Abstract: A storage control system controls the update operations on two buffer address arrays in a data processing system in which a plurality of processors are connected to a shared storage, at least one of the processors having a buffer storage. The first buffer address array is the directory of buffer storage. The second buffer address array contains the same data as that of the first buffer address array. The storage control system updates first the content of the second buffer address array then that of the first buffer address array in response to a block transfer to the buffer storage of the own processor and a store operation conducted by other processor on the shared storage. The storage control system permits to accept a new access request occurred in the own processor on condition that a block transfer to the own processor is finished and that the first buffer address array is updated in association with the block transfer.

Abstract: In order to guarantee the instruction execution sequence in a pipeline control data processing system, the present overlap detector device detects whether or not the operands overlap each other in access width units by comparing the store address specified by a store instruction with the fetch address contained in a fetch instruction following the store instruction. Moreover, the overlap detector device detects whether or not an overlap occurs in an area of the access width based on the store mark, the address in the access width unit stored in the fetch address, and the fetch data length. The overlap detector device detects the presence or absence of an overlap according to the results of operations for detecting these two overlap conditions.

Abstract: Change bits are provided in correspondence with storage information units (blocks or pages) of a storage, and indicate whether or not a "store" operation has been performed into the corresponding storage information units. The change bits are retained in a first retention device in correspondence with the storage information units, and a copy of the change bits in the first retention device is retained in a second retention device. When the store operation is performed to effect a storing of data into the storage, a control device refers to the change bit retained by the second retention device and controls updating of the change bit of the first retention device in accordance with the indication of the change bit referred to.