Isochronous vs. Asynchronous Firewire Data Transfer
So, which type of firewire data transfer does Liquid Mix use?
Both! Asynchronous transfers are used for Liquid Mix bootup, initialisation and for reporting buttons and status back to host. Isochronous transfers are used for Liquid Mix audio streaming because asynchronous does not guarantee a particular data rate.
To use isochronous bandwidth, every device on the bus has to allocate it before it uses it. If the allocation fails because some other devices on the bus got there first, Liquid Mix will show an error message. To reduce the chances of errors, it may be effective to reduce the bandwidth requirement of firewire devices or remove them or choose fewer channels on the Liquid Mix.
Multiple Firewire Busses
The Liquid Mix, like the TC PowerCore and SSL Duende, requires a substantial amount of bandwidth from the firewire bus, especially when it is used to its limit. For this reason, it is beneficial to connect additional firewire devices on a separate firewire bus. Apple Macs which have more than one standard firewire port (400MB/s and/or 800MB/s) are actually running them on the same firewire bus. On a PC, any ports on a single PCI card run on the same bus. In order to add a second firewire bus, it is necessary to install a separate PCI firewire card. In order to ensure that each device is running on its own dedicated bus, it is recommended that a separate firewire bus be added.
For Desktop Macs with PCI (G5) or PCIe (MacPro) slots, this can be achieved by the addition of a PCI or PCIe firewire card. We have tested PCI firewire cards for use with Apple Mac G5s. For Apple laptops with PCMCIA slots, it is possible to add a PCMCIA to the firewire adapter. The new Mac Book Pro features an ExpressCard/34 slot, which is planned to replace the current CardBus PCMCIA standard. For more information about Apple Mac firewire ports and buses, you can consult the Apple website. Information about the firewire ports and firewire expansion capabilities of specific Mac models is shown in the table below.
Computer | Built-In Firewire | Firewire expansion | Recommended Firewire Cards |
---|---|---|---|
Apple Mac Book | 1 x 400MB/s | None | N/A |
Apple Mac Book Pro | 1 x 400MB/s | 1 ExpressCard/34 slot | Texas Instruments & NEC & VIA chipsets |
Apple Intel Core Duo iMac | 2 x 400MB/s | None | N/A |
Apple Intel Mac Mini | 1 x 400MB/s | None | N/A |
Apple Mac Pro | 2 x 400MB/s,1 x 800MB/s | 3-4 PCI Express (PCIe) slots | Texas Instruments & NEC & VIA chipsets |
Mac G4 Powerbook | 1 x 400MB/s,1 x 800MB/s | 1 CardBus PCMCIA slot | Texas Instruments & NEC & VIA chipsets |
Mac G5 iMac | 2 x 400MB/s | None | N/A |
Mac Mini PPC | 1 x 400MB/s | None | N/A |
Mac G5 Desktop | 2 x 400MB/s, 1 x 800MB/s | 3-4 PCI slots | Texas Instruments & NEC & VIA chipsets |
Mac G4 Desktop | 2 x 400MB/s | 3-4 PCI slots | Texas Instruments & NEC & VIA chipsets |
Firewire Card Manufacturer | Firewire Chipset | OHCI Compliant | 1394 Type |
---|---|---|---|
VIA | VT6306 VIA Fire II | Yes | 1394a |
Texas Instruments | TSB43AB22 | Yes | 1394a |
NEC | uPD72874 | Yes | 1394a |
Firewire Card Manufacturer | Firewire Chipset | OHCI Compliant | 1394 Type |
---|---|---|---|
Texas Instruments | TSB82AA2/TSB81BA3 | Yes | 1394b |