1. An embedded multimedia card (eMMC) device, comprising: a flash memory; and a device controller configured to communicate with the flash memory and a host, the device controller comprising: a command storage unit configured to receive and store commands from the host, regardless of a state of a data bus between the device controller and the host, the commands relating to execution of a task; a status storage unit configured to store statuses corresponding to the tasks of the commands stored in the command storage unit; and a task manager configured to manage the command storage unit and the status storage unit for implementation of operations based on the tasks stored in the command storage unit and the corresponding statuses of the tasks stored in the status storage unit.