Virtual realities: All the world on a Mac

Computerworld - Time was, Macs lived in their own world and PCs lived in theirs, and that was that. The line between the two was clear; there was some cross-platform software, but in general, they spoke vastly different languages. You could run some Windows software on Macs, but only through the use of a complex emulation program. This software had the daunting task of creating an entire virtual computer, all the way down to the CPU, and then translating, on the fly, every single operation and instruction between the real Mac and the virtual PC.

All of the PC emulators, however, by virtue of the fact that they had to do so much low-level work to emulate an entirely different CPU architecture, were very, very slow, compared to a real PC.

But when Apple converted its entire product line from PowerPC CPUs to the very same Intel chips used in Windows PCs, the world changed. Now that you don't need a complex software layer to emulate and translate every low-level instruction from one kind of CPU to the other, you can have a Mac that runs Windows at near-native speeds -- at least in theory.

In very short order after the first Intel-based Macs hit the streets, developers proved that Windows on Macs was more than just a theory -- it worked, and it was fast. It was a bit of a chore to set up, though -- certainly beyond the capabilities of your average user -- and was also unsupported by Apple. In other words, it was an interesting experiment, but not ready for prime time.

The arrival of Boot Camp

Almost immediately, however, the world turned upside down once again. Apple itself released the public beta of a dual-boot enabler, called Boot Camp. With very little fuss or trouble, Boot Camp allowed anyone to load and run Windows on an Intel Mac. The next version of Apple’s operating system, Leopard (Mac OS 10.5), will include the ability to run Windows built in.

Macs that run Windows via virtualization are here to stay.

Boot Camp runs Windows operating systems (XP and Vista) and Windows-based applications, and it runs them fast and well and with excellent compatibility. In fact, early tests of Macs running Windows showed that Macs ran Windows apps faster than did many comparable Windows-only PCs. That’s a huge change from the old emulation days.

But the one big flaw of Boot Camp is that you either run Mac OS, or you run Windows, but not both at the same