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4.1: Security Threats Exam Board: OCR Specification: 2020 Types of Malware ​Malware is any type of harmful program that seeks to damage or gain unauthorised access to your computer system. Virus A virus can replicate itself and spread from system to system by attaching itself to infected files . A virus is only activated when opened by a human . Once activated, a virus can change data or corrupt a system so that it stops working . Worm A worm can replicate itself and spread from system to system by finding weaknesses in software . A worm does not need an infected file or human interaction to spread. A worm can spread very quickly across a network once it has infiltrated it. Trojan A trojan is a harmful program that looks like legitimate software so users are tricked into installing it . A trojan secretly gives the attacker backdoor access to the system . Trojans do not self replicate or infect other files. Spyware Spyware secretly records the activities of a user on a computer. The main aim of spyware is to record usernames, passwords and credit card information . All recorded information is secretly passed back to the attacker to use. Keylogger A keylogger secretly records the key presses of a user on a computer. Data is stored or sent back to the attacker. The main aim of a keylogger is to record usernames, passwords and credit card information . Keyloggers can be downloaded or plugged into the USB port . Ransomware Ransomware locks files on a computer system using encryption so that a user can no longer access them. The attacker demands money from the victim to decrypt (unlock) the data . ? ? ? ? Attackers usually use digital currencies like bitcoin which makes it hard to trace them. SQL Injection SQL ( Structured Query Language ) is a programming language used for manipulating data in databases . ​ A SQL injection is when a malicious SQL query (command) is entered into a data input box on a website. ​ If the website is insecure then the SQL query can trick the website into giving unauthorised access to the website’s database . ​ An SQL injection can be used to view and edit the contents of a database or even gain administrator privileges . ' or 1 = 1 DoS Attack A DoS (Denial of Service ) attack is when a computer repeatedly sends requests to a server to overload the system . A server overload will slow the system and may take websites offline temporarily. ​ A DDoS (Distributed Denial of Service ) attack is a coordinated attack using a botnet of infected systems to overload a server with requests . A botnet is a large group of devices controlled and used maliciously by an attacker. Brute-Force Attack Every possible combination is tested in order from start to finish . This is not a quick method but it should break the password eventually and can be sped up if multiple computer systems are used at the same time. Social Engineering Social engineering means to trick others into revealing their personal data by posing as a trusted source . For example, impersonating an IT technician of a school via email and asking for a student's username and password . Data Interception This is when data packets on a network are intercepted by a third party (e.g. a hacker) and copied to a different location than the intended destination. ​ Software called packet sniffers are used to intercept and analyse data packets. 4.1 - Security Threats: 1. What is malware ? [ 2 ] 2a. Describe three characteristics of a virus . [3 ] 2b. Describe three characteristics of a worm . [3 ] 2c. What is a trojan ? [ 3 ] 2d. Describe how spyware and keyloggers work. [ 4 ] 2e. Explain how ransomware works and why it is difficult to trace attackers . [ 3 ] 2f. In your opinion, which malware do you think is the most dangerous and why ? [ 2 ] 3. Describe what an SQL injection is and how an attacker would use it. [ 3 ] ​ 4a. Describe what a DoS attack is and its impact . [2 ] 4b. Describe how a DDoS attack is different to a DoS attack . [2 ] ​ 5a. Describe a brute-force attack. [ 2 ] 5b. Describe social engineering and give an example of when it might be used . [2 ] 5c. Describe interception . [2 ] Q uesto's Q uestions 3.2b - Protocols & Layers Theory Topics 4.2 - Preventing Vulnerabilities

2.1: Primary Storage (Memory) Exam Board: OCR Specification: 2020 Primary vs Secondary Storage Storage in a computer system is split into two categories: Primary Storage: Very quick because it is directly accesse d by the CPU . Typically smaller in storage size . Sometimes called ‘main memory’ . Includes RAM and ROM . Volatile vs Non-Volatile Storage Storage is also split into two types - volatile and non-volatile . ​ Volatile storage is temporary - data is lost whenever the power is turned off .​ Example: RAM Non-volatile storage saves the data even when not being powered . Data can be stored long-term and accessed when the computer is switched on . Example: ROM Why do Computers need Primary Storage? Primary storage is low-capacity , internal storage that can be directly accessed by the CPU . Program instructions and data must be copied from the hard drive into RAM to be processed by the CPU because primary storage access speeds are much faster than secondary storage devices like the hard drive. Types of Primary Storage (Memory) Random Access Memory (RAM) Read-Only Memory (ROM) RAM is volatile (temporary) storage that stores all programs that are currently running . RAM also stores parts of the operating system to be accessed by the CPU. ​ RAM is made up of a large number of storage locations, each can be identified by a unique address . ROM is non-volatile storage that cannot be changed . ​ ROM stores the boot program / BIOS for when the computer is switched on. The BIOS then loads up the operating system to take over managing the computer. RAM ( R andom A ccess M emory) ROM ( R ead O nly M emory) Virtual Memory Programs must be stored in RAM to be processed by the CPU . Even if there is insufficient space in RAM for all programs the computer can use the hard disk drive (HDD ) as an extension of RAM - this is called virtual memory . ​ If new data is needed to be stored in RAM then unused data in RAM is moved to the hard drive so the new data can be transferred into RAM . If the original data is required again, it can be moved back from virtual memory into RAM . Using virtual memory is beneficial because it allows more programs to be run at the same time with less system slow down . Q uesto's Q uestions 2.1 - Primary Storage (Memory): ​ 1. Describe the differences between primary and secondary storage . [ 6 ] ​ 2. Explain the difference between volatile and non-volatile storage . State an example of both types. [ 4 ] ​ 3. Explain why the computer requires primary storage . [ 2 ] ​ 4. For each type of memory below, describe it and state what information is stored within it: a . Random Access Memory (RAM) [3 ] b. Read-Only Memory (ROM) [ 3 ] c. Virtual memory [ 3 ] Secondary Storage: ( Section 2.2 ) Slower because it is not directly accessed by the CPU . Typically larger in storage size . Used for the long-term storage of data and files because it is non-volatile . Includes magnetic , optical and solid state storage. 1.3 - Embedded Systems Theory Topics 2.2 - Secondary Storage

