System-on-chip choices [RISC or DSP solution]

For many years the decision between a RISC or DSP solution was relatively simple as RISCs and DSPs were never integrated on the same device. The rule used was an 80/20 rule. That is, if the greater part of the processing (i.e., 80 percent) is for data, then attempt to do the signal processing on the RISC. If the greater portion of the processing (i.e., 80 percent) is for signals, attempt to do the data processing on the DSP. But with the ability to integrate both RISCs and DSPs onto the same piece of silicon, the choice becomes more complex. With the addition of programmable accelerators, ASIC and FPGAs also integrated on the same piece of silicon, the choices become almost impossible. The correct choice is not always based on a technical basis. The decisions truly become an optimization of flexibility, ease of use, cost, power and performance. Simply put, the winning strategy is to find a solution which has good enough performance, low enough power dissipation, and low enough price to be first to market. This strategy is referred as a P/sup 3/ strategy. This paper outlines a concept to help system designers selecting the right SOC architecture and optimizing the performance by allocating the right tasks to the right processor.