Automated synthesis of microprogrammed controllers in digital systems

The paper presents an integrated procedure, called MCS, for the automated synthesis of microprogrammed controllers in digital systems at the register-transfer (RT) level. To MCS there are two major inputs: a description of the data path of the digital system and a behavioural description of the digital system at the RT level. The result given by MCS is a cost effective controller which can drive the operations of the data path. MCS works in seven major steps: (a) defining an initial basic controller model; (b) generating sequences of control signals; (c) manipulating control-flow statements; (d) compacting parallel operations; (e) determining the lower bound of control word width; (f) determining the control word format; (g) encoding the control memory. The algorithms that MCS uses in carrying out these steps are described. The paper also describes two experiments in which the MCS is used to synthesise the controllers of two small hypothetical CPUs.