1 Universal Serial Bus - Applications USB and IEEE1394 Are Complementary Technologies Digital VCR DVD-RAM DV Camcorder “NIC” DSS Keyboard Mouse Joystick Phone 1394 Domain Video Conf Camera Audio Personal Printers Tape Backup Floppy USB Domain

2 Universal Serial Bus - Applications USB Focus on Low Cost, High Volume Applications  USB is targeted at devices requiring relatively low bandwidth (10Mb/s or less).  The USB, tiered star approach is cheap for downstream nodes, but requires a central host. IEEE 1394 is more expensive and has a different design focus.  IEEE 1394 (FireWire) has no central host, and therefore requires a complete controller at each node.  IEEE 1394 is targeted at applications requiring 100Mb/s+ bandwidth which is not needed for most PC peripherals. » Digital VCRs and other consumer electronics require the bandwidth provided by IEEE 1394.

3 IEEE 1394 Background - Tom’s Hardware IEEE1394 is a high speed isochronous (real-time) serial standard developed by Apple under the FireWire moniker. The first completed specification was delivered by Apple in This standard was later absorbed into IEEE1394 in Requiring no hubs, each bus can support up to 63 devices and up to 1023 busses can be interconnected. A very compelling aspect of 1394 is that it is a peer-to-peer standard, resulting in that a PC is not needed to connect FireWire devices - in fact the PC is simply another "peer" in an IEEE1394 link. This is an unfamiliar notion for most PC users, but, in theory, a digital camera equipped with a FireWire port could be connected directly to an IEEE1394 hard drive and the camera should be able to directly save its files to the drive. At the recent IDF, components of a home entertainment center were entirely wired to one another using IEEE1394.

4 IEEE 1394 Background - Tom’s Hardware A duo of two twisted pair conductors form an IEEE1394 cable. These cables are similar to those used for 10BaseT Ethernet. Two extra wires are used to provide juice for those devices that are not self- powered. Using "fairness" arbitration to ensure that all devices obtain access to the pipe, IEEE1394 also multiplexes different types of digital signals like video, digitized audio, MIDI, as well as device control commands. Much faster than USB, IEEE1394 can transfer data at up to 400 Mb/s (50 MB/s), which is half as fast as the new ATA100 standard used for internal storage. Despite its performance, IEEE1394 is not currently meant as a competitor to ATA, but is targeted for external devices where hot-pluggable devices can either obtain their power from the port (six wire cables must be used) or be self-powered. While IEEE1394 is much faster than USB and uses very little overhead, it is slightly more expensive to implement. For this reason, cheap, low-speed devices such as keyboards, mice, and low resolution digital camera are best suited for USB, while devices demanding high-speed real-time service require 1394.