5.1: Operating Systems Exam Board: OCR Specification: 2020 What is an Operating System? An operating system (OS ) is software that helps to manage the resources of a computer system and provide the interface between the user and the computer’s hardware . ​ There are five main functions of an operating system: Memory Management & Multitasking All programs must be temporarily stored in RAM for the CPU to be able to process them. ​ The OS transfers programs in and out of memory from the hard drive (or virtual memory ) when processing is required - programs are removed from RAM when closed to free up space for other tasks. ​ The operating system can only perform one process at a time , but through memory management it can appear that more than one process is being executed - this is called multitasking . Peripherals Management & Drivers A peripheral is an external device connected to a computer system to input or output data . Data is transferred between external devices and the processor and this process needs to be managed by the operating system . ​ A device driver is a program that provides an interface for the OS to interact and communicate with an external device . Drivers are hardware dependent and OS-specific . The driver translates the OS’ instructions into a format the specific hardware can understand . Because the CPU and the peripheral will process data at different speeds , a buffer is typically used to temporarily store data until it can be processed . User Management The OS allows users to create , manage and delete individual accounts . User accounts can be granted different access rights such as an administrator or guest . The OS will manage security settings such as allowing passwords to be reset and can also be used to monitor login activity . File Management The operating system creates and maintains a logical management system to organise files and directories (folders ). ​ File management allows files to be named , renamed , opened , copied , moved , saved , searched for , sorted and deleted . It also allows users to set access rights for specific files and to view file properties . User Interface The final function of an operating system is to provide a user interface , allowing a human to interact with the computer system . The way in which a user can navigate a computer system is known as human-computer interaction ( HCI ). Graphical User Interface (GUI) The most common type of user interface is a graphical user interface (GUI ) which can be presented in the following ways: Icons are displayed to represent shortcuts to applications and files. Multiple windows can be opened at the same time and switched between. A folder and file system is displayed and manipulated allowing for copying , searching , sorting and deleting data. The interface can be customised , such as changing font sizes and the desktop background . The taskbar allows shortcuts to be pinned for quick access . Menus can be opened from the Start button to display files and shortcuts. System settings can be accessed such as network and hardware options . Command-Line Interface Other types of user interface do exist, such as a command-line interface (CLI ). This type of interface is entirely text-based and requires users to interact with the system by typing commands . This is a complicated process and mistakes could easily accidentally delete data. There are many commands to learn so only experts who have been trained t o learn this interface will be able to efficiently make use of it. Menu-Driven Interface A menu-driven interface displays data in a series of linked menus . Examples include cash machines (ATMs) and old iPods . ​ This type of interface is generally user friendly and easy to use as commands do not need to be memorised. However it can be annoying to find specific data through a large number of menus without a search feature. Touch-Sensitive Interface Another type of user interface is a touch-sensitive interface , used with smartphones and tablets . ​ A human interacts with the device by pressing on a touchscreen , making it very intuitive and suitable for most users without training. Touch-sensitive interfaces may not work with dirty or wet fingers and it will take longer to write text compared to using a keyboard. Voice-Driven Interface A voice-driven interface can be controlled by speaking commands aloud to a listening device. Examples include Amazon's Alexa devices, Apple's Siri technology and Google Home . ​ This interface is intuitive , can be used hands-free and helps to speed up processes . However commands may be misheard or limited in what can be performed. Q uesto's Q uestions 5.1 - Operating Systems: ​ 1. Describe each role of the operating system : Providing a user interface [ 3 ] Memory management (and multitasking) [ 3 ] Peripheral management (and drivers) [ 3 ] User management [ 3 ] File management [ 3 ] ​ 2. Describe 5 different ways the operating system can provide a graphical user interface (GUI) . [5 ] ​ 3. Describe one advantage and one disadvantage of using the following types of human-computer interaction (HCI) : a. Command-Line interface [ 4 ] b. Touch-Sensitive interface [ 4 ] c. Menu-Driven interface [ 4 ] d. Voice-Driven interface [ 4 ] 4.2 - Preventing Vulnerabilities Theory Topics 5.2 - Utility Software

