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The homepage for the HTML section on CSNewbs. Learn how to create an HTML website from scratch and how each tag works. I'm Arthur the Alligator and I'm here to teach you HTML. HTML GUide Show me how to make a webpage in HTML from scratch. List of Tags Show me a list of tags I can use.

The list of topics in the 2020 Eduqas / WJEC GCSE Computer Science specification. Eduqas / WJEC GCSE Computer Science These pages are based on the Eduqas GCSE Computer Science 2020 specification . The content can also be used by students studying WJEC GCSE Computer Science in Wales . This website is in no way affiliated with Eduqas / WJEC . 1. Hardware 1.1 - The Central Processing Unit (CPU) 1.2 - The FDE Cycle 1.3 - Primary Storage 1.4 - Secondary Storage 1.5 - Performance 1.6 - Additional Hardware 2. Logical Operators & Boolean 2.1 - Logical Operators 2.2 - Boolean Algebra 3. Networks & Security 3.1 - Network Characteristics 3.2 - Data Packets & Switching 3.3 - Network Topology 3.4 - Network Hardware & Routing 3.5 - Protocols 3.6 - 7-Layer OSI Model 3.7 - The Internet 3.8 - Cyber Threats 3.9 - Protection Against Threats 4. Data 4.1 - Number Systems 4.2 - Signed Binary 4.3 - Binary Calculations 4.4 - Arithmetic Shift 4.5 - Character Sets & Data Types 4.6 - Graphical Representation 4.7 - Sound Representation 4.8 - Compression 5. Data Organisation 5.1 - Data Structures & File Design 6. Operating Systems 6.1 - Operating Systems 6.2 - Utility Software 7. Principles of Programming 7.1 - Language Levels 8. Algorithms & Constructs 8.1 - Programming Principles 8.2 - Understanding Algorithms 8.3 - Writing Algorithms 8.4 - Sorting & Searching Algorithms 8.5 - Validation & Verification 9. Software Development 9.1 - IDE Tools 10. Program Construction 10.1 - Translators 10.2 - Stages of Compilation 10.3 - Programming Errors 11. Technological Issues 11.1 - Impacts of Technology 11.2 - Legislation Component 2 (Programming Exam) Python Removed content from the 2016 Specification

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 network forensics, penetration tests and methods of protection including anti-malware, firewalls, encryption and two-factor authentication. Based on the 2020 Eduqas (WJEC) GCSE specification. 3.9: Protection Against Threats Exam Board: Eduqas / WJEC Specification: 2020 + Network Forensics & Penetration Testing What is network forensics? Network forensics is the monitoring of a network to identify unauthorised intrusions . Network forensics is used to record and analyse attacks on a network and to gather other information about how the network is performing. It is important for organisations to identify weaknesses in their networks so that they can fix them and be prepared for any type of attack or malware. Footprinting - Footprinting is one method of evaluating a network’s security . This is when a security team puts itself in the attacker’s shoes by obtaining all publicly available information about the organisation and its network . Footprinting allows the company to discover how much detail a potential attacker could find out about a system. The company can then limit the technical information about its systems that is publicly available . Penetration Tests Penetration tests are carried out as part of ethical hacking. Ethical hacking is when an organisation gives permission to specific 'good ' hackers to try and attack a system so that the weak points can be highlighted and then fixed. The purpose of a penetration test is to review the system's security to find any risks or weaknesses and to fix them . There are four main types of penetration tests : Internal tests are to see how much damage could be done by somebody within the company with a registered account. External tests are for white hat hackers to try and infiltrate a system from outside the company . Blind tests are done with no inside information , to simulate what a real attacker would have to do to infiltrate the system. + Targeted tests are conducted by the company's IT department and the penetration team cooperating together to find faults in the system. Anti-Malware & Firewalls Anti-Malware Software Anti-malware software is used to locate and delete malware, like viruses, on a computer system. The software scans each file on the computer and compares it against a database of known malware . Files with similar features to malware in the database are identified and deleted . There are thousands of known malware, but new forms are created each day by attackers, so anti-malware software must be regularly updated to keep systems secure. Other roles of anti-malware software: Checking all incoming and outgoing emails and their attachments . Checking files as they are downloaded . Scanning the hard drive for viruses and deleting them . Firewall