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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

The final part of a quick guide to the basics of Python aimed at Key Stage 3 students. Learn about importing turtle to command a moving object. Python - #6 - Turtle Import the Turtle The turtle library stores all of the code to create and move an object called a turtle . The turtle library must be imported into your Python program before you can use it to draw lines, shapes and colours . Create a new Python program and save the file as PythonTurtle . Write import turtle as the first line of code. Basic Shapes The turtle can be controlled by writing how many pixels it should travel forward and the angle it should point left or right . Moving Forwards turtle.forward(100) will move the turtle forward by 100 pixels. turtle.forward(200) will move the turtle forward by 200 pixels. When using the left command or the right command, the turtle won't actually move , but it will rotate by the number of degrees that you state. For example, typing turtle.left(90) will point the turtle upwards . Rotating Left & Right Copy the code to the right to make the turtle draw a square. Then try to make: A Rectangle A Triangle A Pentagon A Hexagon Square Rectangle Triangle Pentagon Hexagon Hint: To work out the angles, divide 360 by the number of sides. Using Loops You can use a for loop to repeat code . This is especially helpfully with intricate shapes with many sides. The code below will print a square but in only 3 lines instead of the 8 lines from task 2. This is the number of times the code underneath will be repeated . Change it to a higher number to repeat it more often . Each line after the 'for num in range' line must be indented . Press the tab key once on your keyboard to indent your code. Task 3 - Copy the code above to make the turtle draw a square using a loop. Then try to make: A Heptagon An Octagon A Circle A Pentagram (5-sided Star) Square Heptagon Octagon Circle Pentagram Hint: To work out the angles, divide 360 by the number of sides. Advanced Features Choose a background colour turtle .bgcolor("red") Choose the line size and colour turtle.pensize(6) turtle.color("green") Fill a shape turtle.color("yellow") turtle.begin_fill() (put your turtle's directions in here) turtle.end_fill() Lift the pen turtle.penup() turtle.pendown() Speed up/Slow down the turtle turtle.speed(speed=10) Change the turtle's appearance turtle.shape("turtle") Other options include "circle" and "arrow". Task 4 - Use the code above to make: A blue square on a red background. A yellow triangle on a pink background. Two different coloured circles - not touching each other. Three different shapes of three different colours - not touching each other. Complex Shapes Use everything that you have learned on this page to help you create more complex shapes. You could try: A Flower A Word (like your name - you will need to use the penup() and pendown() commands. A Christmas tree A Landscape (green ground, blue sky, yellow sun) <<< Selection

Test your ability to create a more complex program in Python based on a given scenario. Perfect for students learning GCSE Computer Science in UK schools. Extended Task 1 Pete Porker's Pork Pie Emporium Hello, Pete Porker here... I need a new program for customer orders at my bakery . I need the customer to enter how many scotch eggs (49p each ), pork pies (85p each ) and quiche tarts (£1.45 ) they want to order. Next, ask them to confirm their choice . If they are not happy , ask the questions again . If they confirm their choice, print a receipt showing their order and total . To make your program better, you should use validation (either while loops or error handling ) to make sure that a user must enter a correct value. Bronze Award --- Welcome to Pete Porker's Pork Pie Emporium --- Scotch eggs are 45p, pork pies are 85p and quiche tarts are £1.49. Enter the number of scotch eggs to buy: 9 Enter the number of pork pies to buy: 7 Enter the number of quiche tarts to buy: 4 ----- You selected 9 scotch eggs, 7 pork pies and 4 quiche tarts. 9 scotch eggs = £4.05 7 pork pies = £5.95 4 quiche tarts = £5.96 ------- Total: £15.96 There are many ways to create this program, but below are some suggestions : Use inputs with int to let the user enter how many of each item they want. Use total variables , e.g. totaleggs = eggs * 0.45 to work out the total cost for eggs, pies and tarts. Set a finalcost variable by adding the total of the three items together. Use dashes and \n (which makes a new line ) inside speech marks to make your program more presentable . Silver Award --- Welcome to Pete Porker's Pork Pie Emporium --- Scotch eggs are 45p, pork pies are 85p and quiche tarts are £1.49. Enter the number of scotch eggs to buy: 5 Enter the number of pork pies to buy: 3 Enter the number of quiche tarts to buy: 6 ----- You selected 9 scotch eggs, 7 pork pies and 4 quiche tarts. ----- Are you happy with this selection? no Okay, enter your choices again. Enter the number of scotch eggs to buy: 6 Enter the number of pork pies to buy: 2 