Memory modules and stacked memory devices

Abstract

A memory module includes semiconductor memory devices mounted on a circuit board and a control device mounted on the circuit board. Each semiconductor memory device includes a memory cell array to store data. The control device receives a command and an access address from an external device and provides the command and the access address to the semiconductor memory devices. Each semiconductor memory device performs an address swapping operation to randomly swap a portion of bits of the access address to generate a swapped address in response to a power-up signal or a reset signal, and enables a respective target word-line from among word-lines in the memory cell array such that two or more of the semiconductor memory devices enable different target word-lines in response to the access address.