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Learn about the two types of language levels - high level languages and low level languages , as well as the use of interpreters and compilers. Based on the J277 OCR GCSE Computer Science specification (first taught from 2020 onwards). 5.1: Languages & Translators Exam Board: OCR Specification: J277 Watch on YouTube : High-Level & Low-Level Languages Translators (Compiler & Interpreter) There are two types of programming languages used within computer systems: High-Level Languages Why do programmers use high-level languages? H igh-level programming languages use code written in a way that is similar to a natural human language , such as English, making it easier to understand and use the language. Using high-level languages leads to fewer errors and allows for more powerful and complex commands compared to low-level languages. However, a high-level language must be translated into machine code (binary) before it can be run, as high-level languages cannot be executed directly by the CPU . Popular high-level languages: PYT HON C++ Ja v a Visual Basic Low-Level Languages Low-level languages do not closely resemble a natural human language , making it harder for humans to understand and write in. Low-level languages are used when a program must be executed quickly or when programmers need to write code that interacts directly with the hardware , such as device drivers. There are two types of low-level language : Machine Code This is the pure binary code that computers can directly process and execute . It is extremely tedious and difficult for humans to understand and write machine code. However, machine code can be used when a programmer needs to perform a very specific command that can't be done in a high-level language. Machine code will be executed faster than high-level programs because it is already in a format the CPU can execute and does not need to be translated . 0010 1011 0101 0101 0110 0111 0101 0001 0101 0101 0101 0100 1010 1010 1010 1010 1111 1110 0010 1001 0100 1001 0010 0111 0111 0101 0011 1010 1000 0101 0110 0111 0000 1010 1010 0011 1101 1001 0010 1101 0010 0100 1001 0011 1010 1001 0101 0101 0010 0101 0111 0101 0101 1000 1011 0111 Assembly Language Assembly language uses specialised command mnemonics to perform actions . See the Assembly Language section in the programming tab for a list of mnemonics such as INP , OUT and HLT . Assembly language is preferred by many programmers over machine code because it is easier to understand and spot errors . It is faster to execute than high-level languages and, like machine code, can be used to directly control the CPU . INP STA Number1 OUT HLT Number1 DAT Translators A translator changes (translates) a program written in one language into another language (usually machine code ). There are two main types of translator : Interpreter An interpreter converts high-level language one line at a time into machine code and executes it. Compiler A compiler converts high-level language into machine code for execution at a later time. The entire program is converted at once . PYT HON PYT HON 0010 1011 0101 0101 0110 0111 0101 0001 0101 0101 0010 1011 0101 0101 0110 0111 0101 0001 0101 0101 Interpreters vs Compilers Interpreter Compiler Execution Method: An interpreter translates source code (high level code) into machine code one line at a time . Execution Speed: An interpreter is slower than a compiler because the code must be reinterpreted each time the program is run. Complexity: Interpreters are smaller, simpler programs . Error Reporting: In error reporting, the interpreter would encounter the errors and report it to the user immediately and stops the program from running. Repetition: Interpreted programs can be edited and run without translating the whole program . Interpreters must reinterpret the program every time it is run. Execution Method: A compiler translates all the source code (high level code) into machine code in one go . A compiler produces an executable file that will run on other machines without the compiler needing to be installed. Execution Speed: Compilers can produce much more efficient code than interpreters making the compiled programs run faster . Complexity: Compilers tend to be large complex programs . Error Reporting: The compiler would analyse the entire program , taking note of where errors have occurred and record them in an error file . Repetition: Compilation requires analysis and the generation of the code only once , whereas interpreters must re-interpret each time. However, compiled programs have to be re-compiled after any changes have been made. x1 ∞ x1 Q uesto's Q uestions 5.1 - Languages & Translators: 1a. Describe three reasons why programmers use high-level languages . [ 3 ] 1b. Explain one limitation of using high-level languages . [2 ] 2a. Describe a key difference between low-level languages and high-level languages . [ 2 ] 2b. Describe when a low-level language would be used instead of a high-level language . [2 ] 2c. Describe an advantage and a disadvantage of writing directly in machine code . [2 ] 2d. Describe what assembly language is. Give one benefit to using assembly language instead of machine code and one benefit to using it instead of a high-level language . [3 ] 3. Compare high-level and low-level languages by stating which is: a. Easier to understand [ 1 ] b. Requiring translation [ 1 ] c. Quicker to execute [ 1 ] 4. Compare interpreters and compilers for each of the following features : a. Execution Method b. Execution Speed c. Complexity d. Error Reporting e. Repetition [ 10 total ] 4.1 - Boolean Logic Theory Topics 5.2 - IDE