A firewall manages incoming and outgoing network traffic . Each data packet is processed to check whether it should be given access to the network by examining the source and destination address . Unexpected data packets will be filtered out and not accepted to the network. Other roles of a firewall include: Blocking access to insecure / malicious web sites . Blocking certain programs from accessing the internet . Blocking unexpected / unauthorised downloads . Preventing specific users on a network accessing certain files . Other Methods of Protection Double Authentication Also known as two-factor authentication (2FA ), this is a method of confirming someone's identity by requiring two forms of authorisation , such as a password and a pin code sent to a mobile. 4392 Secure Passwords Usernames must be matched with a secure password to minimise the chances of unauthorised users accessing a system. Passwords should contain a mix of uppercase and lowercase letters , punctuation and numbers . Passwords should be of a substantial length (at least 8 characters) and should be regularly changed . ******** User Access Levels Access levels are used to only allow certain users to access and edit particular files. ' Read-Only ' access is when a user can only view a file and is not allowed to change any data . For example, a teacher might set homework instructions as read-only for students to view. ' Read and Write ' access allows a user to read and edit the data in a file. For example, a teacher might set an online workbook as read and write access for students to fill in. It is important to set access levels so that only authorised users can view and change data. The more users who have access to a file, the more likely it is to be compromised. Certain users may also have no access to a file - when they can't view or edit it. Encryption Encryption is the process of scrambling data into an unreadable format so that attackers cannot understand it if intercepted during transmission. The original data (known as plaintext ) is converted to scrambled ciphertext using an encryption key . Only at the correct destination will the encryption key be used to convert the ciphertext back into plaintext to be understood by the receiving computer. A very simple method of encryption is to use the XOR logical operator . XOR is used on the plaintext and key together to create the ciphertext . Using XOR again on the ciphertext and key will reverse the encryption to reveal the plaintext . Encryption using XOR Plaintext = 00110100 Key = 10100110 XOR Ciphertext = 10010010 Decryption using XOR Ciphertext = 10010010 / Key = 10100110 XOR Plaintext = 00110100 Q uesto's Q uestions 3.9 - Protection Against Threats: 1a. What is network forensics ? Why is it important ? [ 3 ] 1b. Explain what is meant by footprinting and why companies do it . [ 2 ] 2. What is an ethical hacker ? [2 ] 3a. Describe the purpose of penetration tests . [2 ] 3b. Describe each type of penetration test . [ 8 ] 4. Describe the purpose of anti-malware software and its different roles . [ 4 ] 5. Describe the purpose of a firewall and its different roles . [ 4 ] 6a. Describe double authentication . [2 ] 6b. State three rules for choosing a strong password . [ 3 ] 7. Describe the three types of access level . [6 ] 8a. Describe the purpose of encryption . [ 2 ] 8b. Explain how encryption works, using the terms plaintext , key and ciphertext . [ 4 ] 3.8 - Cyber Threats Theory Topics 4.1 - Number Systems

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 2 Lottery 17 8 4 13 20 Create a program to simulate a lottery draw. First, create an appropriate print line to welcome the user to your lottery draw. Then let the user enter five numbers between 1 and 20. Next, randomise five numbers between 1 and 20. Check to see how many numbers match and output an appropriate response for each scenario (e.g. “You have not matched any numbers, better luck next time!”) Once you have made the base program implement subroutines and lists . Make it as efficient as possible and professional-looking. Use pauses to reveal each number one at a time like a real lottery draw to build suspense. For this task, you will need to create a document and include the following sections (with screenshots where appropriate): An introduction to explain the Purpose of your program . A List of Requirements for a successful program. Screenshots of your code (with comments in your code to show understanding). Testing – Create a plan to show how you will test your program and then explanations of any errors that you found and how they were fixed . An Evaluation of what worked, what didn’t, and how you met each of your requirements from your original list. Also, discuss further improvements that you could have made to improve your program. Example solution: Helpful reminders for this task: Inputting Numbers Random Numbers Logical Operators Subroutines ⬅ Extended Task 1 (Pork Pies) Extended Task 3 (Blackjack) ➡

