SEMICONDUCTOR MEMORY DEVICE

PURPOSE:To enable the compression/extension processing of temporarily stored data at a high speed by providing an input/output circuit part including a compression circuit and an extension circuit for data to be connected to at least one port in a random access memory part with a multiport and a control means controlling these. CONSTITUTION:The semiconductor memory device is constructed by including a random access memory part 1 with the multiport, an input/output circuit part 4 including a compression circuit 2 and an extension circuit 3 for the data to be connected to at least one port in this, and a control part 5 deciding the operation mode of the input/output circuit part 4 by an external control signal in one semiconductor substrate. Therefore, the compression/extension processing can be performed only by the internal data transmission control between the random access memory part 1 and the built-in control means 5 by the random access memory part 1 and the compression/extension circuits 2, 3 corporated in the common semiconductor substrate. Thus, the compression/ extension processing is speeded up while equipping continuity with the temporary storage of the data and the compression/extension processing of the data.