Enter the number of quiche tarts to buy: 7 ----- You selected 6 scotch eggs, 2 pork pies and 7 quiche tarts. ----- Are you happy with this selection? yes Excellent! Here is your receipt : 6 scotch eggs = £2.70 2 pork pies = £1.70 7 quiche tarts = £10.43 ------- Total: £14.83 There are many ways to improve this program and below are some suggestions : Use a while loop to repeat the input stage until the user is happy with their choices. You will need to ask the user if they are happy with the values that were entered and then use an if statement to repeat the loop if they enter 'no '. Gold Award Example solution: --- Welcome to Pete Porker's Pork Pie Emporium --- Scotch eggs are 45p, pork pies are 85p and quiche tarts are £1.49. Enter the number of scotch eggs to buy: 9 Enter the number of pork pies to buy: 35 Sorry you must enter a number between 1 and 20. Starting again... Enter the number of scotch eggs to buy: 9 Enter the number of pork pies to buy: 20 Enter the number of quiche tarts to buy: 7 ----- You selected 9 scotch eggs, 20 pork pies and 7 quiche tarts. ----- Are you happy with this selection? YES Excellent! Here is your reciept: 9 scotch eggs = £4.05 20 pork pies = £17.00 7 quiche tarts = £10.43 ------- Total: £31.48 There are many ways to make this program even better and below are some suggestions : Include validation so that the user can only enter numbers between 1 and 20 . You will need to use if statements and the and operator to do this. You can include additional features to your program such as rounding the number to two decimal places and including coloured text using the Colorama library (which will only work if you are using an online editor like Replit ). You can use the .lower() command when checking if the user is happy with their choices to automatically accept 'Yes' and 'YES '. If you really want to challenge yourself you could consider outputting the receipt in order from most expensive to least expensive , using if statements to check the three values (although that has not been done in this example on the left). Helpful reminders for this task: Inputting Integers While Loops Calculations Rounding Integers ⬅ 12 - Error Handling Extende d Task 2 (Lottery) ➡

Learn about the purpose and characteristics of intranets, the internet and extranets - all three types of World Wide Web technologies. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification for Unit 2 (Global Information). 1.5 - WWW Technologies Exam Board: OCR Specification: 2016 - Unit 2 The internet is a global network of interconnected networks . The world wide web (WWW ) is not the same as the internet. It is a way of accessing information , using protocols such as HTTPS to view web pages . There are three types of world wide web technologies : Internet Intranet Extranet The internet i s a global network of interconnected networks . The internet is public and users have open access . Examples of use: Accessing web pages to shop and watch videos . Businesses may use web pages to advertise their products and allow customers to purchase items. An intranet is a private network that is only accessible to authorised users (e.g. members of a business or school). Intranets are private and users have closed access . Examples of use: Because an intranet is a secured online area , schools often use an intranet to log in to that displays information for teachers and students (such as test results or upcoming events ). Businesses might use an intranet for employees to see sales and performance data or for communication because it can be accessed remotely . An extranet is a private network that is accessible using the internet but provides access only to authorised users . Extranets are private and users have shared access . Example of use: Hotel booking companies (like booking.com) use an extranet to allow hotel owners to log in via the internet to access and update their information. Network Characteristics When connecting to WWW technologies there are several characteristics that a user must consider: Speed Speed refers to how quickly data can be accessed . For example, an extranet is the slowest network to use because it must be accessed through the internet first. Security Security relates to how likely the data will be kept secure . An intranet is more secure than the internet because only authorised users can log in. Access Levels Access levels , or permissions , refers to who can see what, in terms of data and files . Resources on an intranet can be set so that only certain users can view them. Accessibility This characteristic relates to how available the data is . For example, the internet can be accessed on any network-enabled device, at any time . Q uesto's Q uestions 1.5 - WWW Technologies: 1. Explain the difference between the internet and the world wide web . [2 ] 2. Describe each of the 3 types of WWW technology . You must mention whether they are private or public and what type of access they have. a. Internet b. Intranet c. Extranet [2 each ] 3. Describe at least one example of how each of the 3 types of WWW technology could be used . [6 ] 4. Describe the 3 WWW technologies in terms of each of the 4 network characteristics . You need to think carefully about this; the descriptions under each icon above can help you with certain answers. To start, describe the speed, security, access levels and accessibility of an intranet . [12 each ] 1.4 - Internet Connections Topic List 1.6 - Information Formats

