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Linux Journal: Crusoe: Transmeta's Trump Card

Jan 20, 2000, 03:52 (5 Talkback[s])
(Other stories by Jason Kroll)

"We all knew Linux was ideal for embedded and mobile systems, and many of us predicted more success for Linux in embedded systems than on the desktop. Many of us also suspected (since Linus's remark about a chip with software, and after looking at Transmeta's patent filings) that we'd soon have a chip that translated instructions on the fly into the native language of the chip. Today, Transmeta confirmed suspicions and delivered more than most of us had expected...."

"The fundamental idea behind the Crusoe family of processors is software. Crusoe is, to my knowledge, the only processor with its own special software (please contact me if you know of another). The Crusoe processors have a native language, which is a 128-bit VLIW (very large instruction word) instruction set. This methodology is a bit like RISC times 4; that is, you construct an instruction molecule out of atoms, and each atom would be roughly equivalent to a RISC instruction. The chip then uses no speculative execution, branch prediction, or data flow analysis techniques (which severely waste energy and can create pipeline stalls), but instead carries all information about the instructions and scheduling with the molecule that goes to the processor. VLIW is a neat idea, but it's not the truly exciting thing about Crusoe."

"Crusoe chip software employs Code Morphing. This is what we expected since last summer, but it's true and it's really here. Crusoe software morphs x86 code into its own native language on the fly. Not only that, but it caches the translated instructions (no need to translate data for a data cache), so that it hasn't got to retranslate them. What is the advantage of this? Not only can you write software that would enable a chip to be effectively any chip, but also there's one monstrous advantage for portable computing: the reduction of transistors."

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