NATIONAL 4 & 5 COMPUTING SCIENCE Prepared by M Feldman.

NATIONAL 4 & 5 COMPUTING SCIENCE Prepared by M Feldman

INDEX Backing Storage Devices Backing Storage Devices Backing Storage Devices Backing Storage Devices Bit-mapped Graphic Data Bit-mapped Graphic Data Bit-mapped Graphic Data Bit-mapped Graphic Data Computers and the Environment Computers and the Environment Computers and the Environment Computers and the Environment Computer Software Computer Software Computer Software Computer Software Computer Related Laws Computer Related Laws Computer Related Laws Computer Related Laws Database Database Database Digitised Sound Data Digitised Sound Data Digitised Sound Data Digitised Sound Data Health & Safety Health & Safety Health & Safety Health & Safety Input Devices Input Devices Input Devices Input Devices Language Constructs Language Constructs Language Constructs Language Constructs Languages & Environments Languages & Environments Languages & Environments Languages & Environments Information Solution (Multimedia) Development Process Information Solution (Multimedia) Development Process Information Solution (Multimedia) Development Process Information Solution (Multimedia) Development Process Networks Networks Networks Peripheral Devices Peripheral Devices Peripheral Devices Peripheral Devices A-Z INDEX REVISION QUESTIONS

INDEX Security Risks & Precautions Security Risks & Precautions Security Risks & Precautions Security Risks & Precautions Software Development Process Software Development Process Software Development Process Software Development Process Simulation & Virtual Reality Simulation & Virtual Reality Simulation & Virtual Reality Simulation & Virtual Reality Standard File Formats Standard File Formats Standard File Formats Standard File Formats Synthesised Sound Data Synthesised Sound Data Synthesised Sound Data Synthesised Sound Data Types of Computer Types of Computer Types of Computer Types of Computer Vector Graphics Vector Graphics Vector Graphics Vector Graphics Video Data Video Data Video Data Video Data World Wide Web & Internet World Wide Web & Internet World Wide Web & Internet World Wide Web & Internet A-Z INDEX REVISION QUESTIONS

Backing Storage Bit-Mapped Graphics Computer Related Laws Computer Software Converging Technologies CPU (Central Processing Unit) Data Representation Development Process for Information Solutions High Level Language (HLL) Programming Input Devices Interfaces Networks Output Devices Types of Computers Vector Graphics Video Data WWW, Internet & E-Mail

Index AAAA FFFF KKKKPU BBBB GGGG LLLLQV CCCC HHHH MMMMRW DINSX EJOTY-Z

A Adaptive Maintenance (Information Solutions) Adaptive Maintenance (Software Development) Addressability Algorithms Alpha Testing Alter Colour Depth Analysis (Software Development) Analysis (Multimedia Software Development) Anti Virus Software Application Programs Arithmetic & Logic Unit (ALU) Arithmetical Operators Array ASCII Assignment Statements Authoring Packages AVI (Audio Video Interleave ) Video File Format

B Backing Storage Backing Storage Devices Bandwidth (Network Transmission) Beta Testing Binary System Biometric (security) Bit-Mapped Graphics (Compression) Bit-Mapped Graphics (Resolution & Colour Depth) Bit-Mapped Graphics (Storage) Bluetooth Blu-ray Drive Browser Brightness & Contrast (Graphics) Buses (Data & Address) Bus (Control)

C CD/DVD Drive Central Processing Unit (CPU) Character Set Charged Coupled Device (CCD) Client-Server Network Clock Speed Cloud Storage Computers & The Environment Communications Act Commercial Software Colour Depth & Resolution (Video Data) Compilers Complex Searching (Databases) Complex Sorting (Databases) Computed Fields Computer Misuse Act Computer Processors Computer Program Computer Security Computer Software Computer Storage of Numbers Computer Storage of Text Computer Types Conditional Loops Control Unit Converging Technologies Cookies Copper Cable Copyright, Designs & Patents Act Corrective Maintenance CPU Crop

D Databases Data Protection Act Data Security Data Transfer Speeds Data Types Denial of Service Attack Design (Software Development) Design (Information Solutions Development) Desktop Computer Digital Camera Digital Video Camera Digitised Sound Data Documentation (Software Development) Documentation (Information Solutions Development) DVD/CD Drive

E E-mail Embedded Computer Encryption Evaluation (Software Development) Evaluation (Information Solutions Development) Expert System Exponent

F Fibre Optic Cable Field (Database) File Format (MP3) File Format (RAW) File Format (WAV) File Server File Server Security Fixed Loops Firewalls Flash Memory (Card) Floating Point Representation Flow Chart Foreign Key (Databases) Frame Rate (Video) FreeBASIC Freeware Functions of an Interface

G General Purpose Package (GPP) Gigabyte Graphics Card GIF (Graphic Interchange File) File Format Graphic Storage (Bit-Mapped)

H Hard Disk Drive Health & Safety High Level Languages(HLL) Hub Hypertext Mark Up Language Hypertext Link

I Identity Theft Implementation (Software Development) Implementation (Information Solutions Development) Immersive environments (Virtual Reality) Inkjet Printer Input Devices Input Validation Integers Interface (Functions) Internal Documentation Internet Internet Service Provider (ISP) Interpreters

J JPEG (Joint Photographic Experts Group) File Format Joystick/Joypad

K Keyboard Key Field Keylogger Kilobyte

L Laptop Computer Language Constructs (HLL) Laser Printer Local Area Network (LAN) Local Storage Logical Operators Lossless Compression (.gif) Lossy Compression (.jpeg) Lossless Compression (.wav) Lossy Compression (.mp3) Lossy Compression (.mpeg) Loudspeakers

M Machine Code Macros Magnetic Tape Drive Mailbox Mainframe Computer Main Memory Maintenance (Software Development) Maintenance (Information Solutions Development) Mantissa Megabyte Microphone Microwave Transmission MIDI Data (Common Attributes) Monitors Mouse MP3 (Sound File Format) MPEG (Moving Pictures Expert Group) Video File Format Multimedia Applications (Creating)

N Nested Loops Networks Network Transmission Bandwidth Notebook Computer Numeric Data

O Objects & Operations (Application Programs) Online Fraud Operating Systems Output Devices

P Palmtop Computer Passwords Peer-to-Peer Network Perfective Maintenance Peripherals Pixel Resolution Phising Presentation Software Pre Defined Functions Primary Key Printer Server Procedures Processors (Computer) Programming Rules Pseudocode

R RAW (Sound File Format) Readability Record (Database) Registers Relational Operators Repetition Reports (Database) Rotate

S Sampling Depth Sampling Frequency Satellite Transmission Scale Scanner Search (Database) Search Engine Security Precautions Security Suites Selection Semantics Sequence Shareware Software Portability Sort (Databases) Sound Card Sound Editing Software Smartphones Stages (Software Development Process) Standard Algorithms Standard File Formats Storage of Numbers Storyboard String Data Structure Diagrams Sub Programs Supercomputer SVG (Scaleable Vector Graphics) Syntax Synthesised Sound Data Spyware

T Table (Database) Tablet Computer Technical Guide Text Editor (for entering Source Code) Terabyte Testing (Software Development) Testing (Information Solutions Development) Text Storage Touchpad Translators Trojan

U Uniform Resource Locators (URLs) USB Flash Drive User Guide

V Variables Vector Graphics Vector Graphics (Attributes of Objects) Verification and Validation Video Data Virtual Reality Virus Virus (Anti Virus Software) Virus (Spread of) Virus Infection (Symptoms) VRML (Virtual Reality Mark up Language)

W WAV (Sound File Format) Webcam Web Server Web Storage Wide Area Network (WAN) Wi-Fi WYSIWYG Word World Wide Web (WWW) Worm WEEE

Y-Z Zip Drive

BACKING STORAGE When we use computers, we need to have some kind of backing storage so that our program and data files are no lost when the computer is switched off and where it can be retrieved from, when it is needed again. Backing storage may be local, web or cloud based, or a combination of any of these, depending on the needs of the individual or organisation.

LOCAL STORAGE Local storage is where the individual or organisation owns the computers and their associated backing storage devices. There are initial and running costs, which may be very high, associated with local backing storage: Cost of buying and maintaining the software, computers, backing storage and associated network for sharing of files. Technical support will need to be provided. File security will need to be provided. However, organisations may find that some of the advantages of having local backing storage is that they can have greater control over the degree of security they apply to their files and that, once the initial costs have been met, the running costs are lower than the ongoing costs of renting equipment and backing storage would be.

WEB STORAGE Web storage and DOM storage (document object model) are web application software methods and protocols used for storing data in a web browser. Web storage supports persistent data storage, similar to cookies but with a greatly enhanced capacity and no information stored in the HTTP request header. There are two main web storage types: local storage and session storage, behaving similarly to persistent cookies and session cookies respectively.

SESSION COOKIES & PERSISTENT COOKIES Session cookies are temporary cookie files, which are erased when you close your browser. Webpages have no memories. A user going from page to page will be treated by the website as a completely new visitor. Session cookies enable the website you are visiting to keep track of your movement from page to page so you don't get asked for the same information you've already given to the site. Cookies allow you to proceed through many pages of a site quickly and easily without having to authenticate or reprocess each new area you visit. When you restart your browser and go back to the site that created the cookie, the website will not recognize you. You will have to log back in (if login is required) or select your preferences/themes again if the site uses these features. A new session cookie will be generated, which will store your browsing information and will be active until you leave the site and close your browser. Persistent cookies are files which stay in one of your browser's subfolders until you delete them manually or your browser deletes them based on the duration period contained within the persistent cookie's file.

CLOUD STORAGE Cloud storage is a networked enterprise storage where data is stored not only in the user's computer, but in virtualized pools of storage which are generally hosted by third parties. Hosting companies operate large data centres, and people who require their data to be hosted, buy or lease storage capacity from them. The data centre operators, in the background, virtualize the resources according to the requirements of the customer and expose them as storage pools, which the customers can themselves use to store files or data objects. Physically, the resource may span across multiple servers. The safety and security of the files depends upon the hosting websites. Cloud storage services may be accessed through a web service application programming interface (API), a cloud storage gateway or through a Web-based user interface.

ADVANTAGES & DISADVANTAGES OF CLOUD STORAGE The advantages of using cloud storage include: Companies need only pay for the storage they actually use. Storage maintenance tasks, such as backup, data replication, and purchasing additional storage devices are offloaded to the responsibility of a service provider, allowing organizations to focus on their core business. Cloud storage provides users with immediate access to a broad range of resources and applications hosted in the infrastructure of another organization via a web service interface. Customers have access to technical support. However, the disadvantages of using cloud storage include: On-going costs of paying for this service. Security concerns about possibility of hacking of important data.

HARDWARE Backing Storage Devices Backing Storage Devices include devices such as:  Hard Drives  CD / DVD Drives  Magnetic Tape Drives  USB Flash Drives Backing Storage devices are needed to store data because data held in main memory (RAM) is lost when the computer is turned off.

HARDWARE Backing Storage Devices – Hard Disk Drive Hard Disk Drives use random/direct access and are an example of magnetic storage. You get fastest access to data stored on a hard disc than any other backing storage medium. The storage capacity of a hard disk is also very large, currently about 1 terabyte. Hard disks are usually sealed inside the hard disk drive within the systems box, however external hard disks can be plugged into the computer via a USB port – making it easy to transport large quantities of data.

HARDWARE Backing Storage Devices – CD/DVD Drives Compact Disk (CD) & Digital Versatile Disk (DVD) Drives use random/direct access and are an example of optical storage – meaning data is written to the disk using a laser beam. The storage capacity of a CD-R (Recordable) & CD-RW (Rewriteable) is up to 700 Megabytes. For a DVD-R or DVD-RW it is between 4.7 and 17 Gigabytes. The cost of both is relatively cheap, they are very portable and the large storage capacity makes them very suitable for storing large multimedia files – such as sound, video & graphics.

HARDWARE Backing Storage Devices – Magnetic Tape Drive Magnetic Tape Drives use sequential/serial access – meaning that you have to go through the files in order to teach the one you want. They are an example of magnetic storage. The storage capacity of a Magnetic Tape can be anything from 10 to 100 Gigabytes. Magnetic Tape is now used mainly for backing up data held on computer systems – it is always important that data is backed up (extra copies kept), in case the original data is lost or damaged.

HARDWARE Backing Storage Devices – ZIP Drive ZIP Drives use random/direct access. They are an example of magnetic storage. The storage capacity of a ZIP Disk was either 100 Megabytes (MB), 250 Mb or 750 Mb. Although they have a fairly high storage capacity, the major disadvantage is that the data stored on ZIP disks is not very portable as the disks can only be read by machines with the same disk drive – they are therefore not very commonly used nowadays.

HARDWARE Backing Storage Devices – USB Flash Drive USB (Universal Serial Bus) Drives use random/direct access. They are an example of solid state storage – solid state meaning they have no moving parts, which makes them very robust. They are also very portable – being compatible with most computer systems. The storage capacity of a USB Flash Drive ranges from 1 Gigabyte upwards to 128 Gigabytes.

HARDWARE Backing Storage Devices – Blu-ray Drive Blue-ray Drives use random/direct access. They are an example of optical storage. The storage capacity of a Blu- ray disk ranges from 23.3 Gigabyte (Gb) – 27 Gb for a single-layer disk to 46.6 Gb to 54 Gb for a dual-layer disk. Although a blue-ray disk is the same physical size as a DVD - the increased storage capacity on the blu-ray comes from the laser beam being used to write data being blue and having a shorter wavelength and narrower beam than the red laser used to write to DVDs.

HARDWARE Flash Memory Cards Flash memory cards are used by many small devices such as smartphones, MP3 players and digital cameras to store data. A USB card reader attached to a computer allows data files to be transferred on to backing storage on a computer for editing, printing or storage. The flash memory card can then be wiped clean and used over and over again. Flash memory cards use random/direct access and are an example of solid state storage. Because they are very small and light, they are extremely portable, but can still hold many gigabytes of data. A reasonable data transfer speed would be around 90 Mbps.

Data Transfer Speed & Interface Types Data Transfer Speed: The speed with which data can be transmitted from one device to another is called the data transfer speed. Data rates are often measured in megabits (million bits) or megabytes (million bytes) per second. These are usually abbreviated to Mbps. Interface Type: An interface is how a peripheral device communicates with the processor. A USB is the most common interface would have a typical data transfer speed of around 480 Mbps upwards, depending on the model type. Firewire is another interface often used and would have a data transfer of around 800 Mbps.

BIT-MAPPED GRAPHIC DATA HARDWARE USED TO CAPTURE BIT-MAPPED GRAPHICS Digital cameras can be used to capture still images. Within a digital camera is an electronic circuit called a Charged Coupled Device (CCD). The CCD uses sensors to capture an image projected by the lens which opens when a photograph is taken. The CCD turns the light into analogue signals that are passed to a processor which samples them and turns them into digital data.

