally in the same order as the syllabus, although the material within practical chapters is presented in a natural teaching order to aid both teaching and learning, so may deviate slightly. The material directly relevant to practical skills are covered in the practical chapters 11–21. vi 318540_FM_CAM_IGCSE ICT_i_xii.indd 6 13/02/21 5:33 PM Introduction Features Learning outline Each chapter opens with an outline of the subject material to be covered. The practical chapters 11–21 also state required prior knowledge and source files used. Exercise Chapters 1–10 contain short exercises to help recap and confirm knowledge and understanding of the concepts covered. Exam-style questions Chapters 1–10 conclude with exam-style questions, to provide practice with theory questions. Where these are taken from past papers, the details of the specific past paper appear at the end of the question. Any questions without this reference have been written by the authors of this book. vii 318540_FM_CAM_IGCSE ICT_i_xii.indd 7 13/02/21 5:33 PM INTRODUCTION Task Chapters 11–21 contain tasks throughout. Each task is a step-by-step worked example of a practical examination-style question. They often include the use of source files. The text demonstrates techniques used to solve the task using easy-to-follow step-by-step instructions, along with numerous screenshots, so that practical skills are developed alongside knowledge and understanding. Activities These are examination-style questions in the practical section, usually at the end of a chapter or section. These often include the use of source files. Answers and mark schemes are available on Boost: Advice These provide helpful tips and background throughout the book. Links Numerous topics in ICT are connected together. The Links feature states where relevant material is covered elsewhere in the book. Colour codes and symbols used Some words or phrases within the text are printed in red. Definitions of these terms can be found in the glossary within the Teacher Resource on Boost. viii 318540_FM_CAM_IGCSE ICT_i_xii.indd 8 13/02/21 5:33 PM Introduction In the practical section, words that appear in blue indicate an action or location found within the software package. Blue text that is in chevrons indicated that this is a key to be pressed on the computer’s keyboard, for example: In Chapter 18 Databases, words in orange show field names, for example: In Chapter 20, words in green show the functions or formulae entered into the cell of a spreadsheet, for example: In Chapter 21 all HyperText Markup Language (HTML) is shown is a blue proportionally spaced font and Cascading Stylesheets appear in a cerise proportionally spaced font, for example: ix 318540_FM_CAM_IGCSE ICT_i_xii.indd 9 13/02/21 5:33 PM INTRODUCTION Hardware and software used The practical elements of the syllabus can be undertaken on any suitable hardware platform and using any appropriate software packages. For the purposes of giving examples in this book, we have chosen specific software packages – but the functionality of many other packages is very similar. Many of the skills demonstrated in Chapters 11 to 21 are transferable and can be adapted for other hardware and software platforms. All the tasks and activities within the practical chapters have therefore been created using a PC platform with Microsoft Windows 10 operating system and include the use of Notepad. Independent packages used for the practical sections include packages from Microsoft 365, including Word, Excel, Access and PowerPoint. Google Chrome has been used as the web browser, although we would recommend testing all web pages in at least three different web browsers. For the website authoring section of the book (Chapter 21), all work has been produced in HTML code without the use of a What You See Is What You Get (WYSIWYG) package such as Adobe Dreamweaver and Microsoft Expression Web. Although you may have a WYSIWYG package, it is important to realise that you are expected to have knowledge of underlying HTML and CSS. All HTML written within this chapter is written in HTML version 5, and is W3C validated (at the time of going to print). All cascading stylesheets used have been W3C validated. Using source files Source files that are required for the practical chapters can be found at: www. hoddereducation.co.uk/cambridgeextras and will need to be downloaded onto your local machine or network drive in order to use them. Copy them and give them read/write access. This is essential to ensure that you can use some of the file types included. Changing the source files to match your regional settings Before attempting any of these processes, back up all source files. The.csv (comma separated value) files have commas as separators between fields and full stops within currency values. If your regional settings for these values are different (for example, if you use commas within currency values rather than full stops and your software settings require you to use semicolons for separators between fields), then the source data files will need to be edited for use with the regional settings for your software. You can do this in many different software packages, but the easiest (at this level) is Word. Open the.csv file in Word using FILE and Open. Select the file from the list to open the file, which will look similar to this: x 318540_FM_CAM_IGCSE ICT_i_xii.indd 10 13/02/21 5:33 PM Introduction Select the HOME tab, then the Editing section followed by the Replace icon. Enter a , (comma) into the Find what: box and a ; (semicolon) into the Replace with: box, then click on. Repeat this process, replacing a. (full stop) with a , (comma). All the characters will have been replaced within the file like this: Save the file with the same file name using the File tab and Save. This will ensure that the file is saved in.csv format. Additional support The Theory Workbook and Practical Workbook provide additional opportunity for practice. These write-in workbooks are designed to be used throughout the course. xi 318540_FM_CAM_IGCSE ICT_i_xii.indd 11 13/02/21 5:33 PM INTRODUCTION Command words Command word What it means Analyse examine in detail to show meaning, identify elements and the relationship between them Compare identify/comment on similarities and/or differences Contrast identify/comment on differences Define give precise meaning Demonstrate show how or give an example Describe state the points of a topic/give characteristics and main features Discuss write about issue(s) or topic(s) in depth in a structured way Evaluate judge or calculate the quality, importance, amount, or value of something Explain set out