RE: throughput?USB: 12 MBps (Intel reportedly working on 200 MBps)
Firewire: 400 MBps (though I think there's also a 100 MBps version - someone correct me, please)
The article below is available at:
https://www.tekpress.com/Archives/1999/Mar/usb_fire.html
Universal Serial Bus, or USB, is a new peripheral standard that will eventually replace older seria and parallel busses. It runs faster than the old parallel ports, at 12 Mbps (megabits per second). It has many improvements over SCSI, the standard for fast transfer, as well. The Universal Serial Bus is hot pluggable, meaning that you can plug and unplug devices and they will be instantly recognized - a system restart is not necessary, unlike with SCSI devices. Moreover, a single USB chain can support 127 devices simultaneously, far more than SCSI. USB chains don't need to be terminated, while SCSI chains do. Although USB has many advantages over SCSI, it runs much more slowly. Normal SCSI runs at about 40 Mbps per second, putting USB to shame. However, USB wasn't meant to replace SCSI; it was meant to handle small peripherals like printers, scanners, storage devices, input devices, or even digital cameras. Most new PCs come equipped with USB ports, and Microsoft's Windows 98 has built-in USB support. Even the best-selling PC from Apple, the iMac, uses USB as its main transfer protocol. USB was designed by Microsoft, Intel, and several other PC vendors, so it has the backup it needs to become the standard for new peripherals. In fact, Intel is developing a 200 Mbps USB bus, for even higher speeds without any of the downsides of the parallel port. Currently, there are hundreds of USB devices, and more on the way.
FireWire makes up for USB's lack of speed. Developed by Apple and formally recognized as a standard by the IEEE (Institute of Electrical and Electronics Engineers), FireWire will soon be the new standard for not only high-speed computer peripherals, but digital video as well. FireWire connectors are hot pluggable, and FireWire chains don't need to be terminated. They support up to 63 devices on one chain, and can be expanded with a bridge, which divides a single FireWire bus into segments, each of which can support 63 devices. Unlike SCSI, FireWire devices don't need IDs, which eliminates most of the hassle of setting up a chain. The most important part of FireWire is the raw speed it supports. A FireWire bus transfers data at 400 Mbps, 10 times faster than normal SCSI. While extended SCSI buses can reach speeds up to 640 Mbps, FireWire will also be able to be upgrade to a theoretical limit of 1.5 Gbps. Isochronous transfer allows FireWire devices to get the speed they need from the bus, something SCSI does not provide. Additionally, the physical length limit of a SCSI chain is at most 6 meters, but FireWire can reach up to 72 meters and supports repeaters, which boost signals even further. Practically, the obvious use of FireWire would be high speed hard drives and RAIDs (Redundant Arrays of Inexpensive Disks). FireWire promises to soon replace SCSI as the high speed transfer bus of choice for professionals, backed by giants such as Apple, Compaq, Microsoft, and various digital device manufactures such as Philips, Sony, and Toshiba. Compaq and Apple feature FireWire support in their new PCs. Microsoft has declared FireWire to be part of its PC 2000 specification, so if a PC doesn't have FireWire, it should not run Windows. FireWire is even more versatile, now making a mark in the digital video market. Consumer electronics companies such as Sony, JVC, and Panasonic produce FireWire digital camcorders and VCRs. With the proper software, FireWire would allow real-time digital editing capabilities directly from the camera to the PC.
Will FireWire and USB eventually replace their predecessors, given the widespread use of SCSI and parallel devices? There are already many USB devices, and FireWire is becoming the new digital video standard. Apple has already phased out old serial and SCSI ports in their new Power Mac G3 line, other PC vendors can't be too far behind. Will we see only two types of peripheral connectors on new computers sometime in the near future? Probably not, as backwards compatibility is the main goal of all PC creators. But if peripheral companies start pushing USB and FireWire devices, and PC companies help by bundling them with new computers, it might happen sooner than you'd think.
- Ian Friedman