Learn how to make simple calculations in Python. Try practice tasks and learn through text and images. Perfect for students learning GCSE Computer Science in UK schools. top Python 3b - Simple Calculations Simple Calculations in Python You can perform calculations on numbers in Python using the four main operators : print ( 89 + 47) print ( 89 - 47) print ( 89 * 47) print ( 89 / 47) = 136 42 4183 1.8936170212765957 For addition , use the plus sign + To subtract numbers, use the dash symbol – (but not an underscore _ ) For multiplication , use an asterisk * which can be made by pressing Shift and 8 on a typical keyboard. To divide numbers, use a forward slash / (but not a backslash \ ) Use a string and the calculation to make the output user friendly . print ( "53 x 7 =" , 53 * 7) = 53 x 7 = 371 Simple Calculations Task 1 ( + - * /) Print four different simple calculations, using a different operator ( + - * / ) for each. Make the output user friendly by also showing the calculation (not just the answer). Copy the divide symbol here using Ctrl and C : ÷ Example solution: 18 + 35 = 53 18 - 35 = -17 18 x 35 = 630 18 ÷ 35 = 0.5142857142857142 Using Variables in Calculations You can also perform calculations on variables . The example below has the values of the variables pre-written. You need to store the result in a variable . The total variable has been used to store the result of the multiplication. num1 = 12 num2 = 20 total = num1 * num2 print ( "The total is" , total) = The total is 240 The example below allows the user to input values . num1 = int ( input ( "Enter number one: " )) num2 = int ( input ( "Enter number two: " )) total = num1 + num2 print ( "The to ta l is" , total) Enter number one: 21 Enter number two: 82 The total is 103 = Don't leave the user in the dark, better user interfaces are clear and explain what outputted values mean: num1 = int ( input ( "Enter number one: " )) num2 = int ( input ( "Enter number two: " )) answer = nu m1 - num2 print (num1 , "-" , n um2 , "=" , answer) Enter number one: 83 Enter number two: 29 83 - 29 = 54 = Simple Calculations Task 2 ( Divide by 3) Use an input line with int to ask the user to enter a number . Divide the number by 3 and output the result . Example solution: Enter a number: 11 11 divided by 3 is 3.6666666666666665 Simple Calculations Task 3 ( Add 3 Numbers ) Make three input lines using int to ask the user to enter three numbers . Add the numbers together and output the total . Example solution: Enter the first number: 45 Enter the second number: 32 Enter the third number: 19 The total is 96 ⬅ 3a - Data Types Section 3 Practice Tasks ➡

Learn about different types of utility software including anti-virus, firewall and defragmentation. Based on the J277 OCR GCSE Computer Science specification (first taught from 2020 onwards). 5.2: Utility Software Exam Board: OCR Specification: J277 Watch on YouTube : Utility Software What is utility software? Utility software are dedicated programs used for the maintenance and organisation of a computer system (this is known an 'housekeeping '). Utilities are required to run additional tasks not performed by the operating system . Anti-malware (such as an anti-virus or anti-spyware ), firewall and encryption software are examples of utilities and have been explained in section 4.2 . Data Compression is another utility that has been explained in section 2.5 . Other utility software include backup software , disk checkers , disk formatters and auto-updaters . Defragmentation What is fragmentation and how does it happen? Over time files stored on a hard disk drive may become fragmented - this is when the file is split into parts that are saved in different storage locations . Fragmentation occurs when there is limited contiguous space in which to store a file . This may happen as data is stored and then later deleted on the hard drive . New files are created which may be bigger than the spaces left by the deleted files . The new files are then split up . Fragmentation increases access time - files that are fragmented take longer to load and read because of the distance between the fragments of the file. How does defragmentation work? Empty spaces are collected together on the hard disk drive and file fragments are moved to be stored together. This means that fewer disc accesses are needed (requiring less physical movement ) as file fragments can be read consecutively . What are the effects of defragmentation? A defragmented file takes less time to read and access because the data is stored contiguously . The read/write head of the hard drive does not need to move as far to read the next piece of data because it is in the adjacent memory location , saving time . It also quicker to save new files because there is more free space together so it does not need to split the file and can store the data contiguously . Q uesto's Q uestions 5.2 - Utility Software: 1. Explain what fragmentation is and how a file may become fragmented . [ 3 ] 2. Describe the process of defragmentation . [ 3 ] 3. Explain the effects of defragmenting a hard disk drive. [ 3 ] 5.1 - Operating Systems Theory Topics 6.1a - Impacts of Technology

