comp sci mindmap

comp sci mindmap

Binary
1. Arithmetic overflow
  1. When there are insufficient bits to store the result from addition due to a final carry bit.
2. Binary shift
  1. left shift multiplies by 2
  2. right shift divides by 2
3. Check digit
  1. A calculation on data to create a number included with the data for error checking
  2. When the number is input the check digit is recalculated to check it matches
  3. Therefore valid data can be assumed
Units
1. Bit
  1. binary digit 0 or 1
2. Nibble
  1. 4 bits
  2. Half a byte
3. Byte
  1. Can represent 1 character in ASCII
  2. 8 bits
4. Kilobyte (KB)
  1. 1024 bits
  2. ~1000 bytes
5. Megabyte (MB)
  1. 1024 KB
  2. ~1,000,000 bytes
6. Gigabyte (GB)
  1. 1024 megabytes
  2. ~1,000,000,00 bytes
7. Terabyte (TB)
  1. 1024 gigabytes
  2. ~1,000,000,000,00 bytes
8. Petabyte (PB)
  1. 1024 gigabytes
  2. ~1,000,000,000,000,000
1.1.1 architecture of cpu
1. Von Neumann architecture
  1. a system where cpu runs programs stored in memory
  2. programs consist of instructions and data which are stored in memory adress
  3. made of CU, ALU, MDR and MAR
2. cpu architecture
  1. CPU
    1. brain of the computer
    2. processes all data and instructions
    3. power of cpu is dependent on various things
  2. 3 main parts
    1. CU (control unit)
      Annotations:
      - Controls the cpu Main job is to manage the fetching, decoding and execution of program instructions by following the fetch-execute cycle controls the flow of data inside the cpu (to alu, registers, cache) and outside the cpu (to main memory and input/output devices)
      1. did in notes
    2. ALU
      1. does all calculations
      2. completes simple addition and subtraction, compares the size of numbers and can do multiplications and divisions
      3. performs logic operations and binary shifts
      4. it contains the accumulator register
    3. cache
      1. very fast memory
      2. slower then registers
      3. faster then ram
      4. low capacity, expensive
      5. stores regularly used data so the cpu can access it quickly
      6. different levels depending on speed and storage
Protocols and layers, wireless and wired
1. Common protocols
  1. A protocol is a set of rules that allows two devices to communicate
  2. TCP/IP
    1. Communication over a LAN/WAN
    2. Provides error-free transmission between two routers
  3. HTTP[S]
    1. Web page requests
    2. A client-server method of requesting and delivering HTML web pages
    3. Encryption and authentication for requesting and delivering HTML web pages. Used to transfer sensitive information – e.g., passwords, bank details
  4. FTP
    1. File transfers
    2. Used to send files between computers, typically via a wide area network
  5. POP
    2. Retrieves email from a mail server, removing it from the server and transferring it to your device
  6. IMAP
    1. Email
    2. Used by mail clients to manage remote mailboxes and retrieve email from a mail server.
  7. SMTP
    2. Sends email to an email server
  8. IP
    1. Routes packets across a wide area network. Along with TCP, it makes up the TCP/IP protocol stack.
2. Modes of connection
  1. Wireless
    1. Wifi
      1. 100m range
      2. High bandwidth
      3. High power consumption
      4. Convenient
      5. Slower then wired
      6. Doesn't constrict user
    2. Bluetooth
      1. 10m range
      2. Low bandwidth
      3. Low power consumption
      4. Ideal for connecting headphones or mics
  2. Wired
    1. Fiber optic
    2. Ethernet
      1. Used for communicating on a wired local area network
      2. Provides reliable, error-free, fast communication between two points
      3. User location is limited by the need for a physical cable connection
      4. An Ethernet setup relies on lots of cables, connections, ports and physical hardware, raising costs
      5. Reliable
    3. Copper
Algorithms
1. Computational thinking
  1. Decomposition
    1. break one large, complex problem down
    2. create sub problems
    3. work out each sub problem
  2. Algorithmic thinking
    1. logical way of getting a solution
    2. allows solutions to be reused
  3. Abstraction
    1. keep important info
    2. remove that which is not needed
    3. simplification
2. Designing coding and refining
  1. Flowcharts
    1. line shows direction of algorithm
    2. rhombus is input or output
    3. rectangle is process
    4. diamond is decision
    5. oval is terminal (start/end)
  2. Pseudocode
    1. back of y11 book

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