Learn about laws regarding suitable data disposal of information and computer systems as well as methods including electromagnetic wipe and physical destruction. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification. 5.6 - Data & System Disposal Exam Board: OCR Specification: 2016 - Unit 1 Computer components such as circuit boards, processors and monitors contain hazardous materials that cannot be disposed of in traditional ways such as rubbish collection and landfills. For security reasons, data must also be disposed of carefully so that it is not returned to a readable format by unauthorised viewers . Legislation In recent years, the government has introduced different laws that relate to the safe disposal of computer equipment to help reduce environmental impact . Waste Electronic and Electrical Equipment ( WEEE ) Directive : This provides guidance on how hazardous materials should be disposed of safely . This includes materials such as mercury (found in smartphones and newer monitors ) and toner cartridges in printers . These materials can damage the environment if not disposed of appropriately . Waste Acceptance Criteria ( WAC ): Equipment must meet these rules before it can be sent to a landfill . Hazardous materials, such as the elements in computer monitors , do not meet these criteria and should not be accepted . Hazardous Waste Directive : This ensures businesses safely store hazardous materials and use authorised businesses to dispose of the waste . Hazardous materials include mercury and hexavalent chromium . Data Protection Act ( DPA ): One principle of the DPA specifies that data should only be kept for a reasonable amount of time until it is securely deleted . Data stored on customers should be checked regularly and permanently deleted if no longer required . Methods of Data & System Disposal Overwriting is when new data is written to the hard disk drive to replace the current data - essentially resetting the data . Remember all data stored by a computer is in a binary format . Overwriting just once is usually not enough to remove all evidence of the data and the process may be repeated several times . Overwriting data causes no damage and means the drive can still be used for other purposes afterwards. Electromagnetic wiping uses a machine called a degausser , which has a very strong electromagnetic coil , to completely wipe the hard disk drive . Many large organisations use degaussers to be sure that their data is no longer on the devices they have used so it can’t be restored and accessed by unauthorised viewers . Degaussers are expensive to buy but it allows the device to be used again for other purposes afterwards as it is not physically damaged. A third option is the physical destruction of a computer system or storage device , like a hard disk drive , which guarantees the data is permanently inaccessible . However, physical destruction also renders the storage media unusable again for other purposes. Examples of physical destruction include shredding (e.g. a CD shredder ) or tools such as sledgehammers if no other option is available. Q uesto's Q uestions 5.6 - Data & System Disposal: 1. Describe the purpose of 4 different pieces of legislation relating to how data or computer systems should be disposed of safely . [8 ] 2a. State 3 methods of data and system disposal . [3 ] 2b. Describe 1 advantage and 1 disadvantage of using each method you stated in 2a. [6 ] 5.5 - Digital Security Topic List

Learn about the methods of gathering client requirements such as document analysis, focus groups, interviews, meetings, observation, problem reports, questionnaires, shadowing and suggestion analysis. Based on Unit F160 (Fundamentals of Application Development) for the OCR Cambridge Advanced National in Computing (H029 / H129) (AAQ - Alternative Academic Qualification). Qualification: Cambridge Advanced National in Computing (AAQ) Unit: F160: Fundamentals of Application Development Certificate: Computing: Application Development (H029 / H129) 4.1 - Methods of Gathering Client Requirements Watch on YouTube : Gathering Client Requirements For each of the nine methods of gathering client requirements , you need to know : Its purpose and when it would be used . The type of information and data that can be