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

Learn how to create and use dictionaries in Python. Try practice tasks and learn through text and images. Perfect for students learning GCSE Computer Science in UK schools. top Python 8C - Dictionaries Creating a Dictionary Dictionaries are used in Python to link items of data together . The example on this page uses a footballer dictionary which links a player with a team they played for. To define a dictionary, use curly brackets { } and separate linked data with a colon . A dictionary can be written on one line but the method below makes it easier to read: Printing Data from a Dictionary The first part of the linked data in a dictionary is called the key (e.g. each footballer in my example above). The second part of the linked data in a dictionary is called the value (e.g. each team). Example: key : value "Harry Kane" : "Tottenham Hotspur" A for loop can be used to cycle through each set of keys and values in the dictionary: Practice Task 1 a) Create a dictionary of your teachers and the subject they teach. b) Print their name and the subject they teach on each line. Example solution: Adding and Removing Data from a Dictionary Data can be added to a dictionary by stating the new key and value . You must use square brackets - [ ] The new data will be added to the end of the dictionary. You can print the whole dictionary to see any changes - e.g. print(playerdictionary) Data can be removed from a dictionary by stating the new key to remove in a pop command. You can print the whole dictionary to see any changes - e.g. print(playerdictionary) The whole dictionary can be cleared (reset to blank) using the clear command. Practice Task 2 a) Ask the user to enter a new teacher and their subject. b) Ask the user to remove a teacher. c) Print the list of teachers and check the new teacher has been added and the other one removed. Example solution: Searching Through a Dictionary An if statement can be used to check if a specific key is in a dictionary. If the key is in the dictionary then a message can be displayed using the key and the value . Otherwise, an else statement can output an appropriate response. To search for a value in a dictionary a for loop should be used to cycle through each key . If the value of each key matches the value that is being searched for then it will be printed. Practice Task 3 a) Create a search that allows a user to enter a teacher's name and prints the subject that they teach. b) Include an else statement to print a response if a teacher is not in the dictionary. Example solution: Changing Data & Copying a Dictionary The way to change values is similar to adding new data. The first input below is to determine the key and the second input determines the new value to be changed to. The copy command is used to make a duplicate of a dictionary . Practice Task 4 a) Create a copy of your teacher dictionary. b) Allow the user to enter a teacher and a new subject that they teach. c) Print the copy of the dictionary with the new values. Example solution: Using a Dictionary to Make a Game The code below is used to make a puzzle game where the user has to type in a footballer and the team they played for. I have added comments to explain the different parts of the code. A separate list has been created at the start to store the names of keys (players) that been correctly guessed . A while loop is used to constantly ask the user for players and teams. When they have guessed all 10 players (and the correct list reaches 10 ) the loop breaks and the game end. Instead of a further practice task here, Task 6 of the Section 8 Practice tasks page challenges you to make a similar game using a dictionary. ⬅ 8b - 2D Lists Section 8 Practice Tasks ➡

Learn how to play sound files in Greenfoot. Part 5 of the Greenfoot Tutorial for the Eduqas / WJEC GCSE 2016 specification. 5. Play Sounds 1. Check the Sounds Folder Greenfoot Tutorial Sound files must be placed the ' sounds ' folder of your Greenfoot project to be used in the game. In the Component 2 exam of the WJEC / Eduqas 2016 specification , an audio file will be placed in the sounds folder already . For this example game you can download the audio clips to the right and paste them into your sounds folder . Watch on YouTube: Click the audio icon to download a zip folder of the two sound files below . Copy the files into the sounds folder of your Greenfoot project . < Part 4 - Remove Objects 2. Add the playSound Method Add the code to play the sound at the same time as when the collectible object is removed . The name of the file and its extension (e.g. .wav or .mp3 ) must be written in speech marks after the playSound method. Part 6 - The Counter >