Learn about the negative impacts that data loss will have on an organisation including reputation loss, fines and possible bankruptcy. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification for Unit 2 (Global Information). 6.3 - Impacts Exam Board: OCR Specification: 2016 - Unit 2 If a risk to data (see 6.2 ) occurs then there are a number of different impacts that may consequently negatively affect an organisation . Loss of Intellectual Property 'Intellectual property ' refers to anything that an organisation or individual has designed, developed or created themselves . For an individual, this could be a manuscript , artwork or piece of music . For an organisation, it could be primary data they have collected, blueprints for an upcoming design or a report following data analysis. The impact of having intellectual property lost depends on the property itself and how easy it would be for the victim to recreate or recollect the data . Competitors that stole intellectual property could use it at their advantage. Also, the effect of an upcoming announcement to the public would decrease if it was leaked ahead of time. In 2017 HBO suffered large property leaks when Game of Thrones episodes were stolen before air date resulting in pirated versions appearing online well before they were due to be shown on TV. Loss of Service and Access If usernames and passwords are stolen then individuals may be unable to access services that they have paid for, an example being if WiFi details were stolen so that a hacker can access the internet using someone else's account. If a hacker is permitted access to a system they can change the account settings such as the password to lock out the original owners of that account, leaving them without access. Other services can be targeted with malicious attacks like a DDOS attack so that users cannot log into a web page or online service. If users cannot access an account they may use alternative methods and providers , such as avoiding one type of cloud storage provider that has let them down and choosing another. Breach of Confidential Information Confidential information is of a highly sensitive nature and could lead to other negative impacts if it got into the hands of unauthorised people . Confidential information, such as medical histories, should be stored securely with multiple physical and logical protections in place to ensure that it keeps its integrity . If confidential information was breached then it could lead to a loss of reputation as the holder would be regarded as ineffective at protecting the data . Legal consequences would also follow as the Data Protection Act ( 2018 ) would be broken : fines, court cases and even imprisonment would be possible further impacts. An organisation would expect to see penalties from the Information Commissioner's Office (ICO) if they failed to protect personal details by breaking the DPA . Loss of Third Party Data Many organisations will store data not only for their own purposes but for other individuals and businesses too; a key example being cloud storage providers . Users can store data on public cloud services such as Google Drive or DropBox and access their information using the internet from any networked device they please. If services like cloud storage services are hacked or taken offline (e.g. because of an attack or network problems) and data is lost then customers, especially those that pay, will be furious. This will lead to a loss of reputation, trust and even legal proceedings if personal and sensitive data is lost. Larger businesses will use private cloud storage, hosted in data centres that they maintain themselves, to avoid relying on third parties . Loss of Reputation Organisations spend years to build up a reputation where customers trust them and want to use their products or services. Data loss can immediately destroy that reputation and cause once-loyal customers to look elsewhere and choose their competitors . Failing to keep data safe means that an organisation has been unable to follow their legal and moral duty of keeping information secure and could lead to a loss of trade , resulting in reduced earnings and sales . Identity Theft If an individual's personal information is stolen by attackers then one impact is identity theft - when the attacker uses the victim's data for fraud or impersonation . Identity theft can lead to financial loss to the victim if loans , products or services are purchased in their name . The victim may have to contact their bank and other organisations to cancel transactions and there is no guarantee their money will be returned. Credit checks may be