Chip rewires itself on the fly

A new design from start-up Stretch may revolutionise high-performance hardware

Start-up US company Stretch has announced the S5000, which is the first microprocessor that can add new instructions while operating. The chip combines an existing architecture, the Tensilica Xtensa RISC processor core, with a large reconfigurable area of programmable logic called the Instruction Set Extension Fabric, ISEF. The company's own C/C++ compiler automatically spots areas in a program that require intensive computation, and creates new instructions for the processor to handle those tasks.

"Operations that might have needed hundreds or thousands of standard instructions can be handled in one", Stretch chief executive Gary Banta told ZDNet UK. "Designers that have had to use multiple digital signal processor chips or a dedicated programmable logic chip coupled to a general-purpose processor can get equivalent performance with the S5000, just through writing high-level software." Typical tasks, such as performing encryption or digital video processing on blocks of data, can be executed in single clock cycles.

Banta said that the chip has demonstrated industry benchmarks at 300MHz that outperformed 2GHz competition. "It takes far less time and money to develop products using the S5000," he said, "and major changes to functionality can be implemented with software updates." In designs where the chip replaces a full custom circuit, he said, development costs can be reduced from millions of dollars to tens of thousands, while development time can be reduced from over a year to a few weeks.

Inside the chip, the ISEF is coupled to the rest of the circuit by 128-bit buses and has 32 128-bit registers. It runs in parallel with the other areas of the processor, effectively becoming a fully reconfigurable co-processor, and can be reprogrammed for new instructions at any time during operation. Stretch provides a development environment that runs under XP or Linux, and run-time support through its own BIOS and for Montavista Linux, which is a popular distribution for embedded developers.

Intended initially for video, networking, communications, medical and security applications, the processor will become available in a number of configurations during 2004 and will cost between $35 and $100 (£19.70 and £56.20) in production quantities.