BIT-MAPPED GRAPHIC DATA STORING THE IMAGES IN A DIGITAL CAMERA Once images have been captured by the digital camera and converted into digital format, they are stored in the digital camera on removable backing storage called flash memory. A card reader attached to a computer allows data files to be transferred on to backing storage on a computer for editing, printing or storage. The flash memory card can then be wiped clean and used over and over again.

BIT-MAPPED GRAPHIC DATA CAPTURING IMAGES USING A SCANNER Scanners also use CCDs to capture the image of documents. There is a CCD in the moveable scan head which passes over the document. The light which is reflected back of the document is captured by the CCD as an analogue signal which is then converted into a binary digital signal and stored on backing storage in the computer system attached to the scanner.

BIT-MAPPED GRAPHIC DATA STORAGE OF GRAPHICS DATA A bitmap file format (file extension.BMP), is an uncompressed file format where the bit-map file contains data about each pixel used to make up the image. For a black and white image 1 bit is needed to store each pixel. For an image using 256 colours 1 byte of storage is needed for every pixel and with an image using True Colour this rises to 3 bytes of storage for every pixel. This means that an uncompressed bit-map file can take up a very large amount of storage.

BIT-MAPPED GRAPHIC DATA COMPRESSION OF BIT-MAP GRAPHICS Since bit-map files are so very large they need to be compressed to make the file sizes smaller to reduce the demands on backing storage and the time it takes to transmit these files across networks. Two main methods of compression are used:.GIF (Graphics Interchange Format) which uses lossless compression..JPEG (Joint Photographic Experts Groups) which uses lossy compression.

BIT-MAPPED GRAPHIC DATA GIF (Graphics Interchange Format) FILE FORMAT GIFs use lossless compression which works by using a code to store patterns of bits that occur repeatedly throughout the graphics file. Because the GIF format is based on an 8-bit colour code – files stored in this format are limited to 256 colours, meaning that the GIF format is best suited for storage of drawings, charts and diagrams and is not suited for the storage of photographs. However, an advantage of GIF is that colours can be set as transparent which is useful when displaying a GIF image in a multimedia document, as it does not then obscure the underlying screen pattern.

BIT-MAPPED GRAPHIC DATA JPEG (Joint Photographic Experts Group) FILE FORMAT JPEGs use lossy compression to reduce the file size. Which works by cutting out the parts of the graphics which won’t be noticed by the human eye. As JPEGs use True Colour with 16,777,216 colours available – the lossy compression cuts out some of the very subtle variations in colour. JPEGS are the most suitable file format for storing photographs but are not suitable for storing line drawings as the loss of data would be noticeable here. JPEGs can vary the level of compression – the higher the compression, the smaller the file size but the greater loss of data.

BIT-MAPPED GRAPHIC DATA RESOLUTION AND COLOUR DEPTH Resolution refers to the number of pixels used to represent a graphic. If you increase the resolution the quality of the graphic will increase, but so will the file size. Reducing the resolution decreases both the quality and the file size. Colour Depth refers to the number of bits used to represent the colour of each pixel in a graphic. The higher the colour depth, the greater the file size will be. COLOUR DEPTHNUMBER OF POSSIBLE COLOURS PER PIXEL 1 bit2 – black or white 8 bits256 colours 24 bits16 million + True Colour

BIT-MAPPED GRAPHIC DATA HARDWARE REQUIRED TO DISPLAY GRAPHICS A graphics card is a circuit board inside the computer system which manages the screen display for the computer system. The graphics card has its own processor and memory to store and process the graphics data, which takes pressure of the computer’s memory and main processor. High resolution LCD or TFT screens are also needed to display high quality images.

BIT-MAPPED GRAPHIC DATA EDITING BIT-MAP GRAPHICS Graphics Packages have features which are specially to help create and edit graphics. These special features include:  Enter Text  Select Tool  Alter Tool Attributes  Draw Graphic  Scale Graphic  Rotate Graphic

BIT-MAPPED GRAPHIC DATA EDITING BIT-MAP GRAPHICS - SCALING Sometimes it is necessary to change the size of a picture you have - you can do this by scaling the picture. By entering a percentage number you can make very precise, very tiny changes or, you can use the selection tools to resize the picture roughly, larger or smaller. 100% x 100%80% x 120%

BIT-MAPPED GRAPHIC DATA EDITING BIT-MAP GRAPHICS - ROTATING Depending on the package you are using you can rotate (or flip) a picture by either using the selection tool and turning it in whichever direction you want or, in other packages, you may be required to enter the number of degrees you want to rotate the picture by. Often you will find that both methods of rotation are available in your package and you can choose whichever gives you most precision, should you require that. Rotation 100% x 0 o Rotation 100% x 70 o

BIT-MAPPED GRAPHIC DATA EDITING BIT-MAP GRAPHICS - CROP The crop facility lets you cut out the parts of a graphic you do not want.

BIT-MAPPED GRAPHIC DATA EDITING BIT-MAP GRAPHICS – ALTER COLOUR DEPTH The alter colour depth feature allows the user to change the number of bits used to represent each pixel. Increasing the colour depth will improve the quality but increase the file size. Decreasing the colour depth, decreases the quality and makes the file size smaller.

BIT-MAPPED GRAPHIC DATA EDITING BIT-MAP GRAPHICS – ALTER BRIGTHNESS & CONTRAST Graphics can also be edited to improve their appearance by altering the brightness or contrast.

BIT-MAPPED GRAPHIC DATA EDITING BIT-MAP GRAPHICS – SPECIAL EFFECTS Special effects such as the ones shown in the picture opposite, can also be used to enhance graphics.

COMPUTER SYSTEMS HOW DATA IS STORED IN THE COMPUTER Computers use the binary system to store data. The binary system uses two digits 1 and 0. The number 1 represents “ON” and the number 0 represents “OFF”. 10011010 1 BYTE A binary digit (either 1 or 0) is called a BIT. A group of 8 bits is called a BYTE. 1 BIT

HOW DATA IS STORED IN THE COMPUTER 8 Bits = 1 Byte 1024 Bytes = 1 Kilobyte 1024 Kilobytes (Kb) = 1 Megabyte 1024 Megabytes (Mb) = 1 Gigabyte (Gb) 1024 Gigabytes (Gb) = 1 Terabyte (Tb) 1024 Terabytes (Tb) = 1 Petabyte (Pb) Bit Byte Kb Mb Gb Tb Pb

PROCESSING OF DATA Once the user has INPUT data it is then PROCESSED (in the CPU) and then the results are OUTPUT. If the data is going to be needed again, it is stored in a BACKING STORE. CENTRAL PROCESSING UNIT (CPU) INPUT OUTPUT BACKING STORE

HOW COMPUTERS STORE NUMBERS Integers are whole numbers. The computer can simply convert an integer into its binary equivalent. The size of number which can be stored is restricted by the word size of the computer. EG8 bits gives a maximum binary number of 11111111 = 255 32 bits will have a maximum binary number of 11111111111111111111111111111111 = 4294967295

WORD In computing a WORD is the name given to a collection of BITS treated a single unit by the processor. This means the number of bits that the processor can handle and process in one go. WORD sizes can be 8, 16, 24, 32 or 64 bits.

MACHINE CODE Computers can only understand MACHINE CODE – which is the computers own language. It uses sets of 1’s and 0’s (binary numbers) to represent data and instructions. All other computer languages have to be translated into machine code before the computer can understand them. Machine Code is described as being a low level programming language. 11001110 10101011

HOW COMPUTERS STORE NUMBERS Computers store numbers using binary. A single binary unit (either 1 or 0) is called a BIT and every number is converted into a series of BITS. DECIMAL Place Value 1000’s 100’s 10’s 1’s Number4 7 1 6 = (4x1000)+(7x100)+(1x10)+6 = 4716 in decimal BINARY 8’S 4’S 2’S 1’S =(1X8) + (0X4) + (1X2) +1 =11

FLOATING POINT REPRESENTATION Non-integer numbers (real numbers) and very large or very small numbers are stored using Floating Point Representation. EG123456789 = 0.123456789 x 10 9 Where 0.123456789 is called the MANTISSA and 9 is the EXPONENT. The computer reduces such numbers to form then allocates storage for the mantissa AND the exponent. This method greatly increases the range of numbers which the computer can handle and process.

CHARACTER SET Character Set is the term we give to all the characters represented on the keyboard. Different keyboards, in different countries will have slightly different character sets – depending on what is represented on the keyboard. As the computer has to be able to represent all the characters we use a different code is given for each character. The most common code used is the American Standard Code for Information Interchange – ASCII.

HOW COMPUTERS STORE TEXT TEXT is stored by giving each character its own unique binary code – which is found from ASCII, an internationally used standard code for characters. An example of some ASCII code is shown below: CODECHARACTERBINARY CODE 65A 0100 001 97a 01100001 63? 00111111 13 return 00001101

ASCII CODE Using ASCII(American Standard Code for Information Interchange) to store text makes it more portable. The normal range of ASCII codes is from 32 to 127. Often the codes 0 to 31 are used as non- printable Control Codes – which are used to perform a range of functions, EG: CODE 12 to Clear the Screen CODE 7 to make a Beep The full set of text, number, symbol and control characters which can be represented by the computer is called the Character Set.

REPRESENTING GRAPHICS (How the picture is stored in computer memory) 11111111 01000010 00100100 00011000 00100100 01000010 11111111 11111111 01000010 00100100 00011000 00100100 01000010 11111111 00011000

PIXEL RESOLUTION  If we used smaller pixels the quality of the picture would improve  This is called increasing the resolution Low resolution (few pixels) High resolution (many pixels)

THE COMPUTER SCREEN  The computer screen is made up if 1000s of Pixels either on (1) or off (0)  High Resolution  Many Pixels  Good quality picture  Uses more memory  Low Resolution  Fewer Pixels  Poorer quality picture  Uses Less Memory

COMPUTER PROCESSORS The processor, is the brain of the computer. The more powerful the processor is, the faster your PC will run. The speed of a processor – that is the number of instructions per second that it can carry out - is measured in gigahertz (GHz). Also consider the number of cores. A multi-core processor has more than one processor on a single silicon chip, so it’s better able to handle multiple tasks at once. Most modern desktops have multi-core processors. When buying a new PC, for a basic machine you’ll need a dual-core processor that runs at about 2.5GHz - this will handle everyday basic computing tasks. A home user, looking for a mid-range PC might consider something like an i5 quadcore processor. This is the name of a range of processors from chip-maker Intel – the more expensive processors will give better performance. Keen gamers who want all the power they can get may be tempted by the latest high-power processors such as the i7, Intel’s top-of-the-range processor. However, the fastest processors don’t come cheap and will push up the total cost of a PC considerably. Most modern desktop processors will be 64-bit – this means that they can work with chunks of data made up of 64 binary digits.

THE CENTRAL PROCESSING UNIT (CPU) The Central Processing Unit (CPU) is where the processing takes place in the computer. It contains two parts the PROCESSOR and MAIN MEMORY. RAM ROM Control Unit ALU MAIN MEMORY PROCESSOR INPUT OUTPUT BACKING STORAGE REGISTERS

THE CONTROL UNIT The Control Unit is found in the Central Processing Unit (CPU). The Control Unit makes sure that everything happens in the correct place at the correct time. This means that it decodes instructions sent to the processor and controls peripheral devices (printers, scanners, disc drives etc), as required. The Control Unit also controls the flow of data around the CPU.

THE ARITHMETIC & LOGIC UNIT (ALU) The Arithmetic & Logic Unit (ALU) carries out all calculations (arithmetic) and performs logical operations (it makes decisions).

REGISTERS Registers are memory locations inside the processor. Registers are used to hold the programs and data while they are being processed Control Unit ALU ____Registers____ ________________ Main Memory (RAM)

MAIN MEMORY The Main Memory is made up of two parts RAM (Random Access Memory) and ROM (Read Only Memory). RAM (Random Access Memory)is used to store any program and associated data currently being run on the computer. When RAM is switched off all its memory contents are lost. This is why RAM is sometimes described as being volatile. If the user wants to make any changes to a file, it must first be loaded into RAM before any changes can be made.

MAIN MEMORY ROM (Read Only Memory) keeps its memory contents when the computer is switched off. This is why ROM can sometimes be described as being non-volatile. The contents of ROM cannot be altered by the user (anything stored in ROM must be loaded into RAM before any changes can be made). The operating system program is stored in ROM.

MAIN MEMORY FLASH ROM is similar to ROM, however it can also be used to store data. Flash ROM is used in USB Flash Drives (Memory Sticks) and Flash Memory Cards in digital cameras, mobile phones etc. This is called solid state storage.

ADDRESSABILITY Main Memory is divided into individual storage locations – with each location having a unique number or address. The unique address is used to find the location of data items stored in memory. The ability of the CPU to identify each storage location is called its addressability.

HARDWARE Interfaces An interface is a piece of hardware (and related software), within a computer system. The functions of an interface are:  Temporary Data Storage.  Compensating for differences in speed between the CPU & peripherals.  Data Conversion.

HARDWARE Functions of an Interface Temporary Data Storage Temporary Data Storage by an interface is held in an area of RAM called a buffer. Data is held here whilst it is in transit between the processor and the peripheral.

HARDWARE Data & Address Buses The function of transporting information around within the CPU is done by the Data and Address buses, sets of parallel lines along which binary data is transferred. The address bus specifies the storage location at which data, or instructions are to be fetched from or stored to, and is a uni-directional bus. The data bus carries the actual data or instructions to and from RAM so is bi-directional and contributes to system performance.

HARDWARE Control Bus This is not a true bus, but simply a set of individual lines, each with a separate function that has been grouped together for convenience. Some typical control lines are: Read – activated when data or instructions are to be read from a memory location Write - activated when data or instructions are to be written to a memory location Clock –activated at the start of a routine and is used to synchronize events occurring as instructions are executed Reset –activated at the end of a routine and signals to the processor to return to its status prior to the routine being carried out Interrupt –activated when a peripheral device or other event requests the processors attention and time and current processor status should be stored Non-maskable Interrupt(NMI) – activated when something critical has occurred in the system and cannot be ignored such as power failure.

PROCESSING OF DATA Once the user has INPUT data it is then PROCESSED (in the CPU) and then the results are OUTPUT. If the data is going to be needed again, it is stored in a BACKING STORE. CENTRAL PROCESSING UNIT (CPU) INPUT OUTPUT BACKING STORE

BACKING STORAGE Backing Storage is needed to SAVE work which would be lost when RAM is switched off. Backing stores allow large amounts of data to be stored outside the main memory. Data is saved to backing stores via drives – which are storage DEVICES. All backing stores are storage MEDIA - which include: USB Flash DriveMagnetic Tape Hard Discs CD-R & CD-RW DVD-R & DVD-RW

USEFUL COMPUTER SYSTEMS For any computer system to be useful it has to have both hardware (the parts we can see and touch) and software, called programs or applications. A program is the list of instructions which tell the computer what to do. There are two types of software – Operating Systems and Application Programs.

