Computer Science

Computer Science

1. Networks

   • LANs and WANs
     • LAN (Local Area Network)
       • Cover a small area, usually a single building. All devices on a LAN can share data with each other. Usually privately owned by an organisation or household.
     • WAN (Wide Area Network)
       • WANs spread over a large area using various transmission medias to connect LANs together.
         • The Internet is a great example of a public WAN
   • IoT
   • Connectivity
     • Wired
       • Fibre Optic cables consist of thin strands of glass. They are surrounded by several layers of protective material as it transmits data with pulses of light
       • Unshielded twisted pair (UTP) is a common type of copper cable used to setup a LAN. It consists of thin, copper cables with plastic insulation. It is twisted to avoid interference. Can transfer 1Gbps up to 100 metres
     • Wireless
       • Bluetooth works at up to 10 metres. Great for nearby devices communicating (headphones, keyboards etc).
       • Zigbee uses pow power radio waves to connect thousands of IoT devices with the internal radio transmitters/receivers
       • RFID is Radio-frequency identification. Uses electromagnetic fields to identify and track tags on objects.
       • NFC is Near field communication. It uses electromagnetic fields to create a high speed connection between two devices in close proximity. Used commonly in contactless payment systems
     • Wired vs Wireless LANs
       • For portable devices, wireless is often the preferred option but with other devices it is less obvious. This is why there is a large range of devices using wire and wireless.
   • Topologies
     • Bus
       • All nodes are connected to a single "backbone" with terminators at each end.
         • Advantages
           • Cheap
           • Easy to add extra nodes
         • Disadvantages
           • Prone to collisions when two messages are sent at the same time. CSMA/CD used
           • If backbone is damaged, whole network can go offline
     • Star
       • In this, every node is connected to a central node (usually a router). All traffic is routed through the central node
     • Mesh
       • Mesh in the IoT
         • Mesh networks allow for near infinite amounts of IoT devices to be connected over long distances. They are often used for traffic management in "smart cities" and for home automation.

2. Data

3. Computers

   • Hardware
     • Input and Output devices
     • CPU
   • Software

4. Computational Thinking

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