Data processing array in which sub-arrays are established and run independently

A data processing system which is comprised of:

• a plurality of message routing circuits that have input/output channels which are intercoupled to form an array, and a corresponding plurality of data processing nodes each of which has an input/output channel to a respective message routing circuit;
• each data processing node being adapted to send messages which address other data processing nodes, and each message routing circuit being adapted to pass said messages on said input/output channels to the addresses data processing nodes;
• wherein,
• said data processing system further includes an operator console for manually selecting a subset of said data processing nodes that are to comprise a sub-array, a control module connected to said operator console by a first control channel for receiving commands from said console which define said sub-array;
• a second control channel connected directly to every data processing node and a third control channel connected directly to every message routing circuit which carry control signals from said control module that cause said sub-array to form without any of said messages being passed on any of said input/output channels.