1.3 - Embedded Software: ​ 1. What is an embedded system ? [3 ] ​ 2a. Give two examples of an embedded system. [ 2 ] 2b. Research and describe another two examples of an embedded system. [ 4 ] 1.3: Embedded Systems Exam Board: OCR Specification: J277 Example: A washing machine has a control chip that manages the different program cycles. An embedded system is a computer system built into a larger machine to provide a means of control . ​ Embedded systems perform a specific pre-programmed task which is stored in ROM . ​ An embedded system uses a combination of hardware and software . They perform only specific tasks and often have a small amount of storage and low processing power . Example: A traffic light has a control chip that determines when to change to a green or red light. Q uesto's Q uestions 1.2 - CPU Performance 2.1 - Primary Storage Theory Topics

1.2: Designing Algorithms Exam Board: OCR Specification: 2020 What is an algorithm? An algorithm is a set of instructions , presented in a logical sequence . ​ In an exam you may be asked to read and understand an algorithm that has been written. To prove your understanding you may be asked to respond by actions such as listing the outputs of the algorithm, correcting errors or identifying an error within it. ​ Programmers create algorithm designs as a method of planning a program before writing any code. This helps them to consider the potential problems of the program and makes it easier to start creating source code. There are two main methods of defining algorithms are pseudocode and flowcharts . In exams , OCR will display algorithms in their own 'OCR Exam Reference Language '. Visit the Python section of CSNewbs ---> OCR Exam Reference Language T he OCR exams require specific questions to be written either in OCR Exam Reference Language (shown below) or a high-level programming language such as Python . Basic Commands Annotation // Comments are written using two slashes Assignment name = "Harold" age = 49 ​ Constants and Global Variables constant tax = 15 global name = "Admin" ​ Input / Output name = input ( "Enter your name") print ("Transaction Complete") ​ Casting str (29) int ("102") float (30) bool ("False") ​ Random Number number = random (1,100) Selection Selection (if - then - else) if firstname == "Steven" then​ print("Hello" + firstname) elif firstname == "Steve" then print("Please use full name") else print("Who are you?") end if ​ Selection (case select) switch day: case “Sat”: print(“It is Saturday”) case “Sun”: print(“It is Sunday”) default : print(“It is a Weekday”) endswitch Iteration Iteration (for loop) for i = 1 to 10 step 1 input item next i ​ Iteration (while loop) while firstname ! = "Steven" firstname = input("Try again:") endwhile ​ Iteration (do while loop) do firstname = input("Guess name:") until firstname == "Steven" String Handling Length of a String word = "dictionary" print(word.length ) outputs 10 ​ Substrings (this is known as Slicing ) word = "dinosaurs" print(word.substring (2,3)) outputs nos print(word.left (3)) outputs din print(word.right (4)) outputs aurs ​ Concatenation name = "Penelope" surname = "Sunflower" print(name + surname) ​ String Cases phrase = "The Cat Sat On The Mat" print(phrase .lower ) print(phrase .upper ) ​ ASCII Conversion ASC ("C") returns 67 CHR (100) r eturns "d" File Handling File Handling - Reading Lines file1 = open ("Customers.txt") while NOT file1.endOfFile() print(file1.readLine() ) endwhile file1.close() ​ File Handling - Writing to a (New) File newFile ("paint.txt") file2 = open ("paint.txt") paint = input("Enter a paint colour:") file.writeLine (paint) file2.close() Arrays Declare Array array names[3] ​ array names = "Ella", "Sam", "Ali" ​ Declare 2D Array array grid[4,5] ​ Assign Values names[2] = "Samantha" grid[1,3] = "X" Flowcharts A flowchart can be used to visually represent an algorithm. ​ It is more likely you will need to be able to interpret a flowchart rather than draw one. ​ The flowchart symbols are: Algorithm Examples Below are two different methods for representing the same algorithm - a program to encourage people to buy items cheaply at a supermarket. The program allows the price of items in a supermarket to be entered until the total reaches 100. The total price and the number of items entered are tracked as the program loops. Once the total reaches 100 or more, an if statement checks how many items have been entered and a different message is printed if there are 20 or more items, 30 or more items or less than 20 items. Pseudocode // This is a program to see how many items you can buy in a supermarket before you spend over £100} ​ total = 0 itemsentered = 0 ​ while total < 100 itemprice = input ("enter the price of the next item") total = total + itemprice itemsentered = itemsentered + 1 endwhile ​ if itemsentered >= 20 then print ("You are on your way to saving money.") elif itemsentered => 30 then print ("You're a real money saver.") else print ("Look for better deals next time.") endif Flowchart Reading Algorithms In an exam you may be asked to read an algorithm and prove your understanding , most commonly by listing the outputs . ​ Start from the first line and follow the program line by line , recording the value of variables as you go . ​ When you encounter a for loop , repeat the indented code as many times as stated in the range . Example Algorithm: procedure NewProgram() ​ maxvalue = input() ​ for i = 1 to maxvalue output (i * i) ??????? ​ print("program finished") ​ endprocedure Example Questions: 1. List the outputs produced by the algorithm if the 'maxvalue' input is 5 . ​ 2. State the code that has been replaced by '???????' and what the code's purpose is. Example Answers: 1. Outputs: 1 4 9 16 25 program finished 2. Missing Code: next i Purpose: Moves the loop to the next iteration. Watch on YouTube Structure Diagrams Structure diagrams display the organisation (structure ) of a problem in a visual format , showing the subsections to a problem and how they link to other subsections . The noughts and crosses structure diagram below has subsections in light yellow. Each subsection could be coded by a different person . Structure diagrams are different to flowcharts (those show how data is input, processed and output within a program or system). ​ You may be asked in an exam to draw or fill in a simple structure diagram . Trace Tables Trace tables are used to track the value of variables as a program is run . ​ They can be used to manually track the values in order to investigate why the program isn't working