| 摘要 |
PURPOSE:To alterate a decode output, by reading out the stored data of a rewritable register provided independently from an ROM in the form of a decode output for a specified instruction code. CONSTITUTION:When a coincidence is obtained between the instruction code 20 and the data that is stored in any entry of the 1st register 25, either output of AND gate 271 or 272 turns to ''1'' with the output of the NOR gate 29 turned into ''0'' respectively. Thus the data of the ROM output 24 is blocked by the gate circuit 30, and only the data that is read out of the 2nd register 28 is delivered to the final output line 31 in the form of a decoder output. Then the output 24 data given from the ROM23 is extracted in the form of a decoder output in case no coincidence is obtained between the instruction code 20 and the contents of any entry within the register 25. |
