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Learn about the wide range of style data and information can be presented in, both digitally and physically. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification for Unit 2 (Global Information). 2.1 - Information Styles Exam Board: OCR Specification: 2016 - Unit 2 There are many different ways that information can be styled and presented , both on-screen and physically . There are many more benefits and limitations to using each information style but some key ideas have been described below. T Text Text is a written (or typed ) format of information. ✓ Text provides detailed summaries and explanations . ✓ The format of text can be changed to suit its purpose (e.g. include bullet points or different colours). ✓ Text can be written in different languages so that all literate people can understand. X Large amounts of text can be difficult and time-consuming to read. It is generally less engaging than most other methods. X Text may include spelling errors or be factually incorrect . Graphics Graphics are a visual form of information. Examples include logos , photographs and diagrams . ✓ Graphics are multilingual - they can be understood by anybody regardless of their spoken language. Companies like IKEA will use the same graphics globall y . ✓ Graphics can present an idea or message immediately and can use associations (e.g. the colour red is associated with temperature or anger). ✓ Graphics are a more engaging method of presenting information than text. X Images may take longer to load over a data-restricted network, for example, images in an email may not be automatically downloaded. Video Videos are visual formats of information, often with audio . ✓ More engaging and easier to follow than reading large amounts of text. ✓ Videos can be used to convey a message in a short space of time , e.g. television adverts. ✓ Audio can be added to videos such as music for engagement or narration to explain a process. X Videos usually take up a relatively large amount of storage space , longer videos may take time to upload / download / transfer along a network. X Videos take a long time to create including filming, editing and narration. Animated Graphics Animated graphics are images with multiple frames , such as an animation of the heart showing individual steps that a user can pause and step through in their own time. ✓ Can be used to show a process and is easier to understand than reading text. ✓ Can be understood by all ages and language speakers . X Creating an animated graphic takes time to create , especially educational resources with multiple frames and annotation. 9 Numerical Numerical information is represented by numbers . This can include a wide array of different information including statistics, financial data, dates, ages and distances . ✓ Statistical data is easier to understand and manage in a numerical format than standard text - 234,567 is simpler to work with than "two hundred and thirty-four thousand, five hundred and sixty-seven". ✓ Numerical data can be exported into spreadsheets and presented as graphs to visualise the dat a . X Long numbers can be entered by humans incorrectly and lead to incorrect results . X Formatted data like telephone numbers cannot be stored as numerical because numerical does not allow spaces and does not allow the number to start with 0 . Audio Audio is an information type using sound waves. A common form of audio is music , such as the millions of tracks stored in music libraries like Spotify and YouTube. Non-music examples include spoken instructions and podcasts . ✓ Users can listen to information when they are otherwise busy and could not read, such as when walking or driving. ✓ Visually impaired users who are unable to read can still hear audio and interact with voice recognition software . ✓ Some users prefer listening to instructions rather than reading text . X Audio may not be suitable in some environments e.g. noisy areas . X Words may be misheard and misunderstandings made, possibly due to pronunciations or accents. Tactile Images Tactile images are a form of physical information that can be interpreted by touch . Specialist software is used to create raised lines on paper that people can experience by touching . Geographers can create 3D physical objects of environments such as valleys or volcanoes. This allows researchers and land surveyors to have a better understanding of a geographic area. ✓ Users can better understand a physical environment or prospective design if it is physically built. ✓ Visually-impaired users can feel the object instead of being able to see it. ✓ The tactile image can be used as a prototype for a target audience to feel and comment on. X It is difficult to share a tactile image without physically moving it, unlike digital or paper information styles. X Creating a tactile image requires specialist equipment like a 3D printer. *screams* Subtitles Subtitles are a textual form of information that can be shown along with visual data such as a video. Subtitles are written to transcribe audio , such as speech, into words . ✓ Hearing-impaired users can access audio information formats such as video by reading the subtitles. ✓ Subtitles can be used in noisy