What is i.Link?

What is i.Link?

What is i.Link? i.Link is the brand name for Sony's IEEE 1394 interface, however the 1394 standard also has a backplane interface definition. This is a personal computer, digital audio, and digital video serial bus interface standard that offers high speed communications and isochronous real time data services. i.Link is the Sony Corporations implementation of the IEEE 1394 standard, used for the connection of devices to your personal computer. A single plug and socket connection is provided by i.Link that can have up to 63 devices connected. The data transfer speeds are up to 400 megabits per second.

The IEEE 1394 standard describes the pathway, or serial bus, between one or more peripheral devices and the microprocessor of your computer. Peripheral devices are currently equipped to meet the standard of IEEE 1394. Implementation of IEEE 1394 usually provides several advantages. One of these is the use of a simple common plug-in serial connector on the back of your computer, as well as on many different types of peripheral devices. Another advantage is the use of a thin serial cable, instead of a thicker parallel cable, like what is currently used for printers or other devices. IEEE 1394 implementation also utilize a very high-speed rate of data transfer that will accommodate multimedia applications. Right now this translates into 100 and 200 megabits per second, but much higher rates will become available in the future. The capability of plug and play, and hot plug, without the disruption of your computer is another advantage. One of the best advantages, however, is the ability to create a chain of devices, in numerous ways, without a complicated set up requirement or terminators.

IEEE 1394 implementation is expected to consolidate and replace current serial and parallel interfaces over time. This includes Centronics parallel, RS-232C, and SCSI, or the Small Computer System Interface. The first products that were available with i.link or FireWire include digital video disks, digital cameras, music systems, digital camcorders, and digital video tapes. Due to the fact that IEEE 1394 is a peer-to-peer interface, one camcorder can dub to another without having to be plugged into a computer. A computer that is equipped with the socket and bus capability allows any device, like a video camera, to be plugged in while the computer is running.

To understand i.Link we must basically understand how it works. In IEEE1394 there are actually two levels of interface. The first level of interface is for the backplane bus within the computer. The second level of interface is the point to point interface between the device and the computer, via the serial cable. The two levels are connected by a simple bridge. Up to 50 megabits per second of data transfer is supported by the backplane bus. 100, 200, or 400 megabits per second are supported by the cable interface. Each one of these interfaces can handle any of the data rate possibilities, as well as change from one interface to another as needed. The serial bus works as though the devices were in the slots within the computer and sharing a common memory space. There is a large amount of flexibility in the device configuration in trees and chains from a single socket because of the 64 bit device address.

There are two different types of data transfer in IEEE 1394. These data transfer types are isochronous and asynchronous. Isochronous data transfer makes sure that data flows at a rate that is preset so that an application can handle it in a timed way. For the multimedia applications, this type of data transfer significantly reduces the need for buffering, and helps to ensure a continuous viewer presentation. The asynchronous data transfer type is normally used for traditional load-and-store applications. These are applications where data transfer can be initiated and an application interrupted as a given length of data arrives in a buffer.

The requirements for the IEEE 1394 standard state that a device must be within 4.5 meters of the bus socket. Because of the fact that up to 16 devices , with each device having a 4.5 meter maximum before signal attenuation, can be connected in one single chain, the theory is that you could get a signal as far away as 72 meters from your computer.

The USB, or universal serial bus, is another new approach to connection devices. USB has the same hot plug capability as the IEEE 1394 standard.

USB is a less expensive technology but the data transfer is limited to 12 million bits per second.