as intended . ​ Each row in the trace table represents another iteration . Each column stores the value of a variable as it changes. See below how the trace table is updated for the simple algorithm on the left. num1 = 2 num2 = 5 ​ for i = 1 to 3 output (num1 + num2) num2 = num2 - 1 next i ​ print("complete") For most algorithms, not every variable will be updated in each iteration . ​ Values may not be entered in the order of the trace table either. For example, each iteration outputs num1 + num2 and then decreases the value of num2 by 1. Q uesto's Q uestions 1.2 - Designing Algorithms: ​ 1. What is the definition of an algorithm ? Name two ways an algorithm can be designed . [ 3 ] ​ 2. Using a high-level programming language such as Python , or the OCR Exam Reference Language , write an algorithm that inputs 6 decimal numbers and outputs the total , largest , smallest and average values. [ 8 ] ​ For example, entering 3.1 , 5.3 , 2.3 , 5.4 , 2.9 and 4.4 would output 23.3 (total), 5.4 (largest), 2.3 (smallest) and 3.9 (average). ​ 3. Draw and label the flowchart symbols . [ 6 ] ​ 4. What is the purpose of a structure diagram ? [ 2 ] ​ 5. Create a trace table for the NewProgram() algorithm in the Reading Algorithms section on this page. [ 7 ] 1.1 - Computational Thinking Theory Topics 1.3 - Searching & Sorting

3.2b: Protocols & Layers Exam Board: OCR Specification: 2020 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 reassembles 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 vs MAC Address There are two versions of IP addressing currently used - IPv4 and IPv6 . IPv4 uses a 32-bit address that allows for over 4 billion unique addresses . IPv4 uses a numeric dot-decimal notation like this: 212.58.244.66 4 billion unique addresses may sound like a lot but there are nearly 8 billion people in the world. Therefore a newer version - IPv6 - was developed with a 128-bit address , represented in hexadecimal that allows for a mind-boggling number of unique addresses. A MAC address is a unique hexadecimal number assigned to each network interface card inside a networked device e.g. a router or a laptop . While an IP address may change , the MAC address can’t be changed . 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 . 4-Layer TCP/IP Model The TCP/IP model is 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 . ​ The four layers are explained below: 4 Allows humans and software applications to use the network e.g. browsers (HTTP /HTTPS ) and email (SMTP ) and file transfer (FTP ). 3 TCP breaks the data down into data packets . This layer makes sure the data is sent and received in the correct order and reassembled at the destination without errors. 2 IP is responsible for addressing and routing data packets . The optimal route for the data to take is calculated in this layer. Also known as the 'Internet Layer '. 1 Ethernet sets out the format of data packets . This layer handles transmission errors and passes data to the physical layer . 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. Describe why network designs are split into layers . [ 2 ] ​ 4. Create a diagram similar to the one above and describe each layer of the TCP/IP Model. [ 8 ] ​ 5. Look at the statements below and name the layer that is being described: a. This layer ensures data packets are sent and received correctly. b. This layer checks for errors in transmission and sets out the data packet format. c. This layer allows software like web browsers to interact with the network. d. This layer uses addresses to ensure data packets take the correct route. [ 7 ] 3.2a - Wired & Wireless Networks Theory Topics 4.1 - Security Threats

3.1a: Network Types & Performance Exam Board: OCR Specification: 2020 What is a network? A network is more than one computer system connected together allowing for communication and sharing of resources . 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 Wide Area Network Client-Server Network Clients make requests to a server , the server manages that request and responds. For example, if the user (client) makes a request to access www.bbc.co.uk to a web server. ​ Large services like Amazon and Google will need very powerful servers to handle millions of requests a second. ​ The client is completely dependent on the server to provide and manage the information. The server controls network security , backups and can be upgraded to manage higher demand. Advantages: The network can be controlled centrally from the server to easily backup data and update software . Hardware, software and resources can be shared across the network, such as printers, applications and data files . The network allows for improved scalability , meaning more clients can be easily added to the central server . Disadvantages: Large amounts of traffic congestion will cause the network to slow down . If a fault occurs with the server then the whole network will fail . IT technicians may be required to manage and maintain the network . Malware , such as viruses, can spread quickly across the network. Peer-to-Peer Network For peer-to-peer networks , data is shared directly between systems without requiring a central server . Each computer is equally responsible for providing data. Peer to peer is optimal for sharing files that can then be downloaded. Disadvantages: Without a dedicated server there is no central device to manage security or backups . Backups must be performed on each individual system. Computer performance will decrease with more devices connected to the network, especially if other machines are slow. Advantages: This is a simpler network than client-server to set up as no server is required . Clients are not dependent on a server . Perfect for quickly sharing files between systems , such as downloading media files. 