The Z89138/Z89139 is a fully integrated, dual processor controller designed for voice processing applications. The I/O control processor is a Z8 MCU with 24 KB of program memory, two 8-bit counter/timers, and up to 47 I/O pins. The DSP is a 16-bit processor with a 24-bit ALU and accumulator, 512x16 bits of RAM, single cycle instructions, and 6K words of program ROM. The chip also contains a halfflash 8-bit A/D converter with up to a 16 kHz sample rate and a 10-bit PWM D/A converter. The sampling rates for the converters are programmable. The precision of the 8bit A/D can be extended by resampling the data at a lower rate in software. The Z8 and DSP processors are coupled by mailbox registers and an interrupt system. DSP or Z8