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Learn about the importance of client requirement specifications and the need for specific elements such as functional requirements, process constraints and data formats. 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) 4.2 - Client Requirement Specifications Watch on YouTube : Client Requirement Specifications A client requirement specification is a detailed document that outlines what the client needs from a new system . Elements include the new system’s purpose , functional and non-functional requirements , constraints and success criteria . As well as understanding the importance of creating client requirement specifications , you need to know the purpose of each element and how they can be gathered using the methods from section 4.1 . Client Requirement Specifications Elements of Requirement Specifications Specifications ensure developers and stakeholders fully understand what the client wants the system to do , avoiding misunderstandings and costly changes later. There are several elements of client requirement specifications you need to know : Purpose of the new system Current system deficiencies Requirements ( functional and n on-functional ) Data formats Process constraints Version and source control Client-defined constraints Three considerations for data storage location are local/onsite , cloud and physical storage devices . Budget Time Integration Software Hardware Data storage location Q uesto's Q uestions 4.2 - Client Requirement Specifications: 1. Give three reasons why it is important to create a client requirement specification . [8 ] 2. Describe the purpose of each client-defined constraint . [6 ] 3. Describe the difference between functional and non-functional requirements . [ 2 ] Some cloud storage data centres are built in cold climates , such as Sweden and Norway , to reduce cooling costs for servers that run 24/7 . D id Y ou K now? 4.1 - Gathering Client Requirements Topic List 4.3 - Decomposition Methods

Learn about the importance of planning application development projects, including the advantages and disadvantages of planning and the consequences of not planning. Also covers planning considerations such as budget, time, resources, success criteria and legislation. 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) 3.1 - Planning Projects Watch on YouTube : Purpose of Planning Planning Considerations Planning Projects You need to know why it is important to plan an application development project , as well as the advantages and disadvantages of taking the time to plan . You must also consider the potential consequences if a development team decide not to plan their project. There are several considerations (e.g. budget , time and legislation ) that must be looked at in the planning stage and you need to know how these may impact application development . You need to be aware of copyright , data protection and electronic communication legislation , but for this unit , you do not need to know the details of any specific laws . Importance of Planning Projects Planning application development projects is important as it sets clear goals and direction for the project and identifies required resources (e.g. time , money , people and tools ). Other advantages include better organisation , as team members should know their roles and tasks . Also, planning improves time management as deadlines and milestones keep the project on track . However, there are disadvantages to planning as it takes time and can delay the start of development . Also, plans may become outdated if requirements unexpectedly change mid-project . Avoiding planning entirely will have consequences , such as a higher potential for missed deadlines and overrunning costs due to poor time / budget estimates . Goals may be unclear , leading to confusion , delays or an unusable product . Planning Considerations There are several considerations team members must carefully evaluate in the planning phase of application software development : The three types of legislation cover copyright , data protection and electronic communication . Q uesto's Q uestions 3.1 - Planning Projects: 1. A company developing smartphones is considering whether to skip the planning stage and move straight to design. Give two advantages and two disadvantages of planning and two consequences of not planning an application development project . [6 ] 2. Summarise the impact of the three identified types of legislation on application development . [6 ] 3. Justify which planning consideration you think has the biggest potential impact on the success of a software application development project and why . [ 3 ] 4. Describe the impact of three planning considerations (other than legislation and the one you chose in Q3 ) on application development . [6 ] If a company seriously breaches the Data Protection Act , it can be fined up to £17.5 million or 4% of its global turnover , whichever is higher . D id Y ou K now? 2.2 - Phases of Development Models Topic List 3.2 - Project Planning Tools

