KarbosGuide.com. Module 5c3.

About FireWire IEEE1394

  • IEEE1394 FireWire
  • Device Bay
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  • FireWire is another interface connecting the PC to external units. It does not look very much like the SCSI we know, but is a further development being a serial high speed bus. It also a bit like USB in terms of hot-plugging and simple connections.

    The interface IEEE1394 has a bandwidth of 400 Mbit per second, which is a lot better than USB and comparable to SCSI.

    FireWire handles up to 63 units on the same bus. The units can be plugged and unplugged hot - meaning you do not have to power down the PC.

    The Firewire was expected to replace:

  • Parallel Centronics port (to some extent)
  • IDE
  • SCSI
  • EIDE (later on)

    However, Firewire so far has not become the real big thing for PCs. People with Macintosh computers soon found great use for FireWire, especially to connect high performance flatbed scanners.

    Today Firewire is supported by Windows XP and it is gaining momentum. Among others it is used for:

  • Connecting DV-cameras to video editing adapters
  • High-end scanners
  • Hot-plugged external harddisks from Maxtor with FireWire interface.

    Here is the IEEE1394 port of a digital video camera (marked "DV" for Digital Video). It is very small:

    FireWire for Macintosh

    FireWire was developed by Lucent Technologies, but has ended by Apple, who claims a $1 per port royalty for use. IEEE1394 was conceived by Apple, who proposed it to IEEE, who approved it as a standard in 1995. Firewire is Apple's implementation of the IEEE1394 standard. Other companies have implemented their own versions of IEEE1394. Yes, they are not all the same! (Note: This is the purpose of the IEEE - to approve industry standards, not to make an implementation.)

    Hence all major hardware companies have adapted FireWire in some way. Especially the entertainment electronic industry (Video/games/television) have great hopes with FireWire/IEEE1394. It will connect all types of digital electronics with the PC and this way open up for a much more modular design.

    Since IEEE1394 is advanced and yet claimed to be cheap & simple, the communications protocol can handle a lot of other units including:

  • Network controllers
  • Hard disks, CDROM drives
  • Printers

    Two modes

    The FireWire standard operates with two modes.

  • Asynchronous as other buses. This means that operations across the bus are controlled using interrupt signals. The bus reports to the host when a task is fulfilled.

  • Iso-synchronous . In this mode data is being transferred at a steady preset speed - continuously and without any supervision from the host. This opens up for data streaming useful for video or the multimedia presentation. The FireWire is a peer-to-peer interface. This means that data can be transferred between two units attached to the bus without supervision from the PC.

    FireWire has a 64 bit address bus. Compared to SCSI each unit does not need a unique ID, they are dynamically configured "on the fly". Neither does the bus have to be terminated. All together a lot simpler than SCSI.

    One of the problems with SCSI has been the limitation on distance between the units. FireWire can hold up to 16 units in the same "string" and there can be up to 4.5 meters between two units.

    The first implementations of FireWire will connect it to the PCI bus using the new PIX6-controller, which will be a part of one of Intel's new chip sets. I think it will be at least 2-3 years before we really see this new technology in the market. But it will be worth waiting for it, it opens up for a new world of inter connectivity between TV, PC, video and all other types of electronic gear.

    USB and FireWire - serial buses of the future

    Soon high-end PC probably will hold both these serial I/O buses:

  • USB version 2.0 for all low speed gear.

  • FireWire for high speed I/O to Digital Video recorders, high-end scanners etc.

    Both interfaces are about to be included in the south bridge of the chipsets. In 2002 it was difficult to whether USB 2.0 or Firewire was going to be the new high-speed I/O standard. Probably both of them will have place in the PC architecture the coming 1-2 years.

    Device Bay

    DeviceBay is another standard which follows IEEE1394 and USB. These busses can connect and disconnect units "on the fly", that is while the PC is operating. This ability to "hot plug" requires a new physical connection between the units. DeviceBay may be the answer to this. That is a standard for connection boxes that can hold hard disks, CDROM drives and similar units.

    The mounting frame can be installed without tools and while the PC is running. With this one can imagine a storage unit filled with MP3 -files, which easily can be moved from a PC to the player in the car. Unfortunately, for a while it is only a futuristic dream.

    If DeviceBay really gains widespread usage, it could be the end of loose ribbon cables in the PC cabinet. The whole PC can be made in modules, which all plug into the USB or the FireWire bus as DeviceBay units. The units can then freely be moved between the different computers and other electronic units in the home.

    It is designed for hot plugging units like:

  • Zip drives
  • Tape streamers
  • Modems
  • Hard disks
  • PC-card readers

    These units will fit into a special bay connected to the USB and FireWire buses enabling the hot plug. A good thought; however not all good thoughts end up in good hardware.


    You find technical specifications etc. in these sites:

    Apple about: FireWire

    The IEEE has its own page at http://www.ieee.org

    About DeviceBay: www.device-bay.org

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    Learn more

    Read about chip sets on the motherboard in module 2d

    Read Module 4d about super diskette and MO drives

    Read module 5a about expansion cards, where we evaluate the I/O buses from the port side

    Read module 5b about AGP

    Read module 7a about monitors, and 7b on graphics card

    Read module 7c about sound cards, and 7d on digital sound and music

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