New Sound Technology for PCs

New Technology: Hardware Architecture
New Sound Technology for PCs
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AC97 is a standard created by Intel, Analog Devices, Creative Labs, National Semiconductor, and Yamaha for architecting the audio subsystem. It calls for the separation of the audio subsystem into two chips. The codec itself (the “analog portion”) goes into one chip and any other circuitry (the “digital portion”) goes in the “audio controller.” Keeping the digital stuff away from the analog stuff makes it easier to improve the audio quality of the codecs because digital circuitry produces electrical noise that tends to leak into the analog circuitry.


MMX is a set of 57 new instructions for the Pentium processor designed specifically for the sort of number crunching required in digital signal processing. Computer OEMs, in their unending quest to reduce cost, are calling on the host CPU to perform some of the signal processing – e.g., a host-based wavetable synthesizer. The MMX instructions reduce the burden that such tasks would otherwise have imposed on the CPU. There was a time when many system developers believed that the increasing speed of the CPU would make it possible to do all signal processing on the CPU. There are two flaws in this expectation. First, most DSP algorithms can be made to work better by throwing more computational horsepower at them. Second, system integrators are always looking for more things – many of which involve DSP – to do with their platforms. Thus, the requirements for number crunching tend to grow as the CPU gets faster. MMX helps by reducing the burden of any particular set of DSP functions.
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