Learn about the different protocols used on networks - HTTP, HTTPS, TCP, IP, FTP and SMTP. Also learn about protcol layers in the 4-layer TCP/IP model. Based on the J277 OCR GCSE Computer Science specification (first taught from 2020 onwards). 3.2b: Protocols & Layers Exam Board: OCR Specification: J277 Watch on YouTube : IP & MAC Addresses Protocols & Standards Common Protocols Protocol Layers Protocols A protocol is a set of rules that allow devices on a network to communicate with each other . TCP / IP (Transmission Control Protocol / Internet Protocol) TCP / IP is actually two separate protocols that combine together. TCP is a protocol that allows packets to be sent and received between computer systems. It breaks the data into packets and reorders them back into the original data at the destination. IP is a protocol in charge of routing and addressing data packets . This ensures data packets are sent across networks to the correct destination . It is also an addressing system - every device on a network is given a unique IP address so data packets can be sent to the correct computer system. HTTP is used to transfer web pages over the Internet 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 (Hypertext Transfer Protocol) Transfer Protocols FTP ( File Transfer Protocol ) is used to transfer files across a network. It is commonly used to upload or download files to/from a web server . SMTP ( Simple Mail Transfer Protocol ) is a protocol used to send emails to a mail server and between mail servers . POP ( Post Office Protocol ) and IMAP (Internet Message Access Protocol ) are both protocols for receiving and storing emails from a mail server. POP will delete an email from the email server once it has been downloaded to a device . Pop! IMAP syncs the message with an email server so it can be accessed by different devices . IP Address & MAC Address There are two versions of IP addressing currently used - IPv4 and IPv6 . IPv4 is a 32-bit address , represented in denary , that allows for over 4 billion unique addresses . It has four 8-bit segments of denary values (from 0 to 255) separated by full stops . IPv4 example: 145.13.218.102 IPv6 is a 128-bit address , represented in hexadecimal , that allows for an undecillion unique addresses . It has eight 16-bit segments of four hexadecimal values (0000 - FFFF), separated by colons . IPv6 example: 736E:1029:A4B3:902D:77B2:72FF:AE62:0912 A MAC address is a unique hexadecimal number assigned to each network interface card/controller inside a networked device such as a router or laptop . A MAC address is a 48-bit address made up of six 8-bit pairs in hexadecimal , separated by dashes . While an IP address may change , the MAC address can’t be changed . MAC stands for Media Access Control . Network Interface Card (NIC) MAC example: 19-C2-D1-47-AA-38 Networking Standards Networking standards are rules that allow computer systems to communicate across networks . Standards have been created to ensure devices can exchange data and work together by interpreting signals in the same way , regardless of the manufacturer . TCP/IP Stack & Layers What is TCP/IP? TCP/IP (Transmission Control Protocol / Internet Protocol ) is a set of protocols that operate on different layers . These two protocols are used together to allow computers to communicate on a network . What is a protocol layer? A layer is a division of network functionality - each layer provides a specific function to assist the transmission of the data that is being sent. TCP/IP is split into four layers (named Application , Transport , Internet and Link ). Important Note: You do not need to know any layer names or the purpose of any specific layers in the OCR GCSE J277 specification , just what layers are and why they’re used . Why are protocol layers used? Layers are self-contained , so they allow different developers to concentrate on one aspect of the network at a time . A layer can be taken out and edited without affecting other layers . Protocol layers are used to visualise the different parts of a network , as each of the four layers of TCP/IP has a specific role and is associated with different protocols . Protocols are broken down into well-defined , specific layers to simplify design , making it easier to identify errors (known as troubleshooting ). Each layer uses specific protocols , so layering ensures these protocols are applied in a specific order . This process uses abstraction and layers only communicate with adjacent layers for easy compatibility . Q uesto's Q uestions 3.2b - Protocols & Layers: 1. Describe each of the following protocols . It might be helpful to also draw an icon or small diagram for each one: a. TCP [ 2 ] b. IP [ 2 ] c. HTTP & HTTPS [ 3 ] d. FTP [ 2 ] e. SMTP [ 2 ] f. POP3 & IMAP [ 2 ] 2. State which protocol would be used in the following scenarios : a. Transferring a music file to a friend over the internet. [ 1 ] b. Sending an email to a family member in America. [ 1 ] c. Using a webpage to enter a password securely. [ 1 ] d. Receiving an email from a bank. [ 1 ] 3a. What are networking standards ? [ 2 ] 3b. What is TCP/IP ? [ 2 ] 3c. What is a protocol layer ? [ 2 ] 3d. Give at least two reasons why protocols are split into layers . [ 4 ] 3.2a - Wired & Wireless Networks Theory Topics 4.1 - Security Threats

