MULTI-PROCESSOR SYSTEM WITH CACHE MEMORY

PROBLEM TO BE SOLVED: To provide a data processing system maintaining the completeness of data. SOLUTION: This data processing system includes two or more entities connected to a bus. One or more entities are provided with a cache memory storing data units received from a main memory and a control means committing to that the data units stored in the cache memory are the latest data. The control means includes a means monitoring the activity of the bus and a means which determines whether a corresponding data unit is stored in the cache memory or not in response to the data unit written in the main memory by the entity through the bus in relation to a system bus hold signal generated by the entity and substitutes the stored corresponding data unit with the data unit written in the main memory through the bus during the same operation if the corresponding data unit is determined to be stored in the cache memory.