AMD’s Voyage into the 64-bit Arena: x86-64 Revealed

We just mentioned that AMD couldn't possibly create their own 64-bit architecture from scratch now and expect the market to wait for them so instead they're doing what Intel did about 15 years ago, adapt the x86 ISA. This time around, instead of adding 32-bit support to the 16-bit x86 ISA, AMD is adding 64-bit support to the current 32-bit x86 ISA and calling it x86-64.

This approach offers one very clear benefit, you get the best 32-bit x86 performance AMD is capable of delivering, alongside 64-bit compatibility, in a single core. This alleviates the pressure on the customers in the market for 64-bit processors to wait until the best time to migrate to a 64-bit OS since x86-64 makes it possible to run both 32-bit and 64-bit applications at the top levels of performance all from a single chip.

Basically with x86-64, you get the advantages of having a 64-bit architecture with full x86 compatibility without sacrificing performance. This is exactly what Intel did with the 386 around 15 years ago, and it's what AMD is doing with their K8 that's in development now.

Unfortunately with this comes a major downside, by building on the x86 ISA yet again AMD is still bringing along with them all the added baggage that comes with the x86 ISA. We asked AMD about this noticeable downside and their stance on the issue is simple, they believe that "performance has less to do with instruction set and more to do with implementation," which is what they're banking on with x86-64.