Como no soy programador no se a ciencia cierta cuales son las ventajas de usar software de 64bit y no he tenido la suerte de usarlo todavia, las unicas que se, se refiere al direccionamiento de mas memoria RAM, que topa en los 4 GB para sistemas a 32bits, ademas en 64bits se supone que la preferencia es usar toda la RAM y luego hechar mano de la memoria virtual, el archivo del disco duro que le sirve como memoria temporal y que es muchisimo mas lenta que la RAM.
una reseña del itanium desde el sitio de Intel:
El procesador Intel Itanium 2 brinda completo procesamiento de 64 bits. La tecnología EPIC (informática de instrucciones en paralelo explícitamente) es la piedra angular de la arquitectura de Intel Itanium. Ofrece diversas opciones de implementación avanzadas de paralelismo, predicación y especulación, por lo que se obtiene un paralelismo superior a nivel de instrucción (ILP) para satisfacer las necesidades actuales y futuras de las cargas de trabajo técnicas y empresariales de alto nivel.
El Itanium es compatible con el software de 32 bit que usamos, pero como estaba creado para sobresalir en 64 bits lo hace de manera exageradamente lenta.
ahora el EMT64, de un sitio de programadores, esta en gringes:
Super, do you understand what 64bit extension is?
Neither AMD64 technology nor EM64T technology is an entirely pure 64bit architecture... however, Intel's extension of 64bit is slightly more abundant when it comes to operands and registers.
The only problem is developers probably won't ever make use of them, like they disregarded SSE until the Athlon had it.
Both processors make a valiant attempt to interpret 64bit extended code, yet neither of them have a pure 64bit architecture.
I expressed that EM64T is better than AMDx64, and such is still the case. But the fact of the matter is, both architectures are pure deceit and won't merit true 64bit performance.
They are an attempt to extend the x86 architecture, without changing it.
Like SSE, MMX, and 3DNow, the 64bit extension is just another set of instructions that the processor can take advantage of.
After doing some programming (yes, I went out and bought a 3000+ and a Xeon with EM64T), I was able to find out that AMDx64 is compatible with EM64T, and vice versa.... UNLESS the additional operands that EM64T has available to it are used. I was able to crash the Athlon 64 consistently when such operands were used.
However, the code I compiled on the Athlon worked perfectly on the Xeon.
la parte que me gusta es la que dice: "Estan extendiendo la arquitectura X86 sin cambiarla".
AMD64 del sitio de AMD. Tambien en ingles para variar:
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. In April 2003, the AMD Opteron™ processor for servers and workstations became the first milestone in establishing this new class of computing. AMD introduced the world’s first and only Windows®-compatible 64-bit desktop and mobile processor, the AMD Athlon™ 64 processor, in September 2003. The range of AMD64 processors for servers, workstations, desktops, and mobile PCs allows pervasive adoption of the AMD64 platform. AMD64 replaces terms such as “Hammer” (now “AMD64 Platform”) and “x86-64” (now “AMD64 ISA”).
The need for 64-bit technology is driven by applications that require high performance and address large amounts of physical and virtual memory. 32-bit computers can manage only 4 gigabytes of addressable memory – and 32-bit operating systems can address only about 2 GB. AMD’s evolutionary approach to 64-bit technology enables a gradual transition from 32-bit to 64-bit software and hardware for end users who need greater computing functionality for some or all of their applications. AMD64 is designed to provide superior performance for applications requiring multi-processor scalability, larger addressable memory, video/audio/3-D processing, or high computational accuracy
y La FAQ del sitio de Intel acerca de su EMT64 que a mi ver son la misma cosa que AMD64:
What is Intel® Extended Memory 64 Technology?
Intel® Extended Memory 64 Technology, or Intel®64, is an enhancement to Intel's 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. Click here for a more detailed description of Intel®64. Further details on the 64-bit extension architecture and programming model can be found in the Intel® 64 and IA-32 Architectures Software Developer's Manuals.
Which Intel processors support Intel®64 and when will they be available?
By Q4 of 2006, Intel®64 will be supported in all mobile, desktop and server processors that are based on the Intel® Core™ microarchitecture. All Intel® Xeon® platforms based on the Intel NetBurst® microarchitecture will support Intel®64 as well. Please refer to the processor product list for more information.
How does the performance of 64-bit Itanium® and 64-bit capable IA-32 processor based platforms compare?
The Itanium processor family is and will continue to be the highest performing and most reliable product family we offer for high-end, multi-processor systems. However, the performance differential is constantly changing due to the frequent release of new Itanium and IA-32 processor based platforms. Click here to find the latest performance ratings for all Intel products.
Is Intel®64 the same technology used in the Itanium® 2 processor?
No. Intel®64 is an extension to Intel's processors based on the IA-32 architecture. The Itanium processor family is based on the EPIC architecture. These are two separate families of processors, based on two different architectures. The Itanium processor family is specifically designed for the most demanding mission-critical applications.
Can the Itanium 2 IA-32 Execution Layer run the new Intel®64 code?
At this time, the IA-32 Execution Layer does not support Intel®64 binaries. Intel will evaluate providing this additional capability if and when customers request it.
Which O/S (Operating System) will support Intel's processors with Intel®64?
The following O/S vendors have available or announced product support for Intel®64. Contact each vendor for more details.
