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Learn about network operating systems, open source operating systems and proprietary operating systems. Resources based on Unit F160 (Fundamentals of Application Development) for the OCR Cambridge Advanced Nationals 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) 1.2 - Operating Systems Watch on YouTube : Network Operating System Open Operating System Proprietary Operating System An operating system is software that manages the resources of a computer system , such as memory , users and files . It also provides a user interface so that humans can interact with the device's hardware . An operating system allows application software to be opened and run . There are three types of operating system that you need to know - network , open and proprietary . Operating Systems Network Operating System (NOS) A network operating system (NOS ) is software that manages network resources and allows computers to communicate over a network . Windows Server , developed by Microsoft , is an example of a network operating system . Characteristics of a Network Operating System Allows for the centralised management of users , data and security across multiple devices on a network . Enables resources such as files , applications and printers to be shared over the network . Manages user authentication and permissions control . Oversees remote access and system monitoring tools . The main type of device that uses a NOS is a server . Other devices, such as desktops or laptops , connect to the server to access shared resources . Windows Server is an example of a popular NOS . Advantages of a Network Operating System Administrators can manage users , files and security on a network from one central location . Resources such as files , printer access and applications can be shared across the network . Access levels can be controlled and user authentication helps protect data . An NOS is scalable - more devices and users can be added as needed . Central servers managed by a NOS make it easier to back up and restore important files . Disadvantages of a Network Operating System Purchasing a NOS and maintaining the servers it runs on can be expensive . Setup and management is complex and may require skilled administrators . If the main server running the NOS fails , connected computers may lose access to resources . Heavy traffic or poor configuration could slow the network down . Who uses a Network Operating System? Application developers can use a NOS to build , test and manage apps that work across networks , such as web applications , multiplayer games or cloud tools . This type of operating system is also used by organisations that need to manage multiple devices , users and resources efficiently across a network , such as a small business or a school . Open Operating System An open operating system is open-source , meaning its source code is freely available for anyone to view , modify and distribute . Source code is the original set of instructions written by a programmer using a high-level language such as Python , Java or C++ . Characteristics of an Open Operating System Users have access to the source code and can see how the OS works . The source code can be modified to suit the specific needs of the user . Development and maintenance may be led by an online community . An open OS is usually free with no licensing costs for most versions. Linux is an example of an open operating system . Android is technically an open-source OS , but most commercial Android devices (like Google Pixel phones ) include proprietary components (like Google Docs or Gmail ), which makes the full system not completely open source . Advantages of an Open Operating System It is usually free to use , modify and distribute the source code . Because the source code can be seen and modified , this type of OS is flexible and customisable . There may be updates from an online community maintaining and improving the software . Promotes experimentation to learn how systems work and try new ideas . Disadvantages of an Open Operating System Programming knowledge and skills are required to modify the source code . There may be security risks if someone edits the source code and redistributes it with malicious code . There will be less official support compared to a proprietary operating system . Some proprietary applications (like Microsoft Access for databases) will only work on a proprietary OS (like Windows ). Who uses an Open Operating System? App developers would use an open OS when the device their application will be used on is not tied to a specific proprietary system (like Windows or MacOS ). For example, a charity making a free educational app for developing countries would choose an open OS so it can run on low-cost , older smartphones . It can be customised and tested on a range of devices . Applications for specific single-purpose systems would also use an open OS , such as an information terminal in a museum . Linux could be used to develop a simple user interface and remove unnecessary features . Proprietary Operating System A proprietary operating system is software