It has been apparent for some time that Intel's Itanium pro-cessor has not met expectations, despite billions of dollars of investment by Intel over the past 10 years. The "next generation" 64-bit processor has garnered only a portion of the server market and has no presence on the desktop.
Embarrassingly, Itanium is not even the best-selling 64-bit processor with X86 compatibility. AMD's Opteron, introduced just last year, already outsells it.
Opteron meets a market need: full X86 compatibility at full speed, plus 64-bit extensions that allow certain programs to access a larger memory space. And it delivers those capabilities without a sizable impact on either chip cost or power dissipation.
Itanium, in contrast, uses an entirely new instruction set in a largely vain attempt to increase performance. The chip then adds a second, slower processor that provides an X86 "compatibility mode." Itanium outperforms Pentium 4 mainly on a few scientific applications and benchmarks. Most applications do as well or better on Pentium 4, and Itanium's compatibility mode is far slower than a Pentium 4. Itanium's highly complex and speculative microarchitecture also burns more power than does Pentium 4, which isn't easy.
Intel has been secretly (or not so secretly) working on Plan B ever since the original Itanium flopped three years ago. The company has developed its own 64-bit X86 extensions, known as CT.
Ironically, the company that once derided AMD's copycat strategy has been forced in this case to copy AMD's approach.
The word on Prescott
Intel will not confirm that its new Pentium 4, code-named Prescott, implements CT, but my friend Peter Glaskowsky, editor of the Microprocessor Report, says the Prescott processor has far more transistors in its core CPU and dissipates more power than a 32-bit X86 processor should.
Either Prescott was poorly designed or it secretly implements CT, a feature that Intel, in response to Opteron, will eventually turn on. Intel says only that when 64-bit applications and operating systems are available, "we will be there." The company had best not wait. Hewlett-Packard, which fathered the Itanium architecture that Intel eventually birthed, is now offering Opteron servers in addition to Itanium systems.
Once CT is an official Intel offering, it is difficult to see where the company will position Itanium. Intel can't afford to design future Itaniums solely for the scientific market. That likely leaves Itanium, like the i860, as another next-generation architecture gone awry.
Linley Gwennap is founder and principal analyst of The Linley Group and co-author of "A Guide to Storage Networking Silicon" (www.linleygroup.com/npu).
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