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Computer Science IGCSEPDF 13
142 pagesrevision 46930
PDF 13
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Advantages:
● Faster than serial.
● Suitable for tasks needing high speed.
Disadvantages:
● Expensive (more hardware).
● Data skewing/desynchronisation common over long distances.
● More prone to interference.
5. Universal Serial Bus (USB)
● A standard serial data transmission method, widely used in computing.
● Uses four-wire shielded cable:
○ Red & black → power supply.
○ Green & white → data transmission.
Features
● Supports half-duplex and full-duplex.
● Devices are automatically detected and configured when plugged in.
● Computer loads drivers automatically (if missing, it downloads them).
Advantages
● Automatic device detection.
● Single orientation → prevents incorrect plugging.
● Industry standard (widely supported).
● Supports different data rates (1.5 Mbps – 5 Gbps).
● No external power supply needed.
● Error notifications provided.
● Supports hubs for multiple connections.
● Backward compatible with older versions.
Disadvantages
● Max cable length ≈ 5 metres.
● Some older USB versions unsupported by new hardware.
● Some USB versions relatively slow (<120 MB/s).