environments or when sound cannot be played. ✓ Subtitles can be used for translated speech , such as in promotional videos or television programmes. X Auto-generated subtitles are often incorrect . X Subtitles written by a human take a long time to type up and sync in time with the audio. Tables & Spreadsheets Tables and spreadsheets can store both numerical and textual data ready for analysis . Examples include simple database tables and financial spreadsheets of a company's profits this year. Microsoft Access is an example of database software that uses tables and Microsoft Excel is an example of spreadsheet software. When using spreadsheets (or databases) records can be locked ('record locking' ) so that only one person can make edits at any one time . Edits will be saved before unlocking the file. This will stop data being incorrectly overwritten and will ensure that the data in the spreadsheet is up-to-date , accurate and fit for purpose . Spreadsheets can be linked to other documents such as forms to directly import data from. This data can be ordered into different groups and conditional formatting can be used to automatically organise and style the data. Graphs and charts can be created using values stored in a spreadsheet to easily visualise the data . Modelling can be used to see the effect of variable changes (e.g. will raising the price of one product affect overall profit?). Database tables use queries (advanced searches) to find and display data based on given criteria (such as all males under 35). Mail merge can be used to automatically send emails to the customers highlighted in the query . A report can be generated from the query results to display the information in a structured format . This can be used to make decisions and analyse data . Boolean Boolean is a data type that can only have one of two specified values . These values are most commonly 'True' and 'False' or sometimes 'yes' and 'no'. Braille Braille is an example of a tactile image that can be physically touched . Braille characters represent letters or numbers that can be 'read' by touch - used primarily by those with visual impairments . Devices like braille terminals convert characters on a screen into braille, line-by-line so that blind people can understand the information through touch . A braille printer is used to output braille dots onto paper. ✓ Allows visually impaired users to interact with a computer system using a braille terminal . ✓ A braille printer can print documents written using braille to be given to blind people to 'read'. X Braille terminals can only display a limited amount of information at a time. X Braille is not used by many people except visually impaired people so few resources are written using braille. Charts & Graphs Charts and graphs can be used to present numerical data in a format that is easier to visualise and understand . They can be labelled to show different data values and they make it easier for viewers to identify trends and make comparisons between data. Large quantities of data, like census results, are easier to visualise in a graph than reading huge tables of numbers. ✓ Charts present numerical data in a format that is easier to visualise and understand . ✓ Charts and graphs can summarise information into one image data that would take paragraphs to explain in text. ✓ Displaying information in a graph allows users to easily identify trends and make comparisons between data . X Charts can be misleading or can display incorrect information if the numerical data is wrong. Q uesto's Q uestions 2.1 - Information Styles: 1. Describe the following information styles : a. Tactile Images [2 ] b. Braille [2 ] c. Boolean [2 ] 2. Describe two advantages and two disadvantages for each of the following information styles : a. Text [8 ] b. Graphics [8 ] c. Video [8 ] d. Animated Graphics [8 ] e. Numerical [8 ] f. Audio [8 ] g. Tactile Images [8 ] h. Subtitles [8 ] i. Braille [8 ] j. Charts & Graphs [8 ] 3a. Spreadsheets and database tables can be record locked . Explain what record locking is and why it is used . [4 ] 3b. Describe different ways that spreadsheets can be used. [6 ] 3c. Describe different ways that databases can be used. [6 ] 1.7 & 1.8 - Internet Pros & Cons 2.2 - Information Classification Topic List

Learn about key registers used in the fetch - execute cycle such as the program counter and current instruction register. Based on the J277 OCR GCSE Computer Science specification (first taught from 2020 onwards). 1.1b: Registers & The F-E Cycle Exam Board: OCR Specification: J277 Watch on YouTube : Registers in the FE Cycle Reading instructions The fetch - execute (F-E) 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 requiring attention . Important Registers A register is a small storage space for temporary data in the CPU . Each register has a specific role . There are four essential registers used in the F-E cycle : Program Counter (PC) A register that tracks the RAM address of the next instruction to be fetched . Memory Address Register (MAR) Stores the RAM address of the current instruction (or data ) the CPU needs to access . Memory Data Register (MDR) The MDR stores the instruction that has been transferred from RAM to the CPU . Accumulator (ACC) The ACC stores the result of mathematical or logical calculations . The PC , MAR and MDR are used in the fetch stage , whereas the ACC is used in the execute stage . The PC and MAR store an address (a memory location in RAM ) whereas the MDR and ACC store data (a value ). Fetch - Execute Cycle The essential idea of the F-E 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 ). MDR 5. The instruction is decoded by the contol unit which splits the instruction into an opcode (an action ) and an operand ( data or address ). 