purposes or reasons/make the relationships between things evident/provide why and/or how and support with relevant evidence Give produce an answer from a given source or recall/memory Identify name/select/recognise Justify support a case with evidence/argument State express in clear terms Suggest apply knowledge and understanding to situations where there are a range of valid responses in order to make proposals/put forward considerations Disclaimers Cambridge International copyright material in this publication is reproduced under licence and remains the intellectual property of Cambridge Assessment International Education. Exam-style questions and sample answers have been written by the authors. In examinations, the way marks are awarded may be different. References to assessment and/or assessment preparation are the publisher’s interpretation of the syllabus requirements and may not fully reflect the approach of Cambridge Assessment International Education. xii 318540_FM_CAM_IGCSE ICT_i_xii.indd 12 13/02/21 5:33 PM SECTION 1 Theory Chapters 1 Types and components of computer systems 2 Input and output devices 3 Storage devices and media 4 Networks and the effects of using them 5 The effects of using IT 6 ICT applications 7 The systems life cycle 8 Safety and security 9 Audiences 10 Communication 318540_C01_CAM_IGCSE ICT_001_025.indd 1 13/02/21 3:57 PM 1 Types and components of computer systems In this chapter you will learn about: ★ hardware ★ software ★ analogue and digital data ★ central processing unit (CPU) ★ internal memory (RAM and ROM) ★ input and output devices ★ backing store ★ operating systems ★ types of computer – desktop computers and mobile computers (laptop, smartphone, tablet and phablet) ★ emerging technologies – artificial intelligence (AI) and extended reality (virtual and augmented). Computer systems are now commonplace in every part of our daily life. This first chapter introduces the basic components that make up these computer systems; most of which will be described in much greater depth in later chapters. Basic components, including hardware (both external and internal) and software (both applications and system), are all briefly introduced in the following sections. Comparing books with computers is a good analogy: the actual pages and the ink used on the pages are equivalent to the hardware used to make up computers; the words written on these pages are equivalent to the software. Without the words, the book is useless. Similarly, without software, computers would be of little use to any of us. 1.1 Hardware and software 1.1.1 Hardware Hardware is the general term for the physical components that make up a typical computer system. For example: » keyboard » mouse input device » camera » monitor » printer output device » plotter Hardware falls into two categories: internal and external. The list above are examples of external hardware, which is discussed in detail in Chapter 2. Figure 1.1 considers the following internal hardware devices: » motherboard » central processing unit (CPU)/processor » random access memory (RAM) 2 318540_C01_CAM_IGCSE ICT_001_025.indd 2 13/02/21 3:57 PM 1.1 Hardware and software » read-only memory (ROM) » graphics card » sound card » network interface card (NIC) » internal storage devices (hard disk drive and solid-state drive). Because it is not always possible to see the internal hardware devices, the photographs in Figure 1.2 will give you some idea of the physical appearance of the components described in Figure 1.1. Motherboard Random access memory (RAM) Read-only memory (ROM) The motherboard is a printed circuit Random access memory (RAM) is an Read-only memory (ROM) is a memory board found in all computers. It allows internal chip where data is temporarily used to store information that needs the processor and other computer stored when running applications. This to be permanent. It is often used to hardware to function and communi- memory can be written to and read contain, for example, configuration cate with each other. One of the major from. Since its contents are lost when data for a computer system. These functions of a typical motherboard is power to the computer is turned off, it chips cannot be altered and can only to act as a kind of 'hub' which other is often referred to as a volatile or be read from (hence their name). One computer devices connect to. A typical temporary memory. of the main advantages is that the motherboard consists of a sheet of RAM stores the data, files or part of information stored on the ROM chip is non-conductive material, such as hard the operating system currently in use. not lost even when power is turned off plastic. Thin layers of copper or to the computer. They are often aluminium are printed onto this sheet. referred to as non-volatile memories. These form the circuits between the various components. In addition to circuits, a motherboard contains several sockets and slots to connect the other components. Central processing unit Network interface card (NIC) (CPU)/processor A network interface card (NIC) is a A central processing unit (CPU) or component that allows a computer or processor is an electronic circuit board any other device (for example, a in a computer that can execute printer) to be connected to a network instructions from a computer program. (for example, the internet); it can be INTERNAL COMPUTER The two main components are: wired or wireless. HARDWARE arithmetic and logic unit (ALU) where Each NIC is hard-coded with a unique arithmetic and logical operations are MAC (media access control) address carried out code – refer to Chapter 4) control unit (CU) which takes instructions the decodes and executes the instructions. Graphics card Sound card Internal hard disk drive/ A graphics card allows the computer to A sound card is an integrated circuit solid-state drive (HDD/SSD) send graphical information to a video board that provides a computer with These two devices are covered in display device such as a monitor, the ability to produce sounds. These considerably more depth in later television, or projector. It usually sounds can be heard by the user either chapters of this book. Basically, hard connects to the motherboard (see through speakers or headphones. disk drives (HDDs) are magnetic in above). Graphics cards are usually made Sound cards also allow a user to record nature and are one of the main up of: sound input from a microphone methods for storing data, files (text, a processing unit connected to the computer, and photos and music) and most of the memory unit (usually RAM) manipulate sound stored on a disk. system and applications software. a