Learn about the different types of data and information sources. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification for Unit 2 (Global Information). 5.1 - Data Types & Sources Exam Board: OCR Specification: 2016 - Unit 2 Sources of Information Internal Source Information that comes from within an organisation , such as financial reports, data analysis or employee surveys. External Source Information that comes from outside of an organisation , such as government reports, financial data of competitors or price lists from suppliers. Types of Data Primary Data Data that has been created and collected by yourself or another employee within an organisation . For example, interviews or questionnaires sent within the company. Secondary Data Data that has been created and collected by someone outside of the organisation , such as national census data collected by the government or surveys taken by a competitor. Some secondary data may need to be purchased . Qualitative Data This is descriptive data , often composed of text , that can be observed but not measured . For example, survey responses where customers are asked why they visit a particular shop. Quantitative Data This is measured data , often in the form of numbers , percentages or statistics . For example, survey responses of the amount of time it takes to reach a shop. Q uesto's Q uestions 5.1 - Data Types & Sources: 1. A supermarket wants to find out how many of their customers have bought peaches this year compared to customers at a rival shop . Describe data that they could use for each of the source and data types below (e.g. stock information for peaches in the supermarket would be an internal source of information). Internal source External source Primary data Secondary data Qualitative data Quantitative data [6 ] "Why do you visit this supermarket?" 'Because it is close to home.' 'I like the easy access to parking.' 'I've always gone here.' "How many minutes does it take you to get here ?" 10 25 30 4.3 - Green IT Topic List 5.2 - Data Flow Diagrams

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 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 the characteristics, diagrammatic representations, advantages, disadvantages, and suitability of software development models. These include the waterfall, rapid throwaway, incremental, evolutionary, rapid application development (RAD), spiral and agile models. Resources 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) 2.1 - Software Development Models Watch on YouTube : Software Development Models Waterfall Rapid Throwaway Incremental Evolutionary Rapid Application Development Spiral Agile There are seven software development models you need to know : Traditional models: Waterfall Prototype models: Rapid Throwaway , Incremental , Evolutionary Iterative models: Rapid Application Development (RAD) , Spiral , Agile For each development model , you need to know : Its characteristics . How to represent it in a diagram . Its advantages and disadvantages . The types of development it is suitable for. Software Development Models Each development model has its own video below but you also need to know the advantages and disadvantages of using development models in general. Waterfall Model The waterfall model is a linear and structured approach where each phase is completed one at a time in order . It needs all requirements to be clearly defined at the start , with little to no changes allowed once a phase is finished . This model is best suited for projects with fixed requirements and minimal risk of change . Rapid Throwaway Prototype Model The rapid throwaway prototype model involves quickly creating temporary prototypes to explore ideas and gather user feedback before building the final system . Prototypes are discarded after they help refine requirements , and are especially useful in projects where user needs are initially unclear . This model is suitable when user interaction and efficient interface design are critical . Incremental Model The incremental model develops a system in small , manageable sections with each part being designed , built and tested individually . Functionality is added step by step until the full system is complete . This approach allows for early partial deployment and easier handling of changing requirements over time. Evolutionary Prototype Model The evolutionary prototyping model involves building an initial prototype that is continuously improved based on user feedback until it becomes the final system . Unlike throwaway prototyping, the prototype is not discarded but gradually evolves into the full product , once the user is satisfied . This model is ideal when user requirements are expected to change or develop over time . Rapid Application Development (RAD) The rapid application development ( RAD ) model focuses on quickly building software through iterative development and frequent user