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 how to use random commands in Python. Try practice tasks and learn through text and images. Perfect for students learning GCSE Computer Science in UK schools. top Python 5a - Random Importing Section 5 looks at additional commands that you can import and use from Python’s code libraries . A library is a collection of different commands that automatically come with Python but are separate from the main file. They can be imported (brought in) to your program by using the import command at the start of your program . Imagine Python’s library to be similar to an actual library. There are different sections in a real library (such as History, Geography, Reference) and different sections in Python’s library (such as random or time ). Each real library has many individual books in each section, just like commands in Python. randint() choice() sample() shuffle() random sleep() ctime() strftime() time from random import randint from time import ctime You can import a specific command from one of Python's libraries using the from and import commands at the top of your program . Random Numbers To generate random numbers , first import the randint command section from Python’s random code library on the first line of the program. The randint command stands for random integer . In brackets, state the number range to randomly choose from. The random value should be saved into a variable . from random import randint number = randint(1,100) print ( "A random number between 1 and 100 is" , number) = A random number between 1 and 100 is 39 = A random number between 1 and 100 is 73 = A random number between 1 and 100 is 4 The randint range does not have to be fixed values and could be replaced by variables . Below is a program where the user selects the upper and lower values of the range: from random import randint lower = int ( input ( "What is the lowest number? " )) upper = int ( input ( "What is the highest number? " )) number = randint(lower,upper) print ( "A random number between" , lower , "and" , upper , "is" , number) = What is the lowest number? 1 What is the highest number? 50 A random number between 1 and 50 is 36 = What is the lowest number? 500 What is the highest number? 1000 A random number between 500 and 1000 is 868 Random Numbers Task 1 ( Ice Comet) A special comet made of ice passes the Earth only once every one hundred years , and it hasn't been seen yet in the 21st century . Use the randint command to randomly print a year between the current year and 2099 . Example solutions: Did you know it won't be until 2032 that the ice comet will next pass Earth!? Did you know it won't be until 2075 that the ice comet will next pass Earth!? Random Numbers Task 2 ( Guess the Number) Use randint to generate a random number between 1 and 5 . Ask the user to enter a guess for the number with int and input . Print the random number and use an if statement to check if there is a match , printing an appropriate statement if there is and something different if there is not a match . Example solutions: Enter a number between 1 and 5: 4 Computer's number: 5 No match this time! Enter a number between 1 and 5: 3 Computer's number: 3 Well guessed! It's a match! Choice - Random Word Rather than just numbers, we can also randomly generate characters or strings from a specified range by using the choice command. You must first import the choice command from the random library. Choice works well with a list of values , which require square brackets and commas separating each word . Below is a program that randomly chooses from a list of animals : from random import choice animals = [ "cat" , "dog" , "horse" , "cow"] randomanimal = choice(animals) print ( "A random animal is" , randomanimal) = A random animal is cat = A random animal is horse Choice - Random Character Instead of using a list you can randomly select a character from a string . The program below randomly selects a character from the variable named 'letters ' which is the alphabet . from random import choice letters = "abcdefghijklmnopqrstuvwxyz" randomletter = choice(letters) print ( "A random letter is" , randomletter) = A random letter is e = A random letter is y Random Choice Task 1 ( Holiday Destinations ) Harriet can't decide where to go on holiday and needs help deciding. Make a list of at least 6 destinations (see the animal example above ) and use the choice command (don't forget to import it from the random library ) to print a random destination . Example solutions: Why don't you go to Paris on holiday? Why don't you go to Barcelona on holiday? Random Choice Task 2 ( Vowels ) Use the choice command to randomly select a vowel (look at the alphabet example above ). Ask the user to input a vowel and use an if statement to check if the user's letter matches the randomly selected letter . Print a suitable statement if they match and something else if they don't . Example solutions: Enter a