Learn how to create your own web page in HTML. The guide features 10 easy to follow steps from setting up the basic tags to adding images, videos and more pages. When you see the checklist icon, complete the task in order to make your own HTML web page. HTML Guide 1. Setting up the web page 2. Essential tags 3. Text tags 4. Hyperlinks 5. Images 6. Organisation tags 7. Head tags 8. Videos 9. Colours & Fonts 10. More pages Watch on YouTube: These steps will show you how to make a HTML fanpage so get thinking of an appropriate topic - maybe your favourite book, movie or sports team? Download Notepad++ at home

Learn about the different types of LAN, MAN and WAN networks and how to draw network diagrams. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification. 3.4 - Connection Methods Exam Board: OCR Specification: 2016 - Unit 1 Local Area Network (LAN) A Local Area Network (LAN ) is a network in which the computer systems are all located geographically close to each other , for example, in the same building or on the same site , like a school or office . A type of LAN is a Wired Ethernet LAN ( technically Ethernet is a protocol that controls how data is transmitted over a LAN). Wired Ethernet LANs have a high bandwidth so data can be transferred quickly and because it uses cables the data is harder to intercept than a wireless network. Metropolitan Area Network (MAN) A Metropolitan Area Network (MAN ) connects several LANs together to cover the range of a town or city , for example a university campus network. MANs are usually very efficient at providing fast communication for cities , with high connection speeds through the use of fibre optic cables. Wide Area Network (WAN) A Wide Area Network (WAN ) is a network spanning a large geographical area , such as multiple cities or countries . The internet is the ultimate example of a WAN as it stretches across the entire world. Different types of WAN rules and standards are used: ADSL ADSL ( Asymmetric Digital Subscriber Line ) is a method of transferring data across copper wire telephone lines . ADSL is contended, which means that connection speeds are affected and slowed down by more systems that use the network at the same time . The old copper wires also affect data transfer over long distances and can cause data packet loss . Security is also an issue, as the line is shared with others, making data interception more likely . To improve security, a firewall and/or VPN (Virtual Private Network) may be used. Because ADSL uses the telephone system, a modem is require d at both the sending and receiving ends of the connection. A microfilter is also required to allow internet and telephone access at the same time . ADSL is contended - shared between sites. Internet Service Provider ADSL requires a modem Leased Line Leased Line is a method of providing an uncontended , fixed-bandwidth data connection . The user maintains a dedicated connection that is more secure and, because it is uncontended , will have the same speed all of the time , regardless of how busy the network is . Bandwidth is high , security is better , the connection speed is constant and the network is full-duplex (allowing for data transmission both ways simultaneously). These advantages come at a high cost - possibly hundreds of pounds per month - as well as an expensive installation that can take time to be put in place . As it is a complex configuration , a CSU/DSU (Channel Service Unit/Data Service Unit) device is required to properly terminate the leased line . Internet Service Provider Leased Line is dedicated. C A CSU/DSU is required for a leased line. ISDN ISDN (Integrated Services Digital Network ) transmits video and voice data simultaneously over traditional copper telephone wires . This method uses a circuit-switched network where all data packets take the same route between computer systems. Voice Networks Voice networks primarily transfer audio data using phones and telephone lines . PSTN PSTN (Public Switched Telephone Network ) is the global collection of wired public telephone networks that are used to transmit data over a long distance. PSTN is fixed into position using underground cables and therefore the connection quality is much more consistent than other voice networks. Using a wired connection like a PSTN is more reliable and communication will be clearer than alternatives such as cellular or satellite methods. Cellular Cellular networks require a cell tower (also called a transmitting tower ) to be in close proximity to the communication device. Cellular networks have a greater range than PSTN, but buildings and poor weather can disrupt this point-to-point communication method (where line of sight is necessary ). Each cell tower is also connected to the PSTN . 