COMPUTER SOFTWARE To get programs you can either: Write it yourself. Commercial - buy it from someone else. Shareware – try it out free for a limited period, then either buy it or remove it from your computer. Freeware – a programs written by someone else who will allow you to use it without paying them.

COMPUTER SOFTWARE Operating Systems The operating system program must be loaded to a computer before anything else will work. When the computer is switched on the bootstrap loader program loads the operating system. Once the operating system has been loaded it is then used to control all the application programs and peripheral devices attached to the computer.

COMPUTER SOFTWARE What are the main functions of the Operating System? To provide a human computer interface (HCI) so that the user can interact with the operating system. Managing input and out put to and from peripheral devices. Managing the loading and execution of programs. Managing saving and loading of files to and from backing storage. Error reporting.

COMPUTER SOFTWARE Application Programs Application programs are pieces of software which are designed for tasks. Sometimes the software has been designed to specific tasks – for example as a utility program. One example of a utility program is anti-virus software. This has been created specifically to protect your computer from attack by viruses and cannot be used for anything else.

COMPUTER SOFTWARE Application Programs General purpose packages (GPPs) include programs such as word processing, spreadsheet, database, presentation and graphics. Although each program has been designed for use on particular tasks, for example – word processing for mainly text based documents. It is possible to use software to complete tasks other than that is mas mainly designed for. Where two or more GPPs are combines in a single program, this is called an integrated package.

COMPUTER SOFTWARE Objects & Operations An object is a piece of data in a GPP and an operation is a process which can be carried out on that piece of data, for example: PACKAGEOBJECTOPERATION WORD PROCESSINGCharacterEnter, Insert, Edit, Delete, Copy, Paste, Format WordSpellcheck, Search & Replace SentenceImport/Export ParagraphImport/Export TableAdd Row, Add Column, Split Cell, Merge Cell DrawingCroup, Scale, Move, Send to Front/Back DATABASEFieldEnter, Insert, Edit, Delete, Copy, Paste, Format RecordSearch, Sort, Calculate, Query FileImport/Export LayoutReport SPREADSHEETCellEnter, Insert, Edit, Delete, Copy, Paste, Set Attributes RowFormat, Import/Export ColumnFormat, Import/Export NumberFormat, Import/Export TextFormat, Import/Export FormulaCalculate (sum, average, max, min, if) RowFormat, Import/Export GRAPHICSPixelEnter, Insert, Edit, Delete, Copy, Paste, Format LineScale, Rotate, Crop, Layer, Group, Ungroup CircleScale, Rotate, Crop, Layer, Group, Ungroup RectangleScale, Rotate, Crop, Layer, Group, Ungroup PolygonScale, Rotate, Crop, Layer, Group, Ungroup

COMPUTER SOFTWARE Objects & Operations Objects and Operations which can be carried out in a package help the user to decide which application package is the most suitable to use for particular tasks. As you can see on the previous slide, many of the same objects and operations can be carried out by different packages. In this case, the user should use the package which will enable him to do the task as quickly and as easily as possible.

COMPUTER SOFTWARE Standard File Formats Standard File Formats are used to store data in a way that makes portable – that it can be transferred between different application packages, other than the one it was created with. When you load an application program and create a data file, then save it – information is also saved which associates the data file with the application you used to create it. The means that when you want to reopen the data file, by clicking on the data file name to do this, you will also automatically open the application program.

COMPUTER SOFTWARE Standard File Formats Text can be transferred between different application packages when it is stored in a standard file format which is understood by both packages. ASCII (American Standard Code for Information Interchange) is the most common file format used to store text. ASCII codes each individual character with its own number and because an ASCII file holds no formatting information this makes ASCII file types readable by most application programs. ASCII files therefore are plain text files and can be identified with the file extension.TXT.

COMPUTER SOFTWARE Standard File Formats - Text RTF (Rich Text Format) is a standard file format which can be used to store data from word processing applications. In addition to the text, RTF holds formatting information, ie the styles, sizes, colours, alignment, font used in the documents. Saving a word processed data file in rich text format (RTF) means most data can be transferred to most word processing packages without the format being lost. A rich text file is identified with the file extension.RTF

COMPUTER SOFTWARE Standard File Formats - Text A text (.txt file) is extremely portable as it can be opened in any word processing or text editing application. Another advantage of.txt files is that they take up less storage space than.rtf files. However, a disadvantage of.txt files is that they do not store information about hoe the document has been formatted, things such as alignment style etc.

COMPUTER SOFTWARE Standard File Formats - Sound WAV file format is one step removed from RAW audio data. However WAV files are encoded using lossless compression, by storing the difference between the samples of the audio wave, instead of the actual sound samples themselves, as is done in RAW files. A WAV file can be a quarter of the size of the same audio file stored in RAW but without any loss of sound quality.

COMPUTER SOFTWARE Standard File Formats - Sound MP3 is an audio compression format which uses lossy compression. The lossy technique samples data that cuts out parts of the sound that the human ear cannot hear. Once it has cut the inaudible data it uses Huffman encoding to further compress the file size. Compressing files using MP3 format means that audio files can be compressed by a factor of up to 12 with no noticeable loss of quality. MP3 files take up less space on backing storage than other audio file formats and take less time to transmit on a network.

COMPUTER SOFTWARE Standard File Formats - Graphics A bitmap file format (.bmp), is an uncompressed file format where the bit- map file contains data about each pixel used to make up the image. For a black and white image 1 bit is needed to store each pixel. For an image using 256 colours 1 byte of storage is needed for every pixel and with an image using True Colour this rises to 3 bytes of storage for every pixel. This means that an uncompressed bit-map file can take up a very large amount of storage.

COMPUTER SOFTWARE Standard File Formats - Graphics The.jpeg file format (Joint Photographic Experts Group) - uses lossy compression to reduce the file size. This works by cutting out the parts of the graphics which won’t be noticed by the human eye. As jpegs use True Colour with 16,777,216 colours available – the lossy compression cuts out some of the very subtle variations in colour. jpegs are the most suitable file format for storing photographs, but are not suitable for storing line drawings as the loss of data would be noticeable here. jpegs can vary the level of compression – the higher the compression, the smaller the file size but the greater loss of data.

COMPUTER SOFTWARE Standard File Formats - Graphics The.gif file format use lossless compression which works by using a code to store patterns of bits that occur repeatedly throughout the graphics file. Because the gif format is based on an 8-bit colour code – files stored in this format are limited to 256 colours, meaning that the gif format is best suited for storage of drawings, charts and diagrams and is not suited for the storage of photographs. However, an advantage of gif is that colours can be set as transparent which is useful when displaying a gif image in a multimedia document, as it does not then obscure the underlying screen pattern.

COMPUTER SOFTWARE Standard File Formats - Graphics The.png file format (portable network graphics), uses lossless compression. It can achieve between 5 and 25 per cent more compression that the.gif file format. It can support a bit depth of up to 48 bits per pixel – meaning it has a huge range of colours available. It also allows you to control the transparency of a graphic..png was approved as a standard by the World Wide Web to replace.gif as.png is completely patent- and license-free. The most recent versions of web browsers support.png.

COMPUTER SOFTWARE Standard File Formats - Video The.avi file format (Audio Video Interleave), allows Video files to be stored in uncompressed format. This is a popular file format for Windows applications because it is compatible with the Windows Media Player. Limitations of AVI include: Audio is low quality as it supports only 8-bit samples at a frequency of 11.025 KHz. It is not compressed – so large file size. Resolution is a maximum of only 320 x 240 pixels. Maximum file size of 2 Gigabyte – so not suitable for large projects.

COMPUTER SOFTWARE Standard File Formats - Video.mp4 is the current standard from MPEG (Moving Pictures Experts Group) for compressing video data. mp4’s use lossy compression. This works by looking the differences frame to frame in a video and cuts out the unchanged parts. Although data is lost to achieve compression, when the video is played back the human eye and brain compensate for any loss of data and fill in the gaps.

COMPUTER SOFTWARE Standard File Formats - PDF Adobe Systems developed the PDF file format as a means of publishing and sharing documents across networks, especially the Internet. The PDF file format is used to represent documents in a manner independent of application software, hardware, and operating systems. PDF files can contain clickable links and buttons, form fields, video, and audio. PDFs look just like the originals and preserve all the source file information, even when text, drawings, videos, audio, 3D maps, full-colour graphics, photos, and business logic are combined in a single file.

COMPUTER SOFTWARE Virus A virus is also a piece of software. It is a program which can destroy or damage data stored on a computer system. Viruses can enter your computer system via e-mail, downloads from the Internet, “fun” websites, homemade CD and DVDs and infected portable storage devices, such as a USB Flash Drive.

COMPUTER SOFTWARE Anti-virus Software Every computer system should be protected by installing and using an Anti-Virus program. Anti-Virus software is an example of a utility program. Anti-Virus software is designed to detect and remove viruses from computer systems. It should also scan anything being downloaded to check that the item is virus free. Anti-virus software must be updated at regular intervals to ensure that it can detect and remove the new viruses that are being propagated all the time.

COMPUTER SOFTWARE Virus A virus is also a piece of software. It is a program which can destroy or damage data stored on a computer system. When a virus program is executed it performs four actions: Replication – copies itself to other files, particularly to.com and.exe. Files and the boot sector record. Camouflage – attempts to disguise itself to avoid detection from ant-virus software. Events Watching – when the virus runs it checks for specific events, eg dates which activate the virus. Delivery – this is what the virus does – could be anything from mixing of letters to wiping the entire hard disk drive.

HEALTH & SAFETY Health & Safety regulations require employers to provide: Chairs, computers and work areas that comply with current standards. Computer users are entitled to regular free eye tets and if spectacles are required they should be provided at the employer’s expense. Employees should not work exclusively at computers, they should have regular breaks. Employers should ensure that employees have access to health & safety training so that they understand the issues involved with prolonged computer use.

Computer Related Laws Computer Misuse Act The Computer Misuse Act - was passed because several crimes such as fraud, theft, blackmail and embezzlement had been committed using computers and existing laws did not cover such crimes. The Data Misuse Act means that offenders who commit crimes using a computer can now be prosecuted. The main provisions of the Data Misuse Act are that it is an offence to:  Even attempt to gain unauthorised access to data stored on a computer system.  Attempt to gain unauthorised access to a computer system in order to commit a further crime.  Succeed in gaining access to a computer system and to modify or change the data stored there.

Computer Related Laws Computer Misuse Act This means that under the terms of the Computer Misuse Act it is criminal offence to gain unauthorised access to a computer system, to hack, or write and/or distribute computer viruses.

Computer Related Laws Copyright, Designs & Patents Act The Copyright, Designs & Patents Act is designed to cover breaches of copyright – ie, use of someone’s intellectual property, (something they have created), without their permission. Amongst other things, it covers illegal copying of music, software, photographs, videos. Copyright law is very complicated, but basically you should not use anything you have not created yourself, without the owner’s permission. Sometimes media items are made available on the Internet as “copyright free” or free for “educational purposes”.

Computer Related Laws Data Protection Act The Data Protection Act governs how personal information may be held and for what purposes it may be used. Data about data subjects is held by data users, who must keep it:  Secure, private and use it for only the purposes the stated they were collecting it for.  Accurate and up-to-date.  They must show any data collected to the data subject, if requested.

Computer Related Laws Data Protection Act The Data Protection Act provides Data Subjects with certain rights over data held about them:  To see any data held about them (except data held by the Police, Customs & Excise or the Security Services).  To have any inaccurate data corrected.  To receive compensation for any loss which has occurred from incorrect data held about them. With the increased use of computer networks phishers are increasingly attempting to trick people into divulging personal information, which can then be used for identity theft.

Computer Related Laws Communications Act The purpose of The Communications Act 2003 is the regulation of the provision of electronic communications networks and services. The act introduced new offences for “Improper use of public electronic communications network”, “dishonestly obtaining electronic communications services”, “possession or supply of apparatus etc for contravening”, and includes discloser offences.

DATABASES It is necessary for any large amounts of information to be stored in some kind of order, to allow the information to be accessed easily and quickly - usually in a filing system. You probably use a filing system at home, eg:  store your music CD's or Computer Games in a storage rack  keep your books on shelves

WHAT IS A DATABASE? A database is an organised and structured collection of related data which you can search through. Databases can be:  stored manually (in a filing cabinet or on index cards)  storage could be in book form, eg a telephone directory or dictionary)  stored electronically using a computer system

DATABASE PACKAGES A program that is used for organising data on a computer is called a database package. Data in a database is organised into data files. A data File is a collection of Records of related information about something - with the single pieces of information stored in Fields.

CREATING A DATABASE To create a database file you must first design it - this mean that you must decide:  What it is you want to store (Records)  What information you want in the records (Fields)  What information will be unique to each record (Primary Key)  What the format of the fields will be (eg text, number, alphanumeric, date etc)

DATABASE TERMINOLOGY DATABASE TERMINOLOGY TABLE TABLE – a collection (or list) of related information held in columns and rows. ROW RECORD Each ROW in the table is called a RECORD RECORD (Example: your information in a telephone book is a RECORD) FIELD Each column in the table is a category or FIELD Phone Number Field (Example: a column of phone numbers in a telephone book would be considered as the Phone Number Field) DATA VALUE Each piece of data is a DATA VALUE DATA VALUE) (Example: your phone number in a telephone book is a DATA VALUE)

WHAT DOES A DATABASE LOOK LIKE? A database has columns which are called fields and rows which are called records. Individual pieces of data or information are stored in fields and all the data or information relating to someone or something is stored in a records Fields Records

KEY FIELDS IN DATABASES A primary key is assigned to a field which is used to uniquely identify a particular piece of information on the database so that you can find a particular record in a file as quickly as possible, eg The Scottish Qualifications Authority will have a database of all the students who are sitting National or Higher exams. The primary key field in the database would be the candidate number as each number can only belong to one person - therefore it is unique to them.

KEY FIELDS IN DATABASES A foreign key is a field which is a primary key in another, linked database table. A database can have many tables, linked together using primary and foreign keys, to avoid duplication of data. Linking tables also helps to reduce input errors as, if data has only to be entered once, there is less chance of mistakes.

VERIFICATION It is essential that the information you hold in a database is accurate. To verify data, is to check that it has been entered correctly. Sometimes this is done by the application asking you to enter the data twice, other times the user is asked if what has been typed in is correct. For Example, when you set up or change a password, you are usually asked to enter it twice to verify it.

