Contrasting DSP and Power PC PPC Chips for Real-time ApplicationIntel introduced the i860 reduced instruction set computer (RISC) chip for graphics processing in the late 1980s. Once digital signal processing (DSP) board vendors discovered how well the i860 executed signal and image processing functions, they wrote high-speed libraries, and the high performance real-time processing world used i860-based boards for several years. By the mid-90s, DSP chips, like the TI TMS320C40 and Analog Devices ADSP-21060, had caught up with the i860, and the trend began moving back towards using DSP chips for real-time DSP applications. In the late 1990s, RISC chip families such as the Power PC (PPC) have again become the platform of choice for high performance real-time processing.
The goal of this article is to provide technical insights that will help developers of high performance DSP applications decide when and where to use PPC and DSP chips. This article concludes that the PPC typically outperforms DSP chips for real-time applications today, and industry professionals expect it to do so for the near future. However, data I/O management to and from the PPC is the critical parameter to manage, not numbers of adds and multiplies, as is typically the case for DSP chips. This parameter forces developers to change their design strategy from the Mega Floating-point Operations Per Second (MFLOPS) measure they have used with DSP chips to memory management measures like memory bandwidth and data block processing sizes. This article includes examples that illustrate these issues.
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