collected using it. The advantages and disadvantages of using it. How client requirements determine if it would be used. Gathering Client Requirements Methods of Gathering Client Requirements T here are nine methods of gathering client requirements you need to know : Reviewing existing documents (e.g. manuals and reports ) to understand the current system and requirements . Gathering a small group of users or stakeholders to discuss needs , expectations and ideas . Asking stakeholders structured or open-ended questions to collect detailed requirements . Bringing together clients and developers to share information , clarify requirements , and make decisions . Watching users perform tasks to see how they interact with the current system . Using logged issues or complaints from an existing system to identify new requirements . Distributing structured forms with questions to gather requirements from a wide group quickly . Following a user during their normal tasks to gain deeper insights into workflows and needs . Reviewing client or user-submitted ideas and feedback to shape requirements . Q uesto's Q uestions 4.1 - Methods of Gathering Client Requirements: 1. Explain what document analysis , problem reports , shadowing and suggestion analysis are. [8 ] 2. Give two advantages and two disadvantages of two other methods not mentioned in Q1 . [8 ] 3. The video game company that makes the ' Age of the Dragon ' series faced a letdown in their previous release , ' The Guard of the Veil '. They need to ensure that their next game sells a lot of copies and meets user requirements . Justify which methods they should use to gather client requirements and why . [ 5 ] The original 2010 movie version of ' Scott Pilgrim vs. the World ' had Scott end up with Knives Chau instead of Ramona Flowers , but focus groups disliked that he spent the whole movie fighting for her for nothing , so it was changed . D id Y ou K now? 3.2 - Project Planning Tools Topic List 4.2 - Client Requirement Specifications

Learn about the purpose and characteristics of intranets, the internet and extranets - all three types of World Wide Web technologies. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification for Unit 2 (Global Information). 1.5 - WWW Technologies Exam Board: OCR Specification: 2016 - Unit 2 The internet is a global network of interconnected networks . The world wide web (WWW ) is not the same as the internet. It is a way of accessing information , using protocols such as HTTPS to view web pages . There are three types of world wide web technologies : Internet Intranet Extranet The internet i s a global network of interconnected networks . The internet is public and users have open access . Examples of use: Accessing web pages to shop and watch videos . Businesses may use web pages to advertise their products and allow customers to purchase items. An intranet is a private network that is only accessible to authorised users (e.g. members of a business or school). Intranets are private and users have closed access . Examples of use: Because an intranet is a secured online area , schools often use an intranet to log in to that displays information for teachers and students (such as test results or upcoming events ). Businesses might use an intranet for employees to see sales and performance data or for communication because it can be accessed remotely . An extranet is a private network that is accessible using the internet but provides access only to authorised users . Extranets are private and users have shared access . Example of use: Hotel booking companies (like booking.com) use an extranet to allow hotel owners to log in via the internet to access and update their information. Network Characteristics When connecting to WWW technologies there are several characteristics that a user must consider: Speed Speed refers to how quickly data can be accessed . For example, an extranet is the slowest network to use because it must be accessed through the internet first. Security Security relates to how likely the data will be kept secure . An intranet is more secure than the internet because only authorised users can log in. Access Levels Access levels , or permissions , refers to who can see what, in terms of data and files . Resources on an intranet can be set so that only certain users can view them. Accessibility This characteristic relates to how available the data is . For example, the internet can be accessed on any network-enabled device, at any time . Q uesto's Q uestions 1.5 - WWW Technologies: 1. Explain the difference between the internet and the world wide web . [2 ] 2. Describe each of the 3 types of WWW technology . You must mention whether they are private or public and what type of access they have. a. Internet b. Intranet c. Extranet [2 each ] 3. Describe at least one example of how each of the 3 types of WWW technology could be used . [6 ] 4. Describe the 3 WWW technologies in terms of each of the 4 network characteristics . You need to think carefully about this; the descriptions under each icon above can help you with certain answers. To start, describe the speed, security, access levels and accessibility of an intranet . [12 each ] 1.4 - Internet Connections Topic List 1.6 - Information Formats

