| 摘要 |
PURPOSE:To facilitate the patch processing of a microprogram by comparing an address to read the microprogram with a comparative address regist and a corresponding mask register and changing it to a RAM entry address when they coincide. CONSTITUTION:An address generating circuit 5 reads the microprogram stored in a ROM 7, the microprogram is set to a microinstruction register 8, and simultaneously, it is inputted to a comparing circuit 3. By the comparing circuit 3, the microprogram to be read and the contents of a comparative address register 1 are compared, further, it is compared with the contents of a mask register 2, and when a bit except for the bit to be masked coincides, the fact is outputted to the address generating circuit 5. The address read next from the address generating circuit 5. The address read next from the address generating circuit 5 is inputted from a RAM entry register 4, it is switched, the RAM entry address is outputted, the microinstruction is read from a RAM 6 and it is executed. Thus, the patch processing of the microprogram is facilitated.
|
