Macintel: The Good Is the Enemy of the Best

The good is the enemy of the best.

Repeat that to yourself as you think about Apple's decision to adopt Intel's Pentium architecture for June 2007 and later models.

The good is the enemy of the best.

VHS buried Beta. IBM chose the Intel 8088 CPU over the 8086, the 6809, and the 68000 that was to power the Macintosh. Windows has perhaps ten times the market of OS X, Linux, and all the other desktop operating systems combined.

And now Apple is switching from PowerPC processors to Intel Pentiums.

The good is the enemy of the best.

Today's Intel and AMD CPUs are a far cry from the 8088 and 80286 CPUs used in PC class and AT class computers in the 1980s. They no longer rely on 64 KB banks of memory, and the 640 KB ceiling of early PCs hasn't applied in ages. Intel and AMD make some very powerful CPUs.

But the whole x86 architecture is a throwback to the earliest days of personal computing, a descendant of the Intel 8080 of the mid- to late-70s. Each iteration of chip design adds some neat new features, but each generation also includes full backward compatibility with the architecture of the past. We're talking 30 years of CPU legacy.

You may remember the snail ads Apple ran explaining how the G3 processor zipped past the Intel Pentium. You may recall the way Mac websites and PC tech sites shook their head over the Pentium 4 - a CPU less efficient per clock cycle than the Pentium III that preceded it.

The older PIII architecture was perhaps one-third more efficient, but Intel had a hard time pushing the MHz rating forward - and for the PC user, MHz and GHz means power. It's hard to explain how a 2.7 GHz G5 can do more work in the same amount of time vs. a 3.6 GHz Pentium 4. It's counterintuitive.

The best analogy is a very fuel efficient compact car that seats four vs. a school bus. If you have to transport up to four people, the miserly subcompact wins hands down. If you need to transport 30 kids to and from a school five miles away, the bus driver only has to make a single 10 mile round trip. The driver of the car would have to make 19-20 round trips (three passengers per trip), depending on whether the car spent the day at school or was driven back home at the start of the class.

I don't know what kind of mileage a school bus gets, but I don't think even the most energy efficient hybrids offer twenty times the fuel efficiency.

The Pentium architecture is more like the fuel efficient car. It jumps into traffic when the light changes. It zips along very smoothly. And in most traffic patterns, it will get you to your destination much more quickly than a bus.

The PowerPC architecture is more like the school bus. It handles big loads very well.

This is far from a perfect analogy, since both CPUs are fast and both families of CPUs are getting better (usually more efficient) with each generation. Apple has AltiVec. Intel has hyperthreading. AMD has x86 CPUs that are far more efficient than clock speed would indicate.

The Macintel Future

Intel is already shipping 3.6 GHz CPUs, but the fastest Apple is shipping is 2.7 GHz. Simple math (3.6/2.7) shows that Intel's fastest Pentium runs at a 33% higher speed than Apple's top-end G5. The P4 may be a bit less efficient than the G5, but it would have to be over 25% less efficient before a 3.6 GHz P4 wouldn't outperform a 2.7 GHz G5 overall.

There will be areas where one CPU is more efficient than the other - AltiVec, for instance - but overall the 3.6 GHz P4 will have no trouble matching or beating the 2.7 GHz G5.

There's always progress, and IBM might be able to deliver 3.2 GHz G5s by the end of the year. (We already know the Xbox 360 will use a custom 3.2 GHz triple-core IBM Power CPU and be on the market before the holiday season.) By then Intel may reach the 4 GHz mark, which will still give the P4 a 25% clock speed advantage over Power CPUs.

Clock speed isn't everything, but the market sure latches on to it. Top CPU speeds used to roughly double every 18 months, a corollary to Moore's Law, but that has slowed since the late 90s. Intel broke 3 GHz years ago, but 4 GHz is only now becoming likely. Motorola's G4 architecture tops out at 1.67 GHz, and IBM's G5 - expected to reach 3 GHz a year ago - still hasn't attained the 3 GHz mark.