Test your ability to create a more complex program in Python based on a given scenario. Perfect for students learning GCSE Computer Science in UK schools. Extended Task 1 Pete Porker's Pork Pie Emporium Hello, Pete Porker here... I need a new program for customer orders at my bakery . I need the customer to enter how many scotch eggs (49p each ), pork pies (85p each ) and quiche tarts (£1.45 ) they want to order. Next, ask them to confirm their choice . If they are not happy , ask the questions again . If they confirm their choice, print a receipt showing their order and total . To make your program better, you should use validation (either while loops or error handling ) to make sure that a user must enter a correct value. Bronze Award --- Welcome to Pete Porker's Pork Pie Emporium --- Scotch eggs are 45p, pork pies are 85p and quiche tarts are £1.49. Enter the number of scotch eggs to buy: 9 Enter the number of pork pies to buy: 7 Enter the number of quiche tarts to buy: 4 ----- You selected 9 scotch eggs, 7 pork pies and 4 quiche tarts. 9 scotch eggs = £4.05 7 pork pies = £5.95 4 quiche tarts = £5.96 ------- Total: £15.96 There are many ways to create this program, but below are some suggestions : Use inputs with int to let the user enter how many of each item they want. Use total variables , e.g. totaleggs = eggs * 0.45 to work out the total cost for eggs, pies and tarts. Set a finalcost variable by adding the total of the three items together. Use dashes and \n (which makes a new line ) inside speech marks to make your program more presentable . Silver Award --- Welcome to Pete Porker's Pork Pie Emporium --- Scotch eggs are 45p, pork pies are 85p and quiche tarts are £1.49. Enter the number of scotch eggs to buy: 5 Enter the number of pork pies to buy: 3 Enter the number of quiche tarts to buy: 6 ----- You selected 9 scotch eggs, 7 pork pies and 4 quiche tarts. ----- Are you happy with this selection? no Okay, enter your choices again. Enter the number of scotch eggs to buy: 6 Enter the number of pork pies to buy: 2 Enter the number of quiche tarts to buy: 7 ----- You selected 6 scotch eggs, 2 pork pies and 7 quiche tarts. ----- Are you happy with this selection? yes Excellent! Here is your receipt : 6 scotch eggs = £2.70 2 pork pies = £1.70 7 quiche tarts = £10.43 ------- Total: £14.83 There are many ways to improve this program and below are some suggestions : Use a while loop to repeat the input stage until the user is happy with their choices. You will need to ask the user if they are happy with the values that were entered and then use an if statement to repeat the loop if they enter 'no '. Gold Award Example solution: --- Welcome to Pete Porker's Pork Pie Emporium --- Scotch eggs are 45p, pork pies are 85p and quiche tarts are £1.49. Enter the number of scotch eggs to buy: 9 Enter the number of pork pies to buy: 35 Sorry you must enter a number between 1 and 20. Starting again... Enter the number of scotch eggs to buy: 9 Enter the number of pork pies to buy: 20 Enter the number of quiche tarts to buy: 7 ----- You selected 9 scotch eggs, 20 pork pies and 7 quiche tarts. ----- Are you happy with this selection? YES Excellent! Here is your reciept: 9 scotch eggs = £4.05 20 pork pies = £17.00 7 quiche tarts = £10.43 ------- Total: £31.48 There are many ways to make this program even better and below are some suggestions : Include validation so that the user can only enter numbers between 1 and 20 . You will need to use if statements and the and operator to do this. You can include additional features to your program such as rounding the number to two decimal places and including coloured text using the Colorama library (which will only work if you are using an online editor like Replit ). You can use the .lower() command when checking if the user is happy with their choices to automatically accept 'Yes' and 'YES '. If you really want to challenge yourself you could consider outputting the receipt in order from most expensive to least expensive , using if statements to check the three values (although that has not been done in this example on the left). Helpful reminders for this task: Inputting Integers While Loops Calculations Rounding Integers ⬅ 12 - Error Handling Extende d Task 2 (Lottery) ➡