vowel: i Random vowel: i The vowels matched! Enter a vowel: o Random vowel: u The vowels didn't match! Sample - Random Strings To choose more than one value from a set of data, use the sample command. Sample is used with a list of values and a number representing how many from that list to pick. The code sample(days,2) picks two random values from the list called days . Both examples below perform the same task but, as with most code, there is no one way to solve a problem. from random import sample days = [ "Monday" , "Tuesday" , "Wednesday" , "Thursday" , "Friday" ] two_days = sample(days , 2) print ( "You will be set homework on:" , *two_days) A separate list and then a sample . = You will be set homework on: Thursday Monday = You will be set homework on: Friday Tuesday from random import sample two_days = sample([ "Monday" , "Tuesday" , "Wednesday" , "Thursday" , "Friday" ] , 2) print ( "You will be set homework on:" , *two_days) The list and sample is combined on one line. The sample command actually makes a new list with the number of values selected (e.g. ["Tuesday" , "Thursday"] in the examples above). You can use an asterisk - * - directly before the sampled variable to print just the list values , otherwise the brackets and apostrophes will be printed too. from random import sample names = sample([ "Bob" , "Ben" , "Jen" , "Ken" ] , 2) print ( "The names are:" , names) from random import sample names = sample([ "Bob" , "Ben" , "Jen" , "Ken" ] , 2) print ( "The names are:" , *names) The names are: ['Bob', 'Jen'] The names are: Bob Jen Sample - Random Numbers You can also use the sample command to choose several integers from a given range. By implementing the range command you don’t need to individually write out each number. from random import sample numbers = sample( range (1,100) , 5) print ( "Five random numbers between 1 and 100 are:" , *numbers) Five random numbers between 1 and 100 are: 53 42 11 8 20 Five random numbers between 1 and 100 are: 74 52 51 1 6 Random Samples Task 1 ( Frost Comets) The ice comet from a previous task has broken up into four smaller frosty comets that could pass the Earth anytime from next year to the year 2095 . Print four random years in that range . Example solutions: I predict the frost comets will be seen in these years: 2093 2036 2027 2091 I predict the frost comets will be seen in these years: 2076 2033 2053 2085 Random Samples Task 2 ( Baby Boy ) Aunt Meredith is having a baby boy . Create a program that randomly selects 3 male names from a list of 10 possible names . Example solutions: Hey Aunt Meredith, how about these names: Charlie Eddie Frank Hey Aunt Meredith, how about these names: George Harold Bill ⬅ Section 4 Practice Tasks 5b - Sleep ➡

Learn about the motherboard and the components that are connected to this important piece of computer hardware. The Motherboard What is a motherboard? The motherboard is the main circuit board of a computer that links all other components together. Components can communicate by sending signals and data across pathways called buses . Some components, like the CPU and RAM , are directly installed in special sockets on the motherboard . There are expansion slots for further components like a graphics card . What is connected to the motherboard? Central Processing Unit Random Access Memory Graphics Processing Unit Read Only Memory Cache Memory Sound Card Hard Disk Drive Power Supply Unit What is a motherboard's form factor? Form factor relates to the motherboard's size , shape and how many components it can fit . The three most common form factors are compared below: ATX Micro ATX Mini ITX Standard Small Very Small 32 GB 64 GB 128 GB 7 4 1 Size Max RAM Expansion Card Slots GB stands for gigabytes What ports does a motherboard have? The motherboard contains several ports on the back panel , allowing cables to be connected to input or output data . Below are some of the common ports : USB (Type-A) Connects input devices like keyboards and mice or storage devices like a USB memory stick. USB (Type-C) A newer type of USB that is faster and commonly used to charge devices or transfer data. Ethernet Allows a device to connect to a wired network, most commonly to a router, for internet access. HDMI Connects to a monitor or TV to show the computer's audio and visual output. KS3 Home