affected, leading to future financial difficulty for the victim. Threat to National Security If data of a classified nature (such as military arrangements, security weak-points or upcoming government plans) is lost and falls into the hands (most probably by hacking) of those who intend to bring harm to the country then the consequences can be disastrous. Spies of foreign countries or terrorists could use classified information to target vulnerable locations or events resulting in casualties. Threats could also be economic in nature if large amounts of money are stolen or redirected to malicious bodies. Recent Examples of Security Failure Q uesto's Q uestions 6.3 - Impacts: 1. Describe how each of the impacts above could affect a bank storing large amounts of customer data including financial records. [12 ] 2. Research three recent hacking examples . For each situation describe the impacts that occurred as a result of data loss . [12 ] Click the icons to read BBC News articles about recent examples of hacks and security breaches . Virgin Media Boots Marriott Hotels Facebook Messenger 6.2 - Risks Topic List 6.4 - Protection Measures

Learn about how to write algorithms, including pseudocode and the different flowchart symbols. Based on the 2020 Eduqas (WJEC) GCSE specification. 8.3: Writing Algorithms Exam Board: Eduqas / WJEC Specification: 2020 + Pseudocode Reminder Generally, pseudocode can be written in any way that is readable and clearly shows its purpose. However, the Eduqas exam board advises that pseudocode for the programming exam should follow the conventions below : Annotation { Write your comment in curly brackets} Define data type price is integer firstname is string Declare a variable's value set price = 100 set firstname = "Marcella" Input / output output "Please enter your first name" input firstname Selection (must have indentation) if firstname = "Steven" then output "Hello" + firstname elif firstname = "Steve" then output "Please use full name" else output "Who are you?" end if Iteration (while loop) while firstname ! = "Steven" output "Guess my name." input firstname repeat Iteration (for loop) for i in range 10 input item next i Define a subroutine Declare Sub1 [Subroutine content indented] End Sub1 Call a subroutine call Sub1 Writing Algorithms In an exam you may be asked to write an algorithm using pseudocode . Previous exams have offered up to 10 marks for a single algorithm . While this may seem daunting, it means you can still gain marks for an incomplete program , so don't leave it blank no matter what! You must decompose the problem and break it down into more manageable chunks . Here's an example question : “A teacher is marking tests. Write an algorithm that allows the teacher to input the number of tests to mark and then the mark of each test. Output the average mark, highest mark and lowest mark. The tests are marked out of 100.” This specific algorithm can be broken down into pre-code and three main parts : Part 0: Declare and assign variables. Part 1: Input the number of tests to mark. Part 2: Input the mark of each test. Part 3: Output the average, lowest and highest marks. Part 0: Variables Read the question carefully and work out the variables you will need in your algorithm. I have highlighted them in blue below: “A teacher is marking tests. Write an algorithm that allows the teacher to input the number of tests to mark and then the mark of each test . Output the average mark , highest mark and lowest mark . The tests are marked out of 100.” There is an additional variable to track as the average mark can only be worked out if we also know the total marks . number_of_tests is integer test_mark is integer average_mark is real highest_mark is integer lowest_mark is integer total is integer number_of_tests = 0 test_mark = 0 average_mark = 0 highest_mark = -1 lowest_mark = 101 total = 0 Before you write the actual program, you must declare the variables you will need and assign values to them. Firstly, declare the data type of each variable . A whole number is an integer and a decimal number is a real . The average must be a real data type because it is the result of division (total ÷ number_of_tests) and could be a decimal number . When assigning values, most numerical variables will be 0 . Most string values would be " " . However this question is a bit more complicated - the highest mark must start as a really low value and the lowest mark must start as a really high value . This is ensure the first mark entered becomes the highest and lowest mark - this will make sense later. Part 1: Input Number of Tests output “Enter the number of tests to mark: ” input number_of_tests After declaring and assigning your variables the next parts will depend on the algorithm you need to write. This example requires the user to input the