A memory system includes a central processing unit (CPU), a nonvolatile memory electrically coupled to the CPU and a main memory, which is configured to swap an incoming code page for a target code page therein, in response to a first command issued by the CPU. The main memory can be configured to swap the target code page in the main memory to the nonvolatile memory in the event a page capacity of the main memory is at a threshold capacity. The CPU may also be configured to perform a frequency of use analysis on the target code page to determine whether the target code page is to be swapped to the nonvolatile memory or discarded. The incoming code page may be provided by a disk drive storage device and the main memory may be a volatile memory.