1. A method of executing a packet of chained instructions, the method comprising: executing a first instruction selected from a packet of chained instructions to access a first data operand from a first memory at a memory address specified by the first instruction for delivery solely to a first output port; executing a second instruction selected from the packet of chained instructions to receive the first data operand solely from a second input port connected by a first path in a first network to the first output port, operate on the received first data operand according to the second instruction and generate a result for delivery solely to a second output port, wherein the first path is determined according to the second instruction; and executing a third instruction selected from the packet of chained instructions to receive the result solely from a third input port connected by a second path in a second network to the second output port, store the received result in a second memory at a memory address specified by the third instruction, wherein the second path is determined according to information contained in the packet of chained instructions.