Learn about how to convert between the denary (decimal), binary and hexadecimal number systems. Based on the 2020 Eduqas (WJEC) GCSE specification. 4.1: Number Systems Exam Board: Eduqas Specification: 2020 What is binary? By now you should know that computer systems process data and communicate entirely in binary . Topic 1.4 explained different binary storage units such as bits (a single 0 or 1), nibbles (4 bits) and bytes (8 bits). Binary is a base 2 number system. This means that it only has 2 possible values - 0 or 1 . Because binary is a base 2 number system, binary numbers should be written out with a 2 after them, like this: 10101002 What is denary? Denary (also known as decimal ) is the number system that you've been using since primary school. Denary is a base 10 number system. This means that it has 10 possible values - 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 . Because denary is a base 10 number system, denary numbers should be written out with a 10 after them, like this: 165 10 How to convert from binary to denary: How to convert from denary to binary: What is hexadecimal? Hexadecimal is a base 16 number system. This means that it has 16 possible values - 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E and F . Because hexadecimal is a base 16 number system, hexadecimal numbers should be written out with a 16 after them, like this: 6E16 Hexadecimal is used as a shorthand for binary because it uses fewer characters to write the same value . This makes hexadecimal less prone to errors when reading or writing it , compared to binary. For example, 1001111010112 is 9EB16 . Hexadecimal only uses single-character values. Double-digit numbers are converted into letters - use the table on the right to help you understand. How to convert from binary to hexadecimal: How to convert from hexadecimal to binary: Converting from denary to hexadecimal / hexadecimal to denary To convert from denary to hexadecimal or the other way round you must convert to binary first . Denary > Binary > Hexadecimal Hexadecimal > Binary > Denary Use the videos on this page if you need help converting to or from binary. The most common number systems question in exams are from denary to hexadecimal or from hexadecimal to denary so make sure that you practice these conversions. Q uesto's Q uestions 4.1 - Number Systems: 1. Explain why hexadecimal numbers are used as an alternative to binary . Use an example . [ 3 ] 2. Convert the following values from binary to denary : a. 00101010 2 b. 11011011 2 c. 01011101 2 d. 11101110 2 e. 01011111 2 [1 each ] 3. Convert the following values from denary to binary : a. 35 10 b. 79 10 c. 101 10 d. 203 10 e. 250 10 [1 each ] 4. Convert the following values from binary to hexadecimal : a. 11110101 2 b. 01100111 2 c. 10111010 2 d. 10010000 2 e. 11101001 2 [1 each ] 5. Convert the following values from hexadecimal to binary : a. C2 16 b. 8A 16 c. DE 16 d. 54 16 e. F7 16 [1 each ] 6. Convert the following values from denary to hexadecimal : a. 134 10 b. 201 10 c. 57 10 d. 224 10 e. 101 10 [1 each ] 7. Convert the following values from hexadecimal to denary : a. 32 16 b. A5 16 c. 88 16 d. C0 16 e. BE 16 [1 each ] Watch on YouTube Watch on YouTube Watch on YouTube Watch on YouTube Click the banners above to try self-marking quizzes (Google Form) on these topics. Denary to Binary: Binary to Denary: Binary to Hexadecimal: Hexadecimal to Binary: 3.9 Protection Against Threats Theory Topics 4.2 - Signed Binary

