Flashcards
Chapter 9 - AS Computer Science
Cards in this deck (26)
- 1Data transmissionThe movement of data from one place to another
- 2Serial data transmissionSingle bits sent along one wire
- 3Parallel data transmissionBits are sent down several wires simultaneously
- 4Uses of serial transmission & whyUSE
- Long-distance communication
WHY
- Only needs one signal pathway
- Easier to maintain and it's cheaper - 5Uses of parallel transmission & whyUSE
- Short-distance communication
WHY
- Harder to keep the bits in synchronisation along the wires
- Expensive
(Faster bit-rate in comparison to serial) - 6Bit RateThe number of bits transmitted per second
- 7Baud RateThe rate at which signals on a wire or line may change
- 8BandwidthA measure of the capacity of the channel of data, measured in hertz (Hz)
(how fast the data may be transmitted over the transmission medium) - 9LatencyThe time delay that occurs when transmitting data between devices
- 10Relationship between Bandwidth & LatencyThe higher the bandwidth, the higher the bit rate that can be transmitted
- 11Synchronous Data TransmissionThe computer sending the data will control the transmission rate to be in time with the device receiving the data using the system clock
Once synchronised the two devices can send and receive data without need for any further intervention - 12Asynchronous Data TransmissionThe arrival of data cannot be predicted by the receiver; so a start bit indicates the arrival of data and to synchronise the transmitter and receiver temporarily
- 13ProtocolA set of pre-agreed signals or codes for communication between computers
- 14WANA network over a small geographical distance
- 15LANNetwork that connects networks/computers over a large geographical distance
- 16WLANWireless Local Area Network
- 17Network Interface Card (3)(NIC) enables your computer to connect to a network
Sends “frames” across a network
Contain addresses indicating destination and source address and the block of data that you want to send - 18Bus Network (Positives)- Segment to reduce collision and congestion
- Cheaper than star (fewer cables)
- Easy to add new devices (connect to the main cable) - 19Bus Network (Negatives)- Collision are more likely than Star
- Only one stream of communication at a time
- Slow communication
- If bus cable breaks, the entire network fails
- Less secure (all data sent along one wire) - 20Star Network (Positives)- No collisions (central switch queue system)
- High connection speed (each link is not shared) - 21Star Network (Negatives)- Central switch server is expensive to buy/install
- Server can get congested
- Expensive cabling costs - 22Wireless NetworkAny type of LAN in which the nodes are not connected by wires but use radio waves to transmit data between them
- 23Two main types of Wireless NetworkWi-Fi
Bluetooth - 24SSIDA locally unique 32-character code that identifies a device on a wireless network
- 25SSID (Negatives)Broadcasting the SSID announces publicly your wireless network, which can be seen as a security weakness
- 26Ways to improve network security- Changing the SSID (and hiding it from transmission)
- Wi-Fi Protected Access (WPA/WPA2)
- Use strong encryption (WPA/WPA2)
- Create a ‘white list’ of MAC addresses which are trustworthy
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- Flashcards on Chapter 9 - AS Computer Science, created by Callum Jackson on 29/03/2017.
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- Callum Jackson
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