cooling mechanism (often in the More modern computers (and all form of a heat sink since these cards tablets) use the newer storage systems generate a lot of heat) which make use of solid-state (SSD) connections to a display unit technology and are replacing HDDs in (monitor, TV or projector). many cases. Their function is the same as an HDD. ▲ Figure 1.1 Internal computer hardware 3 318540_C01_CAM_IGCSE ICT_001_025.indd 3 13/02/21 3:57 PM 1 Types and components of computer systems Motherboard: RAM: ROM: Graphics card: Sound card: SSD: HDD: ▲ Figure 1.2 Examples of internal hardware 1.1.2 Software Software is the general term used for the programs that control the computer system and process data. The software considered in this book falls into two categories: applications and system. Applications software provides the services that the user requires to solve a given task. For example: » word processing » spreadsheet » database (management system) » control and measurement software » apps and applets » video editing » graphics editing » audio editing » computer-aided design (CAD). (Refer to Figure 1.3 for more details.) System software is the software designed to provide a platform on which all other software can run. For example: » compilers » linkers » device drivers » operating systems » utilities. (Refer to Figure 1.4 for more details.) 4 318540_C01_CAM_IGCSE ICT_001_025.indd 4 13/02/21 3:58 PM 1.1 Hardware and software Word processing Spreadsheet Database (management system) Word processing software is used to Spreadsheet software is used to organise Database software is used to organise, manipulate a text document, such as an and manipulate numerical data (in the manipulate and analyse data. A typical essay or a report. Text is entered using a form of integer, real, date, and so on). database is made up of one or more keyboard and the software provides tools Numbers are organised on a grid of tables. Tables consist of rows and for copying, deleting and various types lettered columns and numbered rows. The columns. Each row is called a 'record' of formatting. Some of the functions of grid itself is made up of cells, and each cell and each column is called a 'field.' This word processing software include: is identified using a unique combination of provides the basic structure for the creating, editing, saving and columns and rows; for example: B6. Some organisation of the data within the manipulating text of the functions of spreadsheets include: database. Some of the functions include: copy and paste functions use of formulae to carry out ability to carry out queries on database spell checkers and thesaurus calculations data and produce a report (DBMS) import photos/images into a structured ability to produce graphs add, delete and modify data in a table. page format ability to do modelling and 'what if' translation into foreign language. calculations. Apps and applets Applets are small applications that perform a single task on a device (they are usually embedded in an HTML page on a website and can be executed from within a browser). Apps refer to software which can perform a fairly substantial task (such Control and measurement software as, video and music streaming, banking Control and measuring software is application or social media). The term designed to allow a computer or originally referred to software that ran microprocessor to interface with sensors on a smartphone and could be so that it is possible to: downloaded from an ‘app store’. measure physical quantities in the real APPLICATIONS SOFTWARE world (such as temperatures) Programs that allow the control applications (such as a Computer-aided design (CAD) user to do specific tasks chemical process) by comparing sensor software data with stored data and sending out This is software used to help in the signals to alter process parameters (for creation, manipulation, modification example, open a valve to add acid and and analysis of a drawing/design. change the pH). It can be used to produce 2D or 3D diagrams which: can be rotated to view the drawing from any angle can produce full dimensions can be used to estimate manufacturing costs of the final product predict any structural problems. Audio editing software Video editing software Graphics editing software Audio editing software allows a user to Video editing software allows a user the Graphics editing software allows bitmap edit, manipulate and generate audio data ability to manipulate videos to produce and vector images to be changed. on a computer. It allows the user to alter: a new video. It enables the addition of Bitmap images are made up of pixels length of track titles, colour correction and altering/ which contain information about image start/stop time of track adding sound to the original video. brightness and colour. Bitmap graphics conversion between audio file formats Essentially it includes: editors can change the pixels to produce volume of track rearranging, adding and/or removing a different image. Vector graphic editors fading in/out sections of video clips and/or audio operate in a different way and do not use combine multiple sound tracks clips pixels. This type of software manipulates noise reduction applying colour correction, filters and lines, curves and text to alter the stored to create another version of the sound other video enhancements image as required. Both types of editing track (for example, a continuous loop creating transitions between clips in software are chosen depending on the or phone ring tone). the video footage. format of the original image. ▲ Figure 1.3 Applications software 5 318540_C01_CAM_IGCSE ICT_001_025.indd 5 13/02/21 3:58 PM 1 Types and components of computer systems Compiler Linkers Device driver A compiler is a computer program that A linker (or link editor) is a computer A device driver is the name given to translates a program written in a program that takes one or more object software that enables one or more high-level language (HLL) into machine files produced by a compiler and hardware devices to communicate with code (code that is understood by the combines them into a single program the computer’s operating system. computer) so that it can be directly that can be run on a computer. For Without drivers, a hardware device (for used by a computer to perform a example, many programming example, a printer) would be unable to required task. The original program is languages allow programmers to work with the computer. All hardware called the source code and the code write different pieces of code, called devices connected to a computer have after compilation is called the object