Data Rates
When used to describe data transfer rates, one mb equals 1,000,000 bits.
Therefore:
1 mbps (megabit per second) = 1,000,000 bits per second
In addition to the confusion over the value of a megabit (mb), there is also confusion between the megabit (mb) and the megabyte (MB). As noted earlier one byte (B) is comprised of 8 bits (b). So, one megabyte (MB), when used to describe data storage equals 220 or 1,048,576 bytes. When used to explain data transfer rates, one megabyte (MB) is 1,000,000 bytes (B), or 8,000,000 bits (b).
Therefore:
1 MBps (megabyte per second) = 8 mbps (megabits per second)
http://www.wisegeek.com/what-is-mbps.htm
Few if any USB 2.0 device implementations are able to saturate the entire 480 Mbit/s, but this can be achieved with multiple devices on the same bus. Typical USB PC hosts rarely can sustain transfers exceeding 280 Mbit/s, with 240 Mbit/s being more typical. This is likely due to USB's reliance on the host processor to manage low-level USB protocol, whereas FireWire delegates the same tasks to the interface hardware (requiring less or no CPU usage).
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