Abstract: In order to buffer a succession of input data sets to produce a succession of output data sets, an input/output buffer memory circuit includes a plurality of internal memory elements (1), each having a memory capacity capable of memorizing each of the input data sets. An input port (2) and an input control circuit (3) write each of the input data sets in any one of the internal memory elements as an internal data set. At least one random access port (4) carries out a random access to any one of the internal memory elements to subject the internal data set of any one of the internal memory elements to an internal data processing as a processed data set. An output control circuit (6) reads the processed data set out of any one of the internal memory elements and delivers the read data set to an output port (5) as each of the output data sets.