VALIDATION Data is validated to check that it is allowable, sensible and within allowable limits. For example, validation checks would not allow: A numeric field to contain text. A numeric field to contain text. A required field to be left blank A required field to be left blank * Denotes Required Field OR OR Telephone No:

VALIDATION Data is validated to check that it is allowable, sensible and within allowable limits. Some validation checks include: Range Checks – data must be within a certain range, eg a date cannot have more than 31 days or 12 months in it. Range Checks – data must be within a certain range, eg a date cannot have more than 31 days or 12 months in it. Restricted Choice – data must be Restricted Choice – data must be selected from a drop-down menu. selected from a drop-down menu.

ADDING AND ALTERING RECORDS IN A DATABASE Once you have created the basic record structure (by creating the fields) you can begin adding information to each record. Some database applications allow you to alter the record format by adding new fields or deleting existing ones. You will also be able to change the type and size of the fields.

SEARCHING A DATABASE A DATABASE can be queried (searched) for information in two ways: A simple search – which is searching on one field or a complex search searching on more than one field. The advantage of using complex searches is that it narrows down the information you receive, making it easier to fined the precise information you are looking for.

SEARCHING A DATABASE Linking Search Options: You can link the conditions of a search in a field - by using AND or OR - at the end of the search and all the records which match the set of conditions (criteria), you have selected will be displayed, eg if we searched a database for pupils whose “subject” is computing the result could be 3 pupils - Hamilton, Easton and Adie - but if we add the condition that the “grade” is 1 - this time the result is Adie.

KEYWORDS A keyword is a text or code that is stored in a key field and is used to conduct searches and sorts. Some systems use the term string instead of keyword. For example each record in a file containing data about bank accounts would have a field named Account Number - this would contain a string which is unique to that record such as 714568. By choosing your keywords carefully you can save a lot of time when searching databases.

SORTING A DATABASE A sort allows the user to put records into order according to one of the fields. This allows you to arrange the records in a database file in alphabetic or numeric and ascending or descending order. Ascending numeric order would be: 1,2,3,4…, while descending alphabetic order would be, Z,Y,X,W… 1 2 3 4 Ascending Descending Z Y X W To start a simple sort, you must choose a field on which to sort the database, or the order will stay in the order you typed them in.

COMPLEX SORTING A DATABASE A complex sort allows the user to put records into order according to more than one of the fields. This allows you to arrange the records in a database file in alphabetic or numeric and ascending or descending order. Ascending numeric order would be: 1,2,3,4…, while descending alphabetic order would be, Z,Y,X,W… For Example: You might put a staff database in alphabetical order of Surname and then by Initial – both alphabetically ascending and then by Salary Numerically descending – the result of this sort is that staff would be listed firstly alphabetically and then by their salary from highest to lowest.

ALTERING INPUT AND OUTPUT FORMATS Most packages allow you to alter the record format by:  adding, deleting or changing the name of a field  changing field lengths or field types (eg a number field may be changed to a text field field may be changed to a text field  by altering the way the screen looks  by rearranging the position of the fields  by using only selected fields in the printout

REPORTS When you print out any information which is held on your database - this is called a report. When you select information from a database, eg by searching and sorting to find the records you want and getting them into the correct order, you are setting up a report definition. When you select information from a database, eg by searching and sorting to find the records you want and getting them into the correct order, you are setting up a report definition. You could of course print out the whole database - but databases can be very large and you will seldom want to see all the information held there.

COMPUTED FIELDS Databases can have computed field(s) (or calculated field(s)) which will carry out calculations on another field or fields within the database and display the answer (like a cell in a spreadsheet). Eg the average field shown in the diagram is a calculated field: SURNAME:Bruce FORENAME:Robert CLASS:2G Test 1:25 Test 2:31 AVERAGE:28

STORAGE SPACE FOR DATABASE FILES Database files have to be stored - either in main memory or on disc. Main memory is limited in size. Other storage mediums such as hard discs, magnetic tape, CD & DVD R & RWs. For the computer to manage the file storage efficiently we must decide on:  The storage space needed for each record.  The total number of records in the file.

STORAGE SPACE FOR DATABASE FILES From the values of the storage space needed for field names, records and total number of records, we can make a calculation of the total amount of storage space needed for the database file using the formula: data for one record*number of records = total storage We measure the data storage space in bytes. The number of data bytes needed for each record depends on the type of data stored under each fieldname - the next slide shows a simple example of this.

EXPERT SYSTEMS An expert system is a program what has access to a huge database of knowledge about one particular subject. It can make decisions and offer advice based on the knowledge it has. An expert system is made up of three parts:  Facts and rules - known as the knowledge base. This is like a giant database, but is more flexible as it contains rules as well as facts. A knowledge engineer extracts these fact and rules from human experts and put them into a form that the computer is able to understand.

WHO HAS INFORMATION ABOUT ME STORED ON A DATABASE? Some of the organisations which keep personal information of a private and confidential nature about individual people stored in computer systems are:  Doctor’s Surgery, Local Hospital  Driver and Vehicle Licensing Centre  Credit and Finance Companies  Banks and Building Societies  Police Scotland, Special Branch, MI5 Customs & Excise, Dept of Work & Pensions  Employers and Education Authorities etc

COMPUTERS AND THE LAW The Data Protection Act 1984 states that:  Data Users (holders of information) must be registered with the Government  Data must be used only for the registered purpose.  Data must be made known to any subject (the person it’s about) on request - to allow them to check that the information is accurate.  Data must not be made known to any third party (ie it must be kept secure).  The Data User must make every effort to keep the data accurate and up to date.

KEEPING DATA SECURE Steps that can be taken to preserve data kept on computer systems from unauthorised access or deliberate damage include:  Allow only authorised personnel into the computer room by:  using special locks on the door which require a passcode or special card to be inserted  putting security guards on the door  By staff wearing identification badges with photographs  Using biometric security to allows access to the computer rooms.  Protect the computer hardware itself by:  using a “turnkey” system which requires a special key to operate the computer

KEEPING DATA SECURE  If the system is used with communication lines, take it “off-line” when communication is not essential.  Use an operating system which implements user names and passwords (this is especially important in network systems, where there may be unsupervised terminals in many accessible places.  Protect individual files stored on disc by:  making them “read only”  locking them for both “read” and “write” operations  encrypting files so that they are unreadable without a special code  storing important files on portable backing storage only, so that they can be locked away

DIGITISED SOUND DATA Capturing Sound Sound – effects, voice overs and sound tracks can all be used to enhance multimedia applications. Sound can be captured for inclusion in the application usually in one of two ways: By copying tracks directly from a cd-drive (being careful not to break copyright law). Using a microphone to capture sound. A sound card is needed to manage the recording and playback of the sound.

DIGITISED SOUND DATA Capturing Sound In addition to connecting the microphone to the sound card, to capture sound – you will also need audio recording software.

DIGITISED SOUND DATA Capturing Sound The microphone picks up sound waves which are in analogue format – it then sends the sound waves to the sound card which samples them and converts them into digital format. Sound cards have their own processor and dedicated memory to process and store audio data – thus releasing the burden on the main processor and allowing it to continue with other tasks.

DIGITISED SOUND DATA Sampling Depth Sampling Depth refers to the number of bits used to store each sample of sound. The greater the sampling depth, the higher quality of sound. However the greater the sampling depth, the larger the file size will be. SAMPLING DEPTHNUMBER OF SOUND LEVELS 8-bit samples256 sound levels 16-bit samples65,536 sound levels 32-bit samples4 billion + sound levels This means that a sound file with a sampling depth of 32 bits will require four times the backing storage than the same sound with a sampling depth of 8 bits.

DIGITISED SOUND DATA Sampling Frequency (KHz) & Sound Time Sampling Frequency refers to the number of times per second a sample is taken. The greater the sampling frequency, the higher quality of sound. However the greater the sampling frequency, the larger the file size will be. Sound Time simply means the longer the sound lasts, the larger the file size will be.

DIGITISED SOUND DATA File Format - RAW Once the sound card has captured audio data and converted the samples into digital values this is known as RAW, because the sound files have not been subject to further processing. RAW sound files are very large and take up a large amount of backing storage space so some form of compression is needed to reduce the size of the file. The two file formats for compressing audio data are: WAV MP3

DIGITISED SOUND DATA File Format - WAV WAV file format is one step removed from RAW audio data. However WAV files are encoded using lossless compression - by storing the difference between the samples of the audio wave, instead of the actual sound samples themselves, as is done in RAW files. A WAV file can be a quarter of the size of the same audio file stored in RAW but without any loss of sound quality.

DIGITISED SOUND DATA File Format – MP3 MP3 is an audio compression format which uses lossy compression. The lossy technique samples data that cuts out parts of the sound that the human ear cannot hear. Once it has cut the inaudible data it uses Huffman encoding to further compress the file size. Compressing files using MP3 format means that audio files can be compressed by a factor of up to 12 with no noticeable loss of quality. MP3 files take up less space on backing storage than other audio file formats and take less time to transmit on a network.

DIGITISED SOUND DATA Sound Editing Software Sound editing software will allow you to increase or decrease the sampling depth and/or the sampling frequency. It will also allow you to: Crop – shorten the length of the track by cutting parts of it out. Volume – the volume of an audio file can be changes by using the editing software to change the amplitude of the entire audio file or particular instruments within the recording. Reverse – which means playing the recording backwards. Special Effects – such as echo, reverberation etc. Editing the audio file can either increase or decrease the file size. For example, if you crop a file – removing parts of it, the file size will obviously be smaller.

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) In High Level Programming (HLL) the language constructs are the parts (or features) which make up the actual programming language: Data Storage: Numeric & String Variables Input & Output Assignment One-dimensional Arrays Data stored in the computer’s memory is in a storage location with a unique address. A variable is the name that the programmer uses to identify what is in each storage location. Using a meaningful variable name helps the programmer to know what kind of data is being stored handled and retrieved, ie it aids readability.

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) Data Types – the data stored by a program could be a number, a string, a character or an array. Numeric Data – includes all whole and fractional numbers. String Data – is a list of text characters. Array – is a set of the same data of items grouped together using a single variable name.

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) SYNTAX & SEMANTICS SYNTAX - Every programming language has its own particular syntax – the way in which instructions are given to the computer. You must ensure that you use the correct syntax when programming or the computer will not understand. When this happens it is called making a syntax error. SEMANTICS - When programming, the semantics of an instruction relates to the meaning of the instruction, ie what it the instruction does.

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) Input – Data must be taken in by a computer program before it can process it, for example in the COMAL HLL: INPUT “Please enter a number”,mynumber Of course once the data has been processed, we want to see the OUTPUT – PRINT “The number you entered was”,mynumber

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) Assignment Statements are used to give variables a value, eg in FreeBASIC HLL: counter=0 school_name=“St John’s” This means that the variable counter is given a value of 0, however later in the program another assignment statement may be used to update the variable counter, eg: counter=counter+1

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) Operations: Arithmetical Operations Relational Operations Logical Operations An operation is a procedure carried out on a data item and an object is the item of data involved in the procedure. Arithmetical Operators – add, subtract, multiply, divide and square (represented in most HLL by the symbols + - * / ^) Are used for calculations concerning numbers, eg total_price= price_one+price_two net_wage=gross_wage-deductions

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) Relational Operators – can be used in program control structures, eg selection and repetition. Relational Operators include: = equals > greater than < less than >= greater than or equal to <= less than or equal to <> is not equal to

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) Logical Operators include AND, OR and NOT. Logical Operators and Relational Operators are combined in program control structures, eg: IF age =60 THEN PRINT “Discount Given”,discount

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) CONTROL - The basic control structures used in HLL procedural languages are sequence, selection & repetition. SEQUENCE means the order things are done in, eg fill kettle, switch it on, boil water, switch kettle off. If you tried to boil the kettle without any water it would break. The same principle is true with programs – the order you give instructions is important, ie sequence is used to ensure instructions given in the program are executed in the right order.

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) CONTROL - The basic control structures used in HLL procedural languages are sequence, selection & repetition. SELECTION – is based on one or more conditions being used together to decide something – used in conjunction with a conditional statement, eg IF age>= 17 THEN PRINT “You are old enough to drive” ELSE PRINT “You are too young to drive” When the program is run, the condition(s) are tested and if correct, the appropriate action is carried out.

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) CONTROL - The basic control structures used in HLL procedural languages are sequence, selection & repetition. REPETITION – means repeating an action over and over again – by using either a fixed or conditional loop. FIXED LOOPS are used when it is known how many times a chunk of the program has to be repeated, eg if you had a class of 20 pupils the fixed loop might look like this: FOR pupil 1 to 20 DO INPUT “Please enter the pupil’s name”,pupil_name ENDFOR pupil The fixed loop is controlled by a loop counter to count the number of times the loop has to be repeated.

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) CONTROL - The basic control structures used in HLL procedural languages are sequence, selection & repetition. REPETITION – means repeating an action over and over again – by using either a fixed or conditional loop. CONDITIONAL LOOPS – are used when it is not known in advance how many times the loop will have to be repeated, ie because a condition has to be met before the program will proceed on to it’s next part, (conditional loop), for example: INPUT “Please enter an age (11-18)”,age WHILE age 18 THEN PRINT “You must enter an age between 11-18” INPUT “Please enter an age (11-18”),age

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) NESTED LOOPS – are loops which are placed inside another loop. A nested loop could be either a conditional loop or a fixed loop.

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) DATA STORAGE – ARRAYS When a set of date items of the same type, (eg people’s names), are grouped together using a single variable name(eg names) – this is called an array. Each part or element of an array can be identified by the variable name and subscript, using names as example: names (1) – Matthew names (2) – Mark names (3) – Luke names (4) – John names (5) - Moses In this example, the array has 5 parts – the first element in the array is Matthew and the fifth element is Moses.

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) DATA STORAGE – ARRAYS Using arrays lets us take in and store a large amount of the same type of data, eg names, marks etc – without having to repeat the input line(s) again and again. Before we can start using an array, we must first declare the array name and it’s size, so that the correct amount of memory space for the array can be allocated, for example, for an array to take in and store the names and marks of 5 class members: DIM names(5) OF 10, mark (5) of 10 The really useful thing about an array is that the program can refer to the whole array at once or to any single element.

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) SUBPROGRAMS - Programs are usually designed and written using Top Down, Stepwise Refinement. What this means is that we start by identifying the input, process & output of a program and then break each section down into smaller pieces called subprograms. These subprograms will each perform a job in the program. Subprograms can be either written at the same time as the rest of the program or pre-written and imported from a program library when needed. The advantage of using subprograms from a program library is that it speeds up the development of a program because they have already been written and pre-tested. The two types of subprograms used by HLL procedural languages are functions and procedures.

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) FUNCTIONS – Many programs include pre-defined functions. A pre-defined function is a calculation which has been built into the programming language. Some examples of pre-defined functions: INT takes a number and removes the fractional part, leaving the whole number part. ABS takes a number and returns the nearest whole number. SQR returns the square root of any number. LEN returns the number of characters in a string. Every High Level Language will have its own pre-defined functions.

