PURPOSE: To correct a microprogram by storing a flag for showing whether a correction to a data exists or not, storing separately corrected data, selecting the corrected data when the flag shows a correction, and controlling an input/output device.
CONSTITUTION: In a random access memory RAM2, an identifying flag (f) for showing whether data d1 stored in each address a1 of a read-only memory ROM has been corrected or not is stored in each address a1, the data d1 is read out of the ROM, and also the flag (f) is read out of the RAM2, and inputted to a selecting circuit SEL2. Also, a comparing circuit CLC compares the a1 inputted to the ROM, and a corrected address a3 read out of an RAM1, and in case when a condition a1>a3 is formed, a driving signal a1 is transferred to a counting circuit CNT2. The circuit CNT2 which has received said signal is driven by a clock signal clk2, and increases successively an address a4 to be transferred to the RAM1.
KUMAZAKI MASAYUKI
SUMIDA TETSUAKI