Learn what an embedded system is and about different examples of embedded systems. Based on the J277 OCR GCSE Computer Science specification (first taught from 2020 onwards). 2.1: Primary Storage (Memory) Exam Board: Cambridge OCR Specification: GCSE - J277 Watch on YouTube : Primary Storage What primary storage (memory ) is and why computers have it. The key characteristics of Random Access Memory (RAM ) and Read-Only Memory (ROM ). Why computers may use virtual memory and how it works. What You Need to Know Primary Storage Primary storage is high-speed , internal memory that the CPU can directly access . It includes RAM and ROM . Primary storage is needed to provide fast , direct access to the data and instructions required to run programs and start the computer . Random Access Memory (RAM) Read-Only Memory (ROM) RAM is volatile . This means that data is lost when the power is turned off. RAM temporarily stores the instructions and data for programs that are currently running . It also stores parts of the operating system currently in use. The contents of RAM can be changed . Data can be written to RAM and also read from it. ROM is non-volatile . This means that data is saved even when the power is turned off . ROM stores the start-up instructions used to boot the computer and load the operating system. It also stores firmware , such as the BIOS , to check that hardware components are functioning correctly during start-up. ROM is read-only , meaning the contents cannot be changed and can only be viewed . Virtual Memory When RAM is close to full capacity , parts of programs not currently needed can be temporarily moved to a section of secondary storage called virtual memory . When required again , data is moved from virtual memory back into RAM , allowing more programs to run at once without running out of memory . However, virtual memory is much slower than RAM , and excessive use can cause thrashing , significantly reducing performance . Q uesto's Q uestions 2.1 - Primary Storage (Memory): 1. Explain why the computer requires primary storage . [ 2 ] 2. For each type of memory below, describe it and state what information is stored within it: a . Random Access Memory (RAM) [3 ] b. Read-Only Memory (ROM) [ 3 ] c. Virtual memory [ 3 ] 1.3 - Embedded Systems Theory Topics 2.2 - Secondary Storage

Learn about methods of wired and wireless connections to transmit data on the internet, including satellite and bluetooth. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification for Unit 2 (Global Information). 1.4 - Internet Connections Exam Board: OCR Specification: 2016 - Unit 2 The internet i s a global network of interconnected networks . There are multiple methods of connecting to the internet . Wired Connections Copper Cables Copper cables are a cheaper type of wired internet connection that may be poorly insulated and therefore susceptible to electromagnetic interference . Copper cables are more likely to suffer from attenuation (network distortion ). However, they are malleable (easier to bend) and less likely to break than other cables such as fibre optic. They have a lower bandwidth - cannot transmit as much data at once - than fibre optic cables. Fibre Optic Cables Fibre optic cables are a very fast but expensive type of wired internet connection. Signals are transmitted as waves of light through a glass tube. Because of this fibre optic cables are not affected by electromagnetic interference and suffer less from attenuation . Fibre optic cables have a higher bandwidth - can transfer more data at one time - than copper cables but they are more fragile . Wireless Connections Bluetooth Bluetooth is a temporary short-range communication between devices within a limit of about 10 metres . For example, Bluetooth can be used to transfer audio files from one smartphone to another. The close proximity is a disadvantage but no other hardware is required for a connection. Microwave Microwave connections use radio waves to send signals across a large area via microwave towers . It can transmit a large amount of data but antennas must be in the line of sight of each other with no obstructions . Microwave connections are affected by bad weather , leading to higher chances of attenuation (network distortion ). Satellite Satellite networks use point-to-multipoint communication by using satellites above the Earth's atmosphere that receive a transmission and rebroadcast them back to Earth. Because of the distance between the communication device and the satellite (roughly 45,000 miles), there is a delay between data transmission and it being received. GSM / 5G GSM (Global System for Mobile communications ) is a technology for allowing mobile phones to connect to a network for calls and text messages. Advances in mobile technology are classified by generations such as 4G and 5G (the current generation). Each generation is generally faster, more secure and allows for new opportunities. Connection Characteristics When connecting to the internet there are several characteristics that a user must consider: Strength Range Latency Bandwidth Storage Capacity Contention Latency is the delay when sending data across a network. Bandwidth is the maximum amount of data that can be sent across a network at once . Contention refers to whether a network is dedicated ( uncontended ) or shared between users ( contended ). Q uesto's Q uestions 1.4 - The Internet: 1. Compare the differences between copper and fibre optic cables (possibly in a table) by the following features: a. Price b. Bandwidth c. Interference d. Attenuation e. Malleability / Fragility [2 each ] 2. Describe each of the different types of wireless connection . Try to list 1 advantage and 1 disadvantage of using each type. a. Bluetooth b. Microwave c. Satellite d. GSM / 5G [5 each ] 3a. State the 6 characteristics of a network. [6 ] 3b. Describe what is meant by the following characteristics : i. Latency ii. Bandwidth iii. Contention [1 each ] 1.3 - Access & Storage Devices Topic List 1.5 - WWW Technologies

