To prepare a plurality of boot procedures and prevent malicious device alterations.
A CPU includes a determination circuit including an NMOS transistor 601 that has a first end connected to a power line VDD and a second end connected with an input terminal and switches power from VDD to a third end in response to Input A 600 from the input terminal, an electrical fuse 602 that is connected to the third end of the NMOS transistor 601 and becomes conductive when a voltage is applied for a fixed time from VDD upon the switching, a resistor 603 that has one end connected to the electrical fuse 602 and the other end earthed, and an output terminal that is disposed between the electrical fuse 602 and the resistor 603. If there is no executable code on memory upon power input, Input A 600 is input into the input terminal of the determination circuit, the level of Output 604 from the output terminal is determined at the input, and executable code is obtained from a serial interface and started if Output 604 is low.
| WO/2014/035377 | HIGH PERFORMANCE PERSISTENT MEMORY |
| WO/2014/205902 | COMMUNICATION MODULE AND CORRESPONDING PORTABLE TERMINAL |
| JP4666589 | USB devices, USB systems and USB control programs |
Masao Sekiguchi
Takamasa Nakano