number of tests . Part 2: Input Each Mark (Loop) for i = 1 to number_of_tests output “Enter the test mark: ” input test_ mark For part 2 we need the teacher to enter each test’s mark . This is best done as a loop as we do not know how many tests the teacher has to mark until they have typed it in (part 1). All code within the loop must be indented . if test_mark > highest_mark then highest_mark = test_mark endif if test_mark < lowest_mark then lowest_mark = test_mark endif We also need to work out what the highest and lowest marks are. This must be done within the loop as the test marks are entered. The test mark is compared to the current highest and lowest marks . If it is higher than the current highest mark it becomes the new highest mark . If it is lower than the current lowest mark it becomes the new lowest mark . This is why we set the highest_mark and lowest_mark to extreme values at the start - so the first mark entered becomes the new highest and lowest . total = total + test_mark next i The final steps of part 2 are to update the total marks and to close the loop . The total is increased by the test mark that has been entered. The ‘next i ’ command states that the current iteration has ended . The indentation has now stopped. Part 3: Outputs average_mark = total / number_of_tests output “The average mark is:” , average_mark output “The highest mark is:” , highest_mark output “The lowest mark is:” , lowest_mark Before the average can be output, it must be calculated by dividing the total by the number of tests . Then the average , highest and lowest marks can be output . Full Answer number_of_tests is integer test_mark is integer average_mark is real highest_mark is integer lowest_mark is integer total is integer number_of_tests = 0 test_mark = 0 average_mark = 0 highest_mark = -1 lowest_mark = 101 total = 0 output “Enter the number of tests to mark: ” input number_of_tests for i = 1 to number_of_tests output “Enter the test mark: ” input test_ mark if test_mark > highest_mark then highest_mark = test_mark endif if test_mark < lowest_mark then lowest_mark = test_mark endif total = total + test_mark next i average_mark = total / number_of_tests output “The average mark is:” , average_mark output “The highest mark is:” , highest_mark output “The lowest mark is:” , lowest_mark This example is slightly more complicated than some of the recent previous exam questions for writing algorithms. Remember to decompose the problem by identifying the variables you need first. Q uesto's Q uestions 8.3 - Writing Algorithms: 1. A violin player performs a piece of music 8 times . They record a score out of 5 how well they think they performed after each attempt. Write an algorithm using pseudocode that allows the violinist to enter the 8 scores and displays the highest score , lowest score and average score . An example score is 3.7. [10 ] 2. A cyclist wants a program to be made that allows them to enter how many laps of a circuit they have made and the time in seconds for each lap . For example they may enter 3 laps, with times of 20.3 , 23.4 and 19.8 seconds . The program should output the quickest lap time , slowest lap time , total amount of time spent cycling and the average lap time . Create an algorithm using pseudocode for this scenario. [10 ] 8.2 - Understanding Algorithms Theory Topics 8.4 - Sorting & Searching

Test your understanding of for loops and while loops in Python. Try practice tasks and learn through text and images. Perfect for students learning GCSE Computer Science in UK schools. top Python - Section 6 Practice Tasks Task One: Odd Numbers Use a for loop to print all odd numbers between 50 and 70 . You will need to use three values in the range brackets, including a step . Requirements for full marks: A comment at the start to explain what a for loop is. Use just two lines of code. Example solution: 51 53 55 57 59 61 63 65 67 69 Task Two: Fish Rhyme Use two separate for loops and some additional print lines to output this nursery rhyme: "1, 2, 3, 4, 5, Once I caught a fish alive, 6, 7, 8, 9, 10 then I let it go again" in the format shown . Requirements for full marks: Two for loops and two additional print lines (6 lines total). Example solution: 1 2 3 4 5 Once I caught a fish alive. 6 7 8 9 10 Then I let it go again. Task Three: Username & Password Create a program using a while loop that keeps asking a user to enter a username and a password until they are both correct . It may be easier to use a while True loop . You will need to use the and command in an if statement within the loop. Requirements for full marks: A comment at the start to explain what a while loop is. Example solution: Enter username: Ben43 Enter password: hamster Incorrect, please try again. Enter username: Ben44 Enter password: ben123 Incorrect, please try again. Enter username: Ben43 Enter password: ben123 Correct Correct login. Welcome Ben43 Task Four: Colour or Number Use a while True loop to let the user enter either A , B or C . A lets them guess a secret colour . B lets them guess a secret number . C breaks the loop , ending the program. Example solution: Enter A to guess a colour, B to guess a number, C to quit: A Guess the colour: green Incorrect! Enter A to guess a colour, B to guess a number, C to quit: A Guess the colour: pink Correct! Enter A to guess a colour, B to guess a number, C to quit: B Guess the number: 4 Incorrect! Enter A to guess a colour, B to guess a number, C to quit: C Quitting program... ⬅ 6b - W hile Loops 7a - Procedures ➡

