SNC21000 Series is a series of 16 to 500 seconds one-channel single chip voice

synthesizer IC. It built in a 4-bit tiny controller, I/O ports, PWMIO, internal RAM,

ROM, and a PWM Direct Drive Circuit (PWM Voice). By programming through the

tiny controller, user’s varied applications including voice section combination, key

trigger arrangement, output control, and other logic functions can be easily

implemented.