6. The instruction i s executed (run). Any result of an execution is stored in the Accumulator (ACC ) register, such as calculations made by the ALU . 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 1.1b - Registers & The F-E Cycle: 1 . What is the purpose of the registers ? [1 ] 2 . Describe the purpose of each register : a. The Program Counter (PC) [ 2 ] b. The Memory Address Register (MAR) [ 2 ] c. The Memory Data Register (MDR) [ 2 ] d. The Accumulator (ACC) [ 2 ] 3. Draw a diagram with icons and words to show the steps of the Fetch - Execute cycle . [7 ] 1.1a - The CPU Theory Topics 1.2 - CPU Performance

Learn how to use the math library and to refresh the screen (on some editors only). Try practice tasks and learn through text and images. Perfect for students learning GCSE Computer Science in UK schools. top Python 5e - More Libraries Clear Screen Importing the os library and using the .system() command with the "clear" parameter will clear the screen . The console won't clear on offline editors like IDLE but will work with many online editors like Replit. import os print ( "Hello" ) os. system ( "clear" ) print ( "Bye" ) Bye Clear Screen Task ( Trivia Questions ) Ask three trivia questions of your choice to the user and clear the screen between each one. You should display the total they got correct after the third question - to do this you need to set a variable called correct to equal 0 at the start and then add 1 to correct each time a correct answer is given . Example solution: The Math Library The math libraries contains several commands used for numbers: sqrt to find the square root of a number. ceil to round a decimal up to the nearest whole number and floor to round down to the nearest whole number. pi to generate the value of pi (π ). The sqrt command will find the square root of a number or variable placed in the brackets and return it as a decimal number . from math import sqrt answer = sqrt(64) print (answer) 8.0 The ceil command rounds a decimal up to the nearest integer and the floor command rounds a decimal down to the nearest integer . from math import ceil, floor answer = 65 / 8 print ( "True answer:" , answer) print ( "Rounded up:" , ceil(answer)) print ( "Rounded down:" , floor(answer)) True answer: 8.125 Rounded up: 9 Rounded down: 8 The pi command generates a pi value accurate to 15 decimal places . Pi is used for many mathematical calculations involving circles . The area of a circle is pi x radius² . The first example below uses 5.6 as the radius . from math import pi radius = 5.6 area = pi * (radius * radius) print ( "The area of the circle is" , area) The area of the circle is 98.5203456165759 The example below uses an input to allow the user to enter a decimal (float ) number for the radius. It also uses the ceil command to round the area up . from math import pi, ceil radius = float(input( " Enter the radius: " )) area = pi * (radius * radius) print ( "The area of the circle is" , ceil(area)) Enter the radius: 2.3 The area is 17 Clear Screen Task ( Area of a Sph ere ) The formula of a sphere is 4 x π x r² where π represents pi and r is the radius . Use an input line to enter the radius and then calculate the area of the sphere . Round the answer down to the nearest integer using floor and print it. Example solution: Enter the radius: 7.1 The area of the sphere is 633 ⬅ 5d - Coloram a Section 5 Practice Tasks ➡

Learn about the importance of testing applications, test plan structure, test types and test data. Resources based on Unit F161 (Developing Application Software) for the OCR Cambridge Advanced Nationals in Computing (H029 / H129) AAQ (Alternative Academic Qualification). Qualification: Cambridge Advanced Nationals in Computing (AAQ) Certificate: Computing: Application Development (H029 / H129) Unit: F161: Developing Application Software 5.1 - Testing Watch on YouTube : Purpose of testing Test plan structure Test data Types of testing You need to know the purpose , importance , advantages and disadvantages of testing applications , as well as the impacts of not carrying out testing . You must understand the structure and contents of test plans and the importance of testing , remedial actions and retesting during application development. You need to know the role of each type of test data (normal , extreme and erroneous ). Finally, the purpose , advantages and disadvantages of each type of testing (technical and user ) must be known as well as when and how each type should take place . What You Need to Know Purpose of Testing ? YouTube video uploading soon Test Plan Structure ? YouTube video uploading soon Types of Test Data ? YouTube video uploading soon Types of Testing ? YouTube video uploading soon Q uesto's Q uestions 5.1 - Testing: 1. What? [2 ] 2. What? [1 ] 3. What? [1 ] 4. What? [1 ] ? D id Y ou K now? 4.1 - Security Considerations Topic List 5.2 - Application Installation

