| 摘要 |
PURPOSE:To use effectively a state history storage circuit, by selecting address contents to be stored in the state history storage circuit in accordance with detection of two specific patterns provided in a micro instruction word. CONSTITUTION:A micro (mu) instruction word is read out from a mu instruction word memory 12 in accordance with an address from a mu instruction word read address circuit 11. Internal status information designated by the memory 12 is stored successively in a state history storage circuit 20. In this case, when the first specific pattern included in the mu instruction word is detected by a pattern detecting circuit 13, contents of an address register 30 which designates the address of the circuit 20, where state information should be stored, with parallel information are saved in an address buffer 22 after they are increased in an address counter 31 by one. When the second specific pattern of the mu instruction word is detected by the circuit 13, contents of the buffer 22 are stored again in the register 30. A selecting circuit 33 selects contents of the counter 31 or the buffer 22 in accordance with the first and the second pattern detected by the circuit 13 and stores them in the register 30. |
