The PD17704, 17705, 17707, 17708, and 17709 are 4-bit single-chip CMOS microcontrollers containing hardware for digital tuning systems. Provided with a wealth of hardware, these microcontrollers are available in many variations of ROM and RAM capacities to support various applications. Therefore, a high-performance, multi-function digital tuning system can be configured with only one chip. In addition, a one-time PROM model, PD17P709, which can be written only once and therefore is ideal for program evaluation and small-scale production of a PD17704, 17705, 17707, 17708, or 17709 system, is also available.