Learn about computational methods including problem recognition, decomposition, divide and conquer, abstraction, backtracking, data mining, heuristics, performance modelling, pipelining and visualisation. Based on the OCR H446 Computer Science A-Level specification. Exam Board: OCR A-Level Specification: Computer Science H446 3.1f - Standard Algorithms Watch on YouTube : Bubble sort Merge sort Insertion sort Quick sort Linear search Binary search Djisktra's algorithm A* algorithm The OCR A-Level course requires an understanding of algorithms used for sorting , searching and pathfinding including how they can be used for traversing and how to write them in pseudocode or a high-level programming langauge . Bubble Sort Bubble sort repeatedly compares adjacent items and swaps them if they are in the wrong order . Its advantage is that it is very simple to understand and easy to implement . However, it is extremely slow for large lists , with a worst- and average-case time complexity of O(n²) . It performs slightly better (O(n)) if the list is already nearly sorted and the algorithm is optimised t o detect no swaps . Overall, it is easy but inefficient . YouTube video uploading soon Merge Sort Merge sort is a divide-and-conquer algorithm that repeatedly splits a list into smaller sublists , sorts them recursively and then merges them back together . Its major benefit is that it is consistently fast with a time complexity of O(n log n) in the best , average and worst cases , making it very efficient for large datasets . It is also stable and works well with linked lists . However, a drawback is that it requires additional memory to store the temporary sublists , making its space complexity O(n) . Merge sort is therefore reliable but not memory-efficient . YouTube video uploading soon This page is under active development. Check here for the latest progress update. Insertion Sort Insertion sort works by taking each item and inserting it into the correct position in a growing sorted portion of the list . It is efficient for small or nearly sorted datasets and has a best-case complexity of O(n) , making it useful in real-time systems or hybrid algorithms . However, for large , randomly ordered datasets it becomes slow , with average- and worst-case performance of O(n²) . It uses very little memory space - (O(1) - which is one of its key benefits compared to more complex sorts like merge or quick . YouTube video uploading soon Quick Sort Quick sort is a divide-and-conquer algorithm that chooses a pivot , partitions the list into smaller elements and larger elements , and recursively sorts the partitions . Its main advantage is speed : the average-case time complexity is O(n log n) and it is often faster in practice than merge sort due to good cache performance and in-place partitioning . However, if poor pivot choices are made (e.g., always picking the first item in an already sorted list ), the worst case becomes O(n²) . Despite this, quick sort is widely used because good pivot-selection strategies minimise this risk . YouTube video uploading soon Linear Search Linear search checks each item in a list one by one until it finds the target value or reaches the end . Its benefit is that it works on any list (sorted or unsorted ) and is extremely simple to use and implement . The drawback is inefficiency for large datasets because its best , average and worst time complexity is O(n) . This means the time taken grows directly with the size of the list , making it suitable only for small collections of data . YouTube video uploading soon Binary Search Binary search repeatedly halves a sorted list to locate a target value , making it much faster than linear search . Its key benefit is efficiency : the time complexity is O(log n) for best , average and worst cases , meaning performance scales extremely well with large datasets . However, its major limitation is that the data must be sorted beforehand , and maintaining a sorted list can itself be costly . When this condition is met , binary search is one of the most efficient searching algorithms available. YouTube video uploading soon Dijkstra's Algorithm Dijkstra’s algorithm is a pathfinding algorithm used to find the shortest path from a starting node to all other nodes in a weighted graph with non-negative edge weights . It works by gradually exploring the graph , always choosing the next closest unvisited node , updating the shortest known distances to its neighbours and marking nodes as 'visited ' once the shortest path to them is confirmed . The algorithm continues until all nodes have been processed or the destination is reached , guaranteeing the shortest path . YouTube video uploading soon A* Algorithm The A* algorithm is an informed pathfinding algorithm that also finds the shortest path in a weighted graph , but it uses a heuristic (an estimate of the distance to the goal ) to guide its search more efficiently toward the target . A* combines the actual cost from the start to a node with a heuristic estimate of the remaining distance , allowing it to prioritise exploring nodes that appear more promising . YouTube video uploading soon Q uesto's K ey T erms Sorting Algorithms: bubble sort, flag, pass, merge sort, insertion sort, quick sort, pivot Seraching Algorithms: linear search, binary search, precondition Pathfinding Algorithms: Dijsktra's algorithm, A* algorithm, heuristic D id Y ou K now? Halo: Combat Evolved released on the Xbox in 2001 and introduced groundbreakingly convincing enemy AI for the time. Pathfinding algorithms were used more realistically than older games so that enemies wouldn't just run directly at the player but behaved in different ways depending on the situation , such as cooperating , flanking or retreating by reacting dynamically to the player . 3.1e - Data Structure Algorithms A-Level Topics