that is owned by a company or individual and the source code is not accessible for users to view , modify or distribute . Users must typically buy a licence or agree to the terms of use . Characteristics of a Proprietary Operating System The source code is hidden from the user and cannot be legally modified . A paid licence or subscription is usually required to use the software . It may be maintained and updated by the developer(s) who own it . Only the developer controls updates and the features that are added or fixed . Examples include Microsoft Windows (e.g. Windows 11 ), macOS (for Apple desktops and MacBooks ), iOS (for iPhones ) and iPadOS for iPads ). Advantages of a Proprietary Operating System There is an expectation that it is user-friendly and has been well tested . There may be official support and regular updates for improvements and bug removal . A proprietary OS has a high compatibility with proprietary software such as Microsoft Office or Adobe editing apps . The OS is expected to be stable and secure , with access restricted to system files . Disadvantages of a Proprietary Operating System A paid licence to use the OS is often required , which may be expensive . There is limited customisation for users as the source code cannot be seen or modified . Users rely on the vendor (developer ) for updates and bug fixes . Some proprietary OS are designed to only work on specific hardware (such as iOS only working on iPhones ). Who uses a Proprietary Operating System? App developers will need to use a proprietary OS if they are developing applications for a device that requires a specific proprietary OS , for example if they are creating a game for iPhones , they will need to use iOS . A company designing a finance application on desktops with Microsoft Access and Microsoft Excel must use a proprietary OS like Windows so that it can be integrated with these other types of proprietary applications . Q uesto's Q uestions 1.2 - Operating Systems: 1. What is an operating system ? [2 ] 2. For each of the three types of operating systems , create a poster , information sheet or factfile which includes the following information : Characteristics Advantages Disadvantages Example of how it could be used [10 per OS ] Windows 11 is Microsoft's current operating system . Windows 1.0 was their first release, introduced in 1985 and included basic versions of Calculator , Notepad and Paint . D id Y ou K now? 1.1 - Programs & Applications Topic List 1.3.1 - Application Types

Learn how to create simple programs in Python. Try practice tasks and learn through text and images. Perfect for students learning GCSE Computer Science in UK schools. Formerly pynewbs.com. Follow the instructions in each section and try the practice tasks on every page . At the end of each section are larger problems to solve. Pyt hon Sections 0. Setting up Python Installing and Using Python 1. Printing and Variables a. Printing b. Comments c. Creating Variables d. Using Variables Section 1 Practice Tasks 2. Inputting Data a. Inputting Text b. Inputting Numbers Section 2 Practice Tasks 7. Subroutines a. Procedures b. Functions Section 7 Practice Tasks 8. Lists a. Using Lists b. 2D Lists c. Dictionaries Section 8 Practice Tasks 9. String Handling a. Basic String Handling b. Number Handling Section 9 Practice Tasks 3. Data Types & Calculations a. Data Types b. Simple Calculations Section 3 Practice Tasks 4. Selection a. If Statements b. Mathematical Operators ( & MOD / DIV) c. Logical Operators Section 4 Practice Tasks 5. Importing from Libraries a. Random b. Sleep c. Date & Time d. Colorama e. More Libraries (math) Section 5 Practice Tasks 6. Loops a. For Loops b. While Loops Section 6 Practice Tasks 10. File Handling a. Open & Write to Files b. Read & Search Files c. Remove & Edit Lines Section 10 Practice Tasks 11. User Interfaces a. Graphical User Interface 12. Authentication a. Error Handling Extended Tasks Extended Task 1 (Pork Pies) Extended Task 2 (Lottery) Extended Task 3 (Blackjack) Extended Task 4 (Vet Surgery) Extended Task 5 (Colour Collection) Extended Task 6 (Guess the Word) Extended Task 7 (Guess the Number)

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 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 ➡

Learn about six network devices - hub, switch, router, bridge, WAP and NIC. Also, learn about routing tables and cost diagrams. Based on the 2020 Eduqas (WJEC) GCSE specification. 