ROM POWER CONSUMPTION DECREASING METHOD

摘要

PURPOSE:To contrive to lower power consumption by stopping reading action at a machine cycle unnecessary to read a ROM based upon a control signal from an instruction decoder. CONSTITUTION:A data output signal 11 from a ROM 10 enters an instruction decoder 13 through an instruction register 12. The decoder 13 outputs a control signal 14 sent to respective parts of a microcomputer, and outputs the control signal to stop the action of the ROM 10 at the machine cycle unnecessary to read the data from the ROM 10, to a ROM control signal line 15. The control line and the clock pulse signal of a clock pulse line 16 are inputted to an 'or' circuit 17, is phase-inverted by an inverter 18 and inputted to a precharging signal line 6. The precharging signal comes to be a low level at the machine cycle unnecessary for reading, the charge of the bit line is not discharged and the power consumption is lowered.