8. Appendix 1 – USB 2.0 Questions & Answers
What are the benefits of the USB interfaces?
The USB 1.1 and 2.0 interfaces provide many of the same benefits, particularly:
• They are based on serial bus technology.
• Cross-platform capabilities: you can use your USB peripherals on both Mac and Windows platforms.
• "Plug and Play" capability: this incredibly convenient function eliminates any need to turn off or restart the computer when
connecting a new peripheral. Just plug it in and off you go.
• Automatic configuration: your new device is automatically recognized and installed by your operating system, which makes
setting up and using your peripherals a snap.
• The ability to connect several peripherals on the same bus: with USB ports on your computer, you can connect up to 127
peripherals using hubs.
• No need for peripheral addresses or terminators, easy-to-install cables and other features.
What is the difference between USB 1.1 and USB 2.0?
The main difference is speed. USB 1.1, the original version of the interface, is capable of throughput up to 12Mb/s. USB 2.0
supports data speeds up to 480 Mb/s, making it 40 times faster than its predecessor. This increased bandwidth translates into
higher performance in demanding applications requiring high transfer rates.
What are the ideal uses for USB 1.1?
USB 1.1 is ideal for more traditional connections such as keyboards, mice, joysticks and scanners. With its 12Mb/s speed, it
can also be used for more advanced applications such as games and audio software, as well as storage on hard disks,
CD-RW, and other drives. USB 2.0 devices will have far superior performance in these more demanding applications, however.
What are the ideal applications of USB 2.0?
Except low-end devices, such as mice and keyboards, virtually any hardware will benefit from the extra bandwidth provided
by USB 2.0. PC video conferencing applications will be further enhanced by the usability of USB 2.0 digital video cameras.
The new breed of USB 2.0 video capture adapters will enable professionals and consumers alike to record the highest video
quality possible. USB 2.0 scanners will raise the performance bar by offering speeds that match SCSI and FireWire scanners,
at a more affordable price. And USB 2.0 storage devices, such as CD-RW, DVD-RAM and DVD-R/RW, and removable
cartridge drives, will also benefit from the new I/O performance.
Will USB 1.1 devices run faster when connected to a USB 2.0 bus?
Unfortunately, no. The USB 2.0 specification is specifically written to allow developers to design higher speed peripherals that
can take advantage of the extra bandwidth. USB 1.1 devices, though, will still operate at 12Mb/s at full-speed and 1.5Mb/s
at low-speed on a USB 2.0 bus. Even though USB 1.1 devices won’t run any faster, they can work alongside USB 2.0 devices
on the same bus. However, if you plug in a USB 2.0 device to a USB 1.1 bus, the speed of the USB 2.0 device will decrease
to 12Mb/s.
Appendix - USB 2.0 Q & A
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LaCie d2 USB Hard Drive
