AMD has actually been around for quite a while, but it’s their line of Intel-compatible processors that they’re now most famous for. Now however, Intel will be making AMD-compatible processors…
What happened? Basically, Intel lost the 64-bit race.
Intel *does* have a 64-bit CPU of their own, the Itanium, but it’s been plagued by a few critical disadvantages. It’s expensive. Its backwards compatibility mode with the x86 instruction set is extremely slow. Its new architecture is more efficient, but unfamiliar and difficult to work with. And perhaps most important: it’s late. It’s extremely difficult to even get hold of an Itanium-based system and actually do anything useful with it.
AMD on the other hand has their own x86-64 instruction set and is already shipping its 64-bit CPUs, the Opterons, in fairly large quantities. The price is fairly reasonable, in line with what a new faster CPU would have been anyway. And it’s an extension to the existing instruction set, making the transition easier and letting old 32-bit code run at full speed instead of in a slow emulated mode.
With this announcement, Intel has basically just unofficially given up on their Itanium line and decided to support the AMD set. There is an argument to be made that the Itanium chips were really just meant for high-end servers and such and not the home desktop market, and that Itanium will continue to survive in that server market, but it doesn’t look optimistic. With AMD’s chips already out there and Intel making compatible chips, people just aren’t going to bother supporting the Itanium line. All the software will get written for the AMD chips because that’s what’s out there right now, and admins will choose AMD systems for their servers because that’s where all the software will be.
A company can try and support both chips; on a common platform like Linux or Windows it should theoretically just be a matter of recompiling the program. It hasn’t worked out that way historically, though. The same was technically true for NT’s ports to the MIPS, Alpha, and PowerPC architectures, but they eventually wound up on the scrap heap because they simply couldn’t displace the already-existing base of x86 systems.
Why does all this 64-bitness matter anyway? That’s another whole article…