ASYNCHRONOUS RIPPLE PIPELINE

An asynchronous ripple pipeline has a plurality of stages, each with a controller (18) and a register (16). The controller has a register control output (21), and a combined acknowledgement and request output (20), together with a request input (22) and an acknowledgement input (24). The protocol used has a single signal, output on the combined acknowledgement and request output (20) of a stage (30), that functions both as a request to the next stage (32) and an acknowledgement to the previous stage (34).