Learn about how sounds are represented in a computer system including how analogue sound waves are converted into binary. Also, learn about sample rate, bit depth, bit rate and metadata. Based on the J277 OCR GCSE Computer Science specification (first taught from 2020 onwards). 2.4e: Sound Storage Exam Board: OCR Specification: J277 Watch on YouTube : Sample Rate Bit Depth Sound File Size Converting Analogue Sound to Binary Analogue sound waves must be digitally recorded and stored in binary . To record the sound, the amplitude (height ) of the analogue sound wave is measured and recorded in binary at specific intervals . 0010 1011 0101 0101 Analog sound wave ADC (Analog to Digital Converter) Binary sample Sampling an Analogue Sound Wave Digital sampling is discrete (separate) and not continuous like analogue waves. To get the highest quality sound, many samples are taken to recreate the analogue wave as closely as possible . Sample Rate The sample rate (sampling frequency) is the number of times per second the amplitude of the sound wave is measured . It is measured in kilohertz (kHz), for example CD quality is 44.1kHz (44,100 samples per second). The higher the sample rate , the better the audio quality as the digital data more closely resembles an analogue wave . However, higher sample rates result in larger file sizes because more data is stored for each individual sample. A low sample rate will result in a low-quality sound because the digital data does not closely resemble the original analog wave . A higher sample rate will result in a higher-quality sound because the digital data more closely resembles the original analog wave . Bit Depth The bit depth is the number of bits available to represent each sample . For example, a sample with a bit depth of 4 could be 0101 or 0111 or 1010. A sample with a bit depth of 8 could be 01010110 or 1010110 or 11001111. A common bit depth is 16 bits . The higher the bit depth , the more bits are available to be used for each sample. Therefore the quality is often higher as the wave more closely resembles an analog wave . The file size will also be larger if the bit depth is higher, as each sample stores additional bits . low bit rate = lower quality high bit rate = higher quality sound file size = sample rate x bit depth x duration Example: A short audio sample has a bit depth of 4 and a sample rate of 10 samples per second . The clip is 15 seconds long . 4 bits x 10 = 40 bits per second. 40 x 15 = 600 bits . To convert the answer from bits to bytes , divide by 8 . 600 bits ÷ 8 = 75 bytes . Calculating File Size Q uesto's Q uestions 2.4e - Sound Storage: 1. Explain how an analogue sound wave is converted into a binary sample . [ 2 ] 2a. What is a sample rate ? [2 ] 2b. Explain two ways an audio file will be affected if the sample rate is increased . [4 ] 3a. What is bit depth ? [2 ] 3b. Explain two ways an audio file will be affected if the bit depth is increased . [4 ] 4 . An audio sample has a bit depth of 8 , a sample rate of 10 and it is 12 seconds long . What is the file size in bytes ? [ 2 ] 2.4d Image Storage Theory Topics 2.5 - Compression