* Microsoft:
Microsoft currently has two 64-bit operating systems that support Intel®64: Windows* Server 2003 x64 Edition and Windows* XP Professional x64 Edition. In addition, Microsoft will release the Windows* Vista operating system in 2007, which will also support Intel®64.
* Apple:
Apple MAC OS* X Tiger, version 10.4.1 supports Intel®64.
* Red Hat:
Redhat version 3.0 (and greater) supports Intel®64.
* SuSE*:
SuSE 8.2 (and greater), SLES 8.0 and SLES 9.0 supports Intel®64.
* Sun Solaris*:
Solaris 10 x64/x86 supports Intel®64.
* FreeBSD:
FreeBSD version 6.0 supports Intel®64.
Is it possible to write software that will run on Intel's processors with Intel®64, and AMD's 64-bit capable processors?
Yes, in most cases. Even though the hardware microarchitecture 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. However, Intel processors support additional features, like the SSE3 instructions and Hyper-Threading Technology, which are not supported on non-Intel platforms. As such, we believe developers will achieve maximum performance and stability by designing specifically for Intel® architectures and by taking advantage of Intel's breadth of software tools and enabling services.
How will Intel®64 work, and what software is there to take advantage of 64-bit extensions?
Development of a broad "ecosystem", ranging from processors, chipsets and tools to operating systems (O/S), applications, utilities and drivers is expected to take some time to develop. Platforms with Intel®64 can be run in three basic ways (note: a 64-bit capable BIOS is required for all three scenarios):
1. 32-bit O/S and 32-bit applications (Legacy Mode): No software changes are required, however the user gets no benefit from Intel®64.
2. 64-bit O/S and 32-bit applications (Compatibility Mode): This usage requires all 64-bit device drivers. In this mode, the O/S will see the 64-bit extensions, but the 32-bit application will not. Existing 32-bit applications do not need to be recompiled, and may or may not benefit from the 64-bit extensions. The application will likely need to be recertified by the vendor to run on the new 64-bit extended O/S.
3. 64-bit O/S and 64-bit applications (64-bit Mode): This usage requires 64-bit device drivers. It also requires applications to be modified for 64-bit operation and then recompiled and validated.
Will the Intel IA-32 processor with Intel®64 have more registers than IA-32 processors today?
Yes, Intel's IA-32 processors with Intel®64 have 16 General Purpose Registers (GPRs) and 16 XMM registers. The GPRs and XMM registers are 64 bits and 128 bits in width, respectively, in processors with Intel®64. The additional registers are only used by applications running in 64-bit mode. IA-32 processors without Intel®64 have 8 GPRs and 8 XMM registers. The GPRs and XMM registers are 32 bits and 128 bits in width, respectively, in processors without Intel®64. More details can be found in the Intel 64 and IA-32 Architectures Software Developer's Manuals.
Will applications written for the Intel Itanium processor family run on Intel's IA-32 processors with Intel®64 without being re-compiled?
No. The instruction sets for Intel's Itanium processor family are different than the IA-32 processor family. Applications need to be compiled separately for each processor family.
I have two platforms: one based on the Itanium processor family, and one based on an IA-32 architecture processor family with Intel®64. Will the same 64-bit operating system work on both platforms?
No. Different operating systems are required for each type of platform due to the different instruction set architectures. Contact your OS vendor to identify which operating system is needed for your particular platform configuration.
I have two platforms: one based on an IA-32 architecture processor family with Intel®64, and one based on an IA-32 architecture family without Intel®64. Will the same operating system work on both platforms?
Yes, if you are running a 32-bit operating system on both platforms. However, a 32-bit operating system will not take advantage of Intel®64.
If you want to take advantage of Intel®64, the first platform will need to run an operating system designed for 64-bit extensions. Operating systems for 64-bit extended systems will not run on the second platform. Contact your OS vendor to identify which operating system is needed for your particular platform configuration.
Does Intel®64 include support for AMD's 3DNOW!* instructions?
No. Intel's IA-32 architecture does not support the 3DNOW! instruction set today. This has not changed with the addition of Intel®64.
What changes are needed for an IA-32 based platform to run a 64-bit O/S and 64-bit applications?
To run 64-bit applications and a 64-bit O/S, a platform will need an IA-32 processor with Intel®64, along with updated BIOS and drivers that have been modified for Intel®64. Contact your BIOS vendor and adapter vendor to get the BIOS and drivers that have been optimized for platforms with Intel®64.
Will existing 32-bit software run, without being re-compiled, on an IA-32 processor with Intel®64?
Yes, with some notes of caution. Refer to the 64-bit Extension Technology Software Developer's Guide for more details.
Running a 32-bit application on a 32-bit O/S, even with a processor with Intel®64, will execute without issue. With a 64-bit O/S and a 32-bit application the processor is designed to support this mode of operation completely (this is called compatibility mode). It is possible, however, that some applications may have certain dependencies beyond the processor's control (e.g. dependencies on the O/S or drivers) which may cause the applications to not run as expected.
Conclusion, EMT64 y ADM64 son extensiones para usar software de 64 bit, IA64 es una arquitectura de 64 bit pura, hay mas contendientes con procesadores de 64bit puros, pero son de otros nichos y menos conocidos.
