First-in first-out semiconductor memory device

Abstract

The number of bits of data items read in parallel fashion and the number of bits of data items written in parallel fashion are related to be at least a whole number multiple of 2, thereby to achieve enhancement in the efficiency of data transfer between a semiconductor memory device and the exterior thereof. Further, in a semiconductor memory device of FIFO type, the number of stored data items is calculated using the values of a write counter and a read counter, thereby to achieve the accurate acquisition of the number of stored data items even when the operations of reading and writing data items coincide. In a semiconductor memory device having a built-in address counter, the value of the address counter or an external address signal is selected on the basis of an external instruction in order to address a memory cell, thereby to achieve facilitation of random accesses to memory cells and also the clearing of the data items of any desired memory cells.