modules, separately. This simplifies the associated drivers. As soon as a device is code. Once a program is compiled, programming task since it allows the plugged into the USB port of a the machine code can be used again program to be broken up into small, computer, the operating system looks for and again to perform the same task more manageable sub-tasks. However, the appropriate driver. An error message without recompilation. Examples of at some point, it will be necessary to will be produced if it cannot be found. high-level languages include Java, put all the modules together to form Examples of hardware devices that Python, Visual Basic, Fortran, C++ the final program. This is the job of require drivers include printers, memory and Algol. the linker. sticks, mouse, CD drivers, and so on. Operating systems (OS) Utilities The operating system (OS) is essentially Utility programs are software that has software running in the background of been designed to carry out specific a computer system. It manages many tasks on a computer. Essentially, they of the basic functions. Without the OS, are programs that help to manage, most computers would be very maintain and control computer user-unfriendly and the majority of resources. Examples include: SYSTEM SOFTWARE users would find it almost impossible antivirus Programs that allow the to work with computers on a anti-spyware hardware to run properly day-to-day basis. Operating backup of files and allow the user to systems allow: disk repair communicate with input/output operations file management the computer users to communicate with the security computer (for example, Windows) screensavers error handling to take place disk defragmenter. the loading and running of programs to occur managing of security (for example, user accounts, log on passwords). ▲ Figure 1.4 System software 1.1.3 Analogue and digital data Computers can only understand data which is in a binary format (that is, a base 2 number system where only the values 0 and 1 can be used). This is often referred to as digital data (because it can only have discrete, discontinuous values). However, data in the real world is actually analogue in nature. Analogue data is physical data that changes smoothly from one value to the next, and not in discrete steps as with digital data. 6 6 5 5 4 4 3 3 2 2 1 1 0 0 ▲ Figure 1.5 Analogue and digital data 6 318540_C01_CAM_IGCSE ICT_001_025.indd 6 13/02/21 3:58 PM 1.2 Main components of computer systems In Figure 1.5, the graph on the left shows analogue data; an infinite number of values can exist between 0 and 6 (for example, 2.5, 4.652, and so on) because the curve is smooth in shape. The graph on the right shows digital data; notice only the exact values of 0, 1, 2, 3, 4, 5 or 6 can be taken. If analogue data is being sent to a computer, it must first be converted into digital data; this is done by hardware known as an analogue to digital converter (ADC). If the computer is controlling a device (such as a motor) then the digital output from the computer needs to be converted into analogue form. This is done by a digital to analogue converter (DAC). 1.2 Main components of computer systems As already mentioned in Section 1.1, a typical computer system is made up of hardware and software. The diagram in Figure 1.6 shows an example of a computer system consisting of input devices, output devices and secondary storage. These will be discussed in more detail in Chapter 2, but some examples are listed in Table 1.1. ▼ Table 1.1 Examples of input, output and secondary storage devices Device Examples Input devices keyboard, mouse, camera, microphone, sensor, scanner Output devices monitor, printer, speakers, projector, (graph) plotter Secondary storage devices hard disk drive, solid-state drive, pen drive The internal hardware devices were shown in Figure 1.2 – these consist of four key components: » the central processing unit (CPU) (contained on the motherboard) » internal hard disk drive or solid-state drive » random access memory (RAM) » read-only memory (ROM). microprocessor and internal memory and storage devices computer monitor printer mouse keyboard ▲ Figure 1.6 A typical computer system 7 318540_C01_CAM_IGCSE ICT_001_025.indd 7 19/02/21 2:42 PM 1 Types and components of computer systems 1.2.1 CPU The central processing unit (CPU) is the part of the computer that interprets and executes the commands from the computer hardware and software. It is normally part of the computer motherboard. CPUs used to be made up of discrete components and numerous small integrated circuits; these were combined together on one or more circuit board(s). However, due to modern manufacturing techniques, the CPU is now referred to as a microprocessor. This is a single integrated circuit which is at the heart of most PCs and is also found in many household devices and equipment where some control or monitoring is needed (for example, the engine management system in a car). The CPU/microprocessor is made up of a control unit, which controls the input and output devices; an arithmetic and logic unit (ALU), which carries out calculations and makes logical decisions, and small memory locations called registers. 1.2.2 Internal memory Random access memory (RAM) is an internal chip where data is temporarily stored when running applications. This memory can be written to and read from. Because its contents are lost when power to the computer is turned off, it is often referred to as a volatile or temporary memory. This was fully described in Figure 1.1. Read-only memory (ROM) is a memory used to store information that needs to be permanent. It is often used to contain, for example, configuration data for a computer system. Chips used for ROM cannot be altered and can only be read from (hence their name). One of the main advantages is that the information stored on the ROM chip is not lost, even when power is turned off to the computer. They are often referred to as non-volatile memories. This was fully described in Figure 1.1. It is worth noting that that ROM also contains some coding known as the boot file. This code tells the computer what to do when it first starts up; it is often referred to as the BIOS (basic input/output system). When the computer is turned on, the BIOS carries out a hardware check to find out if all the devices are present and whether they are functional. Then it loads the operating system into the RAM. The BIOS stores the date, time and system configuration in a non-volatile chip called a CMOS (complementary metal oxide semiconductor) – this is usually battery powered. Table 1.2 provides a summary of the main differences between