All, > and are 64-bit—the last part of that is welcome news to those who > feared the switch to Intel’s current lineup meant sliding back to > 32-bit computing once Intel chips start showing up in Macs The 3x1, 5x1, 600 and 800 series of P4 CPUs support EM64T. They double as a room heater, though. The dev transition boxes use the 660 series (3.6GHz, 2MB L2, EM64T, Enhanced SpeedStep). You'll notice that the new desktop processor will be significantly lower power (and thus work with quieter cooling). You had better hope AMD have something up their sleeve about this. Their new Pentium-M ("Yonah") won't, however, but it will be dual core. It's beyond me why Intel will release Yonah Q1 next year with Merom due Q3. 6 months of life for a CPU doesn't sound very cool. We have the same thing with the Sossaman core (the ULV Xeon replacement based on Pentium-M) - only 32 bits. Again, the new architecture will replace all of these in Q3 so there's no worrying to be had here. > PowerPC and AMD's Opteron. Pushing 64-bit address space around where > 32-bit can be used, aka Intel's solution, slows things *waaay* down. I was under the impression that the instruction sets were compatible. Perhaps the implementation of EM64T is different to x86-64 in efficiency but I'm going to assume that this'll be fixed up in Conroe/Merom. Intel are shooting themselves in the foot if it isn't. > There's two, and only two, elegant solutions to 64-bit desktop > computing that exist today - linux running on an AMD Opteron, or Mac > OS X Tiger running on a PowerPC970. Everybody else is in the Or the UltraSparc 4. But what are the *mobile* options? AMD have an AMD64-based mobile processor which pales in comparison to the Pentium-M for power use. This is Apple's *CURRENT* challenge - sans the PowerBook G4 12", I find that my 15" 1.5GHz has significantly less battery life than my 1GHz Titanium and really, not much has changed except for the CPU, GPU and battery size. I barely get 3:30 with screen on lowest brightness and all options (illuminated KB, bluetooth, AP etc) turned off. I could pull 5 hours+ on the Tibook in a similar scenario - with wireless enabled. Heck, I could get over 3 hours when encoding DV on the 1GHz ti with screen brightness on full. Apple's decision for an architecture transition is based on performance-per-watt. They want to get power use down. I mean, c'mon, a Pentium dual core 820 (2x2.8GHz) will chew over 200W of power. I just can't get behind that sort of power for a processor. This is the merit of the new Intel processor. The big thing I will miss in this transition is AltiVec. Rosetta won't (currently) translate AltiVec instructions so we can't run our G4/G5 apps on it. The Freescale dual core G4 is certainly a contender for PowerBooks (and it would make sense for Apple to pioneer dual core mobile tech, just like the old days). They haven't abandoned the PPC yet - or so they say and I'd say that the PowerBooks are due for one more revision between now and then. As for broken promises, it was the IBM roadmaps that prompted Apple to promise the 3GHz G5 which has *YET* to appear! Intel have a bit of a history, too, but they seem on track. The last missed delivery I believe was the P3 1.13 based on the Coppermine core, which was unstable and recalled (and later appeared as the Tualatin core). .t