1. A cellular computational platform comprising: a silicon or SOI wafer; a multiplicity of functionally identical, repeating computational hardware units that are integrated on the wafer and that are interconnected electrically and optically, thereby forming a hybrid network, wherein: the platform further comprises a long-range optical waveguide network, integrated on the silicon or SOI wafer, that interconnects computational hardware units over spans greater than ten nearest-neighbor distances; the said long-range optical waveguide network is the only medium that interconnects computational hardware units over spans greater than ten nearest-neighbor distances; each computational hardware unit includes a reprogrammable local memory; each computational hardware unit is connected to other computational hardware units over interconnections that have reconfigurable weights; each computational hardware unit is configured to transmit both electrical and optical signals into the hybrid network for broadcast in a protocol-less manner to other such units in the network, and to respond to protocol-less electrical and optical broadcast messages that it receives from the hybrid network; each computational hardware unit is further configured to reprogram its local memory in response to incoming electrical signals or optical signals or both electrical and optical signals; at least some of the computational hardware units include an optical transceiver configured to transmit signals in a plurality of distinct optical channels and to receive and demultiplex signals in at least one optical channel; the said plurality of distinct optical channels includes at least one common channel adapted to be broadcast to all optically connected computational hardware units and at least one range-limited channel optically coupled to elements that absorb or divert optical power such that optical signals that propagate therein are increasingly attenuated with propagation distance; at least some of the optical transceivers are configured to transmit optical signals into the long-range optical waveguide network on long-range channels with sufficient power to be received and detected at computational hardware units more than ten nearest-neighbor distances away; some but not all of the optical transceivers are configured to aggregate locally generated signals and to transmit them on long-range channels into the long-range optical waveguide network; and some but not all of the optical transceivers are configured to disaggregate signals obtained on long-range channels from the long-range optical waveguide network and to distribute the disaggregated signals to local receivers.