RAM and ROM. ▼ Table 1.2 RAM and ROM differences RAM ROM Temporary memory device Permanent memory device Volatile memory Non-volatile memory device Can be written to and read from Read-only, data stored cannot be altered Used to store data, files, programs, part of operating systems (OS) currently in use Used to store BIOS and other data needed at Can be increased in size to improve start up operational speed of a computer 8 318540_C01_CAM_IGCSE ICT_001_025.indd 8 13/02/21 3:58 PM 1.2 Main components of computer systems 1.2.3 Input and output devices Input devices are hardware that allows data to be entered into a computer (these are covered in detail in Chapter 2). They use either manual entry (such as a keyboard or a mouse) or direct data entry (such as sensors or optical character readers). Essentially, these devices turn input into a form the computer can understand – for example, a mouse turns hand movements into cursor movements on the screen. As mentioned earlier, sometimes the data has to go through an ADC before the computer can make any sense of it. When a computer processes data, and the human operator wants to see the results of the processing, then the computer sends the data to an output device. An output device shows the computer’s output in a form that is understood by a human – for example, as text on a printer or moving images on a monitor. Some devices can act as both input and output. For example, a touch screen can do both, as can a DVD writer/player; but most devices are only capable of either inputting data into a computer or displaying the results of computer processing (output device). Table 1.3 summarises the differences between input and output devices. ▼ Table 1.3 Comparison of input and output devices Input devices Output devices An output device is any hardware device that An input device is any hardware device that takes the output data from a computer and allows a user to enter data or instructions puts it into a human-readable format or uses into a computer directly. it to control another device. An output device is capable of receiving data An input device can send data to another from another device in order to generate an device, but it cannot receive data from output, but it cannot send data to another another device. device. Input devices are necessary for a computer Output devices are needed by a computer to receive commands from its users and data so it can share the results of its processing to process; the devices are under the control with a human; output devices are under the of the user or can be direct data entry. control of the computer. Input devices can be fairly complicated Output devices are less complex than input because they have to ensure that the user devices because they only have to turn can interact with the computer correctly. computer signals into an output. 1.2.4 Backing storage The main memories in a computer are RAM and ROM. However, to permanently store large amounts of data it is necessary to use backing storage. This normally takes the form of the internal hard disk drive (HDD) or solid-state drive (SSD). This is the computer’s main internal storage where the applications software, disk operating system and files (for example, text, photo or music) are stored. A key feature of a backing store is that it must store data permanently – that is, it must be non-volatile. Unlike RAM and ROM, backing storage is not directly addressable (that is, it cannot be read directly by the CPU). The data access time for RAM and ROM is much shorter than it is for backing storage. Backing storage is considerably larger than RAM because it is considerably less expensive per byte. 9 318540_C01_CAM_IGCSE ICT_001_025.indd 9 13/02/21 3:58 PM 1 Types and components of computer systems Backing storage can either be fixed (very often internal to the computer) or removable. The advantage of removable backing storage is that it can be used as a backup in case of data loss or corruption. Data from the main HDD or SSD can be copied onto another device (such as a pen drive or portable HDD) and then stored in a separate location. If the original data on the HDD/SSD has been lost or corrupted, it can be restored from the backup device. Examples of removable storage include external hard disk drives (HDD), external solid-state drive (SSD) and Blu-ray discs. Table 1.4 summarises the differences between backing storage and internal memory. ▼ Table 1.4 Comparison of internal memory and backing storage Internal memory Backing storage RAM contents are lost when computer is Backing storage devices hold their contents powered down; ROM contents are readable permanently, even when powered down. only. RAM and ROM are much smaller memories Have considerably larger capacity to store than backing storage. data than RAM or ROM. Data access time on RAM and ROM is Has much slower data access time than extremely fast. RAM and ROM. Much more expensive per byte than backing Is much cheaper per byte than RAM or ROM. storage devices. RAM and ROM are fixed inside the computer Backing storage can either be fixed (internal memories). (external or internal) or it can be removable. Before data on a backing storage device can RAM and ROM can be read directly by the be read by the CPU, it must first be moved CPU. into RAM; this means backing storage is not directly addressable by the CPU. 1.3 Operating systems Reference to operating systems has already been made earlier on in this chapter (see Figure 1.4). To enable computer systems to function and to allow users to communicate with computer systems, special software, known as operating systems (OS), have been developed. The general tasks for a typical operating system include: » control of the operation of the input, output and backing storage devices » supervising the loading, running and storage of applications programs » dealing with errors that occur in application programs » maintaining security of the whole computer system » maintaining a computer log (which details computer usage) » allowing communication between user and the computer system (user interface). 