feedback . It uses reusable components , time-boxing and constant feedback to speed up the delivery of an effective final product . RAD is best suited for projects that need to be completed quickly and where requirements can evolve during development . Spiral Model The spiral model combines iterative development and risk management , progressing through repeated cycles of planning , risk assessment , engineering ( development and testing ) and evaluation . Each loop focuses on identifying and addressing risks early in the project. It is ideal for complex and high-risk projects where requirements may change over time . Agile Model The agile model is an iterative and flexible approach that progresses in small , usable chunks called iterations (or sprints ). It relies on frequent collaboration with stakeholders and user feedback to adapt to changing requirements . This model is ideal for dynamic projects where quick delivery and frequent updates are important. Q uesto's Q uestions 2.1 - Software Development Models: 1. Choose three development models to explain and draw a diagram for each. [6 ] 2. A large company is making the next sequel in a hugely popular video game series , FieldBattle 2043 . Justify which application development model(s) they should use (and which they shouldn't ). [5 ] 3. Describe the advantages and disadvantages of any development models you have not covered in Q1 or Q2 . [6 ] Agile development is named after the ' Agile Manifesto ' - a set of principles for software development agreed by a group of developers at a ski resort in Utah , USA in 2001 . D id Y ou K now? 1.3.3 - App. Software Types Topic List 2.2 - Phases of Development Models

Learn about utility software including antivirus, firewall, compression, disk partitioners, defragmenters, backup and file managers. Based on the 2020 Eduqas (WJEC) GCSE specification. 6.2: Utility Software Exam Board: Eduqas Specification: 2020 What is utility software? Utility software are dedicated programs used for the maintenance and organisation of a computer system. Antivirus Antivirus software is used to locate and delete viruses on a computer system. The antivirus scans each file on the computer and compares it against a database of known viruses . Files with similar features to viruses in the database are identified and deleted . Firewall A firewall manages incoming and outgoing network traffic . Each data packet is processed to check whether it should be given access to the network by examining the source and destination address . Unexpected data packets will be filtered out and not accepted to the network. Disk Defragmenter As files are edited over time they will become fragmented - this is when the file is split into parts that are stored in different locations on the hard disk drive . Files that are fragmented take longer to load and read because of the distance between the fragments of the file. Defragmentation software is used to rearrange the file on the hard disk drive so that all parts are together again in order. Defragmentation improves the speed of accessing data on the hard disk drive. Backup Software System backup copies data onto a separate storage device in case the original information is lost or corrupted . Backups should be saved regularly and stored in a different location to the rest of the data. Magnetic tape is a common backup medium. A typical backup policy is one known as 'grandfather - father - son' which uses three different backups at a time. Disk Compression Compression is the process of decreasing the size of a file . Disk compression is a utility tool that automatically compresses files when saved so that more data can be stored on the hard disk drive. When a file is to be opened, the program is automatically decompressed . Disk compression increases the amount of space on a hard disk drive but it takes longer to open and close files . Disk Checker This utility is used to scan a hard drive for any corrupted data . The corrupted data is deleted to speed up reading from and writing to the hard drive. More advanced disk checkers are used to scan for bad sectors . A bad sector is a permanently damaged section of the hard drive which can no longer be used and must be skipped over. Disk Formatter Disk Partition Editor This utility tool prepares a storage device such as the hard disk drive to be used by removing the current data and creating a file system . A file system manages how data is stored and accessed . Other devices like a USB stick may need to be formatted before they can be used for the first time . Within memory, partitions are segments of data that have been grouped together logically on the hard disk drive . A disk partition editor allows a user to view and modify these memory partitions . Options include creating, editing and deleting partitions. Clipboard Manager The clipboard is a temporary storage space for copied data. For example, a large amount of text can be copied and stored on the clipboard to be pasted into another document, even when the original file has been closed . The clipboard manager adds more functionality to the clipboard