64 Bit Processors

Here's an overview on 64 bit processors (various sources), more questions than answers: 

 

Intel's EM64T is Intel's true x86_64 initiative. This 3.6GHz Xeon processor is actually the exact same CPU in as the LGA775 Pentium 4F we will see in just a few weeks.

 

AMD's Opteron 150 is the highest performing AMD workstation CPU money can buy. Thus, it is priced around $600 now.  (The nearly identical FX-53 is priced slightly higher). Intel's Xeon 3.6GHz / Pentium 4 3.6F processor is the highest performing Intel workstation CPU money can't buy; although it has shown up in various OEM channels, it really has not hit the market in full force yet.  When it does, we are expected to see it retail for $850.

 

FWIW, I think the Intel version offers hyperthreading, where the AMD chip does not.

 

Some Benchmarks:

Opteron 150 vs. Xeon 3.6 Nocona: http://www.anandtech.com/linux/showdoc.aspx?i=2163&p=1

Athlon 64 vs. Xenon 3.6 Nocona: http://www.anandtech.com/linux/showdoc.aspx?i=2158

 

Processor Cheat Sheet:

http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2118

 

The Dell Precision 670 is available with the aforementioned Nocona: http://www1.us.dell.com/content/products/features.aspx/precn_670?c=us&cs=&l=en&s=bsd&

 

 

Background:

The AMD64 architecture extends the 32-bit x86 architecture (IA-32) by adding 64-bit registers, with full 32-bit and 16-bit compatibility modes for earlier software. Even the 64-bit mode is largely backward-compatible, allowing existing tools targeting x86 (eg. compilers) to be retargeted to AMD64 with minimal effort.  This is in sharp distinction to Intel's competing IA-64 architecture, which makes a complete break from Intel's own x86 architecture.  AMD has released its first generation of AMD64 processors, under the names Athlon 64 and Opteron. The Athlon 64 (codenamed "ClawHammer") is designed for desktop and mobile computers, while the Opteron (codenamed "SledgeHammer") is intended for servers and workstations.

 

IA-64 (Intel Architecture-64) is a 64-bit CPU architecture developed by Intel and Hewlett-Packard for processors such as Itanium. Unlike previous Intel x86 processors, the Itanium is not geared toward high performance execution of the IA-32 (x86) instruction set.  Itanium can switch into 32-bit mode with special jump escape instructions. The IA-32 instructions have been mapped to the Itanium's functional units. However, since the Itanium is built primarily for speed of its EPIC-style instructions, and because it has no out-of-order execution capabilities, IA-32 code executes at a severe performance penalty compared to either the IA-64 mode, or its Pentium line of processors.  

 

Extended Memory 64-bit Technology (EM64T) is an implementation of the AMD64 architecture, an extension to the IA-32 instruction set developed by AMD which adds 64 bit extentions to the x86 architecture.  Intel's first processor to implement the EM64T technology is expected to be a processor codenamed Nocona. The Nocona will eventually become a dual-processor version of the Intel Xeon.  This technology is not compatible with Intel's earlier 64-bit CPU technology, the Itanium processor based on IA-64 technology. It cannot run the same software written for IA-64. EM64T is an extension of the 32-bit x86 or IA-32 instruction set, while IA-64 is a complete rethink from scratch. One of the biggest complaints about IA-64 was that it was not able to run the existing IA-32 software fast enough, since it emulated the older IA-32 instructions rather than directly interpretting them. EM64T shouldn't have such a problem because IA-32 would just be a subset of its own native machine language.

 

Intel tried to keep the existence of EM64T secret for a long time for two reasons. First reason was that it did not want to give its customers mixed signals about the future viability of its Itanium IA-64 processors. However, the success of AMD's Opteron and Athlon 64 processors, based on its AMD64 technology, pretty much meant that Intel had to respond to the competitive threat. Which brings us to the second reason for Intel's secrecy, Intel didn't want to admit that it had to copy from its arch-rival AMD. That's why it gave it the brand name EM64T rather than AMD64, even though they are near identical twins.

 

 

JDK1.4.2 Is available for IA64

JDK1.5beta2 is available for AMD64 (So probably also runs on EM64T)