10 318540_C01_CAM_IGCSE ICT_001_025.indd 10 13/02/21 3:58 PM 1.3 Operating systems 1.3.1 User interfaces Operating systems offer various types of user interface. We will consider four different types: » command line interface (CLI) » graphical user interface (GUI) » dialogue-based user interface » gesture-based user interface. Command line interface (CLI) A command line interface (CLI) requires a user to type in instructions to choose options from menus, open software, etc. There are often a number of commands that need to be typed in, for example, to save or load a file. The user has to learn a number of commands just to carry out basic operations. It is also slow, having to key in these commands every time an operation has to be carried out. However, the advantage of a CLI is that the user is in direct communication with the computer and is not restricted to a number of pre-determined options. For example, Windows has a CLI called the ‘command prompt’. The following command opens the desktop folder in Windows Explorer: %windir%\explorer.exe C:\Users\YourName\Desktop ▲ Figure 1.7 Sample of CLI code The statements in Figure 1.7 show how complex it is just to carry out a fairly straightforward operation using CLI. Graphical user interface (GUI) A graphical user interface (GUI) allows the user to interact with a computer (or MP3 player, gaming device, mobile phone, etc.) using pictures or symbols (icons) rather than having to type in a number of commands. For example, the whole of the CLI code in Figure 1.7 could have been replaced by clicking on the Desktop icon within Windows Explorer. Simply selecting this icon would automatically execute all the commands shown in Figure 1.7 without the need to type it in. GUIs use various technologies and devices to provide the user interface. One of the most common is WIMP (windows icons menu and pointing device) which was developed for use on personal computers (PC). Here, a mouse is used to control a cursor and icons are selected to open/run windows. Each window 11 318540_C01_CAM_IGCSE ICT_001_025.indd 11 13/02/21 3:58 PM 1 Types and components of computer systems contains an application and modern computer systems allow several windows to be open at the same time. An example is shown in Figure 1.8 (here, a number of icons can be seen on the on the bottom of the screen ‘window’): ▲ Figure 1.8 Screen image showing icons A window manager looks after the interaction between windows, the applications and window system (which handles the pointing devices and the cursor’s position). In recent years, devices such as touch screen smartphones and tablets use post- WIMP interaction, where fingers are in contact with the screen allowing actions such as pinching and rotating, which would be difficult to do using a single pointer and device such as a mouse. Table 1.5 summarises the main advantages and disadvantages of CLI and GUI. ▼ Table 1.5 Advantages and disadvantages of CLI and GUI interfaces Interface Advantages Disadvantages The user needs to learn a number of commands to carry out basic The user is in direct communication operations. with the computer. All commands need to be typed in, Command line The user is not restricted to a which takes time and can be error- interface (CLI) number of pre-determined options. prone. It is possible to alter computer Each command must be typed in configuration settings. using the correct format, spelling, and so on. The user does not need to learn any This type of interface uses up commands. considerably more computer memory than a CLI interface. It is more user-friendly; icons are Graphical used to represent applications. The user is limited to the icons user interface provided on the screen. A pointing device (such as a mouse) (GUI) is used to click on an icon to launch Needs a more complex operating the application – this is simpler than system, such as Windows, to operate, typing in commands. which can be slower to execute commands. 12 318540_C01_CAM_IGCSE ICT_001_025.indd 12 13/02/21 3:58 PM 1.3 Operating systems Who would use each type of interface? CLI: a programmer, analyst or technician; basically, somebody who needs to have direct communication with a computer to develop new software, locate errors and remove them, initiate memory dumps (contents of the computer memory at some moment in time), and so on. GUI: the end-user who does not have to (or does not need to) have any great knowledge of how the computer works; a person who uses the computer to run software, play games or store/manipulate photographs, for example. Dialogue-based user interfaces Dialogue-based user interfaces use the human voice to give commands to a computer system. An example of its use is in some luxury modern cars, where voice activation is used to control devices such as the in-car entertainment system or satellite navigation system. By speaking certain commends, such as ‘Hey BMW, drive me to the nearest airport’, the system allows natural speech to enable the driver to intuitively interact with the car. The satellite navigation system will automatically direct the driver to their chosen destination (in this case, the nearest airport). This type of interface could also be used in the home; by using voice commands, it is possible to switch on/off lights, operate electronic equipment and so on. In recent years, devices such as Amazon Alexa, Google Now, Apple Siri and Microsoft Cortana have all been developed to interact with a human by recognising verbal commands. These devices act as a personal assistant. Hey, Alexa, when 11:45 from Terminal 1. is the next flight Would you like me to to Paphos? make you a booking? 100011 011001 001110 011111 000001 Smart device is Human voice is Smart device processes asked question converted into the human command and by a human a binary stream outputs a verbal response ▲ Figure 1.9 Smart voice activated devices Gesture-based interfaces Gesture-based interfaces rely on human interaction by the moving of hands, head or even the feet. Gesture recognition allows humans to interface with a computer in a more natural fashion without the need for any mechanical devices. This type of interface uses techniques known as computer vision and image processing. For example, using our car example again, the following gestures can be used to carry out certain functions: » rotating a finger clockwise near the radio will increase the sound volume (rotating the finger anti-clockwise will reduce the sound volume) 13 318540_C01_CAM_IGCSE ICT_001_025.indd 13 13/02/21 3:59 PM 1 Types and components of computer systems » opening the thumb and next finger will change the track being listened to (for example, in a playlist) » moving the foot under the rear bumper of the car automatically opens the boot lid » moving a hand near a window switch automatically opens a window. There are many other examples. Either a sensor or a camera is used to pick up the gesture and a signal is sent to an on-board computer to carry out the required action. It eliminates the need for an array of buttons and dials on the dashboard. Table 1.6 summarises the main advantages and disadvantages of dialogue-based and gesture-based interfaces. ▼ Table 1.6 Advantages and