Learn how to use mathematical operators in Python. Try practice tasks and learn through text and images. Perfect for students learning GCSE Computer Science in UK schools. top Python 4b - Mathematical Operators Modulo Division The modulo operator - the percentage symbol % - will work out the remainder left over when one value is divided by another. print (30 % 6) = 0 30 ÷ 6 = 5, which is a whole number, so there is no remainder and 0 is output . print (30 % 7) = 2 30 ÷ 7 = 4 remainder 2 ; so the remainder is output . You can use modulo with variables too: num1 = 33 num2 = 4 print ( "The remainder is" , num1 % num2) The remainder is 1 = A common use of modulo is to check if a number is odd or even . If a number has no remainder when divided by 2 then it is even . = num = int ( input ( "Enter a number: " )) if num % 2 == 0: print (num, "is even." ) else : print (num , "is odd." ) Enter a number: 400 400 is even. Enter a number: 191 191 is odd. = Modulo Div i sion Task 1 ( Remainder) Ask the user to input a whole number . Use the modulo operator ( % ) to check if there is a remainder when the user's number is divided by 5 . Print the re mainder. Example solution: Enter a number: 123 The remainder when divided by 5 is 3 Modulo Div i sion Task 2 ( Rollercoaster) Use the odd/even program above to help solve this problem: A rollercoaster only lets people on in groups of 4 . Ask the user to input a number for how many people are in their group. Check if that number is directly divisible by 4 using modulo division ( % ). If it is then print “Perfect groups of four!” Else print “You will be split up” . Example solutions: Welcome to the Hyper Coaster! How many in your group? 6 You will be split up! Welcome to the Hyper Coaster! How many in your group? 12 Perfect groups of four! Integer Division Integer division removes any decimal numbers when performing division , leaving just the integer (whole number ). In Python integer division is performed using // . print (20 / 3) print (20 // 3) = 6.666666666666667 6 Integer Div i sion Task 1 ( Integer Division by 5 ) Use an input line with int to ask the user to enter a number . Use integer division ( // ) to divide the number by 5 without keeping any decimal values . Challenge: Improve your solution by altering the print line to be more user friendly . Example solutions: Enter a number: 27 5 Enter a number: 27 5 goes into 27 5 times. Integer Div i sion Task 2 ( Plane Rows) A large plane has 6 seats in each row. Input the number of passengers on the plane and use integer division to work out how many full rows will be filled. Example solution: How many passengers are there in total? 174 There will be 29 full rows on the plane. Exponent (Powers) An exponent is the number of times a value is multiplied by itself , for example 2 = 2 x 2 x 2 = 8 . The symbol to represent an exponent in Python is ** . For example: 4**2 represents 4 which is also 4 x 4 . 3 2 print (4**4) = 256 base = 5 exponent = 4 print (base**exponent) 625 = Exponent Task 1 ( Square Number) Use an input line with int to ask the user to enter a number . Output the square of this number. Example solution: Enter a number: 12 12 squared is 144 Exponent Task 2 ( Custom Exponent) Use an input line with int to ask the user to enter a number, this will be the base . Make another input line with int to ask for the exponent . Use ** between the base and the exponent and print it. Challenge: Make your solution better by including the base and exponent in the print line. Example solutions: Enter the base: 7 Enter the exponent: 3 343 Enter the base: 7 Enter the exponent: 3 7 to the power of 3 is 343 ⬅ 4a - If Statements 4 c - Log ical Operators ➡

Navigate between all Unit F160 (Fundamentals of Application Development) topics in the OCR Cambridge Advanced National in Computing (AAQ) specification. Qualification: Cambridge Advanced National in Computing (AAQ) Unit: F160: Fundamentals of Application Development Certificate: Computing: Application Development (H029 / H129) Unit F160: Fundamentals of Application Development These pages are based on content from the OCR Cambridge Advanced National in Computing (AAQ) specification . Unit F160 YouTube Playlist Topic 1: Types of Software 1.1 - Programs and Applications 1.2 - Operating Systems 1.3.1 - Application Types 1.3.2 - Application Software Categories 1.3.3 - Application Software Types Topic 2: Software Development Models 2.1 - Software Development Models 2.2 - Development Phases Topic 3: Planning Development Projects 3.1 - Planning Projects 3.2 - Project Planning Tools Topic 4: Application Design Scoping 4.1 - Gathering Client Requirements 4.2 - Client Requirement Specifications 4.3 - Decomposition Methods Topic 5: Human-Computer Interface 5.1.1 - Types of Human-Computer Interaction (HCI) 5.1.2 - Types of Devices 5.2 - HCI Visual Design Considerations 5.3 - HCI Design Documents & Diagrams Topic 6: Job Roles & Skills 6.1 - Job Roles 6.2 - Communication Skills