Learn about the advantages and disadvantages of different types of software including open-source, closed-source, off-the-shelf and bespoke. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification. 2.1: Software Types Exam Board: OCR Specification: 2016 - Unit 1 Software refers to the programs and applications that run on a computer system. Open Source Software Source code is the software code written by programmers . If the software is open source it means that users can view and modify the code . Linux, Python and Firefox are examples of open source software. Benefits Drawbacks Because the source code is available to edit , it can be customised to the organisation's needs . Often shared in the public domain so users can work together to modify, debug and improve a product. Unwanted features can be removed to make the software run faster . There are security risks - some editors may add malicious code to the program. Open source software is often low in price and sometimes free. It may be difficult to receive support as development is often distributed between people in different locations. The code may be prone to errors as it may not have been tested fully. It requires technical skills to be able to adapt source code efficiently and to maintain the code . Closed Source Software If the software is closed source it means the code is restricted for users to view or modify . You buy the right to use the software but you don't actually own it. Microsoft Office, Fortnite and Spotify are examples of closed source software. Closed source software is also known as proprietary software because it is another company's property and protected by law. Benefits Drawbacks The code is well tested and has been professionally developed. Updates will generally be secure . Users must rely on the company to provide updates and fix issues. This might be infrequent or stop completely. The company can be held to account if it does not perform as listed in the terms and conditions upon purchase. Often not free (see Freeware below for free closed source software). Most developers will provide some form of help/support . Users cannot modify, debug or improve the code for their own benefit. Off-the-Shelf Software This is any software made for general use , with features that can be used in different ways and for different purposes . Examples include office software (e.g. Microsoft Office), video games (e.g. Minecraft) and image editors (e.g. Adobe PhotoShop). Back before internet downloads, people had to actually go to shops and buy software off the shelf and install it at home, hence the name. Benefits Drawbacks Should have been tested thoroughly so users can be confident that features will work as expected . Secure updates will be regular. It can be expensive to purchase some software , especially for a single user rather than a business. Some software, such as anti-virus protection, requires yearly licenses . It can be cheaper to purchase than bespoke software as it is not customised for a specific user or organisation. The software may contain additional features that the user / organisation doesn’t need which can reduce the performance of the system. The end users might be familiar with the software and trust the company (e.g. Microsoft Word). Bespoke Software This is any software that has been custom made for a specific organisation or user. For example, programmers might be hired by a company to create software for a specific task. Hospitals and schools use bespoke software to track and manage patients / students. It can be expensive to commission bespoke software as programmers and user interface designers need to be hired and there could be issues with rights to any created software. Benefits Drawbacks The software is built to the company's requirements , it is unique to their needs. Unwanted features can be removed to make the software run faster . Bespoke software is expensive to develop because it is tailor-made for the company. Staff may require training on using the system because it is unique . The look of the software (e.g. design & layout ) can be customised to fit the company's image. Because it has been custom-made, the original programmers may be needed to maintain the software and fix errors . Shareware This software allows the user to trial the program for a limited time before forcing them to buy the product or stop using it. For example, WinRAR is utility software that asks the user to buy the full version after 40 days. This allows the user to get a taste of what the software offers before choosing whether to buy it fully or not . Freeware This is software that is freely available to download and use . These are usually closed-source software that earn money through adverts or additional purchases. Rights to the software remain with the author despite the free access. App developers may release their app as freeware to allow users to try the software and then encourage them to purchase a full version with more features. Unlike shareware, the user should be able to keep using the product for free indefinitely, though their version may have features restricted or adverts enabled. Examples of freeware software include iTunes , Clash of Clans and Adobe Acrobat Reader (for PDFs). Embedded Software An embedded system is when a smaller computer system is installed within a larger device , such as a washing machine, traffic light or car. Embedded systems have a dedicated purpose and often run in real-time . Because of the small size, the embedded software will usually have memory and storage restrictions . Q uesto's Q uestions 2.1 - Software Types: 1. Describe the 7 types of software , listing the advantages and disadvantages of each. a. Open Source b. Closed Source c. Off-the-Shelf d. Bespoke e. Shareware f. Freeware g. Embedded [6 each ] 1.8 & 1.9 - Number Systems Topic List 2.2 - Applications Software

