Doubt has been cast once again on the availability of Motorola's upcoming G4 CPU, also known as the PowerPC 7400 -- or, more specifically, Apple's ability to ship a Mac based on the chip. According to a Register reader who attended the event, Apple staffers speaking at a joint Adobe/Apple software promotion, held in Toronto, "said that the G4 machines would not begin shipping until at least May 2000" and "the Apple on-stage presenter consistently stated that the new G4's will be out 'next year' even though they showed the G4 tests from [May's] Worldwide Developers' Conference". What are we to make of this? Well, Motorola has been consistently saying it will ship the G4 on schedule, and though its timing isn't quite as spot-on as it would have us believe, it does broadly seem to be on course. Last month, Motorola marketing chief Will Swearingen contacted The Register to denounce rumours that the G4 had fallen way behind schedule, and that we should all expect "a major announcement" on the chip's availability in volume "in the third quarter". Swearingen's schedule was in marked contrast to the claims made on an Apple-oriented news site, allegedly by Motorola insiders, that the G4 would not in fact ship in volume before "Q1 2000". Apple does already have some G4 chips, based on Motorola's initial silicon, and that's what it has been using to design the next generation of Power Mac and to give demos of the chip of the kind it made at last May's WWDC. However, the Motorola sources behind the delay claims said that the problem lay with the second and third versions of the G4, and it was here that Motorola had fallen drastically behind. Swearingen said that was incorrect, but then again he didn't deny those claims specifically. And if Apple has been forced to put back shipments of the Power Mac G4 to May 2000, that would be broadly in line with the original claims that the PPC 7400 has been delayed. Of course, it's possible that we've been flung a dummy here -- we weren't at the Apple/Adobe meet in Toronto ourselves, so we'd love to hear from anyone who was there who can confirm or deny what was said by the Apple representatives. But if the claims are correct, where does that leave us? A couple of scenarios present themselves: either Apple's got it wrong, or Motorola has. We'll find out about the chip maker first. Swearingen set a deadline for the G4's launch party. That launch, he pledged, will feature "multiple products, from multiple companies", many of which will be available in volume on the day of the launch. Since Motorola isn't relying exclusively on Apple -- we reckon Amiga may well be party to the celebrations -- it doesn't have to wait for the Power Mac G4 to ship to prove it did what it said it would. That leaves Apple -- is it having problems building a G4-based machine? On the basis of the WWDC demo (not, it has to be said, the most trustworthy of tests), it has, and is believed to be on course for an autumn shipment for the Power Mac G4. Or is it? What's lined up the autumn is actually a machine based on the company's Sawtooth motherboard. Sawtooth brings faster system bus speeds, AGP support and a host of other upgrades, but the only basis for assuming that it will also contain a G4 has been its timing. The next-gen Power Mac must