The EM78M611 is a series of Universal Serial Bus 8-bit RISC Multi-Time Programming (MTP) microcontrollers. It is specifically designed for USB low speed device application and to support legacy device such as PS/2 keyboard. The EM78M611 also support one device address and three endpoints. With no firmware involved, these series of microcontrollers can automatically identify and decode Standard USB Command to EndPoint Zero. The EM78M611 is implemented on a RISC architecture. It has eight-level stack and eight interrupt sources. Each device has 144 bytes of general purpose SRAM and 6K bytes of program ROM, and is embedded with 4 bytes of E2PROM. The EM78M611 has up to 11 pins with the capacity of sinking large current. These series of chips have many powerful features, including : Dual Clock mode which allows the device to run on very low power saving frequency Pattern Detect Application function which is used in a serial transmission to count waveform width