The Z89C00 is a second generation, 16-bit, fractional, two's complement CMOS Digital Signal Processor (DSP). Most instructions, including multiply and accumulate, are accomplished in a single clock cycle. The processor contains 1 Kbyte of on-chip data RAM (two blocks of 256 16-bit words), 4K words of program ROM and 64K words of program memory addressing capability. Also, the processor features a 24-bit ALU, a 16 x 16 multiplier, a 24-bit Accumulator and a shifter. Additionally, the processor contains a six-level stack, three vectored interrupts and two inputs for conditional program jumps. Each RAM block contains a set of three pointers which may be incremented or decremented automatically to affect hardware looping without software overhead. The data RAMs can be simultaneously addressed and loaded to the multiplier for a true single cycle multiply.