The Z89175/176 is a fully integrated, dual processor controller designed for voice processing applications. The I/O control processor is a Z8 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 8K words of program ROM. The chip also contains a half-flash 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 8-bit 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 programs can be directed by events in each other's domain.