Looks like Intel will soon, very soon, have the same type of 64-bit technology in their desktop processor's as AMD does.

http://www.intel.com/products/server/processors/server/pentium4/index.htm

This is a link to the public Intel web site.

Select versions of the Intel® Pentium® 4 processor support Intel® Extended Memory 64 Technology (Intel® EM64T)φ as an enhancement to Intel's IA-32 architecture on workstation platforms. This enhancement enables the processor to execute operating systems and applications written to take advantage of Intel® EM64T. Further details on the 64-bit extension architecture and programming model can be found in the Intel® Extended Memory 64 Technology Software Developer Guide.

The Intel® Pentium® 4 processor supporting Intel® EM64T enables entry-level single processor workstation users 64-bit memory addressability for great application flexibility.

This is similar to what AMD has on their "64-bit" CPU's.

And the point is? In my understanding, 64 bit support of AMD is a genuine product while the 64 bit of Intel is a marketing trick to pull the attention away from AMD. And what the heck do I want with "64 bit memory support"? A fully capable 64 bit processor is ... well ... a fully capable 64 bit processor, isn't it?

Both AMD and INTEL desktop processors are not true 64-bit. only a 64-bit extension architecture....Extended Memory 64 Technology Software.

AMD and INTEL do both have server processors that are TRUE 64-bit, but those are for SERVERS, not normally compatible with desktop OS, and Windows doesn't have a 64-bit desktop OS,

...so for AMD and INTEL it is all just a MARKETING SCAM!!!! A "64-bit LIE"

brmecham - you seem to be inaccurate on a few points - can you provide evidence?

Intel has the Itanium, which is totally 64-bit, with a limited ability to do 32-bit stuff.
AMD doesn't have a totally 64-bit CPU at present - the Opteron is almost identical to the Athlon FX, with more hypertransport links (for multi CPU stuff), registered memory and an extra pin. It's another 32-bit chip with 64-bit extensions.

Microsoft has produced Windows XP 64-bit edition for the Intel Itanium series of processors. It's on their website, if you want to look. Of course, Itanium is still wrong for the desktop, but it can run XP.

Spod, I think it may be your turn to be wrong. AFAIK, WinXP 64-bit edition is designed for 64-bit extended systems, aka x86-64 which is what the Athlon 64 processors are.

Itanium doesn't even use x86, AFAICT, but another architecture called EPIC. To fully understand the difference requires an understanding of basic computer architecture, but in short, they use different machine (and probably even assembly) level languages.

Excuse me, and what is the definition of a 64 bit processor then? Are you saying that a 64 bit processor is the one where Windows 64 bit runs? I am sure you would be excited to learn that 64 bit Linux is available to run on your 64 bit AMD processor.

Anyway, correct me if I am wrong for I do not generally follow up the 64 bit things as close as I would like to but:

AMD has a CPU that uses 64 bit registers and provides 64 bit operations.
Intel has a CPU that can use 64 bit for memory addressing.

The two aren't the same, are they?

Apologies for causing confusion. MS has TWO 64-bit versions of XP - XP for 64-bit is the Itanium version, XP for 64-bit Extended Systems is the AMD64 version. The latter will also support EM64T.

I was addressing the point:
"AMD and INTEL do both have server processors that are TRUE 64-bit, but those are for SERVERS, not normally compatible with desktop OS, and Windows doesn't have a 64-bit desktop OS, "

by saying that AMD don't have a "true" 64-bit CPU in the same way that Intel does (Itanium), the Itanium is compatible with XP (the definitive* desktop OS), and Microsoft does have a "true" 64-bit desktop OS, as well as its AMD64 version (the one that's not out yet).
If you wanted to, you could run 32-bit Windows on an Itanium, but no-one would want to. It's about as fast as a 1.5 GHz P4 in 32-bit x86 stuff, and will only strut it's stuff with programs written for its own architecture.

AFAICT, Intel reverse-engineered AMD64 to produce EM64T. Intel intended to implement all the features of the x86-64 instruction set, including the extra registers the instruction set requires, and the 64-bit memory addressing it enables.
It may be less efficient than AMD's implementation, and the EM64T chips lack other advantages of the AMD64 chips, such as the on-chip memory controller, NUMA & hypertransport for multiprocessor systems. But they should be fully compatible woth XP for 64-bit extended systems and AMD64 games.

*Or at least, most prevalent. I don't want to get into a Linux vs. Windows debate.

Again, I'm trying to balance brevity with completeness, but I hope I've made things clearer.

Errr correct me if I am wrong, but I was under the impression that EM64T is the same set of instructions that AMD use in their A64 CPU:s. Someone (think it was Rusty, not sure) said that Intel bought the instructions from AMD. I also seem to remember that the A64 will get support for SSE3 sometime in the close future. So, essentially, the same protocols, different architecture (there is a first time for everything).
And as for the "lack [of] other advantages of the AMD64 chips", the P4 doesn't seem to need it that badly according to this article from Anandtech. It seems to make up for it in GHz...

http://www.anandtech.com/linux/showdoc.aspx?i=2158&p=1


Finally, Spod, I was under the impression that Itanium emulated 32-bit VERY slow, so I was a bit surprised that you compared it with a 1.5GHz CPU. My information is admitedly just hearsay, thuogh.

The Itanium is based on and derived from the architecture used in the HP server machines. At the time HP designed this architecture (mid 1980s) it was called the Sprectrum architecture. It is now called PA-RISC. The Itanium is a RISC machine and the Itanium "emulates" i86 instructions by executing the i86 instructions in micro code by executing multipule native Itanium (RISC) instructions. Remember RISC processors by definition do not use micro code where as CISC processors by definition do. The native Itanium instruction set was poorly optimized for i86 emulation so this runs slowly.

Also code is seldom "written for" RISC processors but rather is compiled for that processor. RISC processors are not designed for hand written assmembly language and are highly dependent on thier compilers to generate efficent code. In fact it is common for the designers of RISC processors to write extensive documentation just for those that will be writting the compilers to support the processor.

On the other hand the P4 also has many RISC like features but these were optimized to run native i86 instructions.

The AMD Athlon 64 series is a true 64 bit chip. It is however a CICS chip not a RISC chip. Since most high end work station and server 64 bit processors are RISC that may be the reason that some are claiming that the AMD chip is not a "true" 64 bit processor. But it does have a 64 bit instruction set, 64 bit registers and 64 bit memory space, 64 bit memory bus and is therefore a true 64 bit chip.

ISTR hearing that Intel were integrating the equivalent of a 1.5 GHz P4 into the die of newer Itaniums precisely to improve their performance with x86 apps.
You'd still be nuts to buy an Itanium purely for x86 apps, though.