Learn about network topologies including client-server, peer-to-peer, bus, mesh and star. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification. 3.3 - Network Characteristics Exam Board: OCR Specification: 2016 - Unit 1 Network Topologies Network topology refers to the arrangement of computer systems on a network . Devices in a network topology diagram are often called ' nodes ' . Client-Server Network Clients make requests to a server , the server manages that request and responds . For example, if the user (client) makes a request to access www.csnewbs.com to a web server . Large services like Amazon and Google will need very powerful servers to handle millions of requests a second. The client is completely dependent on the server to provide and manage the information. The server controls network security , backups and can be upgraded to manage higher demand. Disadvantages: Large amounts of traffic congestion will cause the network to slow down . If a fault occurs with the server then the whole network will fail . IT technicians may be required to manage and maintain the network . Malware , such as viruses, can spread quickly across the network. Peer-to-Peer Network For peer-to-peer networks , data is shared directly between systems without requiring a central server . Each computer is equally responsible for providing data. Peer-to-peer is optimal for sharing files that can then be downloaded. Bus Topology The nodes are connected to a bus (a central cable which transfers all data on the network). How it works: The bus transfers data packets along the cable . As the data packets arrive at each computer system, the computer checks the destination address contained in the packet to see if it matches its own address . If the address does not match , the computer system passes the data packet to the next system . If the address of the computer system matches the destination address in the data packet, it is accepted and processed. At both ends of the cable are terminators to mark the end of the bus. 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 network speed as more systems are attached. The main cable must also be terminated properly . Token Ring Topology In a token ring network , computer systems are connected in a ring or a loop. How it works: A token (small data packet) is sent around the ring in one direction, being passed from one computer system to the next. A computer seizes the token and includes its own data when it transfers data. As the token arrives at each computer system, the system checks the destination address contained in the packet to see if it matches its own. If the addresses match, the computer processes the data otherwise it ignores it. 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 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 In a star network , each computer system is connected to a central node: a hub or switch . How it works: Each node is connected to the central node (usually a hub or switch ) and transfers its data packets here. The hub/switch looks at the destination address and transfers the packets to the intended computer only. 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 mesh network, each computer system is connected to every other computer system . 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 complete 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 . Configuration Before a computer system can use a network, three pieces of information must be configured (set up) correctly. IP Address An IP address is used to uniquely identify computer systems on a network , allowing communication between them. An example of an IP address is 195.10.213.120. Default Gateway When data is to be sent from one network to another , it must be sent through a default gateway . This default gateway is usually a router that connects the local network to another network . On many home networks , the default gateway will use the same private IP address : 192.168.1.1 Network managers can use automatic configuration which is quicker and easier to set up . A new device can connect to and use a network automatically , such as free WiFi in an airport. Network managers can also set manual configuration which improves security as new devices can’t be used until the addresses have been configured by a technician . This stops unauthorised devices from connecting to the network. Subnet Mask Subnetting is the act of dividing a physical network into smaller 'sub' networks (known as subnets ) . This helps to reduce traffic and means that users can externally access parts of a network (e.g. emails from home) without having to open the entire network. A subnet mask is used to define these subnets . The mask is used to determine the start and end address of each IP address in a subnet. A common subnet mask is 255.255.255.0 as making the first 3 sections full restricts the fourth section to 256 unique values. For example 113.12.14.230 and 113.12.14.157 are in the same subnet but 114.12.14.127 wouldn't be. Q uesto's Q uestions 3.3 - Network Characteristics: 1 a. Describe how peer-to-peer networks and client-server networks function. 