In case you haven't noticed, every microprocessor, RISC processor and most microcontrollers on the planet have added multiplier-accumulator (MAC) circuitry. Why? So they can perform digital signal processing tasks. OK, maybe not enough to drive Texas Instruments off the street, but certainly enough to do reasonable audio and video decode functions.
Intel exemplifies the trend. At its fall Developer Forum, Intel announced it was adding the MMX instruction set to its Xscale RISC processor to better enable multimedia and to lower power consumption. But MMX won't help you compose on your PDA's word processor or handle the phone list on your cell phone. MMX is principally for performing DSP tasks. Oh, and it does a great job of matrix math for other things, like color-space conversion from RGB on the screen to the CMYK for a printer.
In its quest to jump into the wireless-handset chip business, Intel found that what it really needed for all of that portable multimedia stuff, like MPEG-4 video and MP3 audio encoding, was a lower-power DSP, not a blazingly fast RISC.
With several hundred companies pledging allegiance to the Personal Internet Communications Architecture, of which Xscale is the centerpiece, Intel had to find a way to make its RISC a better DSP. So, it reached into its bag of tricks and brought out MMX again. To be accurate, Xscale already has a MAC and can perform useful DSP tasks, but not to the extent required for our portable multimedia future. However, since Intel despises the DSP nomenclature, its description of that function is "media-processing technology with 40-bit accumulator and 16-bit SIMD [single instruction, multiple data]."
Tensilica, the RISC house that already has a strong DSP contender in its Xtensa instruction extensions and optional DSP vector coprocessor, also has decided that more DSP is better. The company recently enabled powerful custom DSP implementations with its Flexible Length Instruction Extension (Flix) instruction-set architecture. And Conexant Systems, which has considerable experience with its own DSP chips, is developing a new DSP engine based on the Xtensa with Flix.
Why do all the RISC architectures want to become DSPs? Because future semiconductor growth is based on communications and multimedia, both of which need DSP technology.
Finally, a market with solid growth potential.
Will Strauss is President of Forward Concepts (Tempe, Ariz.) and is considered an authority on markets driven by DSP technology (wis@fwdconcepts.com).