3.4: Network Hardware & Routing Exam Board: Eduqas Specification: 2020 Network Devices Hub A hub receives data packets from a connected device and transfers a copy to all connected nodes . Switch A switch receives data packets , processes them and transfers them on to the device specifically listed in the destination address of the packet. Router Routers are used to transfer data packets between networks . Data is sent from network to network on the internet towards the destination address listed in the data packet. A router stores the address of each computer on the network and uses routing tables to calculate the quickest and shortest path . Bridge A bridge joins together two networks that use the same base protocols . For example, a bridge could link together a LAN to another LAN . Wireless Access Point (WAP) Provides a link between wireless and wired networks . It creates a wireless local area network that allows WiFi enabled devices to connect to a wired network. Network Interface Card (NIC) A Network Interface Card (often shortened to NIC ) is an internal piece of hardware that is required for the computer to connect to a network . It used to be a separate expansion card but now it is commonly built directly into the motherboard (and sometimes known as a network adapter ). Wireless network interface cards ( WNIC ) permit a wireless network connection. Routing A routing table is a list of the optimal routes for data packets to be sent from one device to another. Routing tables should be kept accurate and up to date to ensure that packets are transferred as quickly as possible . During routing the lowest cost route is calculated . This is the shortest path with the fastest nodes to transfer data. Below is a simplified network and basic routing table showing the lowest cost (optimal) route using node A as the source address. Q uesto's Q uestions 3.4 - Network Hardware & Routing: 1a. Describe the difference between a hub and a switch . [ 2 ] 1b. Explain how a modem works. [ 2 ] 1c. Describe the purpose of a router . [ 2 ] 1d. Describe the difference between a gateway and a bridge . [ 2 ] 1e. State what WAP stands for and describe its purpose . [ 2 ] 1f. State what NIC stands for and why it is required . [ 2 ] 2a. Describe what a routing table is and why they should be maintained . [ 2 ] 2b. In terms of routing, what does a low-cost route mean? [ 2 ] 2c. Copy and complete the routing table below using node J as the source address . [ 4 ] 3.3 - Network Topology Theory Topics 3.5 - Protocols

The first part of a quick guide to the basics of Python aimed at Key Stage 3 students. Learn about comments and printing. Python - #2 - Variables 1. Number Variables A variable is a value that can change . Imagine there are 20 biscuits in a jar. Then I eat one. Now there are only 19. You must state what the value of a variable is before it is used . e.g. biscuits = 20 Task 1 - Create a new Python program and save the file as 2-Variables.py Create a variable called sweets and give it the value 15. Then print sweets. Variable names cannot have spaces . You can use underscores if you want, e.g. num_of_eggs When you are printing variables, you don't put them in speech marks . Otherwise, it will print the variable name and not the value. 2. String Variables A string is a programming term for a collection of characters . When you are giving a variable a string value, it must be written in speech marks . Remember when you print the variable however, it is never printed in speech marks . Task 2 - Create a variable called name and give it the value of your name. Then print the name variable. 3. Using Variables in a Sentence When we have printed the variables so far, they have not been very informative! You can print variables together with sentences so that they mean more. Use a comma ( , ) between variables and sentences . Task 3 - Use the pictures to help you add commas and sentences to your program to be more informative. 4. Using Variables Together You can print more than one variable together in the same sentence by separating them with sentences and commas . If this doesn't work, double-check your program has a comma between each variable and sentence . Task 4 - Type a new print line that uses both your name and your sweets variables together. Use the image to help you. Challenge Programs Use everything that you have learned on this page to help you create these programs... Challenge Task 1 - Funny Animals Create a new Python program. Save it as ' 2-FunnyAnimals.py ' Add a comment at the top with your name and the date. Create a variable for a colour and give it a value (e.g. "blue") Create a variable for an animal and give it a value (e.g. "horse") Print a funny sentence that uses both variables. BONUS : Try to use only one print line. BONUS : Try to use only three lines in total . Remember: Break up variables in a print line by using commas. When you run it, it could look something like this: Challenge Task 2 - Funny Sentence Create a new Python program. Save is as ' 2-FunnySentence.py ' Add a comment at the top with your name and the date. Write a program that uses three variables, an adjective (descriptive word), a number and an animal. Print a funny response using all variables. BONUS : Try to use only one print line. BONUS : Try to use only four lines in total . Remember: Break up variables in a print line by using commas. When you run it, it could look something like this: <<< #1 The Basics #3 Inputs >>>

A list of programming topics including HTML, Greenfoot, Python. All Programming Topics Python HTML Greenfoot Assembly Language App Inventor 2