1b. Give one use for both types of network. 2a. Draw and label a diagram for all 6 network topologies . 2b. Describe 2 advantages and 2 disadvantages of each network topology . 3 . What is an IP address ? Why is it necessary for networks? 4. Describe what is meant by a default gateway . 5a. What is subnetting ? 5b. What is the purpose of a subnet mask ? 5c. State a common subnet mask . How many unique devices can be used on a network with this subnet mask? 6. Describe 1 reason why a network manager may use automatic configuration and 1 reason why they may use manual configuration . Advantages: The network can be controlled centrally from the server to easily backup data and update software . Hardware, software and resources can be shared across the network, such as printers, applications and data files . The network allows for improved scalability , meaning more clients can be easily added to the central server . Disadvantages: Without a dedicated server there is no central device to manage security or backups . Backups must be performed on each individual system. Computer performance will decrease with more devices connected to the network, especially if other machines are slow. Advantages: This is a simpler network than client-server to set up as no server is required . Clients are not dependent on a server . Perfect for quickly sharing files between systems , such as downloading media files. 3.2 - Virtualisation Topic List 3.4 - Connection Methods

Learn about the fundamentals of programming - selection, sequence and iteration. Also find out the difference between local and global variables and constants. Based on the J277 OCR GCSE Computer Science specification (first taught from 2020 onwards). Exam Board: OCR Specification: J277 2.1: Programming Fundamentals Watch on YouTube : Programming Fundamentals Sequence Selection Iteration Operators This section of the specification includes programming topics that are outlined in 1.2 (Designing Algorithms). You must have an understanding of a range of programming techniques , such as how to use selection , loops and operators . The best practice for learning is to try the tasks in the Python pages on this website (see the link to the right). Visit the Python section of CSNewbs ---> Programming Constructs There are three constructs ( ideas of programming ) that are used to control the flow of a program : Sequence Structuring code into a logical, sequential order . Selection Decision making using if statements . Iteration Repeating code using for or while loops . Variables Variables are used to store data in programs. They can be changed as the program runs . A variable has two parts - the data value such as "Emily" and an identifier such as First_Name . An efficient program will use variables with sensible identifiers that immediately state their purpose in the program. Using variable names like 'TotalNum' and 'Profit' rather than 'num1' and 'num2' mean that other programmers will be able to work out the purpose of the code without the need for extensive comments. Local & Global Variables Large programs are often modular - split into subroutines with each subroutine having a dedicated purpose. Local variables are declared within a specific subroutine and can only be used within that subroutine . Global variables can be used at any point within the whole program . Local variable advantages Saves memory - only uses memory when that local variable is needed - global variables use memory whether they are used or not. Easier to debug local variables as they can only be changed within one subroutine. You can reuse subroutines with local variables in other programs. Global variable advantages Variables can be used anywhere in the whole program (and in multiple subroutines). Makes maintenance easier as they are only declared once. Can be used for constants - values that remain the same. Constants π As specified before, a variable is data that can change in value as a program is being run. A constant is data that does not change in value as the program is run - it is fixed and remains the same. An example of a constant in maths programs is pi - it will constantly remain at 3.14159 and never change. Operators Comparison Operators Comparison operators are used to compare two data values . A table of common comparison operators used in programs are below: Arithmetic Operators Arithmetic operators are used to mathematically manipulate values . The most common arithmetic operators are add (+ ), subtract (- ), multiply (* ) and divide (/ ). Further arithmetic operators are shown below: Modulo division (also known