LANGUAGE CONSTRUCTS (HIGH LEVEL LANGUAGE PROGRAMMING) PROCEDURES (called SUB in FreeBASIC) – If you want to use a procedure in a program, you must first define it, ie give it a name, eg get_price When the procedure is used by the program this is known as calling the procedure. Calling the procedure causes something to happen in the program, eg SUB total_price total=price1+price2 PRINT total END SUB total_price

STANDARD ALGORITHMS (HIGH LEVEL LANGUAGE PROGRAMMING) An algorithm is a series of instructions which can be used to solve a problem. Standard Algorithms are algorithms which are commonly used in programming, such as: Input Validation Finding Maximum Finding Minimum Linear Search Count Occurrences

STANDARD ALGORITHMS (HIGH LEVEL LANGUAGE PROGRAMMING) INPUT VALIDATION – is the most commonly used standard algorithm and would typically be used in a conditional loop to check that the input is allowable, eg if checking someone is old enough to have a driving licence: SUB get_age INPUT “Please enter your age”,age IF age <17 THEN PRINT “You must enter an age >=17” INPUT “Please enter your age”,age END SUB get_age

Software Development Languages & Environments

A computer program is a list of instructions which tells the computer what to do. Computer programs (or applications as they are sometimes called), must be written in a language which the computer can understand. Programming languages can be divided into the following groups:  High Level Languages  Low Level Languages (Machine Code)  Special Purpose Languages

HIGH LEVEL PROGRAMMING LANGUAGES  They are easily edited  They have a common internal structure, eg loops, IF statements and CASE statements  Programs can be run on many different types of processors – making the programs portable  They use words which look like English  Most are designed for a specific area, eg education, business, science.  Most have built in error checkers Because many High Level Languages use instructions and commands which are based on English words, they are easy to use and understand by the programmers who write the programs. High Level Languages have many common features:

TRANSLATORS  Compilers  Interpreters Both translators work in different ways and each have advantages and disadvantages when compared to the other. Every program written in a High Level Language (HLL) needs to be translated into machine code (binary) before the computer can carry out (execute) the instructions. There are two main types of translators:

COMPILERS Compiler advantages:  The complete program is translated only once and then saved as executable code – meaning that when the program is used again the machine code version is immediately available for use. As they do not need translated again, they make less demands on the processor.  Compiled programs run faster than interpreted programs.  Compiled code can be loaded and executed (run) on other computers which do not have the translator programs. A compiler translates a complete high level program by converting every instruction into machine code before it executes the program. The machine code version of the program can then be stored in main memory and saved as a file.

COMPILERS Compiler disadvantages:  Program errors are only detected when the program is compiled which means it takes longer to develop the program.  Development of programs is therefore awkward as the whole program has to be compiled before it can be run COMPILER Source Code (High Level Language Program) 0010 INPUT “Please enter…. COMPILER Machine Code (Object Code) 1101 1110 0010 1111 1011 1000 1001 1110 0001 110 Reports Errors The object code is not executed immediately and can be saved separately

INTERPRETERS Interpreter advantages:  It error checks each completed line of a program as it is written – giving instant feedback about any syntax errors in the program – which is useful for people learning to program. EG 0010 // Mrs Feldman 0020 // 30 input "Please enter a number>>";number ":" expected, not ";" An Interpreter translates a high level language program one line at a time then performs the high level command. This process is repeated for each line of the program until the whole program has been interpreted.

INTERPRETERS Interpreter disadvantages: The program needs to be translated every time the program is executed – which makes them run more slowly than similar compiled programs and makes more demands on the processor. INTERPRETER Source Code (A single high-level language instruction, such as PRINT “Mrs Feldman”) INTERPRETER Machine Code Instructions Reports Errors Get Next Instruction Each instruction is executed immediately and cannot be saved separately

INTERPRETER V COMPILER? A programmer may choose to use an Interpreter for translating during implementation of a program, as any errors will be quickly picked up and resolved. Once all the bugs have been removed from the program, the programmer will choose to use a Compiler for translation as this will be faster and the translated code can then be saved as object code – meaning it will require no further translation. Because of this a compiled program is often described as being processor efficient as, having already been translated, it makes less demands on the processor than an interpreted program which needs translation every time it is run.

MACROS A macro is when a set of instructions are recorded, saved and assigned to either a single key or combination of keys - meaning that when the single key or combination key is pressed a sequence of operations are executed. Macros are good for speeding up repetitive tasks and for formatting the appearance of text in a document.

SOFTWARE PORTABILITY  The version of computer language which may be different on other computers, eg there are many versions of BASIC (True BASIC, Visual BASIC, FreeBASIC etc). Software portability means how easily you can transfer any program from one computer to another and depends on:

Information Solution (Multimedia) Development Process

Information Solution Development Process As in the software development unit – there are 7 steps in the process of developing a multimedia application: 1.AnalysisAnalysis 2.DesignDesign 3.ImplementationImplementation 4.TestingTesting 5.DocumentationDocumentation 6.EvaluationEvaluation 7.MaintenanceMaintenance AnalysisDesign Implementation TestingDocumentation Evaluation Maintenance

Information Solution Software Development Process - Analysis The main purpose of the analysis stage is to be clear about what the multimedia project is supposed to do. Before the project is begun it is important to turn ideas into an exact description of what the finished multimedia project is expected to do, for example: What exactly is it supposed to do? What type of system will it be un on? What kind of user will it be targeted at? What kind of user input will there be? What kind of ouput will it be expected to deliver? Once all these points have been clarified a requirements specification for the project is produced and the contents of this are agreed between the developer and the client.

Information Solution Software Development Process - Design The best way to proceed with the design of a multimedia project is to create a storyboard. A storyboard is a detailed plan about the different parts of the project, for example the content, number of slides, number and type of graphics, sound and video files etc. The storyboard will show the layout of these elements and specify the links between them.

Information Solution Software Development Process - Implementation The implementation stage is when the multimedia authoring or the web authoring packages are used to turn the design into a working project. All the assets detailed in the storyboard are gathered together and the multimedia authoring or web authoring packages are used along with these elements to create the project.

Information Solution Software Development Process - Testing Testing involves a series of practical steps being carried out to ensure that the multimedia project works and looks, as it is supposed to do. This would involve checking that the links between pages or slides work correctly, that videos and sound files play correctly, etc. Alpha testing would take place in the developer’s environment and then when any bugs had been corrected, beta testing would be carried out in the client’s environment.

Information Solution Software Development Process - Documentation Documentation includes a User Guide and a Technical Guide. The user guide will outline the main features available and advise how to use the project. The technical guide will contain information about the minimum hardware (processor, RAM, etc) and software (operating system) – needed to be able to load and run the project.

Information Solution Software Development Process - Evaluation The multimedia project is evaluated against the criteria agreed in the specification agreed in the analysis stage. It checks that the project is “fit for purpose” – that is does what it is supposed to do. It checks that the user interface has been well designed and that the multimedia project is easy to navigate.

Information Solution Software Development Process - Maintenance There are three types of maintenance – corrective maintenance is done to fix any bugs that appear once the project is in use and this is the responsibility of the developer. Adaptive maintenance may take place when changes are made to either/or the hardware or the software being used to run the multimedia application. Adaptive maintenance is paid for by the client. Perfective maintenance is carried out to add new features to a multimedia project – this is paid for by the client.

Multimedia Technology Creating Multimedia Applications Remember! - a multimedia application is any project which uses more than one type of media: text, graphics, sound, video. Ways of creating these applications include: Using presentation software to create presentations. Using a WYSIWYG web authoring package. Using multimedia authoring software to create complex multimedia applications. Using a simple text editor to create web pages using HTML coding.

Multimedia Technology Creating Multimedia Applications Presentation software packages allow the creation of complex multimedia applications. These packages have templates to help you structure your slides and will automatically link your slides in sequence. However, they also allow you to hyperlink slides to provide different ways of navigating through the application. Presentation software allows you to include sounds, graphics, animation, video and text in your project.

Multimedia Technology Creating Multimedia Applications WYSIWYG (What You See Is What You Get) editors can be used to create web pages. They are useful as you are able to see on screen what a web page will look like when it is viewed in a browser.

Multimedia Technology Creating Multimedia Applications Multimedia authoring packages can also be used to create multimedia applications. Because the have a graphical user interface it helps to make creating applications easier. The graphical user interface allows you to position objects such as graphics, attach events to the objects and define properties like colour. I also allows you to animate objects and add sound.

Multimedia Technology Creating Multimedia Applications Text editors can be used to create web pages. However as this has to be done by entering Hypertext Markup Language (HTML), this is very time consuming and difficult and requires a lot of expertise.

Multimedia Technology Creating Multimedia Applications The three main ways to view multimedia applications are as follows: Using a browser to view web pages and helping you to navigate from page to page. Data files created using a multimedia authoring package can be displayed using a file player, which is an application created specifically to allow the display of data files like this. Some multimedia and web authoring packages allow you to save your multimedia application as an executable file which can then be run without the need of a player.

Networks A Network is formed when 2 or more computers are linked together. The advantage of having a network is that it allows sharing of data, peripheral devices, communication between them and sharing of software (if the necessary licences are in place). A computer which is not part of a network is called a standalone computer.

Networks Local Area Network (LAN) The advantages of having an LAN include:  Data sharing  Peripheral sharing  Communication  Software sharing (subject to the necessary licences being in place)

Networks Local Area Network (LAN) A Local Area Network (LAN) covers a small geographical area such as a classroom or school building. The transmission media, ie the medium which carries the data within a network can be either copper or fibre optic cable or be wireless.

Networks Local Area Network (LAN) Transmission Mediums Fibre optic cable or copper cable can be used to connect the stations. The signals carried by copper cable are subject to interference, whereas fibre- optic signals are not. Fibre-optic cable also has a higher bandwith – meaning it carries more data per second than copper cable does. Fibre Optic Cable Copper Cable

Networks Local Area Network (LAN) Transmission Mediums Bluetooth and Wi-Fi can be used for wireless connection in a LAN. Bluetooth makes short-range, temporary links between devices like mobile phones, palmtop and laptop computers. Wi-Fi is used to wirelessly connect devices to one another. The range is usually up to 200 metres and is used for routers, laptop computers, games consoles etc.

Networks Wide Area Network (WAN) A Wide Are Network (WAN) covers a larger geographical area than a LAN – typically a country or a continent. The Internet is a WAN which spans the globe – the name Internet coming from Interconnecting Networks. Each network can be located anywhere in the world and include: multinational companies, governments, individuals using an Internet Service Provider (ISP).

Networks Wide Area Network (WAN) A Wide Are Network (WAN) can be used for:  Data sharing  Video conferencing  E-mail  Internet The Internet is a WAN which spans the glob – the name Internet coming from Interconnecting Networks. Each network can be located anywhere in the world and include: multinational companies, governments, individuals using an Internet Service Provider (ISP).

Networks Wide Area Network (WAN) Transmission Mediums Telecommunication links are used to transmit and receive data in a WAN. These links include fibre optic, satellite links and microwave transmission. Fibre optic cables for WANs are frequently laid on the seabed. A single satellite channel is capable of carrying large numbers of separate transmissions.

Networks Wide Area Network (WAN) Transmission Mediums Microwave systems are use dish aerials to transmit data between locations.

Networks Transmission Bandwidth On both LANs and WANs – bandwidth is the measure of the amount of data which can be carried by the communication channel at any one time. Bandwidth is measured in either Megabits per second (Mbps) or Gigabits per second (Gbps).

Networks Client-server Network A client-server network is formed when the client (workstation) is connected to and makes use of the resources available on the server(s). The client (workstation) requires a NIC (Network Interface Card) to connect it to the network.

Networks Peer-to-Peer Network A peer-to-peer network is created when two or more computers are connected and share resources without going through a separate server computer. A peer-to-peer network can be as simple as a couple of computers connected via a Universal Serial Bus to transfer files, or can be a permanent infrastructure that links a half-dozen computers in a small office over copper wires. The main advantage of having a peer-to-peer network is that you do not have the expense of buying a file server, as all the computers on the network have equal status. However disadvantages include, making backups and file security, which are more difficult to implement than on a client/server network.

Networks – Types of Server File Server A file server is used on a client/server network to provide centralised storage for user’s data and programs. Characteristics of a file server include: large amount of RAM and backing storage and fast multiple processors – so that users can access it quickly.

Networks – Types of Server File Server Security Users on a network must identify themselves to the file server by logging on, using their identity (usernane) and password. Users must always remember to log off when they have finished using the network, to keep their user account secure. A file server will have a battery power supply back-up in case of power cuts and usually a magnetic tape drive to keep back up copy of users data and programs.

Networks – Types of Server Printer Server A printer server is used to allow all the clients (workstations) on a network access to printers controlled by the printer server. The printer server also provides a facility for queuing up printing requests so that they are printed out in turn. It will have its own processor and enough RAM to hold print jobs which are sent to it.

Networks – Types of Server Web Server The term web server can refer to either the hardware (the computer) or the software (the computer application) that helps to deliver web content that can be accessed through the Internet. The most common use of web servers is to host websites, but there are other uses such as gaming, data storage or running enterprise applications. A web server is used to provide web pages requested by clients (computers), using the Hypertext Transfer Protocol (HTTP). This means delivery of HTML documents and any additional content that may be included by a document, such as images, style sheets and scripts. A web browser or web crawler, initiates communication by making a request for a specific resource using HTTP and the server responds with the content of that resource or an error message if unable to do so. While the primary function is to serve content, a full implementation of HTTP also includes ways of receiving content from clients. This feature is used for submitting web forms, including uploading of files.

Networks – Hub In a peer-to-peer network, the computers use a hub to connect to available printers.

Networks – Bandwidth Bandwidth is the measure of the amount of data which can be carried by the communication channel at any one time on both LANs and WANs. Bandwidth is measured in either Megabits per second (Mbps) or Gigabits per second (Gbps).

PERIPHERALS The physical parts of the computer – that is the parts we can see and touch, are hardware. The actual computer consists of the systems box. The devices which are attached to the systems box for input, output and backing storage are known as peripheral devices. Systems Box

HARDWARE Input Devices Input Devices consist of hardware peripheral devices such as:  Keyboard  Mouse  Touchpad  Microphone  Digital Camera  Digital Video Camera  Webcam  Scanner  Graphics Tablet  Joystick/Joypad

HARDWARE Input Devices - Keyboard The most common input device to be used with a computer is a keyboard. Every key has switch beneath it, which, when pressed sends the appropriate ASCII code into the computer. Keyboards are used to enter text into the computer.

HARDWARE Input Devices - Mouse Various types of mouse can be used to point and select on the computer screen. They can be either connected to the computer with a wire or be wireless. They can also be optical – with a light under the mouse, where any movement is detected by a sensor or have a ball underneath it, which, when the mouse is moved operates the mechanisms inside the mouse.

HARDWARE Input Devices - Touchpad Touchpads are usually used instead of a mouse on laptop computers. The user moves their finger over the touchpad which, (as the name suggests, is touch sensitive), to control the movement of the pointer on the monitor. Having a touchpad means that you do not need the extra space required for a mouse.

