USB 1.0 vs 1.1

Bill,

if you would like more information read this.

Mauro

All iMac G3s and the early iMac G4s have USB 1.1. See USB Interface.

Part of the problem is that USB was never originally intended for "high-speed" operation and was later expanded. FireWire was started from the ground up for high-speed operation with future expansion for even higher speeds.

The other problem is that 2.0/1.1/1.0 are lousy ways to describe the interface and a lot of the USB marketing/labelling is misleading. Also - the raw data rate doesn't necessarily indicate what the bus can do. There is a lot of overhead in USB, and shared slower speed USB components on the same node can compete for bus bandwidth with higher speed devices.

The latest 2.0 revision supports standard (1.5Mbit/sec), full speed (12 Mbit/sec), and high speed (480 Mbit/sec). The more common 1.1 revision supports standard and full speed. A hub or port labelled USB 2.0/1.1 must support all speeds of that revision. A device labelled USB 2.0 could theoretically meet only the 12 Mbit/sec data rate.

The USB Implementors Forum hates it when a device is called USB 2.0 or USB 2.0 full speed. It sounds too much like a reference to the highest speed interface instead of the previous slower speed. They prefer the terms USB for 1.5/12 Mbit/sec devices, and USB Hi-Speed for 480 Mbit/sec devices. The revision number is pretty much useless, since all devices are meant to be compatible (to some degree) with all hubs/ports.

Bill Johanson:

i Hi YPW,

i Do you know if my firewire linked Handicam will download faster on USB2.0 on a new G5? Or will it just be faster because of processor and RAM?

I don't have much experience with digital camcorders. However - I've seen many specs that would seem to indicate that FireWire 400 outperforms USB Hi-Speed in actual operation. USB requires quite a bit of overhead to "negotiate" for use of the bus, and all negotiations occur at a low data rate. The LaCie d2 "Triple Interface" specs list the following actual data transfer rates:

FW 800: up to 61MB/s; FW 400: up to 40MB/s; USB 2.0: up to 34MB/s

Again - I really don't like the term "USB 2.0" because of some manufacturers who label their products as "USB 2.0 Full-Speed" simply because it uses a USB 2.0 core configured for 12 Mbit/sec operation.

It also depends on your setup. One of the advantages of FireWire is that there are pretty much no low-speed devices on the market. With daisy-chained or hubbed components, there won't be any slower speed devices hogging up bandwidth

If you've got a USB mouse or keyboard ultimately (by a hub) connected to the same port, every 1 bit at 1.5 Mbit/sec will take up the same time as 320 bits of high-speed data or 40 bits of full-speed data. With USB, you've essentially got one pipe to transfer all you data. The slow-speed data on the same "pipe" takes up time that could be used for high-speed data.

Do you know if my firewire linked Handicam will download faster on USB2.0 on a new G5?

iMovie does not support downloading digital video (DV) via USB. iMovie only supports DV over Firewire.