iMac # of USB Buses vs. Connectors?

[TommyWillB]

I was in the Apple store yesterday, and I'm confused about the USB conenctors on the 20" iMac.

Apple's specs (http://www.apple.com/imac/specs.html) for this machine says it has "three USB 2.0 ports, two USB 1.1 ports (on keyboard)"... and that makes perfect sense.

...but when we opened Apple System Profiler, it sayd the machine has 2 "USB Bus" and one (forget the exact teminology) Fast USB bus.

So does that mean each of the USB 1.1 connectors is on it's own bus, while the 3 USB 2 connectors share a single bus?

[symphonix]

The "Fast USB" bus is USB 2.0 and connects to the 3 USB ports at the back of the machine.

The USB1.1 bus is used internally in the machine to connect the Bluetooth module.

The additional 2 USB ports refers to the ones on either end of the Apple keyboard. These run off a USB1.1 hub built into the keyboard, hence the slower standard.

[TommyWillB]

I guess that makes sense...

Thanks!