Patent ID: 7382681

Claim:
A semiconductor integrated circuit device on a semiconductor chip, comprising: (a) an internal bus; (b) a central processing unit coupled to the internal bus; (c) a random access memory coupled to the internal bus and used for a work area of the central processing unit; (d) a flash memory coupled to the internal bus and storing control information; (e) an internal oscillator circuit module including: (i) a control data register assigned to an address in an address space of the central processing unit and operable to store the control information, and (ii) an oscillator generating an internal clock signal of the semiconductor integrated circuit device, a frequency thereof being controlled according to the control information received from the control data register; and (f) an output terminal coupled to the internal oscillator circuit module, and operable to output the internal clock signal to outside the semiconductor integrated circuit device, wherein the control information is stored in the flash memory at a predetermined region that is accessible as a rewriteable region of the flash memory, and wherein the control information stored in the flash memory is loaded to the control data register and the central processing unit is adapted to update the control information stored in the flash memory.