to allow multiple pieces of data to be copied, cut and pasted . System Profiles A system profiler displays detailed information about the applications on a computer system, as well as data about any attached hardware devices . Information is provided and updated in real-time about the performance of software and internal components such as the CPU . Data Recovery Data recovery tools allow deleted, corrupted or otherwise inaccessible data to be returned to a usable state . The data loss may have been caused by physical damage to a drive, corrupt memory partitions or accidental deletion . Most data is not permanently removed when it is deleted so data recovery software can often be used to reaccess files . Revision Control Revision control software manages previous versions of an application so that if an error occurs the program can be returned to a previous state . This is also called version control software and can be used to manage and monitor changes made to files over time. Archiver Archiving is the process of storing important data that is not currently required . It must not be deleted but it shouldn't take up valuable storage space either. An archiver compresses multiple files using lossless compression into one folder . This archived folder can be stored on a computer system or transferred to a storage device and won't take up much space . Cryptographic Utilities A cryptographic utility is used to encrypt data so that it cannot be understood if intercepted . Encryption is commonly for data in transit - being sent between devices . Cryptographic software can also encrypt data at rest - when stored on a hard disk drive for example - so that hackers would be unable to use the data . File Manager This utility tool provides an interface to the user for accessing, editing and moving files and folders on the system. Programs will be displayed in a hierarchical ( ordered ) structure with icons representing the application logo or file type. Files can be ordered in alphabetical, chronological or other orders and the manager provides an abstracted visualisation of where the data is stored. Q uesto's Q uestions 6.2 - Utility Software: 1. What is meant by utility software ? [1 ] 2. Describe each type of utility software : a. Antivirus b . Firewall c . Disk Defragmenter d . Backup Software e . Disk Compression f . Disk Checker g . Disk Formatter h . Disk Partition Editor i . Clipboard Manager j . System Profiles k . Data Recovery l . Revision Control m . Archiver n . Cryptographic Utilities o . File Manager [2 ] 6.1 - Operating Systems Theory Topics 7.1 - Language Levels

Learn about different types of tools used in the data analysis process including data visualisation, data cleaning and GIS. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification for Unit 2 (Global Information). 3.5 - Data Analysis Tools Exam Board: OCR Specification: 2016 - Unit 2 The fifth stage of data analysis is to select the most appropriate tools to analyse the collected data. The method(s) selected will depend on the type of project and the established objectives. Data Tables Databases are often split into tables to be easier to update , view and manipulate . For example, a supermarket database may include a table of product information, another table of suppliers and another for actual stock levels. Separating the data into tables allows for simpler editing and also allows for the display of basic patterns . For example, looking at a table of stock levels in a supermarket can quickly show which products need to be ordered in as they are close to selling out. Data tables allow for the most simple form of pattern discovery and are a good method of speedy, short-term data analysis . However they present data in its current format and cannot show change or trends over time - a product may have a high stock level because it is popular and has just been ordered in, rather than because no-one is buying it. A simplified data table for a supermarket. Visualisation of Data Visualising data (by producing a chart or graph of collected data for example) makes it easier for an audience to see trends and patterns . Visualising data, like the bar chart to the right of the supermarket table from the tool above, makes it easier to understand and quicker to interpret . In this example, It is easier to see using the chart that steak pies are low in stock and should be re-ordered soon. A bar chart of the supermarket data table. Trend & Pattern Identification This tool links heavily to visualisation of data in allowing trends and patterns to be viewed as a visual format - such as producing a line graph of last year’s stock sales. Statistical analysis allows data analysts to examine numerical data and, if done correctly, can highlight relationships between different data elements - such as the price of a product and how many have been sold. Discovering links between variables is known as regression analysis . Data Cleaning Data cleaning ensures that any stored data is up-to-date and accurate , in accordance with the Data Protection Act ( 2018 ). Forms of data cleaning include removing