Digital data processor with two operation units

摘要

In a data processing apparatus executing a plurality of instructions in a pipeline mode by dividing each of the instructions into a plurality of stages, its operation circuit includes a first execution (E) unit capable of execution of operations required by all of the plural instructions and a second E unit capable of execution of operations required by part of the plural instructions only. A queue of data including decoded information of the instructions required for execution of operation stages are stored in a circuit to be selectively supplied by first and second circuits to the first and second E units, respectively. The first and second circuits sequentially select succeeding data in synchronism with the end of operations in the first and second E units respectively. As a result, when a stage of a succeeding instruction requires the result of operation of a preceding instruction being executed, that stage of the succeeding instruction is executed after the second E unit completes the operation of the preceding instruction, even when the first E unit is executing an instruction further preceding the preceding instruction.