US Patent 7092314 Semiconductor memory device invalidating improper control command

A control circuit in a semiconductor memory device accessing a memory cell for a plurality of cycles includes an internal command generating circuit and a mask signal generating circuit. Upon receiving a control command, the internal command generating circuit outputs an internal signal instructing an operation to access the memory cell at H level when a mask signal is at L level, while outputs an internal signal at L level when the mask signal is at H level, because a latch circuit is reset. The mask signal generating circuit outputs the mask signal at H level for a following cycle, when the internal signal is output at H level.