The HT86XXX series are 8-bit high performance microcontroller with voice synthesizer and tone generator. The HT86XXX is designed for applications on multiple I/Os with sound effects, such as voice and melody. It can provide various sampling rates and beats, tone levels, tempos for speech synthesizer and melody generator. It has a single built-in high quality, D/A output. There is an external interrupt which can be triggered with falling edge pulse or falling/rising edge pulse. The HT86XXX is excellent for versatile voice and sound effect product applications. The efficient MCU instructions allow users to program the powerful custom applications. The system frequency of HT86XXX can be up to 8MHz under 2.4V and include a HALT function to reduce power consumption.