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 (potentially thousands of miles ), there is a delay between data transmission and it being received . Satellite networks are beneficial in remote locations , such as natural disaster zones , where the cell tower may not be present or may be damaged. Transmitting large files using satellites may take longer , and it is not recommended for low-latency needs such as video gaming. There are different types of satellites used in communication and networking : Geostationary satellites are used for consistent communication over a specific region , such as TV broadcasts and weather monitoring . They can also be used to transfer data between remote locations . Low-Earth orbiting satellites are closer to the ground so they enable fast communication for internet services . Medium-Earth orbiting satellites are often used for GPS (Global Positioning System ) and other navigation systems . A global positioning satellite is an example of this type of satellite that provides time and geolocation data to GPS receivers back on Earth. Diagrammatical Representation In an exam, you may be asked to draw a diagram representing how networks are connected . This is different from drawing a network topology (e.g. ring or mesh) and refers to: Connection type (e.g. ADSL / Leased Line). Devices (e.g. router / modem), Security methods (e.g. firewall / VPN) Two LANs connected using a Leased line Two LANs connected using an ADSL line Rules for drawing a network diagram: Label each device and label your LANs . Use appropriate symbols and be neat . There are no set symbols, just be consistent (e.g. both modems are the same shape). ADSL must have a modem and VPN router + Firewall . (ADSL is not very secure so it needs to be protected with the VPN router and firewall. It also uses the telephone line across the internet so it requires a modem at both ends). Leased Line must have a router , a direct connection and CSU/DSU . (Leased line is a secure and direct connection - so it doesn’t need a firewall or VPN router and should be direct (not across the internet )). Q uesto's Q uestions 3.4 - Connection Methods: 1a. What is the definition of a LAN ? [ 2 ] 1b. Describe two benefits of using a wired Ethernet LAN . [ 4 ] 2. What is the definition of a MAN ? [ 2 ] 3a. What is the definition of a WAN ? [ 2 ] 3b. What is the difference between a contended and an uncontended network? [ 2 ] 3 c. Describe the differences between a leased line and ADSL . You should discuss security , connection speed and contention ( contended or uncontended ) . [6 ] 3d. Describe the use of any two network devices required for either a leased line and/or for ADSL . [ 4 ] 3e. Describe the purpose of ISDN . [ 2 ] 4a. Compare the use of PSTN and Cellular methods to make telephone calls . [ 4 ] 4b. Explain 1 way that a satellite network should be used and 1 way it shouldn't be used . [ 4 ] 5. Draw a diagram to show how a leased line or ADSL network can be set up between two existing LANs. [6 ] 3.3 - Network Characteristics Topic List 3.5 - Business Systems

Learn about secondary storage types such as solid-state, magnetic, optical and paper. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification for Unit 2 (Global Information). 1.2 - Storage Media Exam Board: OCR Specification: 2016 - Unit 2 Data can be stored on a variety of storage media , each with its own benefits and drawbacks . Magnetic Storage Optical Storage A magnetic hard disk drive (HDD ) is the most common form of secondary storage within desktop computers. A read/write head moves nanometres above the disk platter and uses the magnetic field of the platter to read or edit data. Hard disk drives can also be external and connected through a USB port . An obsolete (no longer used) type of magnetic storage is a floppy disk but these have been replaced by solid state devices such as USB sticks which are much faster and have a much higher capacity. Another type of magnetic storage that is still used is magnetic tape . Magnetic tape has a high storage capacity but data has to be accessed in order (serial access ) so it is generally only used by companies to back up or archive large amounts of data . Optical storage uses a laser to project beams of light onto a spinning disc, allowing it to read data from a CD , DVD or Blu-Ray . This makes optical storage the slowest of the four types of secondary storage. Disc drives are traditionally internal but external disc drives can be bought for devices like laptops. Magnetic Storage Characteristics: ✓ - Large CAPACITY and cheaper per gigabyte than solid state . X - Not DURABLE and not very PORTABLE when powered on because moving it can damage the device. ✓ - Relatively quick ACCESS SPEED but slower than Solid State . Optical Storage Characteristics: X - Low CAPACITY : 700 MB (CD ), 4.7 GB (DVD ), 25 GB (Blu-ray ). X - Not DURABLE because discs are very fragile and can break or scratch easily. ✓ - Discs are thin and very PORTABLE . X - Optical discs have the Slowest ACCESS SPEED . Magnetic Disks are spelled with a k and Optical Discs have a c. Solid State Storage Paper Storage There are no moving parts in solid state storage. SSD s (Solid State Drives ) are replacing magnetic HDDs (Hard DIsk Drives) in modern computers and video game consoles because they are generally quieter , faster and use less power . SSDs can also be external . A USB flash