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2021 Mock Revision, c (b, z), m, ,, Yes sir, : : : : : :, jaf smells -…

- - - - Split the original list into paris, sort the paris by checking each one for the correct order, if they're not, wap them. Then merge the pairs into bigger lists and sort the bigger lists. Keep merging and sorting the lists until the original list is restored and it is sorted
    - - Look at the first and second number, if they're in the wrong order, swap them, then look at the second and third, and do the same. Continue for every pair in the list. The sort only stops when no swaps are made in one run through
  - - - Searches through each item of the list individually, only stops when it finds the item it is looking for or reaches the end of the list.
        
        It is slower than a binary search, but it doesn't require the list to be in order, it also works when letters are involoved
    - - Looks at the middle item, if it is lower than the desired value, it will discard the first half of the list and itself and vice versa, if it is the value it's looking for, the search will end. It will continue to do this with each new half the search creates until it finds what it's looking for or it gets down to the last value.
        
        It is faster than a linear search, but it requires the list to be ordered from lowest to highest
- - - - Geographically confined to one building or site
      - Advantages
      - Disadvantages
    - - Spread over a wide geographical area. Usually used by things like organisations with more than one office
        
        Advantages
        
        Disadvantages
    - - Network used to connect personal devices and spread over a very small area. for example, bluetooth.
        
        Advantages
        
        Disadvantages
  - - - Advantages
        
        Less cost for cables.
        
        Cheaper to set up.
        
        Devices can connect to a network automatically
      - Disadvantages
        
        Data is more vulnerable tobeing intercepted because it is sent through radio waves
        
        They are typically slower than wired networks.
        
        They have less range than a wired network
    - - Advantages
        
        Have higher range and speed
        
        Data is more secure because there is a physical connection
      - Disadvantages
        
        Set up cost is higher
        
        More cables are required
  - - - Advantages - If one node is damaged or disconnected, the entire network DOES NOT go down
        New nodes can be added to the network, simply by connecting them to the switch
        Star networks tend to have higher performance as a message is only passed on to the intended node
      - Disadvantages - The whole network fails if the main switch fails
        A wired star topology is more expensive than a bus
      - A star topology consists of multiple nodes, individually connected to a main hub switch
    - - Disadvantages
        
        If there is an issue with the backbone cable, all of the nodes will fail.
        
        There is a cost to the backbone cable and management of it.
        
        Terminators need to beinstalled.
      - Advantages
        
        It is easier to connect additional nodes to the network
        
        It is generally cheaper to set up due to requiring less cables that a star network.
      - All the nodes on a network are connected through a backbone. Data is sent across the backbone cable to get to its node. If the corRect node is not found, the data continues to a terminator at the end of the backbone cable and the data is destroyed.
  - - - HTTPS - Secure socket layer - HTTP over a secure encrypted connection
      - FTP - File Transfer Protocol - USed to send files from one node to another over the Internet or other network. Used to upload web pages
      - HTTP - Hypertext Transfer Protocol - Used by browsers to access websites
      - SMTP - Simple Mail Transfer Protocol - Old Standard for sending mail onto a mail server
      - IMAP - Internet Message Access Protocol - Accessing Emails from a server
    - - TCP - Transmission Control Protocol - Controls how devices connect to a network. Creates a connection between two devices and checks if the data is sent and delivered
      - UDP - User Datagram Protocol - Alternative to TCP. Is faster and less tolerant of missing info
    - - IP - Internet Protocol - The method in which a computer sends data to another computer across the Internet
    - - MAC Address - Media Access Control - The address is the description of your computer's address. MAC addresses cannot change
  - - - Network Interface Controller - Offers an interface port for a wired connection
        