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 . ​ The network infrastructure of a LAN (such as servers and routers) is usually owned and managed by the network owner . A wide area network (WAN ) has computer systems situated geographically distant to each other, possibly across a country or even across the world . WANs often use third party communication channels , such as connections by internet services providers like BT or Virgin Media. Other network types do exist, such as a Metropolitan Area Network (MAN ) for computer systems connected across a town or city or a Personal Area Network (PAN ) for devices connected and used by an individual . Data Packets When sending data across a network, files are broken down into smaller parts called data packets . ​ Whole files are too large to transfer as one unit so data packets allow data to be transferred across a network quickly . ​ Each packet of data is redirected by routers across networks until it arrives at its destination. Data packets may split up and use alternative routes to reach the destination address. ​ When all the packets have arrived at the destination address the data is reassembled back into the original file. Contents of a Data Packet: Header Payload Trailer Source address Destination address Packet number Protocol The data itself A checksum - this is a calculation on the data to see if any errors or corruption have occurred during transmission . What is a network topology? Network topology refers to layout of computer systems on a local network . ​ Devices in a network topology diagram are often called 'nodes' . Two types of typology are star and mesh . Star Topology Each computer system is connected to a central device , usually a hub or switch . How it works: Each computer system is connected to the central hub or switch and transfers its data packets there. The hub or switch looks at the destination address and transfers the packets directly to the intended computer. Advantages: A star topology has improved security because data packets are sent directly to and from the hub / switch in the centre and not necessarily all devices like in a bus or ring topology. New systems can be attached directly to the central system so the network doesn't need to be shut down . System failures of attached computers won't usually cause complete network failure. Transfer speeds are generally fast in a star topology as there are minimal network collisions . Disadvantages: Extra hardware (the hub or switch) is required to be purchased, installed and maintained. If the central system (the hub or switch) fails then the whole network will be unusable until the error is fixed. Mesh Topology In a full mesh network, each computer system is connected to every other computer system . There is also a partial mesh network where only some nodes (e.g. a printer) are connected to every other node. ​ How it works: Data packets are transferred to the destination address along the quickest path , travelling from node to node. If a pathway is broken , there are many alternative paths that the packets can take. Advantages: If one cable or system fails then data packets can take an alternative route and still reach the destination address. Because of the large possible number of systems and connections, a mesh topology can usually withstand large amounts of data traffic . New systems can be added to the network without disrupting the entire topology . Disadvantages: Because of the possibly large amount of cables required (especially in a full mesh topology) this network layout can be expensive to install and maintain . Redundant cabling should be avoided - this is when cables are connected between systems that won't ever need to communicate . Performance There are several different factors that can affect the performance ( speed ) of a network, such as: The bandwidth available * Interference (e.g. thick walls) Applications being used Number of users at the same time Distance to travel / signal strength Server / CPU Performance Number of data collisions Amount of data to transfer * Bandwidth is the maximum amount of data that can be sent across a network at once . Q uesto's Q uestions 3.1a - Network Types & Performance: ​ 1a. Describe the difference between a LAN and WAN . [2 ] 1b. Give an example of how a LAN and a WAN could each be used . [ 2 ] ​ 2 a. Describe how peer-to-peer networks and client-server networks function. 2b. Give one use for both types of network. ​ 3. Draw and label diagrams of client-server , peer-to-peer , star and mesh networks. [8 ] ​ 4. An office currently uses a star topology but is considering changing to a mesh topology . Describe two advantages and two disadvantages of both topologies. [ 8 ] ​ 5. State five factors that could affect the performance of a network . [5 ] 2.5 - Compression 3.1b - Network Hardware & Internet Theory Topics

6.1a: Impacts of Technology Exam Board: OCR Specification: J277 What are the issues created by technology? As the use of computers and technological devices continues to rise every year, this increase brings with it a range of different types of issues . Categories of issues described on this page include: ​ Cultural issues Environmental issues Ethical issues Legal & Privacy issues Cultural Issues Culture relates to society and how different parts of the world vary in terms of computer and internet usage . The Digital Divide This term relates to the gap between those people who have access to modern digital technology (such as computers and the internet) and those who have limited access . 'Limited access' could be devices at home or shared devices or having lower-performance (cheaper) computers and low-speed internet connections. ​ The digital divide can be seen in different ways , such as: People in cities vs. People in rural areas . Younger people vs. Elderly people. Developed countries vs. Developing countries. The digital divide is an important ethical issue because digital technologies have led to numerous international benefits including boosted growth , improved product delivery , enhanced communication and increased opportunities . However, this impact is uneven and these positive impacts are mostly occurring in technologically-advanced regions such as North America , Western Europe and Japan . Regions like some nations in Africa and Central Asia have limited digital infrastructure and government instability , leading to poor internet speeds , high costs and limited resources . ​ Discussion Points: What do you think can be done to bridge the digital divide? Whose job is it to bridge the gap? Who will pay for the technology? Changes to Work The internet , the development of new technologies such as cloud storage and increased video communication have transformed the way that many businesses operate across the world. Staff may be able to work from home or access documents collaboratively outside of the traditional workplace, such as cafes or on public transport. ​ Some jobs have moved abroad to save costs, such as help centres for online issues. Tasks can be outsourced to freelancers in other countries where people are content to be paid less for their time and services. For example, some companies will hire temporary web developers from countries such as India to work for them for a lower salary than local workers. ​ Another change to work that technology has brought is the loss of jobs , especially low-skilled jobs such as factory workers that have seen their roles replaced by technology and automation . However, technology has also created millions of new jobs , including installing and maintaining the machines that replace other roles. Environmental Issues Environmental issues concern the natural world and the negative effects of producing , using and discarding computer systems and devices. Energy and Material Consumption In the past 30 years, the number of technological devices has increased astronomically and thousands of new devices are manufactured each day . These devices need to be assembled using a range of materials , including plastics , metals and some rarer elements and need a considerable amount of electrical power to run. Certain systems like web servers and data centres must be powered on all day , every day, which uses a large amount of energy . Pollution and Waste Generating the electricity to power computers creates pollution - an average PC could require up to 50% more energy per year than a fridge. Computers are difficult to recycle and discarded components can lead to land, water and air pollution due to harmful materials , such as lead and mercury , leaking into the environment. ​ Smartphone trends are also negative for the environment as new devices are released yearly , with minor upgrades that people buy to appear fashionable and up-to-date. To lessen the environmental impact, people should reuse and recycle their devices. Ethical Issues Ethics relates to what is considered right or wrong . Often this is subjective - people may have differing opinions on the issue. Drones Uses of drones: Filming and photography for television, movies and special events. Monitoring pollution levels in the atmosphere. Tracking and monitoring wildlife , such as rhino populations in Africa. Disaster zone response , such as searching for survivors following an earthquake. Delivery companies are developing drones to quickly deliver goods across cities. Drones are used by the military to target sites in other countries, such as American soldiers deploying surveillance drones in Syria. ​ Discussion Points: Should you need a licence to buy and fly a drone? Should drones be used to monitor the public? Like flying CCTV? Should drones be used to deliver items? Like Amazon packages? If a drone hits a plane and it crashes, what should the punishment be? A drone is an unmanned aerial vehicle (UAV ) that is remotely operated and can be used for a wide range of purposes. Self-Driving Cars Self-driving cars (also known as autonomous vehicles ) are currently in the development and testing stage with companies like Tesla and Amazon. Benefits of self-driving cars include: In theory, driving will be safer because cars are less likely to make mistakes that humans do and they can’t become distracted or tired . Self-driving cars should be more fuel-efficient because they take the most direct route to destinations and do not get lost. ‘Drivers’ in the car can perform other tasks instead of driving, such as work or planning. Autonomous vehicles could include trucks and vans to automate the delivery and freight industries . Trucks could drive overnight to deliver goods whereas currently, human drivers must take breaks every few hours. Drawbacks of self-driving cars include: Cars could still crash as code and software processes may fail. The technology is still in development and will be very expensive for the first few years when self-driving cars are available to purchase. Jobs may be lost such as delivery and truck drivers whose vehicles are equipped with self-driving technology. Other industries like motorway services and hotels may also be affected. ​ Discussion Points: Would you trust a car to drive itself? Who is to blame if a self-driving car crashes? The car maker? The people in the car? The software writers? What should happen to the people whose jobs are taken by self-driving vehicles? Artificial Intelligence Artificial Intelligence (AI ) is the act of computers replacing humans to analyse data and make decisions . In recent years AI has become more common in the home and on devices like smartphones; assistants such as Siri and Alexa are prime examples of modern home AI. AI Chatbots like ChatGPT have become more popular in recent years but have lead to issues such as plagiarism , misinformation and breaking copyright laws . The weather today is cloudy. Benefits of AI include: Processes are sped up as computers can analyse large amounts of data much quicker than a human. AI can be used when a human is unavailable , such as using a symptom checker on the internet for a minor illness rather than booking and waiting for a doctor. Repetitive or time-consuming tasks can instead be completed by a computer , such as searching and sorting scientific data or generating ideas , images or audio from a prompt . Drawbacks of AI include: AI can store and process a lot of personal data , especially personal assistants like Alexa which are always listening for ‘wake words’. This data can be viewed by the company that develops it and could be hacked by attackers. AI is programmed by humans and mistakes in code could have disastrous consequences if the AI is used to make important decisions , such as military deployment. AI GPT tools like ChatGPT can give incorrect results , may use copyrighted material in their response and students may use it to submit work that is not their own . ​ Discussion Points: If a robot harms a human who is to blame? The robot? The programmer? The manufacturer? Us? Would you trust a walking, talking robot assistant in your home? Should ChatGPT be banned in schools or can it be helpful? Should AI make decisions for us? Legal & Privacy Issues Legal and privacy issues regard laws that have been introduced by the UK government to protect data, systems and networks from unauthorised access . See 11.2 for explanations about important computing legislation