customers who have not made a purchase in a certain amount of time (e.g. two years) and periodically checking that user addresses are up to date. Data cleaning would reduce the size of any data table by removing redundant, incorrect or unnecessary data . This would make it easier to work with the data table and would improve the data quality by removing erroneous and irrelevant data. GIS / Location Mapping Geographic Information Systems (GIS ) can be used to add geographic data to any analysis. For example, an organisation can track the geographical location of items or staff e.g. tracking the movement of shipping containers around the world to see production flow. This also works for courier services to see delays and delivery times in real-time . Q uesto's Q uestions 3.5 - Data Analysis Tools: 1. Describe how Fresh Food UK, from the question in 3.4 , could use each of the data analysis tools when trying to determine and present the most profitable stores across the country in the past year . a. Data Tables [3 ] b. Visualisation of Data [3 ] c. Trend & Pattern Identification [3 ] d. Data Cleaning [3 ] e. GIS / Location Mapping [3 ] 3.4 - Stages of Data Analysis Topic List 3.6 - Information Systems

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 about the devices used to host applications, including consoles, desktops, haptics, laptops, servers, smart devices, tablets / hybrid devices and wearables. 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 1.2 - Devices Watch on YouTube : Devices You need to know the characteristics of the eight types of devices shown below that application platforms run on . You must also understand the advantages and disadvantages of each device . What You Need to Know Devices Game consoles are designed specifically for playing video games , usually connected to a TV . Desktops are powerful and customisable personal computers designed for use at a desk . Haptic devices allow users to feel vibrations with touch . Game controllers and smartphones use haptics. Laptops are portable computers with a built-in screen and keyboard , suitable for work on the go . Servers are powerful computers on a network that process requests sent by other systems. Smart devices connect to a network allowing it to communicate with other devices and be controlled remotely . Tablets use a large touchscreen and are more portable than a laptop , ideal for browsing and media . A hybrid device is a laptop with a detachable screen . Wearable devices such as a smartwatch are worn on the body and often monitor the user's condition in real-time . Q uesto's Q uestions 1.2 - Devices: 1. Choose the most appropriate device and explain your answer. [3 each ] a. A graphic designer needs maximum performance and wants to upgrade components over time . b. A student needs a computer to take to lessons and complete homework . c. A hospital wants to provide files and applications to hundreds of staff members . d. A gamer wants the easiest and cheapest way to play the latest games . e. An engineer is designing a virtual reality training simulation . f. A fitness enthusiast wants to track their heart rate and daily exercise . g. A salesperson needs a lightweight device for presentations and note-taking . h. A family wants a device for watching movies and using apps around the house . 2. Compare the following pairs . For each comparison , explain one similarity , two differences and which you would recommend for a given purpose. [ 4 each ] a. Desktop vs Laptop b. Laptop vs Tablet/Hybrid c. Console vs Desktop d. Smart Device vs Wearable Check out the Shorts on the CSNewbs YouTube channel if you are interested in how video game consoles have evolved over time . There are separate videos for PlayStation , Xbox and Nintendo consoles. D id Y ou K now? 1.1 - Application Platforms Topic List 1.3 - Storage Locations

Learn about how to perform binary addition and binary shifts. Based on the J277 OCR GCSE Computer Science specification (first taught from 2020 onwards). 2.4b: Binary Addition & Shifts Exam Board: OCR Specification: J277 Watch on YouTube : Binary Addition Overflow Errors Binary Shifts Issues with Shifts Binary Addition Binary addition is a method of adding binary values without having to convert them into denary. How to add binary numbers: What is an overflow error? An overflow error occurs when a binary value is too large to be stored in the bits available . With a byte (8 bits ) the largest number that can be held is 255 . Therefore any sum of two binary numbers that is greater than 255 will result in an overflow error as it is too large to be held in 8 bits . What is binary shift? Binary shift is used to multiply and divide binary numbers . The effect of shifting left is to multiply a binary number. The effect is doubled by each place that is shifted . x The effect of shifting right is to divide a binary number. ÷ Shifting by 1 has an effect of 2 . Shifting by 2 has an effect of 4 . Shifting by 3 has an effect of 8 . For example, shifting left by 2 places has an effect of multiplying by 4 . Another example: Shifting right by 3 places has an effect