A nonvolatile memory device includes a first memory cell array, a first bi-directional multiplexer, a first register, a second register, a first I/O pad and a second I/O pad. The first memory cell array stores first data. The first bi-directional multiplexer receives the first data and distributes the first data into first sub-data and second sub-data. The first register stores first sub-data from the first bi-directional multiplexer. The second register stores second sub-data from a second bi-directional multiplexer. The first I/O pad outputs the first sub-data from the first register to outside. The second I/O pad outputs the second sub-data from the second register to the outside.