Other name for IA64=expensive junk
Even supercomputers aren't using it. http://www.top500.org/stats/list/36/procfam
Well, in june 2004, there was 84 itanium system in the top 500, one being in the second position... and it have decline since... Windows server 2008 was the last windows system to support the itanium, like Ubuntu LTS 10.04 or red hat 5... in fact, only HP OS continue to support it...
It was not junk... performance was (very ) poor only in 32 bit mode... but 64 bit was very fast... It doesn't matter how good the IA64 architecture is, customers want to run their existing applications, most of which are compiled for x86 and don't come with source code. That leaves you with emulation, which i doubt Intel could make faster than native... Intel can't move to a new architecture because they are held back by all the millions of closed source applications out there.
simply remember that x86 architecture is from 1978 !!! All the new thing are only extension from these original x86... not really something who can lead to top performance due to the backward compatibility... these extension are something like the option for a car... usualy, option make a car better but it become a time that option will not be enough and that a new type of car will be needed... since 1978, the following extension was added to x86 architecture : x87, IA-32, P6, MMX, SSE, SSE2, x86-64, SSE3, SSSE3, SSE4, SSE5, AVX .
Anyway, history repeat itself... intel have launch the first real 32 bit processor 1981 with a new architecture called iAPX 432... customer have not like it because it was incompatible with the 8086... one year later, the 80286 was released... a x86 architecture with a 32 bits extension...
The first time that consumer was able to choose between 32 bits and real 64 bits was in 1989...
We now had two very powerful chips that we were introducing at just about the same time: the 486, largely based on CISC technology and compatible with all the PC software, and the i860, based on RISC technology, which was very fast but compatible with nothing. We didn't know what to do. So we introduced both, figuring we'd let the marketplace decide. ...
Well, we already know the choice of the marketplace : the 486 !!! And the i860 was not bad :
All of the buses were at least 64 bits wide. The internal memory bus to the cache, for instance, was 128 bits wide. Both units had thirty-two 32-bit registers, but the FPU used its set as sixteen 64-bit registers. Instructions for the ALU were fetched two at a time to use the full external bus. The IEEE and Intel referred to the design as the "i860 64-Bit Microprocessor". Intel i860 instructions acted on data sizes from 8-bit through 128-bit. The graphics unit was unique for the era. It was essentially a 64-bit integer unit using the FPU registers as eight 128-bit registers. It supported a number of commands for SIMD-like instructions in addition to basic 64-bit integer math. Experience with the i860 influenced the MMX functionality later added to Intel's Pentium processors.
Yes, a 64 bits processor was released by intel in the same time that the 486...
In conclusion, several time in the computer history, customer was given the chance to choose new architecture who have can evolve further that actual processor... problem of new architecture is that it is not compatible with previous one... in all case, customer have choose the solution with the less performance but the more compatibility... in almost all the case, it is customer who have stop progress... pretty sure that the next generation of processor will be some x86-128 in place of a real fully 128 processor...