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 algorithms including pseudocode and flowcharts. Based on the 2020 Eduqas (WJEC) GCSE specification. 8.2: Understanding Algorithms Exam Board: Eduqas Specification: 2020 What is an algorithm? An algorithm is a set of instructions , presented in a logical sequence . In an exam you may be asked to read and understand an algorithm that has been written. To prove your understanding you may be asked to respond by actions such as listing the outputs of the algorithm, correcting errors or identifying an error within it. Programmers create algorithm designs as a method of planning a program before writing any code. This helps them to consider the potential problems of the program and makes it easier to start creating source code. There are two main methods of defining algorithms : Defining Algorithms - Pseudocode & Flowcharts Pseudocode Pseudocode is not a specific programming language but a more general method of describing instructions . It should be unambiguous, and it should not resemble any particular kind of programming language (e.g. Python or Java), so it can theoretically be turned into working code in any language. 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 Flowcharts A flowchart can be used to visually represent an algorithm. The flowchart symbols are: Algorithm Examples Below are two different methods for representing the same algorithm - a program to encourage people to buy items cheaply at a supermarket. The program allows the price of items in a supermarket to be entered until the total reaches 100. The total price and the number of items entered are tracked as the program loops. Once the total reaches 100 or more, an if statement checks how many items have been entered and a different message is printed if there are 20 or more items, 30 or more items or less than 20 items. Pseudocode Flowchart {This is a program to see how many items you can buy in a supermarket before you spend over £100} total is integer, itemsentered is integer, itemprice is integer set total = 0 set itemsentered = 0 while total < 100 output "enter the price of the next item" input itemprice total = total + itemprice itemsentered = itemsentered + 1 repeat if itemsentered >= 20 then output "You are on your way to saving money." elif itemsentered => 30 then output "You're a real money saver." else output "Look for better deals next time." end if Reading Algorithms In an exam you may be asked to read an algorithm and prove your understanding , most commonly by listing the outputs . Start from the first line and follow the program line by line , recording the value of variables as you go . When you encounter a for loop , repeat the indented code as many times as stated in the range . Example Algorithm: Start NewProgram i is integer maxvalue is integer input maxvalue for i = 1 to maxvalue output (i * i) ??????? output 'program finished' End NewProgram Example Questions: 1. List the outputs produced by the algorithm if the 'maxvalue' input is 5 . 2. State the code that has been replaced by '???????' and what the code's purpose is. Example Answers: 1. Outputs: 1 4 9 16 25 program finished 2. Missing Code: next i Purpose: Moves the loop to the next iteration. Watch on YouTube Q uesto's Q uestions 8.2 - Understanding Algorithms: 1a. Read the algorithm shown on the left and list all outputs in the correct order if the inputs are 2 for height and 72 for weight . 1b. Give the code that is missing from line 25 . 8.1 - Programming Principles Theory Topics 8.3 - Writing Algorithms

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 >>>

Learn about two methods of representing negative numbers in binary - sign and magnitude and two's complement. Based on the 2020 Eduqas (WJEC) GCSE specification. 4.2: Signed Binary Exam Board: Eduqas Specification: 2020 What are Sign and Magnitude and Two's Complement? Sign and Magnitude and Two's Complement are both methods of writing positive and negative binary values . Sign and Magnitude is simpler but will cause incorrect answers if used in binary calculations . Two's Complement is more complex but will generate correct answers when used in binary calculations . Sign & Magnitude The most significant bit (MSB ) is the largest bit of a binary number - the one furthest to the left . The MSB is the sign - it represents whether the binary value is positive or negative . If the sign is 0 then the binary number is positive . If the sign is 1 then the binary number is negative . The other bits represent the magnitude - the value of the binary number. For an 8-bit binary number , the range is -127 to 127 , because only 7 bits are used to define the magnitude. Sign & Magnitude: Problems Sign and magnitude is not commonly used by computers for two main reasons: Performing binary addition and subtraction (see section 4.3 ) will often cause a wrong result . In the example below, -7 + 3 should equal -4 but the result given is 2. + Sign and magnitude creates two different values for 0 - positive 0 and negative 0 which is incorrect. Two's Complement Two's complement is a method of representing positive and negative binary values. It is used often by computers because binary calculations will work correctly and there is only one value for zero. Two's Complement: Denary to Binary To represent a negative value using two's complement follow these steps: Write out the positive value in binary . Start on the right-hand side and move along, copy all 0s until you get to the first 1 . The first 1 is copied too. After the first 1 invert each value (change to its opposite ). So 0 becomes 1 and 1 becomes 0 . 