1. A programmable control system, comprising: a processor for executing a control program; a shared memory storing data associated with the control program, at least one of data associated with sensing and actuating devices, and forced I/O values; and, an I/O processor for performing at least one of input and output functions, the I/O processor and the processor operatively coupled to the shared memory, the I/O processor operatively coupled to a cache memory storing at least a portion of the forced I/O values stored in the shared memory, the I/O processor storing input values in the shared memory based at least in part upon forced I/O values stored in the cache memory, the I/O processor determining output values based at least in part upon forced I/O values stored in the cache memory.