Learn how to play sound files in Greenfoot. Part 5 of the Greenfoot Tutorial for the Eduqas / WJEC GCSE 2016 specification. 5. Play Sounds 1. Check the Sounds Folder Greenfoot Tutorial Sound files must be placed the ' sounds ' folder of your Greenfoot project to be used in the game. In the Component 2 exam of the WJEC / Eduqas 2016 specification , an audio file will be placed in the sounds folder already . For this example game you can download the audio clips to the right and paste them into your sounds folder . Watch on YouTube: Click the audio icon to download a zip folder of the two sound files below . Copy the files into the sounds folder of your Greenfoot project . < Part 4 - Remove Objects 2. Add the playSound Method Add the code to play the sound at the same time as when the collectible object is removed . The name of the file and its extension (e.g. .wav or .mp3 ) must be written in speech marks after the playSound method. Part 6 - The Counter >

Learn about the four network topology types - bus, ring, star and mesh - plus advantages and disadvantages of each. Based on the 2020 Eduqas (WJEC) GCSE specification. 3.3: Network Topology Exam Board: Eduqas Specification: 2020 What is a network topology? Network topology refers to layout of computer systems on a network . Devices in a network topology diagram are often called 'nodes' . What are the different types of network topology? Bus Topology The nodes are connected to a bus (a central cable along which all data is transferred across the network). How it works: Data packets are sent along the main cable (sometimes known as the 'backbone') from the source computer to each other system in turn . Each system checks the destination address of the data packets. If the addresses match then the data is accepted otherwise it is passed on to the next system. Terminators are required at both ends of the bus to mark the end of the cable. Advantages: Because of the simple layout, it is easy to attach another system to the main cable without disrupting the whole network . A bus topology is quick to set up once the main cable has been established making it optimal for temporary networks . A bus topology is cost-effective because it usually contains less cabling than other topologies and requires no additional hardware (like a hub or switch). Disadvantages: Poor security as data packets are passed on to each system on the network. Data collisions are likely - this is when two systems attempt to transfer data on the same line at the exact same time. Resending the data wastes time and slows down the network . The main cable will only have a limited length which can become crowded and slows the network speed as more systems are attached. The main cable must also be terminated properly . Ring Topology Computer systems are connected together in a single loop . How it works: Packets are transferred around the ring in one direction , passing from one computer system to the next in a loop . As the packets arrive at each computer system, the computer checks the destination address contained in the data packet to see if it matches its own address. If the addresses match the computer accepts and processes the data packet, otherwise it passes it on to the next system. Advantages: Data collisions are avoided as data packets are transmitted in one direction around the ring. Attaching more systems to a ring topology won't affect the transfer speed (bandwidth ) as much as other layouts like a bus topology because the data is transferred at a consistent speed . Disadvantages: If any system on the network fails then the whole network fails as the loop is broken and data can't be transferred to all systems. To add a new system to a ring topology the network must be temporarily shut down . Star Topology Each computer system is connected to a central device , usually a hub or switch . How it works: Each computer system is connected to the central hub or switch and transfers its data packets there. The hub or switch looks at the destination address and transfers the packets directly to the intended computer. Advantages: A star topology has improved security because data packets are sent directly to and from the hub / switch in the centre and not necessarily all devices like in a bus or ring topology. New systems can be attached directly to the central system so the network doesn't need to be shut down . System failures of attached computers won't usually cause complete network failure. Transfer speeds are generally fast in a star topology as there are minimal network collisions . Disadvantages: Extra hardware (the hub or switch) is required to be purchased, installed and maintained. If the central system (the hub or switch) fails then the whole network will be unusable until the error is fixed. Mesh Topology In a full mesh network, each computer system is connected to every other computer system . There is also a partial mesh network where only some nodes (e.g. a printer) are connected to every other node. How it works: Data packets are transferred to the destination address along the quickest path , travelling from node to node. If a pathway is broken , there are many alternative paths that the packets can take. Advantages: If one cable or system fails then data packets can take an alternative route and still reach the destination address. Because of the large possible number of systems and connections, a mesh