pm just got a cable modem on Friday from AT&T and simply had to check it out irregardless of the fact that every relative that I have is staying at my house right now. This thing is
fast! I was pulling 2.5Mb/s from MS earlier... but my satisfaction over finally having high bandwidth net access is OT.
I do work in the IA64 division of Intel on IA64 microprocessor design (not on the Itanium/Merced project). I can try and answer questions on the IA64 instruction set and architecture (since this has been released to the public), but not specific questions on future chips (since it's company policy not to discuss future products). As a disclaimer, though, I do circuit design and am not particularly spectacular at architectural details. Definitely better than the average graduate student, but my job generally entails designing high speed cache circuits and I don't tend to track high-level architectural details except out of personal interest.
One correction for
DDad is that IA32 is not being emulated in the Itanium processor. There is an IA32 engine on the chip. I agree that fundamentally these instructions are being converted into an EPIC format, but if you are going to call this "emulation" then you might as well say that the AMD K5, the AMD K6, the Athlon, and the Intel Pentium II and Pentium III processors are all essentially RISC chips running IA32 CISC emulation.
Also, any discussion of relative IA32 performance between the two architectures is a bit premature. Neither company have released very many specific details of their projects, and so it's complete speculation at this point. This autumn's Hotchips and Microprocessor Forum conferences will likely see more specifics and, most likely, some preliminary performance numbers.
As regards 64-bit as the desktop processor of typical user... Using 64-bit registers doesn't buy you much. The most important ability is the capability to get past the addressing limitations of 32-bits (which is 4GB, IIRC). Another useful feature is the ability to manipulate large integers without playing architectural tricks which reduce performance. But in return you pay a performance penalty for the extra bits. Clearly many instructions will be larger since they will contain 64-bit data and addresses, and these will reduce performance by requiring more space in the cache and more bandwidth from the FSB.
Obviously within the next 5-10 years, desktop memory will start to approach 4GB. If we use the potentially optimistic approach of saying that typical desktop memory will double every 18 months and we say that 128MB is typical right now, then we are looking at 7 years before we reach this 4GB being "typical". Clearly for any company to stay competitive in the future, you will need to at least have a plan for implementing 64-bits in their processor line.
Whether Intel's new architecural approach, or AMD's modified architectural approach ends up being the more successful will be decided long in the future. I really couldn't guess, although I really like the IA64 architecture. It is an intriguing instruction set and an interesting new approach.
Patrick Mahoney
IA64 Microprocessor Design
Intel Corp.
pmahoney@mipos2.intel.com
* Not speaking for Intel Corp. *