Semiconductor memory device equipped with serial/parallel conversion circuitry for testing memory cells

Abstract

An input conversion unit converts serial data supplied from the exterior into parallel data. Each of the converted parallel data is respectively written into a plurality of memory cell areas. An output conversion unit converts parallel data constructed by data read from each memory cell area into serial data. An operational unit is activated during a testing mode so as to logically operate on the parallel data read from each memory cell area. By writing predetermined data into each memory cell area in advance, it is confirmed by a logic operation that correct data is stored in each memory cell area. The data can be checked simultaneously for the plurality of memory cell areas so that the operation test in the memory cell areas can be carried out at high speed. Besides, serial data accepted, twice per cycle of a data strobe signal, is converted into parallel data. Each of the converted parallel data is respectively written into a first memory cell area and a second memory cell area. Parallel data read from the first and second memory cell area is logically operated in a testing mode and the operation result is output at once in synchronization with the clock signal. Accordingly, the data can be checked simultaneously for the first and the second memory cell area so that the operation test in the memory cell areas can be carried out at high speed.