Learn about how images are represented in a computer system, including vector and bitmap graphics, file size, resolution, colour depth and metadata. Based on the 2020 Eduqas (WJEC) GCSE specification. 4.6: Graphical Representation Exam Board: Eduqas Specification: 2020 There are two main types of graphics used in computer systems: raster (also known as bitmap ) and vector graphics. Raster (Bitmap) Graphics Vector Graphics Raster graphics are made up of a grid of pixels . Vector graphics use objects (lines and curves ) to mathematically form shapes. If scaled to a larger size, a vector graphic does not lose any image quality . If scaled to a larger size, a raster graphic loses image quality . Raster graphics are generally larger in file size because data is stored for each pixel . Vector graphics are generally smaller in file size . Examples of raster images include photographs and screenshots. Examples of vector graphics include logos and cartoons. How to Calculate File Size File Size = Resolution x Colour Depth The resolution of an image is the width in pixels multiplied by the height in pixels. x The colour depth (also known as bit depth ) is the number of bits that are used to represent each pixel's colour . 1 bit represents 2 colours (0 or 1 / black or white). 2 bits will allow for 4 colours, 3 bits for 8 colours, 4 for 16 etc. A colour depth of 1 byte (8 bits ) allows for 256 different colours . Remember you must multiply the colour depth , not the number of available colours (e.g. 8 not 256). The RGB (Red , Green , Blue ) colour model uses 3 bytes (a byte of 256 red shades , a byte of 256 green shades and a byte of 256 blue shades ) that together can represent 16.7 million different colours. Example Height = 6 bits Resolution = height x width Resolution = 8 x 6 = 48 bits -------------------------- Colour Depth = 1 bit (only 2 colours) -------------------------- File Size = Resolution x Colour Depth File Size = 48 x 1 = 48 bits File Size in bytes = 48 ÷ 8 = 6 bytes File Size in kilobytes = 6 ÷ 1000 = 0.00 6 kilobytes Width = 8 bits Look carefully at the exam question to see if the examiner is expecting the answer in bits, bytes or kilobytes . Always calculate the file size in bits first then: Divide the file size in bits by 8 to convert to bytes . Divide the file size in bytes by 1000 to convert to kilobytes . Metadata for Graphics Metadata is additional data about a file . Common image metadata includes: Dimensions Colour depth Make Model Orientation Exposure time Metadata is important, For example, the dimensions must be known so the image can be displayed correctly . Metadata for a smartphone-taken picture: width in pixels, e.g. 720 height in pixels, e.g. 480 Q uesto's Q uestions 4.6 - Graphical Representation: 1. Describe three differences between raster (bitmap) and vector images . [ 6 ] 2. How many colours can be represented with a colour depth of... a. 1 bit [ 1 ] b . 5 bits [ 1 ] c. 1 byte [ 1 ] 3. How is the file size of an image calculated? [2 ] 4a. An image file has a width of 10 pixels , a height of 8 pixels and a colour depth of 2 . What is the file size in bytes ? [3 ] 4b. An image file has a width of 120 pixels , a height of 120 pixels and a colour depth of 1 . What is the file size in kilobytes ? [3 ] 4c. An image file has a width of 32 pixels , a height of 21 pixels and a colour depth of 1 . What is the file size in bytes ? [3 ] 5. State what is meant by metadata and give three examples of metadata for a graphics file. [ 3 ] 4.5 Character Sets & Data Types Theory Topics 4.7 - Sound Representation

Learn about digital methods of protecting data such as anti-malware, firewall, usernames and passwords, levels of access and encryption. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification. 5.5 - Digital Security Exam Board: OCR Specification: 2016 - Unit 1 ****** Usernames & Passwords Usernames must be matched with a secure password to minimise the chances of unauthorised users accessing a system. Passwords should contain a mix of uppercase and lowercase letters , punctuation and numbers . Passwords should be of a substantial length (at least 8 characters) and should be regularly changed . Digital Security Measures Firewall Firewalls (see 2.3 ) prevent unauthorised access to or from a network . Firewalls filter data packets and block anything that is identified as harmful to the computer system or network. Firewalls can also be used to block access to specific websites and programs. Encryption Encryption is the conversion of data ( plaintext ) into an unreadable format ( ciphertext ) so it cannot be understood if intercepted . Encrypted data can only be understood by an authorised system with a decryption key . Anti-Malware Anti-virus software (see 2.3 ) scans a system and removes viruses . If left to infect a system a virus could delete data or