Universal Serial Bus

One for computer-to-computer device interconnection

First speed factor: maximum rate

Version 1.0: Maximum 1.5 Mbps, intended for Human Interface Devices such as keyboards and mice

Version 1.1: Maximum 12 Mbps, meant for medium-performance devices such as printers

Version 2.0: Maximum 480 Mbps, capable of supporting fast peripherals such as hard drives

Second speed factor: hubbing

Unless otherwise specified, a USB hub splits full bandwidth over the number of ports

A 4-port USB 1.0 hub gives each device 375 Kbps, fine for keyboards but painful for audio and printing

Cabling and Power

Usually uses twisted pair wire star-connected to hub, or in a branching tree of hubs with a single root hub

Maximum pure USB cable length is 5 meters, but there are ways to extend it.

          4 port hub

USB can carry limited 5 volt power, basic assumption 100 mA
Proprietary wireless variant available
Beachwerks can advise on complex power budgeting and grounding considerations

Common use with multiple marine electronics

By connecting NMEA 0183 devices to various multiplexers and switches, you can bring multiple devices into your computer, via one USB port

This can be made fail-safe


Useful for connecting computers to their devices

Special application: "thumb drives" (vertical device on top of the hubs). These can be used for backing up moderate amounts of data.