itanium with x64?

[Valkerie]

is it true that itanium or itanium 2 cannot handle x64 from microsoft? and is it backwards compatible with x32? how much more powerful is itanium? and lastly, is itanium 3 coming out, and will it be windows x64 compatible?

 

[Jeff7181]

The Itanium is not an x86 processor like the Pentium and Athlon models. In order to run x86 (incluiding x86-64) code, it has to emulate the hardware. Doing that isn't very efficient... it takes most of the Itanium's power to emulate an x86 processor, so not much CPU power is left to actually run x86 software, so it runs very poorly. It will never be "Windows x64 compatible."

As I understand it, the Itanium is a highly parallel design, making it better suited for extremely large servers that perform many tasks simultaneously. So when it's running programs written specifically for the Itanium architecture it performs very well.

I haven't heard anything about the Itanium 3... but I haven't looked. The Itanium is more for the enterprise market... something which most people here will never have the experience of working with.

 

[Furen]

itanium (the original) was not x86 compatible. In order to run x86 apps you had to use some crazy emulation layer, so performance was horrendous. The later versions of itanium (not sure if itanium 2 or just later revisions of the first one) had an x86 core added for compatibility. The performance with that new core was much much better, but it still doesnt hold a candle to a dedicated x86 cpu (from what I've heard, it performs like a ~1ghz p3, which is what the extra core basically is). This leads me to the next point: it's incompatible with x86-64 because the x86 core in it is 32 bit.

About performance... like all cpus out there it has it's strong points and it has it weak points. From the little I know of the itanium I can speculate that it has insanely high performance FPUs while the ALUs are just the opposite (FPUs = floating-point unit, ALU = Arithmetic and logic unit). Itanium was Intel's plan to develop a propietary architecture that would eventually trickle down into the mainstream--though intel was the original developer of x86, they signed an agreement with ibm that allowed other companies (AMD) to manufacture cpus based on the ISA (since IBM didnt want to be dependant on a single provider).

Anyway, I'm gonna go read up a bit on itanium and edit this if I find any glaring errors ^^.

 

[ProviaFan]

I have heard people say that Windows for 64 bit extended systems (the Itanium one) has been discontinued. Windows Server 2003 still seems to be available for Itanium, so maybe when I didn't see the former on Microsoft's web site I was just looking in the wrong place...

 

[Leper Messiah]

Originally posted by: Jeff7181
The Itanium is not an x86 processor like the Pentium and Athlon models. In order to run x86 (incluiding x86-64) code, it has to emulate the hardware. Doing that isn't very efficient... it takes most of the Itanium's power to emulate an x86 processor, so not much CPU power is left to actually run x86 software, so it runs very poorly. It will never be "Windows x64 compatible."

As I understand it, the Itanium is a highly parallel design, making it better suited for extremely large servers that perform many tasks simultaneously. So when it's running programs written specifically for the Itanium architecture it performs very well.

I haven't heard anything about the Itanium 3... but I haven't looked. The Itanium is more for the enterprise market... something which most people here will never have the experience of working with.

You know, I was going to type up much the same response, but then I went to lunch. :thumbsup: for doing my work for me.

 

[IntelUser2000]

Actually you are wrong about the 32-bit emulation in Itanium, Jeff7181.

On the first Itanium, and Itanium 2 up to current versions, there is a integrated hardware dedicated to running 32-bit x86 apps when it detects it. However the performance of the hardware is dismal, performing low as 75MHz 486 to 233MHz Pentium II, when the Itanium was at 800MHz.

Itanium 2 had 32-bit x86 performance that's equal to Pentium II with 2/3 of the clock speed, meaning 1GHz Itanium 2 had 32-bit x86 performance of 600-700MHz Pentium II, if such beast existed.

So after couple of years, Intel announced that they'll be releasing a software to dynamically translate 32-bit x86 instructions into 64-bit EPIC Itanium instructions. That was 2003. The result is far improved performance, with 1.5GHz Itanium performing around equal to 1.5GHz Xeon, still not enough, but much more acceptable. The software is called IA-32 EL, or Execution Layer, and it doesn't need the hardware emulator anymore.

Next version of Itanium won't have the hardware emulator, just the IA-32EL software.