1. 2. 3. Two's Complement: Binary to Denary To convert a binary number to denary using two's complement you must remember that the MSB is a negative value . Just add the numbers with 1 together to work out the denary value . Q uesto's Q uestions 4.2 - Signed Binary: Sign & Magnitude 1. Using sign and magnitude , convert the following values to denary : a. 00011101 b. 11100011 c. 10110110 d. 01001111 [1 each ] 2. Using sign and magnitude , convert the following values to binary : a. 83 b. -13 c. -102 d. -24 [1 each ] 3. Describe two problems when using sign and magnitude . [ 4 ] 4. Using sign and magnitude , the range of numbers that can be represented in 6 bits is from - 31 to + 31 . State the range of numbers that can be represented using sign and magnitude in the following bits: a. 8 bits b. 4 bits [1 each ] Two's Complement 1. Using two's complement , convert the following values to binary : a. -20 b. -49 c. -87 d. -113 [2 each ] 2. Using two's complement , convert the following values to denary : a. 10110010 b. 11101110 c. 01101011 d. 10011111 [2 each ] Watch the video to learn how sign and magnitude is used to represent negative numbers in binary . Watch the video to learn how two's complement is used to represent negative numbers in binary . Watch on YouTube Watch on YouTube 4.1 - Number Systems Theory Topics 4.3 - Binary Calculations

This page contains topics from the 2016 Eduqas / WJEC that are not included in the 2020 Eduqas / WJEC specification. Topics from the 2016 Eduqas Specification This page contains information from the 2016 Eduqas specification that was removed for the 2020 specification. Quick Links: Buses & Instruction Sets (RISC & CISC) Protocols (IMAP & POP3) Network Devices (Gateway) Human-Computer Interaction (Command-Line Interface, Touch-Sensitive Interface, Menu-Driven Interface, Voice-Driven Interface) Cyber Attacks (Dictionary Attack, Buffer Overflow, Human Weakness) Software Protection (Secure by Design, Too Many Permissions, Scripting Restrictions, Validation with Parameters) Data Policies (Acceptable Use Policy, Disaster Recovery, Cookies) Environmental Issues (Tips to Reduce Waste, Positive Impacts of Technology) Object Oriented Programming (Greenfoot and Java) Programming Topics (Assembly Language, HTML, Greenfoot) Buses Buses & Instruction Sets Buses Data is transferred within a computer system along pathways called buses . There are three types of bus: Address Bus Data Bus Control Bus Sends a memory address of where data is stored. The address is sent from the CPU to RAM in the FDE cycle. Transfers data between components. Data is sent both ways . Sends control signals from the control unit to other components of the system. Status signals are sent back to the CPU. An instruction set is a list of all the instructions that a CPU can process as part of the FDE cycle . CPUs can have different sets of instructions that they can perform based on their function. The two most common instruction sets are the simpler RISC (Reduced Instruction Set Computer ) and more complicated CISC (Complex Instruction Set Computer ). Instruction Sets Reduced Instruction Set Computer (RISC) Complex Instruction Set Computer (CISC) Complexity RISC has fewer instructions than CISC and is therefore slower for carrying out complex commands but quick for basic tasks . CISC has more complex instructions available and can therefore perform complicated tasks . Cost RISC is generally cheaper to mass produce because less circuitry is required for the smaller instruction set. CISC CPUs are generally more expensive because they require more circuitry to operate. Power RISC CPUs are designed to use less power and run without dedicated cooling systems (like fans) so that they can be used in devices like smartphones . Because CISC CPUs require more circuitry this means that they generate more heat and may require a fan . CISC CPUs therefore are commonly used in desktop computers . Clock Speed RISC CPUs run at lower clock speeds than CISC CPUs. They can perform simpler tasks more quickly than CISC, but are generally not used to carry out complex instructions . CISC CPUs run at higher clock speeds than RISC CPUs. They can perform complex tasks more quickly than RISC. Protocols Protocols POP3 ( Post Office Protocol 3 ) and IMAP (Internet Message Access Protocol ) are both protocols for receiving and storing emails from a mail server. Gateway Network Devices Gateway A gateway joins together two networks that use different base protocols . For example, a gateway could link together a LAN to a WAN . HCI Human - Computer Interaction Command-Line Interface Touch-Sensitive Interface Other types of user interface do exist, such as a command-line interface (CLI ). This type of interface is entirely text-based and requires users to interact with the system by typing commands . This is a complicated process and mistakes could easily accidentally delete data. There are many commands to