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Why Internal FireWire on the G4?

Dan Knight - September 3, 1999

Ben Apple of Mac Junkie wrote an interesting article, G4's concealed FireWire port: The possibilities are intriguing. It was the first I'd heard of an internal FireWire port on the Power Mac G4/450 and G4/500.

Ben's question and mine: why?

Apple obviously feels there will be a demand for FireWire devices inside the box - and within the life span of the Sawtooth motherboard.

The faster G4s already support Ultra DMA/66 drives, which are wicked fast. But they suffer a failing of all IDE-style drives, they require more CPU control than SCSI drives, which means system performance is slightly reduced during drive access.

Another drawback of IDE is that each connector can only manage two drives, a master and a slave. It's not as extensible as SCSI, USB, or FireWire.

FireWire is essentially a very fast serial version of SCSI (see FireWire a Form of SCSI by Alex Timbol). It supports 63 devices, has a bandwidth of 400 Mbps (32 times faster than USB), is hot swappable like USB, and supplies up to 60W of power to FireWire devices.

And, because it's related to SCSI, it requires less CPU control than the IDE family of interfaces.

So by building a internal FireWire port into the Sawtooth motherboard, Apple makes it possible to add additional internal high speed drives without using IDE slave mode (which is slower than master mode) or adding a SCSI or IDE card.

For many users, that alone will save one expansion slot.

It also simplifies internal expansion. Instead of unwieldy ribbon cables and power cables, a single FireWire cable will move data and supply power to internal drives. It's much more elegant than the older SCSI and IDE protocols with their multiple parallel data lines.

Beyond that, Apple has demonstrated bootable FireWire as a technology demonstration. I don't know if this will be a standard feature of the Sawtooth ROMs, but it could always be added in the future. (The Power Mac G4 is the first Mac to support bootable USB. Nothing on Apple's site confirms or denies the ability to boot the G4 with a FireWire device.)

Of course, for Apple to switch to FireWire as its standard drive interface, prices have to come down a lot.

Enter the Next iMac

From my perspective, expanding the FireWire market rapidly is the best argument for Apple building FireWire into the next iMac. Just as last year's iMac drove acceptance of USB, putting FireWire on a consumer computer will nudge the peripherals industry to create more FireWire drives - hard drives, tape drives, removable media drives, etc.

Further, the expanded market will drive prices down.

As already covered in The Truth About USB Speed, USB simply doesn't cut it for hard drives. It's adequate for Zip and Imation drives, but seriously limits the performance of hard drives.

FireWire can solve that problem today.

What about USB 2?

There's a move afoot to expand USB to the 240-320 Mbps range, but the standard has not yet been finalized.

The time is now for Apple to push FireWire, establishing it as the standard high speed bus before USB 2 is available.

And once they do that, the market will grow to the point where it makes economical sense to replace the Ultra ATA boot drive in the Power Mac G4 with a bootable FireWire drive.

And that's undoubtedly a leading reason Apple put an internal FireWire port on the Sawtooth motherboard.

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