in the UK. Loss of Privacy & Hacking There has been a lot of criticism in the last few years about how internet companies and governments are using personal data to invade privacy and track civilians . Facebook was involved in a scandal with using personal data for reasons that were not the original intention. In reverse, WhatsApp and Apple have been criticised for encrypting messages sent by terrorists that police have been unable to track and read. Every week a new company seems to announce that its data has been hacked . Attackers are constantly using botnets and infected systems to crack poorly secured databases and attempting to phish individuals for usernames and passwords. In the past few years, major hacking breaches include Sony, Yahoo and TalkTalk. ​ Discussion Points: Should the UK government be able to see the websites you have visited in the last year? What should happen if a major company is hacked and bank details are stolen? Should they be fined? Pay customers? Prison? Should WhatsApp allow authorities to access encrypted messages? What if they know a terrorist is using it to communicate? Should the UK debate privacy laws before they go into place? Online Crime Unlawfully obtaining personal information and using it for identity theft or fraud . Harassment and threatening others on social media or private messages; blackmail . Cyber attacks are more common - see 3.8 for information about DOS attacks , IP spoofing , SQL injection and more. Sharing copyrighted material such as television programmes, music and video games. Distributing prohibited material such as drugs or weapons on the dark web. ​ See 6.1b for explanations about different laws that have been created to tackle online crime . The increased popularity of the internet and the rising number of users has led to a wave of online crime , taking many different forms, including:​ Q uesto's Q uestions 6.1a - Impacts of Technology: ​ Cultural Impacts 1a. What is the digital divide ? [ 2 ] 1b. Describe 2 examples of how the digital divide can be seen . [ 2 ] ​ 2. Describe in detail 3 ways that technology has changed the way people work . [9 ] ​ Environmental Impacts 1. Describe the different ways that the increasing use of technology negatively impacts the environment . [ 5 ] ​ Ethical Impacts 1a. What is a drone ? [1 ] 1b. Make a list of all of the positive impacts and the negative impacts of using drones . You should have at least 3 on each side. [ 6 ] ​ 2. Describe 2 benefits of using self-driving cars and 2 negative consequences . [4 ] ​ 3. Describe how artificial intelligence can be used for good . [ 4 ] ​ Legal & Privacy Impacts 1. A hack on a bank has occurred. Describe what you think the impacts would be on the following groups of people: a. The customers . b. The bank managers . c. The general public . [ 6 ] ​ 2. Describe 4 different types of online crime . [ 8 ] 5.2 - Utility Software Theory Topics 6.1b - Legislation

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

3.1b: Network Hardware & Internet Exam Board: OCR Specification: J277 Network Devices When sending data across a network, files are broken down into smaller parts called data packets . ​ Whole files are too large to transfer as one unit so data packets allow data to be transferred across a network quickly . ​ Each packet of data is redirected by routers across networks until it arrives at its destination. Data packets may split up and use alternative routes to reach the destination address. ​ When all the packets have arrived at the destination address the data is reassembled back into the original file. Wireless Access Point A Wireless Access Point provides a link between wireless and wired networks . It creates a wireless local area network that allows WiFi-enabled devices to connect to a wired network. ​ Examples of a wireless access point in a public space could be a WiFi or Bluetooth hotspot , for example a WiFi hotspot in a coffee shop or airport to provide access to the internet. ​ A wireless access point may be a separate device or built into another device such as a router. Router Routers are used to transfer data packets between networks . ​ Routers receive data packets and use the IP address in the packet header to determine the best route to transmit the data. ​ Data is transferred from router to router across the internet towards the destination. ​ A router stores the IP address of each computer connected to it on the network and uses a list called a routing table to calculate the quickest and shortest route to transfer data. Switch A switch is used to connect devices together on a LAN . ​ It receives data packets from a connected node, reads the destination address in the packet header and forwards the data directly to its destination. ​ A switch will generate a list of the MAC addresses of all devices connected to it when it receives data , and must scan for a matching destination address before sending. ​ An alternative to a switch is a hub but a hub is slower and less secure as it forwards a copy of received data to all connected nodes . Network Interface Controller / Card A Network Interface Controller (NIC ) commonly also known as a Network Interface Card is an internal piece of hardware that is required for the computer to connect to a network . The card includes a MAC address which is used when sending data across a LAN . An ethernet cable is plugged into the network card to allow data to be exchanged between the device and a network. A NIC used to be a separate expansion card but is now typically embedded on the motherboar d . Transmission Media Although not technically a device, the communication channel along which data is transferred will affect performance . Three common types of transmission media include: ​ Ethernet cables - used typically on a LAN to transfer data between nodes and hardware such as switches. Examples include Cat5e and Cat6. Fibre Optic cables - very fast but more expensive and fragile cables typically used to send data quickly along a WAN . Data is sent as pulses of light . Coaxial cables - older , slower , copper cables that are not used as much in modern times as they can be affected by electromagnetic interference . The Internet 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 . ​ Servers provide services on the internet , such as a web server which responds to the web browser (client) request