A memory device comprises a first memory area including a first memory cell array having a plurality of first memory cells each for storing N-bit data, where N is a natural number, and a first peripheral circuit for controlling the first memory cells according to an N-bit data access scheme and disposed below the first memory cell array, a second memory area including a second memory cell array having a plurality of second memory cells each for storing M-bit data, where M is a natural number greater than N, and a second peripheral circuit for controlling the second memory cells according to an M-bit data access scheme and disposed below the second memory cell array, wherein the first memory area and the second memory area are included in a single semiconductor chip and share an input and output interface, and a controller configured to generate calculation data by applying a weight stored in the first memory area to sensing data in response to receiving the sensing data obtained by an external sensor, and store the calculation data in one of the first memory area or the second memory area according to the weight, wherein the plurality of first memory cells and the plurality of second memory cells are included in a first chip having a first metal pad, the first peripheral circuit and the second peripheral circuit are included in a second chip having a second metal pad, and the first chip and the second chip are vertically connected to each other by the first metal pad and the second metal pad.