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

Learn about operational issues including disaster planning, change management and data security. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification. 5.2 - Operational Issues Exam Board: OCR Specification: 2016 - Unit 1 What are operational issues? Operational issues refer to potential problems that could disrupt the workflow and efficiency of an organisation . They relate to processes within an organisation and the way that the company operates on a daily basis . Security of Information Definition: Organisations must ensure that data is stored securely to minimise the chances of data loss , corruption or unauthorised manipulation . Having information stolen through a hacking attempt, for example, would negatively impact the company and its customers and possibly lead to consequences such as poor publicity , a loss of business and reputation , fines and bankruptcy . One principle of the Data Protection Act is that data must be stored securely . Organisations can use security methods such as firewalls , antiviruses or physical protection such as biometrics to keep personal information secure . Health & Safety Definition: Ensuring that employees, clients and visitors are physically protected on-site . The organisation should create a health and safety policy that staff need to read and possibly sign at the start of their work placement. The policy should include information about how to avoid injury when using the systems, how to safely maintain the equipment and whom to contact for help . Disaster & Recovery Planning Important data is often stored on a computer network, so a detailed and effective disaster recovery policy must be in place in case an unexpected disaster occurs. 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 . Organisational Policies Definition: Creating policies that outline acceptable computer and network use . Workplaces and schools often require people to sign an acceptable use policy ( AUP ) before being allowed to use the network . An AUP may include the philosophy of the organisation , rules for the personal use of IT resources and the consequences of breaching the policy . An AUP is similar to codes of practice from 5.1 . Change Management Definition: Change management is a formal approach by an organisation to lead a change in the way a business or project is run . This may include editing budgets , redefining expected deadlines , reconsidering how resources are used or changing staff roles . Advantages of change management: Reduces the likelihood of things going wrong during development. Creates a clear log of changes and improvements that are to be made. Allows changes to be approved and discussed before they happen. Formalises the process and sets out clear rules for changes . Disadvantages of change management: Can make the process of change more complicated . It can reduce the responsiveness of developers if everything must go through a formal process. It can be challenging to implement successfully. To work effectively, it needs everyone to follow the process . Scales of Change There are two main reasons why major change will occur in an organisation. Change Drivers Definition: Companies must change to stay up to date with the times and new technology . Change drivers are factors that force a business to change , such as: New legislation New competitors in the market New platforms (e.g. mobile technology and game consoles) to sell products on Economic changes Changes in business practice Social changes Change Needs Definition: Companies must change if the needs and focus of the organisation are altered over time . This reflects the changing needs of the business , often due to advancements in technology , such as: New equipment (e.g. replacing a slow network with a faster fibre optics network) Customer interaction (e.g.communicating with customers in new ways, such as social media apps) Workplace shifts (e.g. providing remote access for employees to access work and services at home) Q uesto's Q uestions 5.2 - Operational Issues: 1. Describe 3 possible consequences to an organisation if data is not stored securely . [6 ] 2. Describe the purpose of a health and safety policy and state 3 things that may be included in one. [4 ] 3a. Describe, giving specific examples , different types of possible disaster . [5 ] 3b. Describe the steps an organisation should take before , during and after a disaster occurs . [10 ] 4. Describe 3 things that may be included within an Acceptable Use Policy (AUP ). [3 ] 5a. What is change management ? Give 2 examples of when change management may be used. [4 ] 5b. Describe the advantages and disadvantages of a company deciding to implement change management . [8 ] 6a. Describe the difference between change drivers and change needs . [2 ] 6b. Describe 3 examples of change drivers and 3 examples of change needs . [6 ] 5.1 - Ethical Issues Topic List 5.3 - Threats

Homepage for learning about computer science in school. Discover topics across GCSE and Level 3 IT subjects, plus programming languages including Python, HTML and Greenfoot. C omputer S cience P ros Official 2026 CSPros: Henry C Rohan Finlay Adam Chantel Olivia Jessie Kelvin Lucas Gajanan Danny Marcus José Claudia Charlie Ryan Harry Ethan Henry P Yash Marcus Thomas Walter Folu Asher Pippa Zach Leighton Jess James Holly Zac Ryan 2025 CSPros: Jack Harry Aarav Trisha Mario Hiba Rory Clark Lucy Divya Luke Callum James Zoya Timucin Matthew 2024 CSPros: 2023 CSPros: Henry Zain Iman Alex I-C Alex B Tomos Aidan Rahul Hussain Diyar Sam Harry Will Alex H 2022 CSPros: Logan Eleanor Mark Edward Alfie Henry Enzo Sam George Harry Ella Kav

Learn about the advantages and disadvantages to individuals and organisations when using the internet. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification for Unit 2 (Global Information). 1.7 & 1.8 - Internet Pros & Cons Exam Board: OCR Specification: 2016 - Unit 2 The internet has become easier and cheaper to access since the mid 1990s and today it is almost taken for granted. The rise of the internet, and the services it provides, has lead to advantages and disadvantages for both individuals and organisations . Advantages for Individuals Increased speed of personal communication Allows for instant messaging, emails and video chats across the world. Easy access to information The internet has free resources such as CSNewbs and Wikipedia, plus academic journals for research & study. 24/7 access to services Shopping, browsing and banking can be completed when convenient for the user. Social interaction with others Social media, discussion forums and online games provide entertainment and social interaction. Disadvantages for Individuals Potential for identity theft Uploading personal data and storing sensitive information risks hackers obtaining and utilising it. Cost of connection & services Internet service providers (ISPs) charge a monthly fee and equipment like a router needs installation. Cyberbullying & trolling The abuse of others on social media is possible. Anonymisation makes it harder to catch offenders. Spreading misinformation 'Fake news' or biased information can be easily spread on social media and lead to incorrect assumptions. Source of distraction Staff and students may neglect their work and study for entertainment or social media. Advantages for Organisations Share data quickly globally Files and information can be sent instantly to locations across the world. Cloud storage can store data. Online services always available E-commerce businesses can operate 24/7 globally, permit users to browse and accept payments. Easy internal communication Staff can use emails, video calls or instant messages to communicate. Open up the workplace Staff can work from home, on the commute to/from work and outside of the office. Disadvantages for Organisations Malicious attacks & threats Websites can be hacked / taken offline with DDoS attacks. Data can be stolen or corrupted. Cost of maintaining services Most companies require an IT department to oversee device installation and maintenance. Reputation and controversies Companies that leak data will damage their reputations. Social media posts could backfire. Q uesto's Q uestions 1.7 - Internet Pros & Cons: 1. List 5 points for the following categories (you may need to include researched / your own points for some): a. Advantages of the internet for individuals [5 ] b. Disadvantages of the internet for individuals [5 ] c. Advantages of the internet for organisations [5 ] d. Disadvantages of the internet for organisations [5 ] 1.6 - Information Formats Topic List 2.1 - Information Styles

