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Computer Science - Coggle Diagram

- - - - Architecture of the CPU
        
        What is the CPU?
        
        CPU stands for processing unit
        
        also known as the brains of the computer - the CPU processes data and controls hardware (hard drive, input / output devices)
        
        What is the FDE cycle?
        
        The FDE cycle is a process the CPU goes through when processing instructions
        
        Stands for Fetch - Decode - Execute
        
        Fetch - First instruction is loaded from Main Memory into CPU
        
        Decode = Decodes instructions
        
        Execute = Instruction is carried out
        
        Cache = Stores temporary storage
        
        Memory Management unit = The ss hardware that handles virtual memory and operations involving cache
        
        CPU clock = Measures the number of cycles that the CPU executes per second
        
        Control unit = controls how data moves around the CPU, controls input and output
        
        Registers = a kind of temporary storage
        
        Hyperthreading = Where the CPU will divide up its physical cores
        
        Bus = carries data to its designated location
        
        ALU unit = Stands for Arithmetic and Logic - handles maths instructions
      - Von Neumann Architecture
        
        Von Neumann created the concept for a modern computer (Stored program computer)
        
        Stored Program computers use 5 special registers for processing
        
        Program Counter = used to locate where the next instruction needs to go in order for it to be executed correctly by the CPU
        
        Memory Address Register - Updated by the Program Counter to hold the location of the next instruction that has to be fetched from RAM - then this information is then taken to RAM by the address bus
        
        Memory Data Register = Instructions from main memory are stored in the MDR before being moved to the correct register in order to be processed
        
        Current instruction register = where the current instruction being processed is being held and decoded
        
        Accumulator (ACC) = Temporarily stores data while calculations are being performed by the ALU
    - - CPU Performance
        
        Core = Another name for a processing unit - CPU's will often typically have more than one processing unit and each unit will be called a core - they contain ALU's, CU's and Registers
        
        Clock = The clock will measure how many instructions the CPU is able to take out per second - often it ticks over 3 billion times (3ghz), this means 3 billion instructions have been processed
        
        Cache = a small amount of temporary memory that stores instructions likely to be reused again by the CPU in the near future
        
        Overclocking = When a CPU is ran at a higher speed than intended by manufacturers - allowing more instructions to be processed
    - - Embedded systems
        
        Vehicles
        
        Digital Watches
        
        GPS Systems
        
        Fitness Trackers
        
        Central heating
  - - - Memory
        
        Used to store data in a computer system - can be either Temporary or Permanent
        
        Memory is split up into 2 categories - Main memory (can be directly accessed by CPU) and Secondary storage (Non volatile memory outside of the CPU)
        
        RAM (Random access memory)
        
        ROM (Read only memory)
        
        Flash Memory
        
        Virtual Memory
        
        Volatile Memory = Memory that is lost when a computer turns off / loses power
        
        Disk Thrashing
    - - Storage
        
        Magnetic Storage
        
        Optical Storage
        
        Solid State storage
    - - Units of Storage
        
        A bit - the smallest possible size of unit (4 digits)
        
        A byte is 8 bits
        
        A kilobyte is 1024 bytes
        
        A megabyte is 1024 kilobytes
        
        A gigabyte is 1024 megabytes
        
        a Terabyte is 1024 gigabytes
    - - Data storage
        
        Data can be stored in Binary, Characters (letters), images and sound.
        
        Metadata is data about data
        
        Typically will tell you about how many bits are in the photo, the image width, the resolution and the
    - - Compression is where bits in a file are reduced in order to make the file size smaller to save space on a device
      - Lossy Compression
        
        Lossy compression will permanently delete data from the file and therefore the quality of the file will be reduced
      - Lossless compression
        
        Lossless compression will allow for the file size to be reduced while withstanding the same quality as the original file before compression
  - - - Networks and topologies
        
        Types of networks
        
        LAN's
        
        Local area networks typically only cover a small geographical area such as a school or a small office building
        
        WAN's
        
        Wide area networks cover large geographical areas such as a town or a country.
        
        The internet is considered a WAN
        
        Connect users by connecting multiple LAN's in different geographical locations
        
        Networking
        
        Advantages
        
        Userscan sharefiles
        
        users can share connections with other devices
        
        Users can access their files from any device on the network
        
        servers can control security, back up data and complete software updates
        
        Disadvantages
        
        Increased security reasks
        
        Malware and viruses can spread quickly between computers
        
        If a server crashes, the computers will not work
        
        Networking is a group of devices that are connected to eachother
    - - Common Protocols
        
        TCP
        
        Transmission control protocol
        
        IP
        
        Internet protocol
        
        HTTP
        
        Hypertext transfer protocol
        
        HTTPS|
        
        hypertext transfer protocol secured
        
        FTP
        
        file transfer protocol
        
        POP
        
        Post office protocol
        
        IMAP
        
        internet message access protocol
      - Encryption
        
        A process that scrambles readable text so it can only be read by the person who has a decryption key
- - - - Abstraction
        
        Abstraction involves filtering out the information we dont need in order to be able to concentrate on the information that we do need.
        
        An example of this would be ; A drawing of a metro map that only has important landscapes and stops mapped out.
      - Decomposition
        
        Breaking down a problem
      - Algorithmic Thinking
        
        An algorithm is a set of steps that is followed to carry out an instruction
        
        Algorithms can be designed using pseudocode an flow diagrams
        
        Algorithms are starting points