> For example: A device running at 2mb speed that sends > 500kb in a second uses a full 1/4 of the entire USB > bandwidth. This automatically chops the 12mb down to > 9mb, and the 480mb down to 360mb. A 12mb device that > sends 6mb cuts it in half.
This is true for a 12Mbps bus (both USB 1.1/2.0), but not for a 480Mbps bus (USB 2.0).
USB 2.0 uses split transaction for 1.5Mbps/12Mbps devices, so an 8Mbps USB-1.1 device theoretically only occupies 8Mbps (+some overhead) bandwidth on a 480Mbps bus.
# the overhead might be large, but it is not 320Mbps.
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> For example: A device running at 2mb speed that sends
> 500kb in a second uses a full 1/4 of the entire USB
> bandwidth. This automatically chops the 12mb down to
> 9mb, and the 480mb down to 360mb. A 12mb device that
> sends 6mb cuts it in half.
This is true for a 12Mbps bus (both USB 1.1/2.0), but not for a 480Mbps bus (USB 2.0).
USB 2.0 uses split transaction for 1.5Mbps/12Mbps devices, so an 8Mbps USB-1.1 device theoretically only occupies 8Mbps (+some overhead) bandwidth on a 480Mbps bus.
# the overhead might be large, but it is not 320Mbps.