Patent ID: 7577954

Claim:
An image forming apparatus connected to an external instrument, said image forming apparatus comprising: a CPU configured to execute general control, said CPU including a control register and a status register; a ROM configured to store data; a memory configured to store data; a firmware maintenance device configured to accept firmware for updating the ROM transmitted from the external instrument via a kernel of an operating system configured to control the image forming apparatus, said firmware maintenance device maintaining the firmware on the memory; a mode transition requesting device configured to request the kernel to execute transition to a control register enable mode that enables direct access by means of a user process in relation to the control register in a user mode upon receiving a ROM update instruction from the external instrument via the kernel; a condition transition device configured to change an interruption mask of the status register and execute transition to an interruption inhibition condition upon receiving a positive response from the kernel such that the control register enable mode is successfully entered; a writing device configured to write the firmware maintained on the memory into the ROM after the interruption inhibition condition is entered; and a system restart requesting device configured to request the kernel to restarts a system of the image forming apparatus after the writing of the firmware into the ROM is completed.