as modulus ) reveals the remainder from the last whole number . For example: 9 % 4 = 1 (4 goes into 9 twice (8) with a remainder of 1) Integer division (also known as quotient ) reveals the ‘whole number of times ’ a number can be divided into another number : 9 // 4 = 2 (4 goes into 9 fully, twice) The symbol ^ represents exponentiation . However, Python uses ** to represent exponentiation. For example '2^3 = 8' is equivalent to '2³ = 8'. Logical Operators Logical operators typically use TRUE and FALSE values which is known as Boolean . You can find more information about Boolean values in section 4.1 . Q uesto's Q uestions 2.1 - Programming Fundamentals: Programming Constructs 1. Describe and draw a diagram for the 3 programming constructs . [6 ] Variables 1. What is the difference between local and global variables ? [4 ] 2. Describe two advantages of using local variables . [2 ] 3. Describe two advantages of using global variables . [2 ] 4. What is a constant ? Give an example . [2 ] 1.3 - Searching & Sorting Theory Topics 2.2 - Data Types

Learn about the benefits of compression and the differences between lossy and lossless compression. Also, learn how compression ratios work. Based on the J277 OCR GCSE Computer Science specification (first taught from 2020 onwards). 2.5: Compression Exam Board: OCR Specification: J277 Watch on YouTube : Compression Benefits Lossy Compression Lossless Compression 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 function properly if data were permanently removed, such as 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 Q uesto's Q uestions 2.5 - 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 ] 2.4e Sound Storage Theory Topics 3.1a - Network Types & Performance

Learn about the three elements of computational thinking - abstraction, decomposition and algorithmic thinking. Based on the J277 OCR GCSE Computer Science specification (first taught from 2020 onwards). 1.1: Computational Thinking Exam Board: OCR Specification: J277 There are three key components to computational thinking (smart problem solving): Abstraction is when you ignore unnecessary information and focus only on the important facts . Abstraction is used because it simplifies a problem to make it less complex . This makes it more straightforward to understand the problem and create a solution . Decomposition is when you break a problem down into smaller tasks so that it is easier to solve . Each individual problem can be separately tested and solved . Decomposition also enables different people to work on the different parts of a larger problem that can later be recombined to produce a full solution . Algorithmic thinking is the final stage as logical steps are followed to solve the problem . The problem is broken down using decomposition into smaller problems . The required data and relevant data structures are considered using abstraction . Watch on YouTube : Abstraction Decomposition Algorithmic Thinking Q uesto's Q uestions 1.1 - Computational Thinking: 1. What does the term 'abstraction ' mean? Why is it important ? [2 ] 2. What is meant by ' decomposition '? Why is it important ? [ 2 ] 3. What is algorithmic thinking ? What does it involve? [3 ] Theory Topics 1.2 - Designing Algorithms

Learn about security threats, including botnets and DDoS attacks and both physical and digital security mitigations. Resources based on Unit F161 (Developing Application Software) for the OCR Cambridge Advanced Nationals in Computing (H029 / H129) AAQ (Alternative Academic Qualification). Qualification: Cambridge Advanced Nationals in Computing (AAQ) Certificate: Computing: Application Development (H029 / H129) Unit: F161: Developing Application Software 4.1 - Security Considerations Watch on YouTube : Security threats Physical security Digital security You need to know the risks that specific security threats pose to applications , including botnets , DDoS attacks , hacking and malware . You need to know how both physical security mitigations (e.g. biometrics , locks and RFID ) and digital security mitigations (e.g. encryption , firewalls and anti-malware ) protect application software against threats . What You Need to Know Security Threats ? YouTube video uploading soon Physical Security Mitigations ? YouTube video uploading soon Digital Security Mitigations ? YouTube video uploading soon Q uesto's Q uestions 4.1 - Security Considerations: 1. What? [2 ] 2. What? [1 ] 3. What? [1 ] 4. What? [1 ] ? D id Y ou K now? 3.2 - Protocols Topic List 5.1 - Testing

Test your understanding of working with files in Python, including reading, searching, writing and editing. Try practice tasks and learn through text and images. Perfect for students learning GCSE Computer Science in UK schools. Python - Section 10 Practice Tasks Task One Create a file in Python called DaysOfTheWeek.txt. Write the days of the week into the file in a single print line but put each day on a new line. Check the file to see if it has worked. Example solution: Task Two Create a file called Colours.txt. Use a for loop to ask the user to enter 8 different colours. Write each colour onto the same line, with a space between the colours. Close the file and open it again in read mode and print it. Example solution: Task Three Create a file named "Holiday.txt". Ask the user to enter the family name, destination and and number of passengers. Print each family's details on their own line. Bonus: Edit this program to add a search feature to look for the family name. Example solution: Task Four Use the holiday file from task three above. You are going to change the destination. Ask the user to enter a family name and then a new destination. Update the destination with the new value. Check the file to ensure the destination has been updated successfully. Use section 10c to help you with this task. Example solution: ⬅ 10c - Remove & Edit Lines 11 - Graphical User Interface ➡