The first part of a quick guide to the basics of Python aimed at Key Stage 3 students. Learn about comments and printing. Python - #1 - The Basics 1. Start with Commenting Programmers write A LOT of code. They need to understand exactly what they have written, especially if they are working as part of a team or returning to code after working on other projects. To help them understand what they have written, programmers use comments to annotate (explain) their code . Task 1 - Create a new Python program and use # to write a comment that says your name and the date. Save the file as 1-Basics.py In Python, type the # symbol then your message to write a comment. Comments are not printed when you run a program! It is a good idea to start every program with a comment, so you know what the program is about . 2. Printing to the Screen The most basic and common command you will use in Python is print . Inside the print brackets, you can write a message within speech marks . Your print command should turn purple - don't use any capital letters in Python unless it is inside speech marks! Task 2 - Write a nice message by using the print command, brackets and speech marks. Press F5 to run your program. 3. More Printing You can write multiple print lines one after another to print on different lines. Task 3 - Add two more print lines to your program. You can choose any message that you like. 4. New Lines You can use the special command \n to start a new line . This allows you to write on multiple lines but only use one print line. Use the backslash ( \ ) not the forward-slash ( / ). Task 4 - Use \n to write a 3 sentence conversation in only one line of code. Challenge Programs Use everything that you have learned on this page to help you create these programs... Challenge Task 1 - Days of the Week Create a new Python program. Save it as ' 1-Week.py ' Add a comment at the top with your name and the date. Create a program that prints the days of the week, with each day on a new line. BONUS : Try to use only one print line. BONUS : Have no empty spaces at the start of each line. When you run it, it should look like this: Challenge Task 2 - Conversation Create a new Python program. Save it as ' 1-Conversation.py ' Add a comment at the top with your name and the date. Create a program that prints a 6-line conversation between two people. It is up to you what these two people are talking about. BONUS : Try to use only one print line. BONUS : Have no empty spaces at the start of each line. When you run it, it could look something like this: #2 Variables >>>

The most common errors made in Grennfoot when making a game and how to fix them, including when missing punctuation is expected or the end of file is reached while parsing. Common Greenfoot Errors Greenfoot Home If the world becomes greyed out and you can't click on anything then an error has occurred. The actor with the error will have red lines on it. When an error occurs, a red squiggly line will appear underneath the problem. Hover your mouse over the line and a helpful message will appear to help you solve the issue. Some of the more common errors (and how to fix them) are listed below: ; expected Every line with a white background must end in a semi colon ( ; ) ) expected You have missed a bracket . Count the number of open brackets and the number of closed brackets on a line and make sure you have an equal number of both. reached end of file while parsing You are missing at least one curly bracket ( } ) at the end of your program . Press enter to move onto a new line at the bottom; you must have a closed curly bracket with a yellow background and another closed curly bracket with a green background . cannot find symbol You have typed a command incorrectly . Greenfoot uses a system where commands have no spaces and each word after the first word is uppercase . Such as isKeyDown not IsKeyDown and not isKeydown. Check your spelling and capitals carefully. Stuck ? If you start typing but can't remember what commands come next, press Ctrl and Space together to show a list of all possible commands that you can use.