disadvantages of dialogue-based and gesture-based interfaces Interface Advantages Disadvantages » no need for a driver to take their » still unreliable, with many hands off the steering wheel commands not being » in a home, very useful for people recognised or needing with disabilities, because many to be repeated several Dialogue-based tasks can be carried out by the times (especially if there is interface spoken word only background noise) » possible to use as a security » can be quite complex to set feature, because voice recognition up could be used to identify a person » user needs to know which commands can be used » replaces mechanical input devices » possible for unintentional » no physical contact required movement to be picked up » very natural interface for a human » only works fairly near to the operator camera or sensor (maximum » no training needed to interface with of 1.5 metres) Gesture-based interface the computer » may only accept a limited number of movements (for example, it may take several attempts to find out exactly what finger movements are recognised) 1.4 Types of computer There are many types of computer systems in existence. The following summarises some of the more common types currently available: 1.4.1 Desktop computers Desktop usually refers to a general-purpose computer that is made up of separate monitor, keyboard, mouse and processor unit. It is distinguished from, for example, a laptop computer by the fact that it is made up of a number of separate components, which makes them not very portable. Because laptop and desktop computers tend to be used for very similar purposes, it is worth making a comparison between the two types of computer. ▲ Figure 1.10 Desktop computer 14 318540_C01_CAM_IGCSE ICT_001_025.indd 14 13/02/21 3:59 PM 1.4 Types of computer The advantages of desktop computers over laptop computers are: » Spare parts and connections tend to be standardised, which usually results in lower costs. » Desktop computers are easier, and less expensive, to upgrade or expand. » The desktop tends to have a better specification (for example, faster processor) for a given price (often due to size and construction constraints in laptops). » Power consumption is not critical because they usually plug straight into a wall socket, and the larger casings allow a better dissipation of any heat build-up. » Because they are usually fixed in one location, there is less likelihood of them being damaged or stolen. » Internet access can be more stable because a desktop computer is more likely to have a wired internet connection (the user will always have the same data transfer rate); however, due to their portability, laptop computers usually use wireless internet connectivity where the signal can be very variable (giving variable data transfer rate). They do have disadvantages when compared to laptop computers: » The most obvious is that they are not particularly portable because they are made up of separate components. » They tend to be more complicated because all the components need to be hooked up by wiring, which also clutters up the desk space. » Because they are not particularly portable, it is necessary to copy files on, for Link example, a memory stick, when you want to do some work elsewhere (for For more on example, doing office work at home); although cloud storage has diminished cloud storage see this disadvantage recently, it still may not be possible to save sensitive data Section 4.1. files on the cloud. The main uses of desktop computers include: » office and business work (word processing, spreadsheets, finance software and databases being the main use) » educational use (using interactive software to teach or learn from) » use as a gaming device (for example, games such as chess, crossword puzzles, fantasy games, and so on) » general entertainment (for example, live or ‘catch-up’ streaming of television programmes). 1.4.2 Mobile computers Mobile computers, by their very name, suggest a group of computers which are considerably more portable than desktop computers. Such computers fall into four categories: » laptop computers » smartphones » tablets » phablets. 15 318540_C01_CAM_IGCSE ICT_001_025.indd 15 13/02/21 3:59 PM 1 Types and components of computer systems Laptop (or notebook) Laptop (or notebook) refers to a type of computer where the monitor, keyboard, pointing device and processor are all together in one single unit. This makes them extremely portable. Key features you would expect to find in a laptop: » lightweight (to aid portability) » low power consumption (and also long battery life) » low heat output (cooling is very important). Laptop computers do have advantages when ▲ Figure 1.11 Laptop computer compared to desktop computers: » The most obvious advantage is their portability; they can be taken anywhere because the monitor, pointing device, keyboard, processor and backing store units are all together in one single unit. » Because everything is in one single unit, there are no trailing wires (only one single cord is used). » They take up much less room on a desk, so they can be used anywhere (for example, in a café). » Their portability allows them to take full advantage of Wi-Fi features. » Because they are portable, they can link into any multimedia system. Laptop computers also have disadvantages when compared to desktop computers: » Because they are easily portable, they are also easier to steal! » They have limited battery life so the user may need to carry a heavy power adaptor. » The keyboards and pointing devices can sometimes be more awkward to use. » It is not always possible to upgrade them, for instance by adding more RAM. The main uses of laptop computers include: » office and business work (word processing, spreadsheets, finance software and databases being the main use) » educational use (using interactive software to teach or learn from) » used as a gaming device (for example, games such as chess, crossword puzzles, fantasy games, and so on) » general entertainment (for example, live or ‘catch-up’ streaming of television programmes) » used in control and monitoring (because they can be operated anywhere using their internal battery, it is possible to use laptops to gather data directly from the environment – for example, they can be plugged into a gas boiler during maintenance to monitor its performance). 