of diving by 8 . How to shift a binary number: Binary Shifts Watch on YouTube Watch on YouTube Q uesto's Q uestions Binary Addition: 1. Explain what an overflow error is. [ 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 ] Binary Shifts: 1a. Draw a diagram to show the effect of multiplying and dividing a binary number . [2 ] 1b. Draw a diagram or table to show the effect a shift has for each place from 1 to 4 . For example, a shift of 1 place has an effect of 2. [4 ] 2. State the effect of the following shifts: a. Shift right by 2 places. b. Shift left by 1 place. c. Shift left 3 places. d. Shift right by 4 places. [ 1 each ] 3. Shift the following binary numbers and state the effect of the shift: a. 10101011 : Shift left by 2 places. b. 11101100 : Shift right by 3 places. c. 00001011 : Shift right by 2 places. d. 01101110 : Shift left by 1 place. [ 2 each ] 2.4a - Number Systems Theory Topics 2.4c - Character Storage

Learn about the advantages and disadvantages of networks, the five types of network - LAN, WAN, PAN, MAN and VPN - and differences between wired and wireless networks. Based on the 2020 Eduqas (WJEC) GCSE specification. 3.1: Network Characteristics Exam Board: Eduqas Specification: 2020 What is a network? A network is more than one computer system connected together allowing for communication and sharing of resources . There are many benefits but also some drawbacks to using a network compared to having an unconnected ('standalone' ) computer: Advantages of Networks Easily share files , software and hardware between computers. Disadvantages of Networks There is an initial cost because network devices like routers are required . Larger companies will need to buy and maintain a server . Log in from any connected computer and access your data and files. A network manager / administrator might need to be employed to maintain the network . An administrator can monitor network activity and control security settings. Data from computers on the network can be automatically backed up on central storage. Security breaches are more likely and malware , such as worms, can spread quickly across the network. If the web server fails , all connected computers won't be able to access files or log on . Network Types Networks can be split into different types , usually categorised by their geographical distance apart and the area that they serve. Local Area Network A local area network (LAN ) has computer systems situated geographically close together , usually within the same building or small site , like a school or office . Wide Area Network A wide area network (WAN ) has computer systems situated geographically distant to each other, possibly across a country or even across the world . The internet is an example of a WAN that spans the globe. Personal Area Network A PAN is a personal network for an individual , such as a photographer connecting a smartphone, desktop computer and printer together. Metropolitan Area Network A MAN is larger than a LAN but smaller than a WAN and typically covers a relatively large area like a university campus, town or city . Virtual Private Network A VPN allows for a secure and encrypted connection to a public network like the internet. It is often used to protect an individual's privacy by concealing their real location. Wired & Wireless Networks Wired Connections Wireless Connections Wireless connections, such as WiFi or Bluetooth , use no cables but require a wireless network interface card (WNIC ). Wireless connections generally have a slower speed and can be affected by the computer's distance from the wireless router as well as obstacles like walls or bad weather. Wired connections use physical cables , such as copper or fibre optic wires , and require a network interface card (NIC ) to connect to a network. These wired connections use a wired connection protocol - most commonly Ethernet . Restricted Movement Faster More Secure NIC Required Freedom of Movement Slower Less Secure WNIC Required Q uesto's Q uestions 3.1 - Network Characteristics: 1. A retirement home for the elderly is considering installing a LAN , give 3 benefits and 3 drawbacks they might find of using a network . [6 ] 2a. Describe the difference between a LAN and WAN . [2 ] 2b. Give an example of how a LAN and a WAN could each be used . [ 2 ] 3 . Explain the differences between a PAN , MAN and VPN . [ 3 ] 4. For each of the scenarios below, state which network type would be most suitable : a. The IT rooms of a secondary school . [ 1 ] b. A study in a house with a desktop and printer. [ 1 ] c. Using online banking when abroad on a holiday to stay secure . [ 1 ] d. A large technology company with offices across Europe . [ 1 ] e. Council offices with several locations across Manchester . [ 1 ] 5. Briefly compare wired and wireless networks . [ 8 ] 2.2 - Boolean Algebra 3.2 - Data Packets & Switching Theory Topics

