Driven by the rise of silicon-photonics, optical signaling is moving inexorably from the domain of long-distance communications to chip-chip and even on-chip application. If we are to have on-chip signals that are optical, an obvious question is to ask is whether we can do more than simply communicate with light. Could we, for example, store and process information directly in the optical domain, rather than having to go through time and energy consuming optical-electrical-optical conversions? It is just such capabilities that we demonstrate here, using a novel integrated photonics platform that embeds chalcogenide phase-change materials into standard silicon photonics circuits. Specifically we show that our phase-change photonics platform can deliver binary and multilevel memory, arithmetic and logic processing, as well as synaptic and neuronal mimics for use in neuromorphic, or brain-like, computing, and all …