"Configurability offers SoC designers the freedom to create highly differentiated chips that provide a competitive advantage," Schlachte said. Configurable CPUs, he argued, have lower power consumption, require fewer transistors, and are less expensive to manufacture.
Schlachte noted that ARC was one of the pioneers of configurable processors, and is now moving towards configurable subsystems for audio and video applications. An example is the ARC Player Subsystem, which includes a 32-bit ARC 600 family core with media extensions, MPEG-4 video decoder, MP3 decoder, audio/video synchronization, and a voice recorder module.
Nigel Topham, chief architect at ARC, provided more detail about the "benefits" of configurability. By adding a small number of additional, application-specific instructions, he said, users can experience significant speed gains, code size reductions, and increased energy efficiency, all with a "small increase" in die size.
Configurable custom logic can also replace lookup tables, he said. While a lookup table can require 100 clock cycles to decode a symbol, a configurable processor can reduce this time to one clock cycle, Topham claimed. He also said configurable custom logic can provide 20X better energy efficiency, improved cache performance, and a reduced memory bandwidth.
Multimedia SoCs will require a massive growth in complexity, but clock frequencies will not rise significantly, Topham said. Thus, multi-core parallelism is essential, and this requires configurability in terms of the number and connectivity of cores. Thus, he said, platform architectures will become configurable multi-core architectures.
Topham briefly described the VRaptor Media Architecture, introduced earlier in October, which supports an ARC 700 family core with a single-instruction, multiple-data (SIMD) accelerator and DMA engine.
After his talk, Topham's claim about energy efficiency was challenged by an audience member who noted the increasing problem with leakage power. "There is no single answer to the problem of leakage power," Topham said. "But we think configurability allows us to produce a solution that is inherently more power efficient."