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Architecture of Liberation

Although there’s been plenty of press coverage of Transmeta as a new venture, what often gets lost is the technology itself. Crusoe is a hybrid software/hardware chip whose sole purpose is to run software designed for other microprocessors. Much of what Intel and others accomplish in silicon, Transmeta has shifted to software. The advantages? First, the chips themselves take less silicon, making them cheaper to build. Second, a simpler chip consumes less power-a paramount concern for portable computers. But perhaps the most far-reaching impact is that in crafting Crusoe, Transmeta has come up with an innovative approach free of many of the problems that have plagued chip design for the last two decades.

Before Crusoe, every microprocessor ever built has come with its own published “instruction set”-an explicit contract that spells out how the chip will work with software. An instruction set promises that if developers write software that does X, the resulting action from the chip will be Y-now and forevermore.

The problem is that once a new chip is designed, it is locked in time. As software inventory for the chip builds, it becomes next to impossible to make improvements to the instruction set. Software development is hampered too, since any new program must obey the laws of the chip’s instruction set in order to work. Microprocessor designers want chips to run faster, but they must also make them run on existing software. So they squeak out increments of speed with tricks such as resequencing instructions to the processor. But implementing major changes is next to impossible. It’s like a very bad three-legged race, with software and hardware engineers tied at the hip-never able to move fast toward adopting state-of-the-art products, so dependent are they on each other’s design choices and the choices of previous generations.

Ditzel himself has firsthand experience with the difficulty of making fundamental improvement in a chip’s initial design. At Sun Microsystems, where he worked before founding Transmeta in 1995, he was in charge of changing the instruction set for the company’s SPARC brand of microprocessor. Although he embarked on the project in 1990, it wasn’t until last year that the new instruction set was ready for use. “You need time for the industry to catch up, to get software out there, to get applications converted,” Ditzel told TR before the company’s IPO. “It’s a really big deal.”

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