learn so only experts who have been trained t o learn this interface will be able to efficiently make use of it. Another type of user interface is a touch-sensitive interface , used with smartphones and tablets . A human interacts with the device by pressing on a touchscreen , making it very intuitive and suitable for most users without training. Touch-sensitive interfaces may not work with dirty or wet fingers and it will take longer to write text compared to using a keyboard. Menu-Driven Interface A menu-driven interface displays data in a series of linked menus . Examples include cash machines (ATMs) and old iPods . This type of interface is generally user friendly and easy to use as commands do not need to be memorised. However it can be annoying to find specific data through a large number of menus without a search feature. Voice-Driven Interface A voice-driven interface can be controlled by speaking commands aloud to a listening device. Examples include Amazon's Alexa devices, Apple's Siri technology and Google Home . This interface is intuitive , can be used hands-free and helps to speed up processes . However commands may be misheard or limited in what can be performed. Cyber Attacks Cyber Attacks Dictionary Password Attack This uses a file containing every word in the dictionary and cycles through them all. This method is relatively easy to program but will only break the simplest passwords . Buffer Overflow Attack A buffer is a temporary storage location . A buffer overflow attack causes a program to try to store more data in a buffer than it can hold which can lead to adjacent memory locations being overwritten . An attacker can use the buffer overflow to insert malicious code to change data or steal confidential data . Human Weakness The biggest weakness in online security is often not the systems in place but carelessness or mistakes made by humans . Social engineering means to trick others into revealing their personal data by posing as a trusted source . For example, impersonating an IT technician via email and asking to send a username and password. Humans can accidentally compromise data by downloading malicious files or being unsafe online, like using the same password for multiple different accounts. Attackers can access unauthorised information in person by shoulder surfing and watching them as they enter sensitive data such as a PIN or password. Software Protection Software Protection The following methods of protection are considered in the design, testing and creation stages of developing software . Secure by Design This method puts security as the most important concept when creating and designing software . By focusing on security when designing software there should be less need for later updates and patches and attacks are less likely to succeed . Too Many Permissions Apps require permission to use device features (such as the camera or microphone of a smartphone) when they are downloaded. Programmers should only request permission for features that the software requires . Some malicious apps steal data or spy on users - and the worst part is that you've given permission for it to do it! Users can avoid suspicious apps by reading reviews, checking there are no unnecessary permission requests , only downloading the software you need / will use and uninstall apps if permissions change . Scripting Restrictions A script is a set of instructions executed on a website. For example, Facebook uses a JavaScript script to post a status and another to read your private messages. The Same Origin Policy (SOP) is a security precaution that prevents websites from using scripts on other sites that you have open . For example, if you are using JavaScript to post a status on Facebook then visit an infected site, that site can't also use JavaScript to access your Facebook data, because even though they both use JavaScript, they are from a different origin . Without SOP an infected website could access personal data or infect a computer with malware by maliciously using the same scripts as other websites you have used . Programmers should set scripting restrictions when creating websites. Validation with Parameters A parameter is a measure that is used when validating data , it is usually a range or limit. For example, the parameters of a length check may be whether the data is between 1 and 10 characters . Programmers must ensure validation is used on websites with suitable parameters to prevent attacks such as an SQL injection. Data Policies Data Policies Data policies are written documents that clearly define how data should be managed in an organisation. It is important that all employees stick to these policies and requirements so that data is kept safe and can be replaced if lost or corrupted. The following methods are examples of common data policies. Acceptable Use Policy (AUP) Workplaces and schools often require people to sign an acceptable use policy (AUP) before being allowed to use the network. It is a list of rules and expected behaviour that users must follow when using the computer systems. Typical rules include: Which websites are off-limits (such as social