Memory card, semiconductor device, and method of controlling memory card

An operation method performed by a controller coupled to a nonvolatile semiconductor memory in a semiconductor storage device, the controller including a CPU, a ROM in which a first firmware is stored, and a RAM on which the first firmware is loaded to be executed by the CPU, the operation method comprising:

• receiving from an outside of the semiconductor storage device, a command containing a modifying firmware and an interrupt vector having address information indicating an address on the RAM;
• acquiring the received modifying firmware and interrupt vector contained in the command when the command is a predetermined command;
• storing the acquired modifying firmware and interrupt vector into the nonvolatile semiconductor memory;
• detecting a trigger signal from an outside of the semiconductor storage device;
• reading the first firmware stored in the ROM and the interrupt vector stored in the nonvolatile semiconductor memory when the trigger signal is detected and expanding the modifying firmware stored in the nonvolatile semiconductor memory and the interrupt vector onto the RAM;
• and
• notifying the CPU of the expansion to execute functions of the first firmware and the modifying firmware in accordance with the address information of the interrupt vector to modify the first firmware.