Learn about sorting algorithms - merge and bubble sort - and searching algorithms - linear and bubble search. Based on the 2020 Eduqas (WJEC) GCSE specification. 8.4: Sorting & Searching Algorithms Exam Board: Eduqas / WJEC Specification: 2020 + Merge Sort Merge sort is a sorting algorithm based on the idea of ‘divide and conquer ’. A merge sort divides a list into half , again and again until each data item is separate . Then the items are combined in the same way as they were divided , but now in the correct order . When the individual lists are all merged together as one list again, then the data is in order and the algorithm will end . Bubble Sort This algorithm is based on the comparison of adjacent data elements . Data elements are swapped if they are not in the correct order . A bubble sort is not suitable for large sets of data. Linear Search A linear search is the most simple search algorithm. Each data item is searched in order from the first value to the last as if they were all laid out in a line . The list does not have to be in any order before it is searched . This search is also known as a sequential search because the list is searched in a sequence from start to end. For large lists , this search is not very efficient . Binary Search A binary search is a much more efficient searching algorithm as it generally searches through fewer data and is often much quicker - especially for large data sets. In a binary search, the middle point of the data is selected with each iteration and many data items can be ignored. However, the list of data must already be sorted in order before a binary search can take place. Q uesto's Q uestions 8.3 - Searching & Sorting Algorithms: Linear Search Explain step-by-step how the number 8 would be found in the following list using a linear search : 12, 5, 3, 2, 8, 19, 14, 6 [4 ] Binary Search Explain step-by-step how the number 2 would be found in the following list using a binary search : 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 [6 ] Merge Sort Explain step-by-step how a merge sort would sort the following list of numbers: 4, 8, 5, 1, 3, 6, 7, 2 [6 ] Bubble Sort Explain step-by-step how a bubble sort would sort the following list of numbers: 3, 2, 6, 4, 1, 4 [6 ] Watch on YouTube Watch on YouTube Watch on YouTube Watch on YouTube 8.3 - Writing Algorithms Theory Topics 8.5 - Validation & Verification

Learn about the seven steps of the fetch-decode-execute cycle and important registers in the CPU. Based on the 2020 Eduqas (WJEC) GCSE specification. 1.2: The FDE Cycle Exam Board: Eduqas / WJEC Specification: 2020 + The Fetch - Decode - Execute (FDE) cycle is performed by the CPU millions of times every second. This cycle is how the CPU processes data and instructions for each program or service that requires its attention. Important Registers A register is a small storage space for temporary data in the CPU . Each register has a specific role . There are five essential registers used in the FDE cycle : Program Counter (PC) A register that tracks the RAM address of the next instruction to be fetched . Memory Address Register (MAR) A register that tracks the RAM address of the instruction that is to be fetched . Memory Data Register (MDR) The MDR stores the instruction that has been transferred from RAM to the CPU . Current Instruction Register (CIR) A register that stores the instruction that has been fetched from RAM , and is about to be decoded or executed . Accumulator (ACC) The ACC stores the result of mathematical or logical calculations . Fetch - Decode - Execute Cycle The essential idea of the FDE cycle is that instructions are fetched from RAM , to be decoded (understood) and executed (processed) by the CPU . 1. The Program Counter (PC ) register displays the address in RAM of the next instruction to be processed . This value is copied into the Memory Address Register (MAR ). 0054 2. The PC register is increased by 1 . This prepares the CPU for the next instruction to be fetched. 0055 3. The CPU checks the address in RAM which matches the address held in the MAR . 0054 4. The instruction in RAM is transferred to the Memory Data Register (MDR ). 5. The instruction in the MDR is copied into the Current Instruction Register (CIR ). MDR MDR CIR 6. The instruction in the CIR is decoded (understood) and executed (processed). Any result of an execution is stored in the Accumulator (ACC ) register. CIR ACC 7. The cycle repeats by returning to the first step and checking the program counter for the address of the next instruction . Q uesto's Q uestions 1.2 - The Fetch - Decode - Execute (FDE) Cycle: 1 . What is the purpose of the registers ? [1 ] 2 . Describe the purpose of each register : a. The Program Counter (PC) [ 1 ] b. The Memory Address Register (MAR) [ 1 ] c. The Memory Data Register (MDR) [ 1 ] d. The Current Instruction Register (CIR) [ 1 ] e. The Accumulator (ACC) [ 1 ] 3. Draw a diagram of the seven steps of the Fetch - Decode - Execute cycle . [7 ] 1.1 - The CPU 1.3 - Primary Storage Theory Topics