The bridge was born at the end of 2000 from the Oxford Semiconductor studios in Abingdon, UK: the company specialized in the study and production of UART serial communication chips had long since prepared a first generation bridge, able to act as a "bridge" between the hard disk and IDE / ATA burners and the FireWire or 1394 interface invented in 1995 by Apple.
But Oxford 911 represents an extra step, on the one hand because it allows you to reach a transfer rate, a higher transfer speed and on the other hand because it can do it with all types of data: let's see how.
In the use of large archives for digital audio and video, for DTP and photo editing, the speed of hard drives and their ability to maintain a constant high flow in the transfer of data to and from the unit The central are very important factors for the efficiency of the processing and for a faster achievement of the results.
In all transfer operations the optimal performance is obtained when moving large elements; in the case of small data sizes it is not possible to notice differences: an example may be that of consulting a directory, with the display of 4k blocks each you will not notice any difference between a firewire hard disk with fast mechanics and one with slow mechanics .
With an OXFW911 bridge designed by Oxford Semiconductor even the most common tasks become faster thanks to the integration of a 512 ka 16 bit flash memory in the device to minimize waiting states and reduce the time required for protocol conversion. In the image below you will find a performance graph comparing a hard disk inserted inside a computer and the external one connected to a Bridge Oxford 911: as you can see the difference in performance varies according to the size of the blocks transferred, the limit maximum obviously depends on the performance of the hard disk that does not succeed many times, with the current ATA 100 mechanics to saturate the whole band made available by the bridge.
The transfer speed does not only depend on the bridge but also on the operating system used, on the Firewire card on PCI used or on the chip inserted on the motherboard when this is already supplied in the basic equipment as in all the latest Macs.
Thanks to the optimization achieved in the use of a 32-bit ARM 7TDMI chip present in the bridge, it is possible to obtain higher performance with small blocks of data with an IDE disk mounted externally than in the same disk mounted internally!
Obviously if the machine has a fast IDE bus or an ATA 100 or 133 interface and a hard disk of the latest generation, the transfer rate on large data blocks will generally be better. The potential of an internal ATA 100 interface for large files are higher than that of an external firewire, also made with Oxford bridge but with the Video, audio and DTP applications and the current mechanics the difference will be difficult to perceive.
Obviously the case of an external Firewire disk costs more than the installation of an internal disk, especially when you can use a free IDE channel in your machine but it could be an excellent solution for those who have to move data often from a computer to the other and for those who like the user of iMac or laptops does not have space to add internal disks.
The performance: From the tests we carried out with several external Firewire disks equipped with this interface, we had no problem importing DV movies from the Digital camera connected via Firewire to the hard disk itself: it is an excellent solution for those who own a Mac with a G3 or G4 processor of 400 Mhz or higher to remedy the possible low capacity of the internal disk.
With the current hard drives on the market, especially the 3.5-inch ATA 100 hard drives, it is not difficult to reach a transfer rate of 30-33-35 MB almost at the limit of the capacity of the current Firewire implementation and not much below the obtainable bandwidth with ATA 100 on PCI card. The advantages compared to the previous bridge implementation are felt not only for the direct treatment of data but also for backups making the purchase of an external Hard Disk equipped with Oxford Bridge 911 a great deal.
Before buying an external Firewire disk, therefore make sure you know which bridge it is equipped with, those with older bridge or without particular indications are slower and in any case should be less expensive. We remind you that the theoretical speed that can be reached by Firewire is of 45/50 MB / s.
For all the information on peripherals and Firewire technology, please refer to the specific section of MacProf.