| 摘要 |
PURPOSE:To realize a data processor which is suited for application as a 1-chip microcomputer, by giving an indication to hold the memory contents to the processor main body by means of the operation holding signal when an abnormal drop of the power supply voltage is detected. CONSTITUTION:An indication to hold the memory contents is given to a data processor main body by means of the operation holding signal when an abnormal drop of the power supply voltage is detected. For instance, when a main power supply VDD of a microprocessing unit MPU lowers less than the reference voltage Vref, the operation holding signal OH of the unit MPU is set at a low level by a comparator 6. The signal OH is latched by the NIF signal showing the final of the execution of an instruction, and the signal RAME which inhibits the data writing is set. Then the unit MPU is held after the execution of the instruction is through. The power of a latch 1 and a read/write memory RWM is supplied from an auxiliary power supply VsTB. Thus the contents of the memory RWM are held although the power supply VDD has a drop. |