        Receives data in the form of packets and forwards them to their destination
    - - Records which computers are connected to which ports - cuts down on unnecessary transmission.
    - - Low bandwidth - cheap
    - - A physical layering network device which is used to connect multiple devices in a network
    - - Wireless Access Point - Uses a radio transceiver to allow wireless connections to a network. Can be used to extend the range of a wireless network
    - - Wired or Wireless
    - - High Bandwidth More expensive, 40 terabits per second
- - - - 1000 bytes - A kilobyte
      - 1000 kilobytes - 1 megabyte
      - 1000 megabytes - 1 gigabyte
      - 1000 gigabytes - 1 Terabyte
      - 1000 terabytes = 1 petabyte
      - 4 bits = 1 nibble
  - - - Original file can be restored
      - Essential for text files, otherwise there would be missing text
      - Useful when the same data occurs many times
    - - Original file can not be restored
      - Can't be used with text files
      - Can be used for bitmap images or audio files
    - - Less time to upload / download
      - Less internet congestion
      - Makes streaming audio and videos possible
      - Can get around attachment size when emailing
    - - E.g aaaaaaabbbbb turns into 7a5b
      - A run is compressed into two bytes, the first is a number showing how many items were in the original run, the second is the original character
  - - - A simple black and white image can be created using binary
        We use 1 for white and 0 for black
      - However many images need to use colours
      - The higher the colour depth of an image, the larger the file of that image will be
    - - Image resolution is the number of pixels in a specific area of the image - This is usually measured in PPI , pixels per inch
      - In a low resolution image, the images appear blocky and more pixelated as less pixels are used to fill the space - The higher an images resolution, the larger the file will be
    - - Metadata includes information about the file itself
      - The data used in metadata information includes things like:
        
        File Type
        
        Date Created
        
        Author
        
        The height and width of the image
        
        The resolution
        
        The colour depth
  - - - A sound is initially captured with a microphone and converted into a digital signal
      - An analogue to digital converter will capture the sound by measuring the amplitude (height) of the sound wave. This is called a sample
      - The sound recorded at certain points is given a numerical value and stored in a file for later use
    - - Sample rate is the number of samples recorded per second. Sample rate is measured in hertz. The higher the hertz, the closer the sound sounds to the original
      - The higher sample rate, the larger the resultant file size
    - - Bit depth refers to the number of bits used to record each sample - The higher the bit depth, the more accurately a sound can be recorded, but the larger file size
      - Bit rate is simply a measure of how much data is processed for each second of sound
        The equation for calculating bit rate is:
        Bit depth x Sample rate
- - - - Or Gate - Gives an output of 1 if either input is 1
      - Not Gate - Changes the input from a 0 to a 1, and vice versa
      - And Gate - Gives and output of 1 if both inputs are 1
  - - - Along with internal hardware, additional hardware allows the user to interact with the outside world, these devices are input/output devices.
        
        Input devices include:
        
        Mouse
        
        Keyboard
        
        Camera
        
        Microphone
        
        Output devices include:
        
        Screen
        
        Speakers
        
        Printer
        
        LEDs
    - - There are two types of software: System Software and Application Software
        
        System Software
        
        System software is any software that assists in the running and overall management of the computer system.
        This can include the operating system, security software and file management software
        
        Application Software
        
        Application software is any software added to a system that enables a user to perform a specific task.
  - - - Buses
        
        Collections of wires used to transmit data between components of the CPU and other parts of the system.
        A processor may have separate buses for data and instructions
      - The Clock
        
        Sends out a signal alternating between 1 and 0, which is used to synchronise when instructions should be carried out. The number of clock cycles per second is called clock speed
      - The Cache
        
        The caches is a very fast memory in the CPU, slower than registers, but faster than RAM. It stores regularly used data to access it quickly. They have less capacity and are more expensive than RAM.
      - The ALU
        
        The ALU does all the calculations, completing simple math equations as well as logic operations
- - - - Making up a story to gain a person's interest and encourage them to give money and data
    - - Similar to blagging, phishing is sent by a person or organisation pretending to be a legitimate business. When a person clicks on the link and logs in, information is stolen from the victim.
    - - A type of attack that redirects a user from a genuine website to a fake one that looks real. When the user logs in, the attacker will then use the information to log in to the real account
    - - Looking over someone's shoulder in order to read the information they have inputted before memorising it
  - - - Malware that infects another computer, then replicates itself to be passed on to another computer
        
        Therefore, anti-virus software hosts a large database of known viruses. If a virus is detected it will place all important data in a secured folder until it is safe
    - - A trojan appears to be a piece of harmless software, but actually contains malicious code
    - - Hijacks the data on a computer system by encrypting it and then demands a ransom for unencrypting it
    - - Covering up a malicious website with fake ads
  - - - A simple method of checking someone's identity. They should be strong, many characters long, use a combination of letters, numbers and symbols. These should often be changed regularly. Weak or default passwords are a big security risk.
    - - Using scanners to identify a specific part of the body
        
        Retina
        
        Fingerprints
    - - is used by most website services that require account registration to confirm the email address belongs to the person. It is also used to stop people from using fake email addresses to stop people from signing up for things.
    - - 'Completely Automated Public Turing Test to tell Humans And Computers Apart' - It is designed to prevent programs from automatically doing certain things, like creating accounts on a website. It usually consists of a simple task such as typing out a blurred to distorted word.