to display a web page . The web server processes the client request to prepare the web page and return it so the web browser can display it to the user . ​ A website must be hosted (stored) on a web server so that it can be accessed by others using the internet . A unique domain name (e.g. csnewbs.com) must be registered with a domain registrar – this is a company that checks the name is valid and not already taken . What is the Internet? DNS Servers ​A DNS ( Domain Name System ) server stores a list of domain names and a list of corresponding IP addresses where the website is stored. ​ The first thing to understand is that every web page has a domain name that is easy for humans to remember and type in (such as www.csnewbs.com ) as well as a related IP address (such as 65.14.202.32) which is a unique address for the device that the web page is stored on. The steps taken to display a web page: 1. A domain name is typed into the address bar of a browser . 2. A query is sent to the local DNS server for the corresponding IP address of the domain name . www.facebook.com 3. The local DNS server will check if it holds an IP address corresponding to that domain name. If it does it passes the IP address to your browser . 66.220.144.0 4. The browser then connects to the IP address of the server and accesses the web site . If the local DNS server does not hold the IP address then the query is passed to another DNS server at a higher level until the IP address is resolved. If the IP address is found, the address is passed on to DNS servers lower in the hierarchy until it is passed to your local DNS server and then to your browser. Cloud Storage The cloud refers to networks of servers accessed on the internet . Cloud computing is an example of remote service provision . Cloud servers can have different purposes such as running applications , remote processing and storing data . ​ When you store data in 'the cloud', using services such as Google Drive or Dropbox, your data is stored on large servers owned by the hosting company . The hosting company (such as Google) is responsible for keeping the servers running and making your data accessible on the internet . ​ Cloud storage is very convenient as it allows people to work on a file at the same time and it can be accessed from different devices. However, if the internet connection fails , or the servers are attacked then the data could become inaccessible . Cloud Storage Characteristics: ​ ✓ - Huge CAPACITY and you can upgrade your subscription if you need more storage. ​ ✓ / X - Cloud storage is difficult to rank in terms of PORTABILITY , DURABILITY and ACCESS SPEED because it depends on your internet connection. A fast connection would mean that cloud storage is very portable (can be accessed on a smartphone or tablet) but a poor connection would make access difficult . ​ ✓ - Cloud storage is typically free for a certain amount of storage. Users can then buy a subscription to cover their needs - Dropbox allows 2 GB for free or 2 TB for £9.99 a month. Q uesto's Q uestions 3.1b - Network Hardware & Internet: 1a. Explain how a switch works. [ 2 ] 1b. Describe the purpose of a router . [ 2 ] 1c. State what WAP stands for and why it is used . [ 2 ] 1d. State what NIC stands for and why it is required . [ 2 ] 1e. State the differences between the three main types of transmission media . [ 3 ] ​ 2a. State what the internet is and how it is different to the world wide web . [ 2 ] 2b. What is web hosting ? [ 2 ] ​ 3a. What is a DNS server ? [ 2 ] 3b. Describe, using a mix of text and icons / images , how a DNS server is used to display a web page . [5 ] 3c. Describe how a DNS server searches for an IP address if it is not found on the local DNS server . [ 2 ] ​ 4a. Describe what cloud computing is. [ 2 ] 4b. State two advantages and two disadvantages of the cloud . [ 4 ] 3.1a - Network Types & Performance Theory Topics 3.2a - Wired & Wireless Networks

About CSNewbs Plus (CSN+) CSN+ is a premium collection of resources made for teachers that follows the Computer Science specifications covered on the website . ​ Currently, these resources are in development , with the Eduqas GCSE resource pack arriving first, based on the Eduqas GCSE Computer Science 2020 specification . < Free zip folder download of all resources for Eduqas GCSE topic 1.1 (The CPU) *Updated Jan 2021* ​ Resources included for each topic: Lesson Slides Starter activity (to print) Task resources (e.g. diagrams or worksheets to print) Task answers What is included in the CSNewbs+ GCSE collection? 39 presentation slides 39 starters 39 task answer documents 19 revision activity pages 7 topic tests & answers ​ ​ See below for more details: + Complete presentation slides for each of the 39 theory topics in the Eduqas GCSE 2020 specification . ​ PowerPoint and Google Slides compatible. Activity resources to print . Including diagrams , tables and worksheets for lesson tasks . All answers included for teachers to use. Starter questions that recap the previous topic. For teachers to print before the lesson. All answers included in the lesson slides. 39 starters . Comprehensive answers for all lesson tasks . 39 task answer documents containing answers for over 100 lesson tasks for teachers to use . Revision templates for students to complete, to print on A3 paper . 19 pages and 7 revision lesson slides . Exercise book headings and the driving question (lesson focus) 7 end-of-topic tests with brand new questions . All answers included for teachers. What is included on the presentation slides? The following breakdown shows the presentation slides for 1.1 (The CPU): A title slide The content covered from the Eduqas GCSE specification Exercise book headings and the driving question (lesson focus) Answers to the starter activity questions Lesson objectives An explanation of the topic Clear explanations of the content First task. Students use slides or CSNewbs to complete. All answers on separate teacher document. Task 2. Table provided in teacher resource pack to print. Further explanations of the content Further explanations of the content with diagrams. Further explanations of the content with diagrams. Task 3. Answers in the teacher document. Plenary to check the students' understanding of the lesson topics. < Free zip folder download of all resources for Eduqas GCSE topic 1.1 (The CPU) *Updated Jan 2021*