The Z89390 is a CMOS Digital Signal Processor (DSP). Single-cycle instruction execution and a Harvard bus structure promotes efficient algorithm execution. The processor contains 512 word data RAM and 64K word of external program address space is accessible. Six register pointers provide circular buffering capabilities and dual operand fetching. Three vectored interrupts are complemented by a six level stack. The CODEC interface enables high-speed transfer rates to accommodate digital audio and voice data. A dedicated Counter/Timer provides the necessary timing signals for the CODEC interface. An additional 13-bit timer is available for general-purpose use.