Remember the days when knowing something about computers was a prerequisite for writing about them?

ZDNet's David Coursey continues to astound me. Yesterday he wondered aloud what Apple could do to keep OS X from running on standard PCs if Apple were to ditch the PowerPC line for an x86-based CPU, or to keep Windows from running on Apple Macs if they became x86-based.

I'd link to the editorial but it's really not worth the minimal effort it would take.

First, there's the question of whether it's even necessary for Apple to migrate. Charlie pointed out that Apple remains profitable. It has 5% of the market, but that's beside the point. They're making money. People use Apple Macs for a variety of reasons, and those reasons seem to vary, but speed rarely seems to be the clinching factor. A decade ago, the fastest Mac money could buy was an Amiga with Mac emulation hardware--an Amiga clocked at the same speed would run Mac OS and related software about 10% faster than the real thing. And in 1993, Intel pulled ahead of Motorola in the speed race. Intel had 486s running as fast as 66 MHz, while Motorola's 68040 topped out at 40 MHz. Apple jumped to the PowerPC line, whose clock rate pretty much kept up with the Pentium line until the last couple of years. While the PowerPCs would occasionally beat an x86 at some benchmark or another, the speed was more a point of advocacy than anything else. When a Mac user quoted one benchmark only to be countered by another benchmark that made the PowerPC look bad, the Mac user just shrugged and moved on to some other advocacy point.

Now that the megahertz gap has become the gigahertz gap, the Mac doesn't look especially good on paper next to an equivalently priced PC. Apple could close the gigahertz gap and shave a hundred bucks or two off the price of the Mac by leaving Motorola at the altar and shacking up with Intel or AMD. And that's why every pundit seems to expect the change to happen.

But Steve Jobs won't do anything unless he thinks it'll get him something. And Apple offers a highly styled, high-priced, anti-establishment machine. Hippie computers, yuppie price. Well, that was especially true of the now-defunct Flower Power and Blue Dalmation iMacs.

But if Apple puts Intel Inside, some of that anti-establishment lustre goes away. That's not enough to make or break the deal.

But breaking compatibility with the few million G3- and G4-based Macs already out there might be. The software vendors aren't going to appreciate the change. Now Apple's been jerking the software vendors around for years, but a computer is worthless without software. Foisting an instruction set change on them isn't something Apple can do lightly. And Steve Jobs knows that.

I'm not saying a change won't happen. But it's not the sure deal most pundits seem to think it is. More likely, Apple is just pulling a Dell. You know the Dell maneuver. Dell is the only PC vendor that uses Intel CPUs exclusively. But Dell holds routine talks with AMD and shows the guest book signatures to Intel occasionally. Being the last dance partner gives Dell leverage in negotiating with Intel.

I think Apple's doing the same thing. Apple's in a stronger negotiating position with Motorola if Steve Jobs can casually mention he's been playing around with Pentium 4s and Athlon XPs in the labs and really likes what he sees.

But eventually Motorola might decide the CPU business isn't profitable enough to be worth messing with, or it might decide that it's a lot easier and more profitable to market the PowerPC as a set of brains for things like printers and routers. Or Apple might decide the gigahertz gap is getting too wide and defect. I'd put the odds of a divorce somewhere below 50 percent. I think I'll see an AMD CPU in a Mac before I'll see it in a Dell, but I don't think either event will happen next year.

But what if it does? Will Apple have to go to AMD and have them design a custom, slightly incompatible CPU as David Coursey hypothesizes?

Worm sweat. Remember the early 1980s, when there were dozens of machines that had Intel CPUs and even ran MS-DOS, yet were, at best, only slightly IBM compatible? OK, David Coursey doesn't, so I can't hold it against you if you don't. But trust me. They existed, and they infuriated a lot of people. There were subtle differences that kept IBM-compatible software from running unmodified. Sometimes the end user could work around those differences, but more often than not, they couldn't.

All Apple has to do is continue designing their motherboards the way they always have. The Mac ROM bears very little resemblance to the standard PC BIOS. The Mac's boot block and partition table are all different. If Mac OS X continues to look for those things, it'll never boot on a standard PC, even if the CPU is the same.

The same differences that keep Mac OS X off of Dells will also keep Windows off Macs. Windows could be modified to compensate for those differences, and there's a precedent for that--Windows NT 4.0 originally ran on Intel, MIPS, PowerPC, and Alpha CPUs. I used to know someone who swore he ran the PowerPC versions of Windows NT 3.51 and even Windows NT 4.0 natively on a PowerPC-based Mac. NT 3.51 would install on a Mac of comparable vintage, he said. And while NT 4.0 wouldn't, he said you could upgrade from 3.51 to 4.0 and it would work.

I'm not sure I believe either claim, but you can search Usenet on Google and find plenty of people who ran the PowerPC version of NT on IBM and Motorola workstations. And guess what? Even though those workstations had PowerPC CPUs, they didn't have a prayer of running Mac OS, for lack of a Mac ROM.

Windows 2000 and XP were exclusively x86-based (although there were beta versions of 2000 for the Alpha), but adjusting to accomodate an x86-based Mac would be much easier than adjusting to another CPU architecture. Would Microsoft go to the trouble just to get at the remaining 5% of the market? Probably. But it's not guaranteed. And Apple could turn it into a game of leapfrog by modifying its ROM with every machine release. It already does that anyway.

The problem's a whole lot easier than Coursey thinks.