From Physical Devices to RTL Models: Abstraction and Validation in Hardware Engineering

Abstract

This paper introduces the foundational principles underlying hardware engineering models and argues that abstraction is their defining characteristic. Because abstraction necessarily omits detail and constrains what engineers can build, models are inherently incomplete in specific respects - or, as George Box famously observed, "All models are wrong, but some are useful". At the same time, abstraction is essential for simplification, which is key to managing complexity. More abstract models also tend to simulate faster because fewer details must be considered. This paper subsequently examines a range of abstraction methods in digital design - sometimes referred to as design disciplines - including lumped models, value-discrete models, and time-discrete models. Together with constraints that define the validity of the abstraction and design guidelines, these abstraction methods establish design disciplines. This paper further relates these forms of abstraction to pre-clustered design elements such as transistors, gates, registers, and transfer functions. These pre-clustered elements define abstraction levels, such as the gate level, and are presented as a key enabler of increased design productivity.