drive ( USB stick ) is another type of solid state storage that is used to transport files easily because of its small size. Memory cards , like the SD card in a digital camera or a Micro SD card in a smartphone , are another example of solid state storage. Paper storage includes printed or hand-written documents, notes, forms, schedules and maps. Paper is relatively inexpensive in small quantities but it can take up a lot of space compared to small devices like USB sticks. Producing paper is environmentally damaging and requires physical security methods to keep safe. Paper, such as a timetable, can be written on if times change and easily carried on a person. However, paper in the form of an essay must be re-printed to add changes . Solid State Characteristics: ✓ - High CAPACITY but more expensive per gigabyte than magnetic . ✓ - Usually DURABLE but cheap USB sticks can snap or break . ✓ - The small size of USB sticks and memory cards mean they are very PORTABLE and can fit easily in a bag or pocket. ✓ - Solid State storage has the fastest ACCESS SPEED because they contain no moving parts . Paper Storage Characteristics: X - Low CAPACITY as each page can only hold a certain amount of information. Paper also takes up physical space . X - Poor DURABILITY as paper can easily tear and become damaged in rain. ✓ / X - PORTABILITY varies as single sheets of paper can be easily folded and placed in a pocket. However, large stacks of paper can be difficult and expensive to transport. X - Paper's ACCESS SPEED , in terms of searching for a specific item, is slow , especially if the paper storage has not been organised efficiently . Q uesto's Q uestions 1.2 - Storage Media: 1. State 3 examples of each type of storage media . For example, a CD for optical storage. [3 each ] 2. Compare each type of storage media in terms of capacity , durability , portability and access speed . You may decide to do this as a table or poster. [16 ] 3. Identify the most suitable device (not the media ) and justify its suitability for the following scenarios: a. Backing up a large database at the end of each day. [5 ] b. Keeping a copy of a cleaning schedule for hotel staff. [5 ] c. Making copies of a promotional video to hand out to audience members at a dancing event. [5 ] 1.1 - Holders of Information Topic List 1.3 - Access & Storage Devices

Learn about the three factors that affect computer performance - cache memory size and levels, clock speed and the number of cores. Based on the 2020 Eduqas (WJEC) GCSE specification. 1.5: Performance Exam Board: Eduqas Specification: 2020 The performance of a computer system is affected by three main factors: Cache Memory: Size & Levels What is cache memory? Cache memory is temporary storage for frequently accessed data . Cache memory is very quick to access because it is closer to the CPU than other types of memory like RAM . What are the 3 levels of cache memory? Level 1 cache is the smallest level but it is also the fastest . Level 2 cache is larger than level 1 but slightly slower. Level 3 cache is located outside of the CPU core which makes it slower than the first two levels but it is much larger . How does cache memory work? When the CPU searches for data , it looks first in level 1 cache, then level 2 and then level 3 . If the data has been found , this is called a 'cache hit '. If the data is not found then the CPU searches in RAM instead which takes more time - this is called a 'cache miss '. How does cache memory improve performance? Cache memory is closer to the CPU than RAM , meaning that it can provide data and instructions to the CPU at a faster rate . A computer with more cache memory (e.g. 8MB instead of 4MB) should have a higher performance because repeatedly used instructions can be stored and accessed faster . Larger level 1 and level 2 cache sizes will improve a computer's performance as data can be accessed extremely quickly . What is the limitation of cache memory? Cache memory is costly, so most computers only have a small amount . Multiple cache misses will result in data latency (delay) as information is accessed from RAM which is further away from the CPU. Clock Speed What is clock speed? Clock speed is the measure of how quickly a CPU can process instructions . Clock speed is measured in Gigahertz (GHz) . A typical desktop computer might have a clock speed of 3.5 GHz . This means it can perform 3.5 billion cycles a second . How does clock speed improve performance? The faster the clock speed, the faster the computer can perform the FDE cycle resulting in better performance because more instructions can be processed each second . How does overclocking and underclocking affect performance? Typical clock speed: 3.5 GHz Underclocking Overclocking 3.9 GHz 3.1 GHz Overclocking is when the computer's clock speed is increased higher than the recommended rate. This will make the computer perform faster, but it can lead to overheating and could damage the machine . Underclocking is when the computer's clock speed is decreased lower than the recommended rate. This will make the computer perform