Provided is a computing system and method. The computing system may back up, based on an overlay scheme, a task of an internal memory in an external memory, and the task may be restored to the internal memory from the external memory. The computing system may include a first memory to store data associated with a first task processed in a processor, as a first data structure, a second memory to store backup data of the data associated with the first task, and a memory controller to copy, to the second memory, data other than data previously backed up in the second memory among the data associated with the first task, when the data associated with the first task is backed up in the second memory to process a second task in the processor.