media or gambling sites), Download permissions (such as who can download and install software) Email communication (such as appropriate language). Punishments if rules of the AUP are broken. The AUP is sometimes known as a Code of Conduct . This is an example of a formal code of practice , with written rules and clear expectations . An informal code of practice would not be officially written down , such as personal habits and preferences (e.g. email layout or desk organisation). Disaster Recovery With important data often stored on a computer network, it is absolutely vital that a detailed and effective disaster recovery policy is in place in the event of data being lost due to an unexpected disaster. Disasters include natural disasters (e.g. fire, flood, lightning), hardware failure (e.g. power supply unit failing), software failure (e.g. virus damage) and malicious damage (e.g. hacking). There are three clear parts to a disaster recovery policy: Before the disaster: All of the possible risks should be analysed to spot if there are any weaknesses in preparation. Preventative measures should be taken after the analysis, such as making rooms flood-proof or storing important data at a different location . Staff training should take place to inform employees what should happen in the event of a disaster. During the disaster: The staff response is very important – employees should follow their training and ensure that data is protected and appropriate measures are put in place. Contingency plans should be implemented while the disaster is taking place, such as uploading recent data to cloud storage or securing backups in a safe room and using alternative equipment until the disaster is over. After the disaster: Recovery measures should be followed, such as using backups to repopulate computer systems. Replacement hardware needs to be purchased for equipment that is corrupted or destroyed. Software needs to be reinstalled on the new hardware. Disaster recovery policies should also be updated and improved . Cookies A cookie is a small piece of data that is stored by websites when you visit them. They allow the website to identify the user and are often used to speed up processes , such as: Automatic login (by saving account details) Save items into a basket (such as pizza delivery sites) Display adverts related to your previous search terms . Although they can be used to save time, some argue that cookies can be intrusive and store too much information. Environmental Issues Environmental Issues Tips to Reduce Waste Turn off computers , monitors and other connected devices when not in use . Adjust power options to help minimise power consumption. Devices with the Energy Star sticker use between 30% and 70% less electricity than usual. Repair older devices rather than throwing them away. Ink jet printers use up to 95% less energy than laser jets. Think twice about printing paper, don't waste ink and remember to recycle paper . Positive Environmental Impacts Communication advancements (such as video messengers) reduces pollution as people do not have to travel to speak to each other. This is especially beneficial in business - workers can talk from the office and do not need to catch a plane to speak. Smart devices can monitor usage and reduce energy waste - such as smart air conditioners and home security systems. Collaboration software (such as cloud-based technology and Google Docs) allows experts to work together and share data. The internet and research databases allows scientists to study the environment more efficiently. Documents can be viewed on a screen rather than printed out - books and newspaper articles can be read on kindles / tablets saving paper and ink . New materials and more environmentally-friendly processes have been developed thanks to increased technology and research. Object Oriented Programming Object-Oriented Programming (OOP) Java is an example of object-oriented programming (OOP) where a programmer is able to code objects that can be visually placed onto a background. Greenfoot is an IDE for Java . Superclass A class from which other 'subclasses' will inherit characteristics ; e.g. hippos, crocodiles and polar bears will inherit properties from the Animals superclass. Object A single object from a class ; e.g. one crocodile object from the Crocodile class. Class A set of objects which share the same properties ; e.g. all PolarBears will behave in a similar way. Comment Two / symbols will allow you to write a comment to explain the code . Method A series of instructions that an object will follow . The act() method will loop in Greenfoot when the play button is pressed. Programming Programming Topics Variable Scope & Lifetime The scope of a variable refers to the parts of the program where the variable can be viewed and used , e.g. a variable with global scope can be accessed anywhere in the program . The lifetime of a variable is the amount of time the variable is stored in memory and therefore can be used , e.g. local variables can only be accessed throughout the subroutine they are created in. Programming Languages: Assembly Language HTML Greenfoot Theory Topics