topology can usually withstand large amounts of data traffic . New systems can be added to the network without disrupting the entire topology . Disadvantages: Because of the possibly large amount of cables required (especially in a full mesh topology) this network layout can be expensive to install and maintain . Redundant cabling should be avoided - this is when cables are connected between systems that won't ever need to communicate . Q uesto's Q uestions 3.3 - Network Topology: 1. Draw and label diagrams of all four topologies . [12 ] 2a. A school currently uses a bus topology but is considering changing to a ring topology . Describe two advantages and two disadvantages of both topologies. [ 8 ] 2b. An office currently uses a star topology but is considering changing to a mesh topology . Describe two advantages and two disadvantages of both topologies. [ 8 ] 3.2 - Data Packets & Switching Theory Topics 3.4 - Network Hardware & Routing

Learn about the benefits of compression and the differences between lossy and lossless compression. Also, learn how compression ratios work. Based on the 2020 Eduqas (WJEC) GCSE specification. 4.8: Compression Exam Board: Eduqas Specification: 2020 What is compression? To compress a file means to make its size smaller . Benefits of compression include: Files take up less storage space (so more files can be stored). Files can be transferred quicker (because they are smaller). Files can be read from or written to quicker . There are two methods that are used to compress files: Lossy and Lossless . Lossy Compression Lossy compression uses an algorithm (set of instructions) to analyse a file and remove data that cannot be heard or seen by humans . For example, a lossy algorithm would analyse the sound waves of an audio file and remove any frequencies which humans cannot hear. This process reduces the size of the file . Further lossy compression will remove data that humans can see / hear . For example, the dog image to the right has been strongly compressed using a lossy algorithm and some data has clearly been removed. Lossy compression removes the data permanently , so the file can never return to its original form . Lossy compression is often used with images , audio and video to reduce the file size, for example to send over the internet. Lossless Compression Lossless compression reduces the size of a file without permanently removing any data . Because of this, the file is returned to its original form when decompressed, so no quality is lost . A file that is compressed with a lossless algorithm is usually larger than a file compressed with a lossy algorithm because no data has been permanently removed. Lossless compression is used with files that would not work if data was removed, for example executable files (e.g. programs and games) or word documents . Remember that lossy and lossless compression do not just refer to images. Below is an audio file that has been compressed with lossy compression . Data has been removed so the audio quality has decreased. 197 KB 81 KB 43 KB Compression Ratios Original File Size Compression Ratio = Compressed File Size 4 Mb = 5:1 20 Mb Example: A file has been compressed from 20 megabytes down to 4 megabytes. This is a compression ratio of 5:1. To calculate the size after compression , divide the original size by the first ratio value, then multiply it by the second value. For example, the new size for file 1 is (210 ÷ 10) x 3 = 63 MB. Triple-click the final column to see the right answers. Q uesto's Q uestions 4.8 - Compression: 1. Describe 3 benefits of compressing a file . [ 3 ] 2. Describe the differences between lossy and lossless compression . [4 ] 3. A student needs to compress a Microsoft Word document to send in an email. Suggest which type of compression they should use and why . [ 2 ] 4a. A text file was 72 KB and was compressed to 8 KB . State the compression ratio . 4b. An audio file was 4.5 MB and has been compressed to 0.9 MB. State the ratio. 4c. A 20 MB file is compressed with a ratio of 5:2 . What is the size of the compressed file ? [ 1 each ] 63MB 164KB 96KB 4.7 Sound Representation Theory Topics 5.1 - Data Structures

The fourth part of a quick guide to the basics of Python aimed at Key Stage 3 students. Learn about calculations and simple mathematical operators. Python - #4 - Calculations 1. Creating Calculations To add in Python use + To subtract in Python use - To multiply in Python use * To divide in Python use / Task 1 - Create a new Python program and save the file as 4-Calculations.py Print 4 different calculations - use each operator once.(add/subtract/multiply/divide) Python is very clever, so don't be afraid to make your own calculations using larger numbers and more than one operator . 