Explains the components of the CPU, the different registers, buses, how the FDE cycle works, CPU performance factors, pipelining, Von Neumann architecture and Harvard architecture. Based on the OCR H446 Computer Science A-Level specification. Exam Board: OCR A-Level 1.1 - Structure and Function of the Processor Specification: Computer Science H446 Watch on YouTube : CPU components Registers Buses The FDE cycle CPU performance Pipelining Von Neumann vs Harvard Contemporary architecture The Central Processing Unit ( CPU ) is the most important component in every computer system. The purpose of the CPU is to process data and instructions by constantly repeating the fetch-decode-execute cycle . In this cycle, instructions are fetched from RAM and transferred into the registers of the CPU to be decoded and executed . CPU Components The CPU has three key components : The control unit directs the flow of data and instructions inside the CPU and manages the FDE cycle , especially decoding instructions . The arithmetic logic unit ( ALU ) performs all arithmetic calculations and logical operations inside the CPU . Registers are small , ultra-fast storage locations that temporarily hold data , instructions or addresses during processing . The CPU also contains cache memory , which is temporary storage space for frequently accessed data . Registers A register is a small storage space for temporary data , instructions or addresses in the CPU . Each register has a specific role in the FDE cycle : The Program Counter ( PC ) stores the memory address of the next instruction to be fetched from RAM . The Memory Address Register ( MAR ) stores the memory address currently being accessed , which may be an instruction or data . The Memory Data Register ( MDR ) stores the data that is transferred from RAM to the CPU . The Current Instruction Register ( CIR ) stores the instruction that has been fetched from RAM . The Accumulator ( ACC ) stores data currently being processed and the result of calculations or logical operations made by the ALU . Buses Data and signals are transmitted between components across internal connections called buses . There are three types of computer bus : The data bus transmits data and instructions between the CPU , memory and other components such as input/output devices . It is bidirectional (data is sent both ways ). The address bus transmits the location in memory that the CPU is accessing . It is unidirectional (one-way ) from the CPU to RAM . The control bus transmits control signals (e.g. 'read ' or 'write ') from the CPU to coordinate other components . It is bidirectional . The FDE Cycle In the Fetch Decode Execute (FDE ) cycle , instructions are fetched from RAM , then decoded (understood) and executed (processed) in the CPU . This cycle is performed by the CPU millions of times every second using the registers and buses explained above. This cycle is how the CPU processes data and instructions for each program or service that requires its attention . CPU Performance The performance of the CPU is affected by three main factors : Clock speed is t he number of cycles per second , so a higher clock speed means more instructions can be executed per second . The number of cores is important as more cores allow a CPU to carry out multiple instructions simultaneously , improving multitasking and parallel processing . Cache memory is small and very fast memory inside the CPU that stores frequently used instructions , reducing the time needed to access RAM . Pipelining Pipelining is the concurrent processing of multiple instructions . An instruction can be fetched while another is decoded and another is executed . This overlapping of instructions increases the overall speed of program execution . Computer Architecture Computer architecture refers to the design and organisation of a system’s components and how they interact . There are two types of architecture to know: Von Neumann architecture uses a single main memory (RAM ) that stores both program instructions and data . This means instructions and data travel along the same buses , which can cause a bottleneck (congestion ). Harvard architecture separates the storage of program instructions and data into two different memory locations . This allows instructions and data to be fetched at the same time , improving performance . You also need to know about c ontemporary (modern) architecture , which includes features such as onboard ( integrated ) graphics , performance boosting mode , out-of-order execution and virtual cores . Q uesto's K ey T erms Components of the CPU: control unit (CU), arithmetic logic unit (ALU), registers, cache memory Registers: program counter (PC), memory address register (MAR), memory data register (MAR), current instruction register ( CIR), accumulator (ACC) Buses: data bus, address bus, control bus, unidirectional, bidirectional FDE Cycle: fetch stage, decode stage, execute stage CPU Performance: clock speed , number of cores , cache memory Pipelining: pipelining Computer architecture: Von Neumann, Harvard, contemporary D id Y ou K now? The Apollo Guidance Computer ( AGC ) for NASA's Apollo 11 mission , when humans first set foot on the moon , had a CPU clock speed of about 1 megahertz - slower than many GCSE-level calculators used today. A-Level Topics 1.2 - Types of Processor