Abstract: A semiconductor integrated circuit including circuit groups and driving the circuit groups with respective power supply voltages, digital-to-analog converters that supply the power supply voltages to the circuit groups, and delay measurement circuits that measure delays of circuit element of the circuit groups. This semiconductor integrated circuit includes a central processing unit that establishes settings of registers based on measurements by the delay measurement circuits to control each of the power supply voltages.

Abstract: A microprocessor, including a synchronous type memory having several parts, includes a power saving feature that places at least some parts of the memory in a non-operating state when instructions not requiring access to the memory are executed. An enable signal is generated when access is not required and a signal supplying circuit supplies a synchronous signal when the enable signal is not generated and supplies a signal in a predetermined state to place at least some parts or all parts of the memory in the non-operating state to reduce power consumption.

Abstract: A clock frequency divider for generating a basic clock signal which provides operation timing for a semiconductor integrated circuit operating in accordance with a program. The clock frequency divider comprises a frequency-dividing factor register for storing a frequency-dividing factor which can be rewritten by the program, and a frequency-dividing circuit for frequency-dividing a source clock signal having a fixed frequency in accordance with the frequency-dividing factor stored in the frequency-dividing factor register, whereby a basic clock which provides a processing rate optimum for a program to be executed being obtained.

Abstract: As the incrementer of the invention comprises a shift register for its lower order bits, while its higher bit portions are constructed in the same way as a conventional incrementer, the incrementer can give output signals directly to a memory and the like without the necessity of decoding the same, and the incrementer is free from carry propagation delay possibilities, which assures an improved rate of operation of the incrementer as a whole.