Learn about the three main types of secondary storage - magnetic, optical and solid-state. Also, learn about the characteristics of secondary storage media including reliability and durability. Based on the J277 OCR GCSE Computer Science specification (first taught from 2020 onwards). 2.2: Secondary Storage Exam Board: OCR Specification: J277 Watch on YouTube : Secondary Storage Six Characteristics Magnetic Storage Optical Storage Solid State Storage Secondary storage is non-volatile storage used to save and store data that can be accessed repeatedly. Secondary storage is not directly embedded on the motherboard (and possibly even external ) and therefore further away from the CPU so it is slower to access then primary storage . Storage Characteristics you should know: CAPACITY : The maximum amount of data that can be stored on the device. DURABILITY : The strength of the device, to last without breaking . PORTABILITY : How easy it is to carry the device around . ACCESS SPEED : How quickly data on the device can be read or edited . COST : The average price it costs to purchase the storage device. RELIABILITY : The likelihood of the device continuing to perform well over time . Magnetic Storage A magnetic hard disk drive (HDD ) is the most common form of secondary storage within desktop computers. A read/write head moves nanometres above the disk platter and uses the magnetic field of the platter to read or edit data. An obsolete (no longer used) type of magnetic storage is a floppy disk but these have been replaced by solid state devices such as USB sticks which are much faster and have a much higher capacity. Another type of magnetic storage that is still used is magnetic tape . Magnetic tape has a high storage capacity but data has to be accessed in order (serial access ) so it is generally only used by companies to back up or archive large amounts of data . Magnetic Storage Characteristics (Hard Disk Drive): ✓ - Large CAPACITY and cheaper COST per gigabyte than solid state . ✓ - Modern external HDDs are small and well protected so they are DURABLE and PORTABLE , however because of the moving parts, they should not be moved when powered on because it can damage the device. X - Slower ACCESS SPEED than solid state but faster than optical storage . Optical Storage Optical storage uses a laser to project beams of light onto a spinning disc, allowing it to read data from a CD , DVD or Blu-Ray . This makes optical storage the slowest of the four types of secondary storage. Disc drives are traditionally internal but external disc drives can be bought for devices like laptops. Magnetic Disks are spelled with a k and Optical Discs have a c. Optical Storage Characteristics: X - Low CAPACITY : 700 MB (CD ), 4.7 GB (DVD ), 25 GB (Blu-ray ). X - Not DURABLE because discs are very fragile and can break or scratch easily. ✓ - Discs are thin and very PORTABLE . Also very cheap to buy in bulk. X - Optical discs have the Slowest ACCESS SPEED . Solid State Storage There are no moving parts in solid state storage. SSD s (Solid State Drives ) are replacing magnetic HDDs (Hard DIsk Drives) in modern computers and video game consoles because they are generally quieter , faster and use less power . A USB flash drive ( USB stick ) is another type of solid state storage that is used to transport files easily because of its small size. Memory cards , like the SD card in a digital camera or a Micro SD card in a smartphone , are another example of solid state storage. Solid State Characteristics: X - More expensive COST per gigabyte than magnetic . ✓ - Usually DURABLE but cheap USB sticks can snap or break . ✓ - The small size of USB sticks and memory cards mean they are very PORTABLE and can fit easily in a bag or pocket. ✓ - Solid State storage have a high CAPACITY and the fastest ACCESS SPEED because they contain no moving parts . Q uesto's Q uestions 2.2 - Secondary Storage: 1. Rank magnetic , optical and solid-state storage in terms of capacity , durability , portability , speed and cost . For example, magnetic has the highest capacity , then solid-state, then optical. This could be completed in a table . [15 ] 2. Justify which secondary storage should be used in each scenario and why it is the most appropriate: a. Sending videos and pictures to family in Australia through the post . [ 2 ] b. Storing a presentation to take into school . [ 2 ] c. Storing project files with other members of a group to work on together . [ 2 ] d. Backing up an old computer with thousands of files to a storage device. [ 2 ] 2.1 - Primary Storage Theory Topics 2.3 - Data Units