permit access to unauthorised users . Anti-spyware software removes spyware on an infected system so hackers cannot view personal data or monitor users. Organisations should install and regularly update anti-virus and anti-spyware programs. Permissions Permissions is the creation of different levels of file access so that only authorised people can access and change certain files . There are different levels of file access : No access Read-only Read/write Q uesto's Q uestions 5.5 - Digital Security: 1a. Describe why usernames and strong passwords are necessary. [2 ] 1b. State 3 rules for choosing a strong password . [3 ] 2. Describe the purpose of anti-virus and anti-spyware software. [4 ] 3. Describe the roles of a firewall . [4 ] 4. Explain what encryption is. [3 ] 5. What are permissions ? What are the 3 levels of access ? [5 ] 5.4 - Physical Security Topic List 5.6 - Data & System Disposal

Learn about the different phases in software development models including planning, requirements, feasibility, design, construction / creation, testing, implementation (phased / parallel / big bang (crash)), documentation creation and maintenance. 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) 2.2 - Phases of Software Development Models Watch on YouTube : Phases of Software Development Models There are seven phases of software development models you need to know. As well as knowing the common phases and the key tasks within each phase , you must also understand how and why phases interact with each other and why they may iterate . Phases of Software Development Models Key Phases Planning (including requirements and feasibility ) Design Construction / Creation Testing Implementation (including phased , parallel and big bang ( crash ) methods) Maintenance Documentation creation Phased Parallel Big Bang Q uesto's Q uestions 2.2 - Phases of Software Development Models: 1. Describe the common tasks in each of the first four phases of software development . [8 ] 2. Explain the three implementation methods : phased , parallel and big bang (crash ). [6 ] 3. Describe the common tasks in the final two phases . [4 ] 4. Explain why it is important that phases interact with each other. [ 2 ] Maintenance is important - as of 2025 , some US air traffic control towers still use and maintain systems using Windows 95 and floppy disks because of their reliability . D id Y ou K now? 2.1 - Software Development Models Topic List 3.1 - Planning Projects

Learn how to easily remove objects in Greenfoot in only two lines of code. Part 4 of the Greenfoot Tutorial for the Eduqas / WJEC GCSE 2016 specification. 4. Remove Objects Greenfoot Tutorial 1. Removing Objects Watch on YouTube: Open the editor for your main character . Underneath the if statements for using the arrow keys is where we type the removal code . If you have chosen a different collectible object, type the exact name of that class instead of Orange (e.g. Apples or Ants). 2. Add Danger to your Game Use the same code as you did earlier but change the class (instead of Orange. class I have chosen Sheep. class ). Time to code your main character to be removed if they are touched by the enemy objects ! Open the editor for your enemy class . The removal code is placed beneath the code you have already written. Check out the extension page if you want the game to stop when the main character is removed. < Part 3 - Random Movement Part 5 - Play Sounds >

Learn about the different protocols used to transfer data across a network, including TCP/IP, FTP, SMTP and Ethernet. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification. 2.7 - Protocols Exam Board: OCR Specification: 2016 - Unit 1 What is a protocol? A protocol is a set of rules that allow devices on a network to communicate with each other . Protocols to Transfer Data: TCP / IP / UDP TCP ( Transmission Control Protocol ) breaks data down into small packets to be transferred across a network and reorders them back into the original data at the destination . TCP checks for errors when sending data packets, which makes it slower than UDP for data transfer, but it guarantees that no packets have been lost on the way. IP ( Internet Protocol ) is in charge of routing and addressing data packets to ensure data is transferred across networks to the correct destination . It is also an addressing system - every device on a network is given a unique IP address . TCP and IP are often used together to transfer data across the internet. UDP ( User Data Protocol ) is a faster alternative to TCP for transferring data. It is used where low latency ('low lag') is important, such as online gaming and video chat . However, UDP does not automatically check for errors so packets are more likely to be lost or received out of order . HTTP is a protocol that can be used to transfer web pages on the world wide web so that users can view them in a web browser . All URLs start with either HTTP or HTTPS (e.g. https://www.csnewbs.com ). HTTPS is a more secure version of HTTP that