Why Apple chose Core Duo, and what’s coming next

When Apple kicked into high gear to ready iMac for a January launch, it didn’t have many Intel processor options to choose from. The 64-bit Pentium 4 CPUs used in Developer Transition Kits were too hot and too dear in price and power consumption. Celeron was cheap, but it had “bottom rung” written all over it, and Centrino, Intel’s one-stop notebook solution, was too confining and had already been done to death in notebooks.

Given those choices, Apple ended up shipping iMac with a CPU brand that Intel hadn’t announced yet. The 2 GHz Core Duo, aka T2500, takes advantage of Intel’s 90nm process to pack two power-efficient 32-bit Pentium-M processor cores (with 2MB of cache shared between them) onto a single chip. It fit the bill: Apple sorely needed dual core, both for buzz-phrase value and to get some benchmarks that made the single-core PowerPC G5 look like a half-fast desktop wuss next to its Intel replacement.

Core Duo did its job. The iMac is a dandy box, the finest of desktops, and MacBook Pro is a grand — if a bit undercooked — notebook. With lots of help from Intel’s compiler geniuses, iMac outbenched iMac G5 and brought home the essential X factor (clean multiple of measured performance). All Core Duo had to do to win a race against 1.67 GHz PowerPC G4 in integer performance was show up.

With iMac and MacBook Pro on their way, Apple’s now ready to move on with the next phase of Intel adoption. During my last trip to the Apple campus, when Mac mini was rolled out, an Apple rep raised my enterprise antennae by asking, “Now the question is, what CPU will we put in the new Xserve?”

That’s not really a question, though; Apple stalled development on Xserve last year before it could make the leap to PCI Express and 667MHz DDR2 RAM. Apple will go with Intel’s Bensley server platform, and if it gets impatient again, it can go with the dual-core Dempsey, the final hurrah for Netburst. The same chipset that handles Dempsey will handle Woodcrest, the first 64-bit multicore Core Microarchitecture server CPU. Don’t confuse Core Microarchitecture with Core Duo, either. Dempsey is new school, a proper redesign. It’ll do Xserve proud and make users happy — unless Apple throttles it with 32-bit OS X Server.

There is really only one performance challenge Apple faces in its Intel transition, and that’s the water-cooled wonder of the workstation world, the Power Mac G5 Quad.  Intel may surprise me, but I think it’ll take Clovertown, Intel’s quad-core server CPU, to best the Quad. Clovertown is slated to ship in 2007, however, and Steve Jobs doesn’t like to miss deadlines. Can Apple get Clovertown out early? Will it settle for a Dec. 31 announcement and a “coming soon” to keep its promise to kill PowerPC by year’s end?

Looks like Apple vs. Apple will be the year’s hot ticket.