Design-for-adaptivity of microarchitectures

In the last decade we have witnessed a steady trend towards functional diversification of hardware, because an application specific hardware component is a lot easier to design and optimise than a general-purpose one. Therefore, a modern microelectronics system often contains several application specific cores, each targeted for a particular function. As operating conditions issues are becoming more important, we start to see non-functional diversification in terms of performance and energy consumption; it is expected that a system can operate in a wide spectrum of environmental conditions and it should support a hierarchy of energy-saving modes. As a result, "mode-specific" processing cores are gaining popularity. The number of possible combinations of functional and nonfunctional variations of hardware components is becoming unmanageable and is leading to inefficient silicon utilisation. In this paper we explore a novel approach to hardware design which allows building computation systems capable of adjusting to operating conditions through dynamic reconfiguration. We demonstrate the approach by designing an asynchronous microprocessor core that can operate in a wide range of supply voltages and can adjust its functionality towards a specific application and operating mode. Our methodology is based on a novel model of hardware description and on self-timed design techniques.