The MSM64422/64424 is a low power 4-bit microcontroller using OKI original CPU core nX-4/ 20. Integrated into a single chip are 64/128 nibbles of EEPROM, PWM generation circuit, 8-bit timer counter, 8-bit synchronous serial port, time base counter, low voltage detection circuit, watchdog timer, 4-bit input port, one or two input-output port(s). For the oscillator circuit, it is possible to choose from the crystal oscillation circuit or the 3-pin RC oscillation circuit (resistor R and capacitor C are externally connected). Most suitable for small-sized security systems such as the key-less entry.