Oki’s ML67Q4050/4060 Series Advantage Microcontrollers are equipped with a Flash security bit that protects the internal Flash ROM contents from unauthorized reads. If the Flash security bit is set during Flash programming, the JTAG port of the MCU is also disabled, making it impossible for the JTAG to interface with the MCU. To disable the security bit when this occurs, use the Boot-ROM, serial Flash programming method to pop the Flash security bit and enable the JTAG connection.