HARDWARE Input Devices - Microphone If any type of sound is required to be input to a computer system a microphone is needed. Sometimes a microphone is used along with voice recognition software so that instructions can e given to the computer or text dictated.

HARDWARE Input Devices – Digital Camera Digital Cameras use a lens which focuses reflected light from the subject being photographed into a sensor called a Charged Coupled Device (CCD). The information captured by the CCD is digitised and stored in the camera’s memory – usually on removable memory cards. Memory Cards have a large backing storage capacity – meaning the can store a large number of photographs – the number depends on the resolution of the photos and the compression used – most digital cameras will use JPEG compression.

HARDWARE Input Devices – Digital Camera A Digital Video Camera works in much the same way as a digital camera – using a CCD. A digital video camera is used to capture moving pictures. Storage mediums used by digital video cameras include – DVD-R, Hard Disk, Flash ROM. Whichever backing storage medium is used, it has to have a large storage capacity because of the large file sizes associated with video.

HARDWARE Input Devices – Webcam A Webcam is a small digital video camera, which is usually built into the monitor (in laptops), or placed beside or on the monitor, of a desktop computer. The resolution of a webcam is not as high as a digital video camera and the webcam has to be connected to a computer system in order to capture or store images. Webcams can be used for video conferencing – which allows people in different locations to conduct meetings.

HARDWARE Input Devices – Scanner A scanner is used to capture hard copies of documents, including photographs and convert them into digital format so that they can be manipulated or stored on a computer. The scanner can also be used in conjunction with optical character recognition software, to scan in text based documents in a format which will allow them to be edited on a computer.

HARDWARE Input Devices – Joystick/Joypad Joysticks are often used to control video games, and usually have one or more push-buttons whose state can also be read by the computer. Joypads generally feature a set of action buttons handled with the right thumb and a direction controller handled with the left. The direction controller has traditionally been a four-way digital cross (also named a gamepad). Joypads are the primary means of input used on many video game consoles.

HARDWARE Output Devices Output Devices include hardware peripheral devices such as:  Printers (laser, ink-jet)  Monitor (TFT & LCD)  Loudspeakers Output devices are used to pass data out of a computer system.

HARDWARE Output Devices – Laser Laser Printers are peripheral output devices used to obtain hard copy of output from a computer. Laser printers may produce black & white (monochrome) or colour prints. The resolution (quality) of a print out is measured in dpi (dots per inch) and the speed of printing in ppm (pages per minute).

HARDWARE Output Devices – Inkjet Inkjet Printers are peripheral output devices used to obtain hard copy of output from a computer. Laser printers may produce black & white (monochrome) or colour prints. Inkjet printers are good at producing high quality photo prints. The resolution (quality) of a print out is measured in dpi (dots per inch) and the speed of printing in ppm (pages per minute).

HARDWARE Output Devices – Monitors Monitors are peripheral output devices used to display output from a computer on a screen. Monitors may be, LCD (Liquid Crystal Display) or TFT (Thin Film Transistor. The resolution of a monitor is measured in pixels – length x breadth. The higher the resolution, the better the picture quality. LCD screens work by using a thin and lightweight film of liquid crystals and transistors to control light passing through the screen. LCD screens can run on batteries as they do not need a lot of power and are typically found on devices such as smart phones, tablets and laptop computers.

HARDWARE Output Devices – Monitors Monitors are peripheral output devices used to display output from a computer on a screen. The resolution of a monitor is measured in pixels – length x breadth. The higher the resolution, the better the picture quality. As with LCD screens, TFT screens use transistors to produce high quality displays. Although TFT screens are more expensive than LCD screens, their main advantage is that animations and graphics are displayed to a higher quality than is possible using LCD screens.

HARDWARE Output Devices – Loudspeakers Loudspeakers are output peripheral devices used to output sound from a computer system. The loudspeaker is connected to the sound card in the systems box. The sound card changes the stored digital sound into analogue format for outputting through the loudspeakers.

HARDWARE Functions of an Interface Data Conversion Data Conversion is needed to change data being input in analogue format from a peripheral device, into digital format so that the processer can handle it. The opposite happens when data is being output from the processor in digital format, it has to be converted into analogue format so that we can see or hear it.

SOFTWARE DEVELOPMENT

PROGRAMMING STAGES Computer programs are developed to solve problems. When developing a solution to a problem there are 7 stages that should be followed: 1AnalysisAnalysis 2DesignDesign 3ImplementationImplementation 4TestingTesting 5DocumentationDocumentation 6EvaluationEvaluation 7MaintenanceMaintenance

ANALYSIS (1 ST STAGE OF DEVELOPMENT) This stage is commonly done by a Systems Analyst. The Analyst studies the problem, so as to understand it. They observe any existing system that is to be replaced or upgraded and interview any relevant staff. They will also examine any existing documentation. All the information gathered is combined into a formal document called the Requirements Specification. The Analyst devices a solution and produces a System Specification detailing how the new system will operate.

DESIGN (2 ND STAGE OF DEVELOPMENT) For large problems the designers take the analysts system specification and produce a design for each part of the solution, everything from screen designs to what the final output will look like. They will also ensure that suitable help and error messages are built into the software to aid the user.

DESIGN (2 ND STAGE OF DEVELOPMENT) A common way of representing the design is using a top down approach. This means starting at the top (ie identifying the inputs, processes and outputs) and then breaking the problem into tasks which can be broken down into smaller tasks, and so on… There are 2 common methods used to represent designs in this way: Structure Diagrams Pseudocode

DESIGN (2 ND STAGE OF DEVELOPMENT) Structure Diagrams – is a graphical based design notation. Here boxes are used to show the solution. Example: Top Box with Program Name in it. Procedure box Sequence or Command Box Selection or Decision Repetition

DESIGN (2 ND STAGE OF DEVELOPMENT) Flow Chart – is a graphical based design notation. Here boxes are used to show the solution. Examples: light is on, it's likely you need to turn on the monitor.

DESIGN (2 ND STAGE OF DEVELOPMENT) Pseudocode – is a text based design notation. Here the design is written in words but structured as before. Example: First the major steps are identified: 1 get data from user 2 calculations 3 display results Now break each step down into smaller steps: 1.1 get length 1.2 get width 1.3 get height

IMPLEMENTATION (3 RD STAGE OF DEVELOPMENT) The program must be structured (ie written in self- contained units (procedures – called SUB in FreeBASIC) of code). Variable, procedure (sub) and function names must be meaningful. Internal documentation is essential (ie ‘ followed by an explanation of what particular pieces of coding should do). Once you have completed breaking down your problem in to pseudocode, you can now write the code to match your design. The rules for your program are:

TESTING (4 TH STAGE OF DEVELOPMENT) When the program coding is complete, alpha testing of the solution takes place in the developer's environment. Beta testing or acceptance testing as it is sometimes known, will take place in the customer's own environment for testing under actual working conditions.

TESTING (4 TH STAGE OF DEVELOPMENT) Test 1 – Normal expected data. Test 2 – Data at the limits of the problem (Extreme) Test 3 – Data beyond the limits, ie data that the program has not been designed to cope with (Exceptional) Some simple guidelines for testing:

TESTING (4 TH STAGE OF DEVELOPMENT) Eg A Program has been written that accepts two numbers between 1 and 10, adds them together and displays the result. The test data table could look like the following: Num 1Num 2Outcome 1 (Normal) 8 7 15 2(Extreme) 0 11 Invalid Data 3(Exceptional)abc prog fails

DOCUMENTATION (5 TH STAGE OF DEVELOPMENT) The documentation which accompanies software consists of three major parts: The Software Licence, the User Guide and the Technical Guide. The Software Licence details the conditions under which you a permitted to use the software. The User Guide will contain detailed instructions to help the user load and operate the software. This usually comes in the form of ‘help’ files built into the software containing, instructions and online tutorials which take you through the main features of the program. The Technical Guide contains technical requirements and a structured listing of the program.

EVALUATION 6 TH STAGE OF DEVLOPMENT Comment on the overall solution – does the program do what it is supposed to do? – ie is it Fit for Purpose? Comment on the User Interface – the HCI – does it have help screens and prompts for the users? Does the HCI have visual appeal and a good screen layout? Readability – how easy is it for another programmer to understand your code if maintenance to the program is needed? To aid readability you should ensure you use meaningful variable names, internal documentation, indentation and white space. Consider the following points:

EVALUATION 6TH STAGE OF DEVLOPMENT Comment on the test data and the reasons you chose it. Describe any problems you had and how you overcame them. Suggest any improvements (perfective maintenance) you could make if you had time. Suggest any alternatives that would be easier than writing a program. Eg, buying or adapting a commercial program.

MAINTENANCE 7 TH STAGE OF DEVELOPMENT Maintenance begins as soon as the software is delivered to the customer. As testing can never by completely extensive, errors can and do appear, once the customer begins to use the program. Correcting these errors is called corrective maintenance. Sometimes the customer wishes to adapt the software to cope with changes in their hardware or software. This is know as adaptive and perfective maintenance.

MAINTENANCE 7 TH STAGE OF DEVELOPMENT Corrective maintenance is the responsibility of the developers. As testing can never be completely extensive some errors will not appear until beta testing takes place and/or the customer begins using the program. The developers are responsible for correcting such errors (including the cost).

MAINTENANCE 7 TH STAGE OF DEVELOPMENT Perfective maintenance takes place when the software is operating correctly but the customer now wants changes made that were not in the original system specification. These changes could be because the customer, once they are using the software, has thought of even better ways they could use it if these changes (perfective maintenance) were carried out. The cost of perfective maintenance is met by the customer.

MAINTENANCE 7 TH STAGE OF DEVELOPMENT Adaptive maintenance takes place when the system hardware and/or software has changed. This could be the installation of a new processor or a different operating system. The software may need adaptive maintenance so that it will run on the new system. The cost of adaptive maintenance is met by the customer.

MAINTENANCE 7 TH STAGE OF DEVELOPMENT It is important that any program is made readable, to aid maintenance of a program. Ways of making a programme readable include: Internal Documentation (comment lines) Meaningful Variable Names Good use of White Space Indentation Modular

SOURCE CODE TEXT EDITORS Source Code Text Editors come as part of a programming language, for example, FreeBASIC. Text editors like these, have features such as automatically highlighting command words as they are entered, by putting them in upper case and/or particular colours. They will also automatically indent the program structures such as loops or conditions. A good text editor will also have an error reporting facility, which will indicate the type of error you have made and it’s location.

FreeBASIC Toolbar for Text Editor New Open Save Save All Close Cut Copy Paste Undo Redo Compile Compile & Run Quick Run Close

FreeBASIC Text Editor – Colour Coding Black Bold -restricted commands such as input, print etc.. Grey -REM (internal documentation) statements start with ‘ Blue -data types such as integer, single, string Black not bold -variables Red -any screen text (which will be displayed when the program is run)

FreeBASIC Text Editor – Syntax FreeBASIC is not case sensitive, but tend to use lower case. INPUT -use, (comma) PRINT-can use either, or ; DIM-sets data types (eg as integer, string, single etc. DIM-use shared for parameter passing SUB-used like a procedure CALL-used in main program which is after subprograms Assignment-=

FreeBASIC DATA TYPES & VARIABLES The three main data types used in FreeBASIC are: INTEGERS – numbers that have no decimal or fractional part in them, EG -99, 103576, -10000, 107 SINGLE – any other type of number, EG 3.7654, 10101.3746, -0.0003, 1.5 STRINGS – any other combination of characters, EG Fred, ABC 123Y, My name is Kim, 1X5sy.

VARIABLES Variables are used in programs so that data can be assigned to them for processing. This is useful since we can run a program over and over and use different data each time. Variables must be one word with no space. We can get around this by linking words using the underline symbol. This helps to make programs readable. EG get_data, calculate_type.

INTERNAL DOCUMENTATION It is important that you make remarks (internal documentation or comment lines), throughout your program. This improves readability, which will help if you need to go back and change a program (maintenance) at a later date. In FreeBASIC lines in grey beginning with ‘ are remark statements (Internal Documentation) and tell the computer to do nothing, ie the computer ignores any line with ‘ at the beginning.

FreeBASIC REM STATEMENTS (INTERNAL DOCUMENTATION) A simple rule at the start of a program is to have the first few lines as ‘ (which will be coloured grey) to give the program name, date it was written and so on. Eg: ‘ Adding ‘ by Fred Bloggs ‘ 17 January 2007 DIM first_number as integer INPUT “Please enter…. In the above program the first three lines are all REM statements (internal documentation), the first line to actually do anything would be the line beginning DIM…

FreeBASIC HOW TO SELECT & PASTE DATA FROM FreeBASIC INTO A WORD DOCUMENT To PRINT a FreeBASIC program: Go to EDIT, SELECT ALL RIGHT CLICK, COPY OPEN a new blank word processing document RIGHT CLICK, PASTE Your FreeBASIC program structured listing is now represented as a word process document and can be printed and/or saved.

FreeBASIC HOW TO SAVE A FreeBASIC PROGRAM To SAVE a FreeBASIC program: Go to FILE, SAVE AS Select the PROGRAMS folder within your MY DOCUMENTS folder Give your program an appropriate name Click SAVE Your FreeBASIC program will now be saved into your programs folder within your “My Documents” folder.

FreeBASIC HOW TO LOAD AN EXISTING PROGRAM INTO THE FreeBASIC TEXT EDITOR To LOAD an existing program file into FreeBASIC: LOAD FreeBASIC Go to FILE, OPEN SELECT the PROGRAMS folder within your MY DOCUMENTS folder SELECT the program you want to load DOUBLE CLICK on the program to load and open. Your FreeBASIC program will now be displayed – allowing you to either edit it or run it.

CONVERGING MULTIMEDIA TECHNOLGIES - Smartphones We use the term “convergence of technology” to describe a device which can provide two or more multimedia functions. A smartphone is a good example of converging technology as they: Can be used to send and receive voice calls. Send and receive text messages. Capture pictures and video. Access the Internet. Play MP3 music and video games. They also have features we would expect to find on a palmtop computer such as simple database, spreadsheet and word processing software; a calculator and a touchscreen.

SIMULATION & VIRTUAL REALITY Virtual reality is where the user is immersed in the computer generated world and can interact with it through special headsets, data gloves fitted with sensors, or even whole body suits with multiple sensors. Virtual reality can be used for things such as: Training pilots by simulating a plane in flight environment. Simulating a fantasy world created by game-maker. Simulating scientific experiments.

SIMULATION & VIRTUAL REALITY In immersive environments a range of sensors such as magnetic trackers, optical positioning sensors and ultrasonic tracking systems are used. Video output uses 3d technology. Whereas audio output is achieved by surround sound. Very powerful graphics cards are needed in the computer system to ensure that images quality images are output at high speed.