slower but will increase the lifespan of the machine . Number of Cores What is a core? A core is a complete set of CPU components (control unit, ALU and registers). Each core is able to perform its own FDE cycle . A multi-core CPU has more than one set of components within the same CPU. How does the number of cores improve performance? In theory, a single-core processor can execute one instruction at a time , a dual-core processor can execute two instructions, and a quad-core can execute four instructions simultaneously . Therefore, a computer with more cores will have a higher performance because it can process more instructions at once . What are the limitations of having more cores? If one core is waiting for another core to finish processing, performance may not increase at all. Some software is not written to make use of multiple cores , so it will not run any quicker on a multi-core computer. Q uesto's Q uestions 1.5 - Performance: Cache Size & Levels 1a. What is cache memory ? [ 2 ] 1b. Describe the three levels of cache memory . [ 3 ] 1c. Describe what is meant by a ' cache hit ' and a ' cache miss '. [ 2 ] 1d. Describe two ways that more c ache memory will mean performance is higher . [ 4 ] 1e. Explain why most computers only have a small amount of cache memory. [ 1 ] Clock Speed 2a. What is clock speed ? What is it measured in? [ 2 ] 2b. Explain how a higher clock speed improves performance . [ 2 ] 2c. Explain the terms 'overclocking ' and 'underclocking ' and explain the effects of both on the performance of a computer. [ 4 ] Number of Cores 3a. What is a core ? [ 2 ] 3b. Explain why a quad-core processor should have a higher performance than a dual-core processor . [ 3 ] 3c. Explain two reasons why having more cores doesn't necessarily mean the performance will be better . [ 2 ] 1.4 - Secondary Storage 1.6 - Additional Hardware Theory Topics

Learn about the benefits of compression and the differences between lossy and lossless compression. Also, learn how compression ratios work. Based on the 2020 Eduqas (WJEC) GCSE specification. 4.8: Compression Exam Board: Eduqas Specification: 2020 What is compression? To compress a file means to make its size smaller . Benefits of compression include: Files take up less storage space (so more files can be stored). Files can be transferred quicker (because they are smaller). Files can be read from or written to quicker . There are two methods that are used to compress files: Lossy and Lossless . Lossy Compression Lossy compression uses an algorithm (set of instructions) to analyse a file and remove data that cannot be heard or seen by humans . For example, a lossy algorithm would analyse the sound waves of an audio file and remove any frequencies which humans cannot hear. This process reduces the size of the file . Further lossy compression will remove data that humans can see / hear . For example, the dog image to the right has been strongly compressed using a lossy algorithm and some data has clearly been removed. Lossy compression removes the data permanently , so the file can never return to its original form . Lossy compression is often used with images , audio and video to reduce the file size, for example to send over the internet. Lossless Compression Lossless compression reduces the size of a file without permanently removing any data . Because of this, the file is returned to its original form when decompressed, so no quality is lost . A file that is compressed with a lossless algorithm is usually larger than a file compressed with a lossy algorithm because no data has been permanently removed. Lossless compression is used with files that would not work if data was removed, for example executable files (e.g. programs and games) or word documents . Remember that lossy and lossless compression do not just refer to images. Below is an audio file that has been compressed with lossy compression . Data has been removed so the audio quality has decreased. 197 KB 81 KB 43 KB Compression Ratios Original File Size Compression Ratio = Compressed File Size 4 Mb = 5:1 20 Mb Example: A file has been compressed from 20 megabytes down to 4 megabytes. This is a compression ratio of 5:1. To calculate the size after compression , divide the original size by the first ratio value, then multiply it by the second value. For example, the new size for file 1 is (210 ÷ 10) x 3 = 63 MB. Triple-click the final column to see the right answers. Q uesto's Q uestions 4.8 - Compression: 1. Describe 3 benefits of compressing a file . [ 3 ] 2. Describe the differences between lossy and lossless compression . [4 ] 3. A student needs to compress a Microsoft Word document to send in an email. Suggest which type of compression they should use and why . [ 2 ] 4a. A text file was 72 KB and was compressed to 8 KB . State the compression ratio . 4b. An audio file was 4.5 MB and has been compressed to 0.9 MB. State the ratio. 4c. A 20 MB file is compressed with a ratio of 5:2 . What is the size of the compressed file ? [ 1 each ] 63MB 164KB 96KB 4.7 Sound Representation Theory Topics 5.1 - Data Structures