works with another protocol called SSL (Secure Sockets Layer ) to transfer encrypted data . You should see a padlock symbol in the URL bar if your connection to that website is secure. HTTP/HTTPS (Hyper Text Transfer Protocol) FTP (File Transfer Protocol) FTP ( File Transfer Protocol ) is used to transfer files across a network. It is used most often to upload or download files to/from a file server . ICMP ( Internet Control Message Protocol ) collects network status information (such as router errors) and is used for troubleshooting . SNMP ( Simple Network Management Protocol ) is a protocol that records network statistics , such as router usage . Network Management Protocols Email Protocols SMTP ( Simple Mail Transfer Protocol ) is a protocol used to send emails to a mail server and between mail servers . POP ( Post Office Protocol ) is for downloading and storing emails from a mail server. TCP/IP Protocol Stack The TCP/IP protocol stack is a model split into 4 layers . The model is used to visualise the different parts of a network as each of the four layers has a specific role . Splitting a network design into layers is beneficial to programmers as it simplifies design , making it easier to modify and use . Each layer has a certain purpose and is associated with different protocols . 4 Allows humans and software applications to use the network e.g. browsers (HTTP /HTTPS ), email (SMTP / POP ), file transfer (FTP ) and network management (SNMP ) applications. 3 TCP breaks the data down into data packets . This layer makes sure the data is sent and received in the correct order and reordered at the destination without errors. UDP can also be used for faster , but less reliable , data transfer . 2 The network layer is also known as the ' Internet Layer '. IP is responsible for addressing and routing data packets . The optimal route for the data to take is calculated in this layer. ICMP may be used here for network monitoring . 1 This layer handles transmission errors and passes data to the physical hardware such as routers . It also sets out the final format of data packets . Q uesto's Q uestions 2.7 - Protocols: 1. Describe each of the following protocols . Also, state the protocol's full name and draw an icon or diagram for each: a. TCP b. IP c. UDP d. HTTP & HTTPS e. FTP f. ICMP g. SNMP h. SMTP i. POP [1 each ] 2. State which protocol would be used in the following scenarios: a. Transferring a music file to a friend over the internet. b. Sending an email to a friend in Japan. c. Checking for errors on a network. d. Having a video call with a colleague in London. e. Receiving an email from the bank. f. Watching a video on YouTube. g. Checking the statistics of usage on a network [1 each ] 3. Summarise each layer of the TCP/IP stack and identify the protocols used in each layer . [ 8 ] 2.6 - Software Troubleshooting Topic List 3.1 - Server Types

Learn about how to perform binary addition and binary subtraction. Based on the 2020 Eduqas (WJEC) GCSE specification. 4.3: Binary Calculations Exam Board: Eduqas Specification: 2020 What are binary calculations? Binary addition and binary subtraction are methods of adding or subtracting binary values without having to convert them into denary. How to add binary numbers: How to subtract binary numbers: Overflow & Underflow Errors Overflow and underflow errors occur when there is not enough space to accurately represent a binary number in the bits available . What is an overflow error? An overflow error occurs when a binary value is too large to be stored in the bits available . In technical terms, an overflow error occurs if a carry (remainder) is present on the most significant bit (MSB ). The CPU then sets the overflow flag to true . The most significant bit (MSB ) is the largest bit (always the one furthest to the left ) of a binary value (e.g. 128 for an 8 bit value). A flag is an alert signal . It is either on or off. The overflow flag is turned on by the CPU when an overflow occurs. What is an underflow error? An underflow error occurs when a number is too small to be stored in the bits available . The value is too close to 0 to be accurately represented in binary. Q uesto's Q uestions 4.3 - Binary Calculations: 1a. Describe the terms ' most significant bit ' and ' flag '. [ 2 ] 1b. Using the terms from 1a , explain what an overflow error is. [ 2 ] 1c. Describe what is meant by an underflow error . [ 2 ] 2. Add together the following binary values. If an overflow error occurs you must state one has occurred. a. 010110012 and 010001012 [2 ] b. 110110112 and 010111012 [2 ] c. 001101102 and 011010112 [2 ] d. 110110112 and 010101112 [2 ] e. 011011012 and 110101102 [2 ] 3. Subtract the following binary values; put the first value on top of the second value: a. 100110102 and 000110002 [2 ] b. 110110112 and 010111012 [2 ] c. 011101102 and 011010112 [2 ] d. 110110112 and 010101112 [2 ] e. 111011012 and 110101102 [2 ] Watch on YouTube Watch on YouTube 4.2 Signed Binary Theory Topics 4.4 - Arithmetic Shift