2. Using Inputs and Calculations You can ask the user to enter numbers by writing input lines. Python can then perform calculations using the numbers that the user has entered. Don't forget to add int ( and double close brackets when using numbers ! Task 2 - Copy the new code from the picture. Change the text and num1 so you are dividing by 5 not 3. Don't delete your earlier code , just add this underneath. I have cropped the images to make the new code clearer. 3. Using Calculations in a Sentence When we have printed the calculations so far, they have not been very informative! You can print calculations together with sentences so that they mean more. Use a comma ( , ) between calculations and sentences . Task 3 - Use the pictures to help you add commas and sentences to your program to be more informative. Challenge Programs Use everything that you have learned on this page to help you create these programs... Challenge Task 1 - Multiplication Create a new Python program. Save it as ' 4 -Multiplication.py ' Add a comment at the top with your name and the date. Write an input line ( don't forget int ! ) that asks the user to enter number 1. Write an input line ( don't forget int ! ) that asks the user to enter number 2. Multiply number 1 and number 2 together and print the answer. BONUS : Try to show number 1 and number 2 in the print statement (see practice task 3 to help you). Remember: Break up variables in a print line by using commas. When you run it, it could look something like this: Challenge Task 2 - Retirement Create a new Python program. Save is as ' 4-Retirement.py ' Add a comment at the top with your name and the date. Write an input line ( don't forget int ! ) that asks the user to enter their age. Print the year that they will turn 65. (This is slightly tricky. Hint : You need to know their age, and you need to know the current year. You need to subtract something, and you need to add something. Try using scrap paper to help you figure it out.) BONUS : Use only one print line. BONUS : Try to use only two lines in total . Remember: Break up variables in a print line by using commas. When you run it, it could look something like this: <<< #3 Inputs #5 Selection >>>

Learn about the three logical operators - NOT, AND and OR - as well as truth tables. Based on the J277 OCR GCSE Computer Science specification (first taught from 2020 onwards). 4.1: Boolean Logic Exam Board: OCR Specification: J277 Watch on YouTube : Boolean Operators & Truth Tables Logic Gate Diagrams What is a logical operator? Inside of each computer system are millions of transistors . These are tiny switches that can either be turned on (represented in binary by the number 1 ) or turned off (represented by 0 ). Logical operators are symbols used to represent circuits of transistors within a computer. The three most common operators are: NOT AND OR What is a truth table? Truth tables are used to show all possible inputs and the associated output for each input . The input and output values in a truth table must be a Boolean value - usually 0 or 1 but occasionally True or False. NOT AND OR A NOT logical operator will produce an output which is the opposite of the input . NOT is also known as Negation . The symbol for NOT is ¬ An AND logical operator will output 1 only if both inputs are also 1 . AND is also known as Conjunction . The symbol for AND is ∧ An OR logical operator will output 1 if either input is 1 . OR is also known as Disjunction . The symbol for OR is ∨ NOT Logic Gate AND Logic Gate Symbol OR Logic Gate Symbol Truth Table Truth Table Truth Table Multiple Operators Exam questions could ask you complete truth tables that use more than one logical operator . Work out each column in turn from left to right and look carefully at which preceding column you need to use. NOT B A AND NOT B A OR (A AND NOT B) As binary is a base-2 number system , the number of rows required in a truth table will double with each new input in the expression in order to show the unique combinations of inputs. The examples above use just two inputs (A + B) so 4 rows are required. e.g. A = 2 rows / A + B = 4 rows / A, B + C = 8 rows / A, B, C + D = 16 rows Logic Diagrams You may be asked in an exam to d raw a logic diagram when given a logical expression . Draw any NOT symbols or expressions in brackets first. A logic diagram for C = ¬A ∧ B A logic diagram for D = C ∨ (A ∧ B) Q uesto's Q uestions 4.1 - Boolean Logic: 1. Copy and complete the following truth tables: 1b. Simplify the expression in the second truth table. 2a. A cinema uses a computer system to monitor how many seats have been allocated for upcoming movies. If both the premium seats and the standard seats are sold out then the system will display a message. State the type of logical operator in this example. 2b. For the more popular movies, the cinema's computer system will also display a message if either the premium seats or the standard seats have exclusively been sold out. However, it will not output a message when both have been sold out. State the type of logical operator in this example. 3. Draw a logic diagram for C = (¬B v A) ∧ A . 3.2 - Testing Theory Topics 5.1 - Languages & Translators