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The x64 Vs AMD64 Vs EM64T Vs Itanium Riddle – What is what?

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While I tried to learn more about the 64-bit processors, here is what I found out. There are two different sets of architectures present in the world today. The first is called the x64 architecture processors, which is based on the AMD64 and/or Extended Memory 64 Technology (EM64T) as the case of manufacturer may be. The other one is the Itanium processors, which is based on the Explicit Parallel Instruction Computing (EPIC). Nice terms right? Lets try to demystify these. Here is what I found about them.

The x64 platforms in 64-bit computing are offered by two main vendors – AMD and Intel.

AMD64 – AMD64 is AMD’s 64-bit platform that extends the industry-standard x86 instruction set architecture and defines a new class of computing. The AMD64 platform is the first designed to deliver full compatibility with existing x86 solutions and world-class 64-bit performance. To read more FAQs about the AMD64 technology go here. As of now, there are three ranges of processors that AMD offers which use the AMD64 technology
• AMD Opteron processor for servers and workstations
• AMD Athlon 64 processor for desktops and notebooks
• AMD Turion 64 mobile technology for notebooks

I do not want to go into the details of each type right now. In case you are interested AMD’s website might just be the best place for you to search more.

Extended Memory 64 Technology (EM64T) – The Extended Memory 64 Technology is Intel’s enhancement to its IA-32 architecture. The enhancement allows the processor to run newly written 64-bit code and access larger amounts of memory. These extensions do not run code written for the Intel Itanium processor. To read more FAQs about this technology, go here. As of now, there are these three ranges of processors that Intel offers which use the EM64T technology
• Intel Pentium D processor
• Intel Pentium processor Extreme Edition
• Intel Xeon processor

Interestingly enough, while searching, I found a site which states that Intel has commented that EM64T and AMD64 are the same, practically; apart from the differences – well I found this funny. Is everything not the same except for the differences??? :) :) Here is the comment that I got from the site "Even though the hardware micro-architecture for each company's processor is different, the operating system and software ported to one processor will likely run on the other processor due to the close similarity of the instruction set architectures".

The IA platform in 64-bit computing is offered by Intel.

Itanium- The Itanium Processors moves users beyond proprietary Reduced Instruction Set Computer (RISC) architecture. This platform is based on the Explicitly Parallel Instruction Computing (EPIC) architecture. Now what is EPIC? EPIC is a 64-bit microprocessor instruction set, jointly defined and designed by Hewlett Packard and Intel. To read more about it, read here. As of now, Intel offers the Intel Itanium 2 Processor supporting this technology.

Well, hope this was a good summary and a nice set of links to read through!!

But wait a minute. I forgot to discuss what is x64. x64 is Microsoft's generic designation for the Advanced Micro Devices AMD64 and Intel EM64T 64-bit Instruction Set Extensions to the x86 architecture. It stands for Extended 64.

More later ... !

Comments

  • Anonymous
    March 01, 2006
    > "There are two different sets of architectures present in the world today"

    Of course, you meant "in the Microsoft World". Because there are more 64-bit processors available on the market: Sun Sparc, HP-PA, DEC Alpha, etc...

  • Anonymous
    March 01, 2006
    Yes, that is correct. I was just looking at it from the MS point of view for this blog. I am already working on the next set of available options, which I would update and publish in some time.

  • Anonymous
    March 06, 2006
    This blog aims at clarifying the issues which 32-bit developers might be having when they start migrating...

  • Anonymous
    April 24, 2006
    Before we discuss this, it is important for the users to understand a few facts about 64-bit platform...

  • Anonymous
    May 11, 2006
    That means can I run my 32 bit RHEL AS2 on Xeon processor machine and install 32 bit oracle database on it.

  • Anonymous
    June 23, 2007
    Which is better then and why? Would you have the same performance with EM64T as with Itanium or vice versa?

  • Anonymous
    August 03, 2007
    Thanks for spelling this out. I was researching this same issue and it was good to find a quick summary that confirms what I think I thought!

  • Anonymous
    April 12, 2008
    thx man .. gave me all i needed to know