SIMULATION & VIRTUAL REALITY The graphics below illustrate just some ways in which virtual reality can be used. Interactive Computer Game Virtual Reality Room for training purposes Holodeck from Star Trek

SYNTHESISED SOUND DATA Common Attributes of Notes Stored As MIDI Data A MIDI file holds data on the properties or attributes of the sound, as detailed below: ATTRIBUTEMEANING InstrumentThis tells the MIDI system which instrument the note is being played on, for example a trumpet sound which it has stored on a ROM chip. PitchThis determines how high or low the note is. VolumeThis controls the loudness or amplitude of the note. DurationThis determines the length of a note. TempoThis is the rate of speed at which the piece of music is set.

SYNTHESISED SOUND DATA Synthesised sound data can be created using MIDI (Musical Instrument Digital Interface). MIDI is the standard interface used by musical instruments such as keyboards or any other musical instrument which has had MIDI installed on it. MIDI enables notes played on the instrument to be transferred to a computer system, edited and played back. The MIDI standard covers both: The data format used to store the sound. The hardware connection between the computer and the instrument(s).

TYPES OF COMPUTERS EMBEDDED COMPUTER An embedded computer is a computer built into the system it is controlling. Embedded computers are found inside things like cars, washing machines, games consoles etc. Embedded systems can have a processor, RAM, ROM, Input & Output interfaces all stored on a single chip. Embedded computers process data in real-time.

TYPES OF COMPUTERS DESKTOP COMPUTERS Desktop computers use mains electricity and as the name suggests, sit on a desktop. They are not portable. The common peripherals are: Keyboard Mouse Monitor (Liquid Crystal Display) Loudspeakers Storage Devices typically include Hard Disk Drive and CD/DVD drives. A network interface card (NIC) is also needed to connect to a local area network (LAN).

TYPES OF COMPUTERS PALMTOP COMPUTER Palmtop computers are so called because they are small enough to be carried in one hand while being used. Sometimes they are also called PDAs (Personal Digital Assistants) or handheld computers. They come with an LCD screen for output and may have a small keyboard, however, input is usually via a touch sensitive screen using a stylus. They are battery operated. Many mobile phones now have the same features as palmtop computers – these are called smart phones.

TYPES OF COMPUTERS LAPTOP / NOTEBOOK COMPUTERS Laptop (and Notebook) computers are designed to be used whilst resting on your lap. The come with an LCD monitor for output and a keyboard and trackpad for input. As with a desktop computer they will have a hard disk and cd/dvd drive for storage, however it is likely that solid state storage (SSD) will start to replace hard disk drives in laptops and notebooks, as they are very robust – having no moving parts. They are battery operated and will come with a wireless interface card.

TYPES OF COMPUTERS TABLET COMPUTERS Tablet computers have a large touch sensitive screen – used with a stylus for drawing and writing. They can be used for web-browsing, e- mail, music, games etc.

TYPES OF COMPUTERS MAINFRAME COMPUTERS Mainframe computers are very large computer systems, that can occupy a whole room. It will have a huge amount of RAM, processers and storage devices such as tape and disk drives. They can process very large amounts of data at high speed. Mainframes are multi- user or multi-access systems as they are connected to hundreds of dumb terminals (dumb meaning that the terminal has no processing or storage devices – all the processing and storage being done by the mainframe.

TYPES OF COMPUTERS SUPERCOMPUTERS The most powerful and fastest computer is the supercomputer. These computers are used for intensive or demanding mathematical calculations or the production of very high quality graphics, for example the digital animation used in films.

TYPES OF COMPUTERS CLOCK SPEED A processor’s clock speed is measured in Gigahertz(GHz) – one GHz being approximately 1000 million pulses per second. Looking at the clock speed of a computer system is one method which can be used to indicate how well a system is performing. Another way of comparing system performance is to use application based tests. The same task is carried out using the same application on different computers, the time taken is noted and then compared to see which is fastest.

VECTOR GRAPHICS What are the basic features of Vector Graphics? They are scalable – resolution independent. Individual objects in a vector graphic can be edited. Graphics can be assembled by placing objects in layers.

VECTOR GRAPHICS Standard formats for Vector Graphics: Scalable Vector Graphics (SVG) format Scalable = resolution independent. Vector = represents objects by defining a series of attributes.

VECTOR GRAPHICS Common attributes of vector graphic objects: Position Shape Size Rotation Line Layer Fill Common attributes for a circle, filled with red

VECTOR GRAPHICS Attributes of a 3D image: Shape Position Size Rotation Texture

VECTOR GRAPHICS Standard formats for Vector Graphics: Virtual Reality Markup Language (VRML) A standard language used to model and animate geometric shapes. Used to define 3D environments for the WWW (World Wide Web) #VRML V2.0 utf8 Navigationlnfo {type "EXAMINE"} Shape { geometry Box { } } VRML used to model a simple box

VIDEO DATA Hardware – Digital Video Camera High quality moving images (video clips) can be captured using a digital video camera. Digital video cameras use arrays of light-sensitive sensors to capture images, have small LCD screens so that you can see and check what you are capturing and come with features such as zoom and image stabilisation.

VIDEO DATA Storage & Output Video data can be stored in uncompressed – AVI (Audio Video Interleave) format, or compressed in MPEG (Moving Pictures Expert Group) format. A graphics card is needed in the computer system to output video data. The graphics card takes the video data file, decompresses it and then coverts the digital data signal to that it can be output to the screen. As the graphics card has its own memory and processor, this removes the burden of processing and storing video data from the main processor.

VIDEO DATA Storage - AVI Video files can be stored in uncompressed format using AVI (Audio Video Interleave). This is a popular file format for Windows applications, ie it is compatible with the Windows Media Player. Limitations of AVI include: Audio is low quality as it supports only 8-bit samples at a frequency of 11.025 KHz. It is not compressed – so large file size. Resolution is a maximum of only 320 x 240 pixels. Maximum file size of 2 Gigabyte – so not suitable for large projects.

VIDEO DATA Storage - MPEG Because video files can be very large – one second of uncompressed video could demand 53 Megabytes of storage, video data is compressed to make less demands on backing storage and more easily transmitted across networks. MPEG (Moving Pictures Experts Group) is a series of standards for compressing video data. MPEGs use lossy compression. This works by looking the differences frame to frame in a video and cuts out the unchanged parts. Although data is lost to achieve compression, when the video is played back the human eye and brain compensate for any loss of data and fill in the gaps.

VIDEO DATA Quality – Colour Depth & Resolution Videos are usually captured in true colour which requires 24 bits for every pixel. Reducing the colour depth reduces the file size but limits the number of colours displayed and degrades the quality of the video. Resolution of a video clip is expressed as the number of pixels per frame – measured in height in pixels x width in pixels. Increasing the resolution improves the quality but increase the file size. Decreasing the resolution degrades the quality but decreases the file size.

VIDEO DATA Quality – Frame Rate Video is a sequence of frames (individual pictures) taken one after the other. When played back quickly the brain and eyes are tricked into seeing a moving image. Frame rate (fps) measures how many frames are processed per second. The standard rate for a video clip is 30 fps. Reducing the frame rate (fps) to 15 fps would reduce the file size but result in a jerky, unsatisfactory playback. Cropping the video will also reduce file size, but will result in some frames being lost.

VIDEO DATA Editing Once a video has been captured video editing software can be used to edit the clips: Cropping can be used to cut out unwanted parts of frames, or unwanted frames. Add Effects – such as transitions like fade or dissolve can be added to mark the change from one scene to another. Add Titles can be used to place titles or credits onto a clip. The titles and credits themselves can have effects added to them. Add sound tracks allows sound tracks to be selected, edited and attached to specific frames.

The World Wide Web (WWW) The World Wide Web (WWW) is like a giant multimedia database holding all the information available on the Internet

The Internet? The Internet is a world wide network of computers.

WHAT CAN WE USE THE INTERNET FOR? To find information: The internet is a vast source of information. We can find out about things that interest us. The information can be in multimedia form, ie text, graphics, sound, video and even animation. To communicate: It is possible to send messages to other people using the Internet.

Hypertext Mark-up Language Web Pages are written in a special language called Hypertext Mark-up Language(HTML). The pages can be created using either special web authoring software which creates the HTML automatically or created using a general purpose package(GPP) and then saved in HTML. Web pages have to be saved in HTML before they can be opened in a web browser.

What do we need to use the Internet? Hardware and Software - running a web browser program

Internet Explorer The Web Browser we use to view WWW pages. Internet Explorer is Communications Software Internet Explorer Toolbar. type the address of the site you want here

Finding Information URLs Uniform Resource Locators. These are like addresses. Every page has one. If you know the URL you can go straight to the page directly. Hypertext Links These are Hypertext Links which take you from one web page to another. This is called surfing the net.Hypertext Links Search Engine Software which finds web pages for you. You tell it what to look for. Favourites Folder Once you find a useful site it can be stored in the favourites folder so that you can get there quickly next time.

Finding Information URLs Uniform Resource Locators (URLs). The URLs of every webpage are unique and each one can be broken own to give more information, for example: HTTP://www.computing.com/int2/car.html This tell us that the page will be retrieved using hypertext transfer protocol This tells us the name of the web server which is storing this page This tells us the name of the directory where the page can be found on the web server This tells us the name of the web page. They usually end in.html or.htm – but other page types can be used.

Finding Information There is so much information available on the Internet these days that it would be impossible to find exactly what you are after without some kind of help. You will all be familiar with using a Search Engine such as Google when you want to find out information about a specific topic. A Search Engine is essentially a database which catalogues all web pages on the Internet according to key words. When you want to look for a topic you enter keywords into the search box provided. The search engine examines the billions of records it stores and returns you a list of results in a web page format. It tries to sort the results for you by putting the ones it thinks are the most relevant at the top. It also provides you with a brief description of the data that it found and a direct link to the web page.

Electronic Mail (e-mail) E-mail is short for electronic mail. What this means is that we can send and receive messages to other people through our computer. To be able to use e-mail you must have a computer with a modem and a connection to a telephone line. The modem is used to convert the e-mail messages back and forwards between the code the computer can understand into the code that can be transmitted (sent), over the telephone lines to and from other e-mail users. We also need to have a mailbox and an e-mail address. The mailbox is provided by an Internet Service Provider (ISP).

Electronic Mail (e-mail) Once you have a mailbox and an e-mail address you can set up an address book for contacts e-mail addresses. You can also set up mailing lists (groups) to enable you to send the same message to a whole lot of people in one operation. It is also possible for you to set up folders within your mailbox so that you can save incoming e-mails about any particular topic into a folder just for that – which makes it easier to find if you want to go back and read it again at a later date. It is important that you never open e-mails or attachments from contacts you do not know. This is because the may be infected with a computer virus, which could spread to your computer if the file(s) were opened.

COMPUTER SECURITY At the same time as the amount of computers accessing and using networks grows, so does the security risks associated with computers. Security risks include: Viruses Worms Trojans DOS (Denial of Service) Attacks Spyware Keylogging Phishing Identity Theft Online Fraud

COMPUTER SECURITY How are Viruses Spread? A virus is a computer program which has been deliberately created to cause damage or disruption to a computer system. When a virus program is executed it performs the following actions: Replication – copies itself to other files, particularly to.com and.exe. Files and the boot sector record. Camouflage – attempts to disguise itself to avoid detection from ant-virus software. Events Watching – when the virus runs it checks for specific events, eg dates which activate the virus. Delivery – this is what the virus does – could be anything from mixing of letters to wiping the entire hard disk drive.

COMPUTER SECURITY Symptoms of a Virus Infection Common symptoms that a computer has been infected by a virus include: Computer rebooting unexpectedly. Unusual sound or visual effects. Unwanted generation and sending of e-mail. Displaying unwanted messages. It is important to note that Worms and Trojan Horses are categorised as “malicious code”.

COMPUTER SECURITY How are Viruses Spread? Viruses can be spread from a computer which is infected to another via backing storage media such as USB Flash Drives and homemade CD or DVDs. “Fun” websites can provide free downloadable material which may not be from a reputable source – the downloads may be infected. E-mail – this is now the most common way to spread viruses. You should delete immediately, without opening – any e-mail you received from an unknown sender.

COMPUTER SECURITY WORMS A worm is a malware computer program that replicates itself in order to spread to other computers. Often, it uses a computer network to spread itself, relying on security failures on the target computer to access it. Unlike a computer virus, it does not need to attach itself to an existing program. Worms almost always cause at least some harm to the network, even if only by consuming bandwidth, whereas viruses almost always corrupt or modify files on a targeted computer.

COMPUTER SECURITY TROJANS A Trojan is a program that pretends to be a helpful program. Unlike viruses, Trojans do not replicate themselves but they can be just as destructive. One of the most menacing types of Trojan is a program that claims to rid your computer of viruses but instead introduces viruses onto your computer.

COMPUTER SECURITY DOS (Denial of Service) Attacks DOS Denial of Service attacks occur when networks are targeted to try and bring them to a standstill. DOS attacks can either target a particular device on the network, for example the file server by using a malware program such as a worm. Or, they may make so many bogus requests to the network, using what is often termed “zombie “ computers, that there is no resources left for use by genuine users. DOS attacks can cost organisations a lot in terms of wasted manpower, loss of business and damaged reputation. Zombies File Server DOS attacks violate the acceptable use policies of virtually all Internet service providers (ISPs). They also usually represent breaches of the laws of individual countries.

COMPUTER SECURITY SPYWARE Spyware is software that secretly gathers user information through the user's Internet connection without his or her knowledge, usually for advertising purposes. Spyware applications are typically bundled as a hidden component of freeware or shareware programs, that can be downloaded from the Internet; however, it should be noted that the majority of shareware and freeware applications do not come with spyware. Once installed, the spyware monitors user activity on the Internet and transmits that information in the background to someone else. Spyware can also gather information about e-mail addresses and even passwords and credit card numbers.

COMPUTER SECURITY KEYLOGGING A keylogger is a hardware device or a software program that records the real time activity of a computer user, including the keyboard keys they press. Keyloggers are used by IT departments to troubleshoot technical problems with computers and business networks. Keyloggers can also be used by organisations to monitor the network usage of people without their direct knowledge. Keyloggers are sometimes part of malware packages downloaded onto computers without the owners' knowledge. Malicious individuals may use keyloggers on public computers to steal passwords or credit card information.

COMPUTER SECURITY PHISHING Phishing is usually attempted by sending an e-mail to a user falsely claiming to be an established legitimate organisation, in an attempt to trick the user into surrendering private information that will be used for identity theft. The e-mail directs the user to visit a Web site where they are asked to update personal information, such as passwords and credit card, social security, and bank account numbers, that the legitimate organization already has. The Web site, however, is bogus and set up only to steal the user's information. Phishing is a form of hacking used to “fish” for personal information.

