Though most signals in a natural environment are analog, today's emerging technologies and applications require digital data to operate quickly and efficiently. This need for digital signal processing is evident even in small market segments like PC multimedia, which is expected to account for less than 10 percent of the total DSP market by 1999 (according to Forward Concepts, Tempe, Arizona).
Multimedia applications such as speech, audio, graphics acceleration, and communications have an insatiable appetite for MIPS (millions of instructions per second) and MACS (number of multiply-accumulate cycles per second). Digital signal processors can execute one MAC per clock cycle, compared to five or six clock cycles per MAC by a general-purpose processor. Thus a general-purpose processor MIPS is roughly to of a DSP MIPS. This makes a 90-MHz 64-bit CPU roughly equal to a 20-25 MIPS DSP, if 100% of the CPU's power is available for signal-processing tasks.
By design, DSPs can easily handle high-MIPS requirements without burdening the host processor, and they can efficiently manage multiple MAC-intensive applications which will bring a general-purpose processors to a grinding halt. Adding more MIPS to the host processor doesn't always help. In network environments where the general-purpose processor is regularly interrupted, this execution stall problem is compounded.
Cost, of course, is also a key consideration, especially in consumer applications where DSPs can act as function accelerators. When signal processing tasks are handled off of the motherboard-providing correct task assignment between DSPs and CPUs for higher system performance-DSPs become an even more cost-effective solution.
As PC multimedia and similar signal-processing applications evolve into new, more powerful applications, designers and consumers will continually seek the most cost-effective and highest performance solution-digital signal processors.