16 318540_C01_CAM_IGCSE ICT_001_025.indd 16 13/02/21 3:59 PM 1.4 Types of computer Smartphones Smartphones allow normal phone calls to be made, but also have an operating system (such as iOS, Android or Windows) allowing them to run a number of computer applications (known as apps or applets). They allow users to send/receive emails, use a number of apps, use a camera feature (to take photos or videos), MP3/4 players (for music and videos), and so on. Smartphones communicate with the internet either by using Wi-Fi hot spots or by using 3G/4G/5G mobile phone networks. Some of the typical features of smartphones include: » high-definition, anti-glare displays » front- and back-facing cameras (which are used to take photos, videos or act as a webcam when doing video calls over the internet) » lower weight and longer battery life than laptops ▲ Figure 1.12 Smartphone » use Bluetooth for connection to printers and other devices » make use of flash (solid state) memory and cloud storage facilities to back up and synchronise (often just referred to as ‘sync’) data sources » they use a number of sensors to carry out the following functions: – proximity sensors to detect if the device is close to, for example the ear, which allows it to block unintended ‘touches’ – accelerometers, which detect movement and orientation of the device (for example, move the display from portrait to landscape to view videos, or allow it to be used as a ‘steering wheel’ in-car racing games) – can use sophisticated speech recognitions systems (such as Siri) to enable the user to ask the device to look for things (such as search the address book). The new generation of smartphones are becoming even thinner and lighter, because they make use of OLED (organic light emitting diode) touch screens. Future smartphones will also use OLED touch screens that are coated with a crystalline layer that allows the phones to be partially solar powered; this allows them to use Li-Fi (similar to Wi-Fi, except communication uses visible light rather than radio waves). Communication using Li-Fi is considerably faster than with Wi- Fi (much higher data transfer rate); it is also more secure (by stopping internet ‘piggybacking’). The Li-Fi system can also be used during aeroplane flights because it does not use radio waves and therefore does not interfere with flight control systems. Advantages of smartphones: » They are very small in size and lightweight – therefore they are very easy to carry and have on your person at all times (this is more difficult with laptops because they are much bulkier and much heavier). » You can use them to make phone calls, but also connect to the internet while on the move. 17 318540_C01_CAM_IGCSE ICT_001_025.indd 17 13/02/21 3:59 PM 1 Types and components of computer systems » Because they use Wi-Fi and mobile phone networks they can be used almost anywhere (this is not the case with laptops or desktops; although tablets also use the same technology). » They have apps which make use of sensor data provided by the smartphone, for instance location data for maps – this can provide services that are not available on desktops or laptops. » They have a reasonable battery life compared to laptops. Disadvantages of smartphones: » The small screens and keyboards make pages difficult to read. » It is more difficult and slower when typing things in (laptops and desktops have much bigger screens and much larger keyboards). » Web browsing and photography can quickly drain the battery. » Memory size in most phones is not very large when compared to laptops and desktops – although it is comparable with tablets (however, the latest generation smartphones come with 1 TiB memories). » Not all website features are compatible with smartphone operating systems. » Because of their small size, it is much easier to lose a smartphone or for it to be stolen compared to laptops or desktops. » The data transfer rate using mobile phone networks can be slower than with Wi-Fi – this makes streaming of video or music, for example, less than satisfactory at times. Tablets Tablets are becoming an increasingly used type of mobile computer. They work in a similar way to a smartphone. Tablets use touch screen technology and do not have a conventional keyboard. The keyboard is virtual; that is, it is part of the touch screen and keys are activated by simply touching them with a finger or a stylus. However, it is possible to buy tablet cases which contain a normal-sized keyboard. Internet access is usually through Wi-Fi or 3G/4G/5G (mobile phone) connectivity. Like smartphones, tablets are equipped with a series of sensors which include camera, microphone, ▲ Figure 1.13 Tablet accelerometer and touch screen. The typical features of tablets are identical to those of a smartphone (described earlier). Advantages of tablets compared to laptops: » very fast to switch on (no time delay waiting for the operating system to load up) » fully portable – they are so lightweight that they can be carried anywhere » touch screen technology means they are simple to use and do not need any other input devices » can use several apps as standard (such as built-in camera, MP3/4 players and so on) 18 318540_C01_CAM_IGCSE ICT_001_025.indd 18 13/02/21 3:59 PM 1.4 Types of computer » not much heat – they use solid-state technology » battery life of a tablet is a lot longer » when the power button is pressed, it goes into standby, but remains connected to the internet so the user still hears alerts when emails or other ‘events’ are received. Disadvantages of tablets compared to laptops: » tend to be rather expensive when compared to laptops (but this will probably change with time as they become more common) » they often have limited memory or storage when compared to a laptop (although some of the latest devices have 1 TiB memory capacity) » if 3G/4G/5G mobile phone networks are used, they can be expensive to run if the internet is being accessed frequently » typing on a touch screen can be slow and error-prone compared to a standard keyboard » transferring of files often has to be done through an ‘application atore’; this lack of ‘drag and drop’ facility can prove to be irritating to users » laptops tend to support more types of file format than tablets and are also better equipped to run different types of software. Some of the latest smartphones have been designed as a hybrid between a tablet and a smartphone; these are referred to as a phablet. They have much larger screens than a smartphone but are smaller than a tablet. All the features of a smartphone (described earlier) also apply to phablets together with the typical features of a tablet. Smartphones Phablets Tablets up to 5.1 inches in size between 5.1 inches and 7 inches over 7 inches in size (that is, 13 cm) (that is, 13 cm to 18 cm) (that is, over 18 cm) ▲ Figure 1.14 Comparison of smartphone, phablet and tablet

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