US Patent 9479175 Semiconductor device and electronic device

A semiconductor in which the area of a circuit that is unnecessary during normal operation is small is provided. A semiconductor device including a first circuit has a function of storing a start-up routine in the first circuit and executing the start-up routine, a function of operating the first circuit as a buffer memory device after executing the start-up routine, and a function of loading the start-up routine into the first circuit from outside before the semiconductor device is powered off.