AMD's Athlon 64 and Sempron CPUs, like their Athlon XP ancestors, are more efficient than Intel's P4s, and AMD indicates this by by using a performance rating in each chip's name. Thus the Athlon XP 2800+ runs at 2.25 GHz but provides performance roughly equal to a 3 GHz P4. AMD's performance ratings tend to be on the conservative side.

Benefits of AMD's approach include less heat, less power consumption, and less need for cutting-edge bus speed - the same kind of benefits the G3 and G4 processors offered in Macs.

Which CPUs in Macintels?

The big question is which Intel CPUs will Apple be using in future Power Macs, PowerBooks, iMacs, iBooks, eMacs, and minis. As the personal computing world begins the transition to 64-bit CPUs (such as the G5), let's hope that Apple has the foresight to put 64-bit Pentiums in the top-end models, at the very least. On the consumer side, 32-bit CPUs should be good enough for years to come.

You can almost guarantee that the Macintel models will have digital rights management built right into the CPU, a feature Intel has been working on. I suspect Apple will design OS X for Intel in such a way that it won't run on CPUs that don't have DRM, just one way of keeping OS X off of standard Windows boxes and undermining Apple's hardware business.

One factor that I hope Apple will address over the next year is AltiVec support. Rosetta, Apple's PowerPC emulation layer, doesn't currently support AltiVec. At the very least, someone should write a software emulator, but it would be even better if Apple worked with Intel to build some AltiVec support into the next generation of Intel CPUs.

One nice thing about the PC world is that there are lots of CPU choices. Pentium and Celeron from Intel. Athlon 64 and Sempron from AMD. A few other manufacturers as well. And many times the same connector is used for a large range of CPUs, making it easy to upgrade when faster CPUs come to market. I hope that's something Apple will allow, although they have gone out of their way to make CPU upgrades a thing of the past on Macs for years now. (Easy CPU upgrades disappeared with the Power Mac G4.)

How Fast Can Apple Grow?

Right now, Apple is growing 40% year-over-year while using PowerPC-based hardware. While they may not win the GHz speed wars, they do win on looks, overall performance, reliability, functionality, and elegance.

Now imagine Apple offering a dual-core 3.6 GHz Pentium 4 system that has the looks and elegance of the Power Mac G5. Further imagine that Microsoft, never one to overlook an opportunity to sell Windows, ports Virtual PC to OS X on Intel. No more CPU emulation, so Windows on a Macintel computer should be close to the performance on a dedicated Windows PC.

Do you see the potential to bring in switchers who won't need to leave their Windows apps behind? It's huge!

Unless Apple really botches things, Intel-based Macs will have the same stability OS X users are used to, and clock speed will be directly comparable with Windows computers. Factor in Virtual PC, and Apple could quickly rise to 10% market share.

Another benefit of putting OS X on Intel is that Apple could produce a fully interactive OS X demo that would run from a CD (or, more likely, DVD) on standard Wintel hardware and lets current Windows users try OS X without investing in new hardware.

Because Microsoft owns Virtual PC, they shouldn't see any threat at all from Apple moving to Intel. In fact, because Mac users tend to buy more software than Windows users, Microsoft may come out ahead.

More than that, Apple should come out well ahead of where they are today. I suspect they'll be #2 behind Dell by the time the entire line has switched to Intel CPUs.

And with the growth, we'll see an even more diverse range of Macintosh computers. Perhaps an ultralight portable, a quad processor Power Mac, and a DIY Power Mac for geeks that lets them choose their own CPU, hard drive, video card, etc.

The good is the enemy of the best, but that doesn't have to be a bad thing. In the long run, going Intel could be best for Apple and for Mac users. 

• Link: The Megahertz Myth, Apple, AMD and Intel, Sander Sassen, Hardware Analysis, undated