COMPUTER SECURITY IDENTITY THEFT Identity theft occurs when someone pretends to be someone else, by assuming that person's identity, often in order to access resources or obtain credit and other benefits in that person's name. The victim of identity theft (the person whose identity has been assumed by the identity thief), can suffer adverse consequences if they are held accountable for the thief’s actions. Identity theft occurs when someone uses another's personally identifying information, like their name, identifying number, or credit card number, without their permission, to commit fraud or other crimes.

COMPUTER SECURITY ONLINE FRAUD Online fraud is the term used to cover all crimes committed using the Internet. Online fraud can be committed in several ways, some of which include: By using hacking into a computer system and altering or stealing data held within the system. By using a keylogger to steal passwords to online account or bank card numbers. Identity Fraud. Online shopping fraud. The frauds listed above are just some of a very extensive lists of frauds that can be carried out over the Internet.

SECURITY PRECUATIONS SECURITY PRECUATIONS Given the numerous security risks that are associated with using a computer or any other device which has access to the Internet, it is important that both individuals and organisations take security precautions to ensure the safety of their identity related data etc. Security precautions which can be taken include: Anti-virus software. Passwords/encryption. Biometrics. Security protocols and firewalls. Use of security suites.

SECURITY PRECUATIONS ANTI-VIRUS SOFTWARE SECURITY PRECUATIONS ANTI-VIRUS SOFTWARE Every computer system should be protected by installing and using an Anti-Virus program. Anti- Virus software is an example of a utility program. Anti-Virus software is designed to detect and remove viruses, worms and Trojans from computer systems. It should also scan anything being downloaded to check that the item is virus free. Anti-virus software must be updated at regular intervals to ensure that it can detect and remove the new viruses that are being generated all the time.

SECURITY PRECUATIONS PASSWORDS SECURITY PRECUATIONS PASSWORDS The security of both standalone computers and networked computers can be improved by using passwords. A password is a secret word or string of characters used for user authentication to prove identity or access approval to gain access to a resource, which should be kept secret from those not allowed access. The most secure passwords are usually formed from a combination of letters (both upper and lower case), numbers and other characters.

SECURITY PRECUATIONS ENCRYPTION SECURITY PRECUATIONS ENCRYPTION When we use the Internet or any other communication network, a great deal of our time online involves sending others our own information. Ordering something over the Internet, whether it's a book, a CD or anything else from an online vendor, or signing up for an online account, requires entering in a good deal of sensitive personal information. A typical transaction might include not only our names, e-mail addresses and physical address and phone number, but also passwords and personal identification numbers (PINs). All reputable organisations which use networks will have various security measures in place to stop hackers obtaining your personal information. The most popular forms of security all rely on encryption, the process of encoding information in such a way that only the person (or computer) with the key can decode it.

SECURITY PRECUATIONS BIOMETRICS SECURITY PRECUATIONS BIOMETRICS Some computer networks use biometric security to ensure only authorised users can gain access. Biometrics is authentication techniques that rely on measurable physical characteristics that can be automatically checked. There are several types of biometric identification schemes: Face - the analysis of facial characteristics. Fingerprint - the analysis of an individual's unique fingerprints. Hand geometry - the analysis of the shape of the hand and the length of the fingers. Retina - the analysis of the capillary vessels located at the back of the eye. Iris - the analysis of the coloured ring that surrounds the eye's pupil. Signature - the analysis of the way a person signs his name. Vein - the analysis of pattern of veins in the back if the hand and the wrist. Voice - the analysis of the tone, pitch, cadence a nd frequency of a person's voice.

SECURITY PRECUATIONS FIREWALLS SECURITY PRECUATIONS FIREWALLS Firewalls are used to stop hackers and viruses from accessing a computer. Firewalls can be either hardware or software-based. A router is a good example of a hardware device that has a built-in firewall. Most routers can be configured to limit traffic from certain IP addresses or block requests based on other criteria. Software programs that monitor and restrict external access to a computer or network can also serve as firewalls. A network firewall only allows authorized traffic from the Internet to flow in and out of the network.

SECURITY PRECUATIONS SECURITY SUITES SECURITY PRECUATIONS SECURITY SUITES Security suites combine utility programs such as anti-virus, firewalls, anti-spyware and other malicious software, together with parental controls and password storage to protect your computer and/or network from attack.

COMPUTERS & THE ENVIRONNMENT The measurement of greenhouse gasses produced from the manufacture and use of computing equipment is known as a Carbon Footprint. Using computers can have both a positive and negative effect on the environment

COMPUTERS & THE ENVIRONNMENT Negative effects: Raw materials and energy used to manufacture computing equipment, including smartphones. Energy used to power laptops, desktops, mainframes & servers. Internet use is increasing all the time. As it increase, so does power consumption, as we need servers to keep the Internet running and power to create and run the websites used.

COMPUTERS & THE ENVIRONNMENT Positive effects: Most manufacturers are now producing devices with low-energy consumption. Many workers now telecommute – which means they work from home, meaning they are not using fuel to get to work. This also applies to firms who use teleconferencing for meetings instead of people travelling to them.

COMPUTERS & THE ENVIRONNMENT WEEE is waste electronic and electrical equipment like computers, smartphones, televisions, fridges, washing machines, microwaves & kettles. Businesses that produce or sell electrical and electronic equipment must offer a facility to take back and dispose of this kind of equipment in an environmentally acceptable way.

COMPUTERS & THE ENVIRONNMENT Computer equipment may contain hazardous materials which could pose a serious risk to health if dumped in landfill sites and not disposed off correctly. Sometimes it is more environmentally friendly to upgrade or refurbish computers instead of scrapping them and replacing them with a new one.

COMPUTERS & THE ENVIRONNMENT Identity theft can be another consequence of not disposing of computers properly. If a computer is to be scrapped, the hard disk should be shredded. The hard disk in a recycled computer should be re-written multiple times to completely obliterate any existing data.

REVISION QUESTIONS (HIGH LEVEL LANGUAGE PROGRAMMING) 1.What is a variable? 2.Give three data types. 3.What type of data would a string be used for? 4.Give an example of numeric data. 5.Give the names of three loops and describe what each could be used for. 6.What is an array? 7.Give an example of a predefined function. 8.Give two types of documentation which accompanies and program and describe what each is used for. 9.Explain the difference between a function and a procedure. 10. What is a syntax error? 11.Which standard algorithm should be used for: (a) finding an item in a list (b) finding the highest and lowest items in a list (c) checking input is allowable (d) counting how many times something appears in a list

REVISION QUESTIONS (HIGH LEVEL LANGUAGE PROGRAMMING) 1.What are the 7 stages in the software development process? 2.Give two types of documentation which accompanies and program and describe what each is used for. 3.Give two types of translators? 4.Suggest which translator is best used when developing a program and why. 5.What is a macro? 6.Give three features of a high level language (HLL). 7.What is a computer’s own language called? 8.Which runs fastest and interpreted or compiled program? Explain your answer. 9.Explain the term readability and how you can make a program readable. 10. What is a text editor used for?

REVISION QUESTIONS DATA REPRESENTATION 1.What is a bit? 2. How many bits are in a byte? 3.Give the largest number which can be represented using 8 bits in a binary system. 4.What is an integer? 5.Explain the difference between a mantissa and exponent? 6.What is a character set? 7.Give an example of a control character. 8.What is ASCII short for? 9.How many characters can be represented in ASCII? 10.Put the following in increasing order of size, smallest first: kilobyte, bit, megabyte, gigabyte, byte, terabyte. 11.Explain the term resolution, as applied to graphics.

Revision Questions Networks 1.What is a network? 2.What is the difference between a LAN (local area network) and a WAN (wide area network)? 3.Describe how the Internet operates. 4.Why do you need an ISP (Internet Service Provider) to access the Internet? 5.Describe two types of transmission medium and give an advantage for each. 6.Explain what WiFi is. 7.Explain what Bluetooth is. 8.What is bandwidth? 9.Give three advantages of using a LAN. 10.Which has the higher bandwidth – copper cable or fibre optic cable?

Revision Questions Networks (2) 1.What is a client-server network? 2.What does a client need in order to enable it to connect to a network? 3.Give two types of server. 4.Describe what can be used to aid network security. 5.Which type of server aids ques? 6.How could security be controlled on a network? 7.What is a file server used for? 8.In what ways does a file server differ from a desktop computer?

Revision Questions Input Devices 1.Why are input devices needed? 2.List four input devices. 3.What do laptop computers have instead of a mouse? 4.Which input device is used to input sound? 5.Give two input devices which could be used to enter text. 6.Give two input devices which could be used to capture video and suggest which would give the higher quality of video and why. 7.Which input device is used for selecting? 8.A CCD is found in both a digital camera and a scanner. What is it’s full name and what does it do? 9.Explain how you could use a scanner and OCR software to upload a hard copy of a document into a computer and edit it.

Revision Questions Backing Storage 1.Why is backing storage needed? 2.Name three backing storage devices. 3.What type of access does a magnetic type drive use? 4.Which backing storage device gives you the fastest access to data? 5.How much data can typically be stored on a CD-ROM? 6.What type of storage does a USB Flash Drive use? 7.Explain the difference between backing storage and a backup. 8.Give two backing storage mediums which use: 9.Suggest why floppy disks are now used very infrequently. (a) Magnetic Storage. (b) Optical Storage.

Revision Questions Video Data 1.What hardware is needed to capture video data? 2.Which video capturing hardware, captures data at the highest quality? 3.What effect would lowering the colour depth have on a video file? 4.Give the limitations of storing a video file in AVI format? 5.What type of compression does MPEG use and how is it achieved? 6.How is the resolution of a video clip expressed? 7.What type of colour is a video usually captured in? 8.What does the expression fps mean? 9.Explain what would happen to a video file if the colour depth and the fps were reduced. 10.Give three ways in which a video file can be edited. 11.Why is a graphics card needed to output video?

REVISION QUESTIONS CPU (CENTRAL PROCESSING UNIT) 1.Name the three parts of the CPU. 2.Explain the difference between RAM and ROM. 3.What is Flash ROM? 4.Explain the purpose of the ALU. 5.What does the Control Unit do? 6.What are the registers used for? 7.What is used to store programs and data permanently?

REVISION QUESTIONS TYPES OF COMPUTERS 1.What is an embedded computer? 2.Explain why it is necessary for embedded computers to process data in real time. 3.What is the difference between a palmtop computer and a smart phone? 4.Suggest a business which would use a mainframe computer and why. 5.Which types of computers are unlikely to have a keyboard? 6. Which type of computer will typically use a touchpad? 7.What is usually used for input on a palmtop computer? 8. What is clock speed an indicator of? 9. What is clock speed measured in? 10. List the key features of a: (a) palmtop computer (b) laptop computer (c) desktop computer (d) mainframe computer

Revision Questions Output Devices 1.What are output devices used for? 2.List three output devices. 3.Give two differences between a CRT monitor and an LCD monitor. 4.Give two types of printers. 5.Explain how the resolution of a printer is measured. 6.In printers, what is ppm short for? 7.Which type of printer is good for printing high quality photographs? 8.What is needed along with loudspeakers to output sound? 9.What is the resolution of a monitor measured in?

Revision Questions Interfaces 1.Give three functions of an interface. 2.Why is a printer buffer needed? 3.Explain why an interface is needed for data conversion. 4.Explain the terms analogue and digital. 5.What format is data in when it is being input into a computer system, analogue or digital?

Revision Questions WWW, Internet & e-mail 1.What is a hotspot? 2.What computer language is used to create web pages? 3.Which feature of e-mail allows you to send messages to a lot of people in one operation? 4.Why should you never open an e-mail from someone you don’t know? 5.What is a browser used for? 6.What are search engines used for? 7.Give the name of the piece of text used to carry out a search. 8.What is URL short for? 9.What is an ISP and why doe you need one? 10.How would you know if there was a hyperlink or a hotspot on a page?

Revision Questions Computer Related Laws 1.Give the names of three computer related laws. 2.What does a hacker do? 3.Give three examples of activities which may breach copyright law. 4.What is phishing? 5.What act governs the storage and use of personal data? 6.What is a person who has data held about them called? 7.What is intellectual property and which Act governs it?

Revision Questions Computer Software 1.Why do computers need software? 2.Explain the difference between an application program and an operating system program. 3.What is an integrated package? 4.State three functions of an operating system. 5.Give the name and the primary function of three application packages. 6.What is a standard file format? 7.Name two standard file formats for text files. 8.What is an object? 9.Suggest three operations which could be carried out on an object. 10.What is a virus? 11.Describe three ways in which a virus may be spread. 12.Give two common symptoms of a virus infection. 13.What should you do if you receive an e-mail from an unknown sender.

Revision Questions DEVELOPMENT PROCESS FOR INFORMATION SOLUTIONS 1.List the seven stages of the software development process for a multimedia application and describe what happens at each stage. 2.What is a storyboard? 3.Give an advantage of using a multimedia authoring package to create a multimedia application. 4.What does WYSIWYG stand for? 5.Explain why using a text editor to create a multimedia application can be difficult. 6.What is the advantage of using a presentation package to create a multimedia application. 7.Give three types of maintenance which might be carried out on a multimedia application and why each might be needed. 8.Describe the three main ways that multimedia applications can be viewed.

Revision Questions BIT-MAPPED GRAPHICS 1.Give two pieces of hardware that can be used to capture bit-mapped graphics. 2.What is a CCD and how does it work in: (a) A Digital Camera? (b) A Scanner? 3.What is used for backing storage in a digital camera? 4.Give two pieces of hardware needed to display graphics. 5.List five ways in which a graphic may be altered and describe the effect of each. 6.What is a pixel? 7.How many bits are needed to store a pixel in True Colour? 8.Explain why the GIF file format is not suitable for storing photographs. 9.What effect does increasing the resolution have on a bit-mapped graphic file? 10.Explain the difference between lossless and lossy compression and give the file type where you would expect each to be used.

Revision Questions VECTOR GRAPHICS 1.Explain the terms scalable and resolution independent as applied to vector graphics. 2.Identify the features of three attributes of an svg and suggest how they may be edited. 3.How is an svg stored? 4.What is Virtual Reality Markup Language (VRML) used for? 5.Describe how vector graphics can be built up in layers. 6.What are the advantages of using graphics in SVG format? 7.What does VRML enable a programmer to do?

Revision Questions Converging Technologies 1.Describe the features of a smartphone that make it an example of converging technology. 2.What features of DTV can be used for accessing multimedia applications. 3.Suggest two things that virtual reality could be used for. 4.Explain why virtual reality can be seen as an immersive environment. 5.Give two types of sensors used in virtual reality. 6.What type of output is used for virtual reality? 7.Why is a powerful graphics card need for virtual reality? 8.Describe how users can manipulate and interact with a virtual world.

NATIONAL 4 & 5 COMPUTING SCIENCE Prepared by M Feldman.

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NATIONAL 4 & 5 COMPUTING SCIENCE Prepared by M Feldman.

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