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

Learn about algorithms for data structures such as stacks, queues, linked lists and trees, as well as how to traverse trees with depth-first and breadth-first traversal methods. Based on the OCR H446 Computer Science A-Level specification. Exam Board: OCR A-Level Specification: Computer Science H446 3.1e - Data Structure Algorithms Watch on YouTube : Stacks Queues Linked Lists Trees Tree traversal Being able to read , trace and write code for data structure algorithms (stacks , queues , linked lists and trees ) is vital. Stacks A stack stores data in a last in , first out (LIFO ) order, meaning the most recently added item is the first one to be removed . It works much like a stack of plates - you can only add or remove from the top . Two integral functions are push and pop . The push operation adds (or “pushes”) a new item onto the top of the stack . The pop operation removes (or “pops”) the item from the top of the stack . Stacks are commonly used in undo features , function calls and expression evaluation , where tracking the most recent item first is important . YouTube video uploading soon Queues A queue stores items in a first in , first out (FIFO ) order, meaning the first item added is the first one removed . New items are added at the rear of the queue using an enqueue operation, and items are removed from the front using a dequeue operation. Queues are often used in task scheduling , print spooling and data buffering , where operations must occur in the same order they were requested . YouTube video uploading soon Linked Lists A linked list is a dynamic data structure made up of a series of elements called nodes , where each node contains data and a pointer to the next node in the sequence . Unlike arrays, linked lists do not store elements in contiguous memory locations , making it easy to insert or delete items without having to shift other elements . The head is the first node in the list , and the last node usually points to null , indicating the end of the list . YouTube video uploading soon Trees A tree is a hierarchical data structure made up of nodes connected by branches , starting from a single root node . Each node can have child nodes , and nodes without children are called leaf nodes . Trees are useful for representing data with natural hierarchies , such as file systems or organisational charts . A binary search tree is a special type of tree where each node has at most two children - a left and a right . All values in the left subtree are smaller than the parent node , and all values in the right subtree are larger . This structure allows for efficient searching , insertion and deletion of data , often much faster than in lists or arrays . YouTube video uploading soon Tree Traversal 'Tree traversal ' refers to the method used to visit every node in a tree data structure in a specific , organised order . Depth-first (also called post-order ) traversal explores a tree by moving as far down one branch as possible before backtracking , visiting nodes in a deep , top-to-bottom manner . It uses a stack to keep track of nodes still to explore , pushing new branches onto the stack and popping them when backtracking . Breadth-first traversal explores the tree level by level , visiting all nodes on one level before moving down to the next . It uses a queue to hold nodes in the order they should be visited , ensuring the traversal expands outward evenly from the root . YouTube video uploading soon This page is under active development. Check here for the latest progress update. Q uesto's K ey T erms Stacks and Queues: stack, queue, last in first out (LIFO), first in first out (FIFO), push, pop, enqueue, dequeue, pointer Linked Lists: linked list, null Trees: tree, binary tree, binary search tree, root node, branch, depth-first traversal, breadth-first traversal D id Y ou K now? Spotify playlists work like linked lists because each song links to the next , allowing tracks to be added , removed or reordered instantly without reshuffling the whole playlist. This makes the app fast and efficient even when handling huge playlists with thousands of songs . 3.1a-d - Algorithm Complexity A-Level Topics 3.1f - Standard Algorithms