In many ways Itanium represents a change for Intel. Having dominated the desktop PC processor market, the company hopes that its 64-bit silicon will become the de facto choice in the next generation of booming e-commerce solutions, powering both mid-tier and back-end servers throughout the Internet infrastructure. It believes it can achieve this by bringing the same price/performance model to the high-end server market as it did so successfully to the desktop PC market. Intel also contends that the chip, as well as offering good value for money, offers a lower total cost of ownership than rival CPUs, while at the same time beating the 64-bit competition on raw performance as well.
Itanium offers considerable benefits over RISC-based processor architectures. Enhanced parallel processing is crucial among these, through a technique that Intel refers to as EPIC (Explicitly Parallel Instruction Computing). EPIC consists of predication and speculation. Branch prediction is a method used by current processors that makes guesses as to what calculations are likely to be needed, and performs them accordingly. Predication is a technique for making more accurate guesses, reducing the number of incorrect predictions, saving wasted processor cycles. Speculation operates with the same intention in mind, loading instructions and data onto the CPU before theyre needed.
A compiler is the software that translates programming languages into the machine code for Itanium to understand. These identify the parallelism in a programs code that EPIC uses and are critical to the success of this method. Accordingly Intel has made a great deal of talking to the software industry, creating compilers for C, C++ and Fortran to enable developers to port 32-bit apps over to IA-64. This will make Itanium the first new processor architecture to arrive with usable software already in the market.
To promote the uptake of Itanium a large number of prototype systems have been given to OEMs. So far six major OSes have been successfully tested on the platform including Windows 2000 and Linux, and at the recent Intel Developer Forum eight manufacturers were demonstrating early version of their systems. These included IBM, Compaq, Sun and SGI, which despite having their own 64-bit processors will all offer Itanium solutions. SGI has announced plans to offer a 512-way system, demonstrating that Itanium is as scalable a platform as RISC-based architectures.
Having co-developed the Itanium with Intel, HP is happy to move its customers away from its own PA-RISC architecture. A spokesperson for the company stated that, over time, the percentage of the performance increases from RISC processors has been reduced. Essentially, theyve run out of headroom. IA-64 offers them a new path to increasing performance. Due to its involvement in the development of Itanium, HP has the advantage that its HP-UX operating system is binary compatible with Itanium, making it possible for its customers to move over to IA-64 from its PA-RISC systems without making any changes.
The chip will debut at 733MHz and 800MHz and represents a new level of processor complexity, sporting 320 million transistors. In fact, only 25 million of these are in the core, the rest being in the cache and the floating-point units (FPUs). The chip will feature two levels of on-die cache, running at full core speed. A Level 3 cache will be on the cartridge. The chip will be available with either 2Mb or 4Mb configurations, although Intel hasnt yet disclosed exactly how this amount will be divided up between the three levels of cache.
Due to the high densities of memory required in the target market, the i460GX chipset will only support SDRAM rather than RDRAM but will be able to address a maximum of 64Gb - important for large clusters.
With IA-32 processors recently hitting the gigahertz and above level, the 800MHz entry-level clock speed of Itanium may seem lacklustre. However, the large I/O capabilities of Itanium will allow it to perform millions of instructions at once using a fully optimised 64-bit app, a factor that will be more important to many businesses than raw clock speed. To give a real-world example, a business processing many transactions per second over its servers will become more cost effective. In addition, more transactions will be able to be performed in a smaller number of systems, which will have the knock-on effect of enhancing manageability. In a server farm, fewer systems doing more work will be easier and cheaper to maintain than many less powerful systems.
While Itanium marks Intels entry into the high-end server and workstation market, the standard PC desktop machine will continue to be based on 32-bit architecture. The next-generation Willamette is set to replace Pentium III, while its successor Foster will offer high-end performance for the segment of the sever market that wishes to remain in the 32-bit domain.
64-bit Computing
The 64-bit question
So what of the future for IA-64?
The Competition