Abstract: An arbitration system for a machine tool control has multiple processors and a local memory associated with each processor. The arbitration system allows one processor to access data stored in a foreign memory, i.e. the local memory of a second processor so that the time required for one processor to gain access to data used by another processor is relatively short. The system includes an external arbitration control which arbitrates requests for access to a foreign memory from each of the processors. The system also includes a plurality of local arbitrators each associated with a particular processor to arbitrate requests for access to its processor's bus and memory from a plurality of users including the external arbitration control, a DRAM controller and a direct memory access controller.