| 摘要 |
PURPOSE:To allow one exception detecting means to initiate two kinds of branch instruction exceptional interruption by providing a flag which determines whether interruption is caused as an exception of the branch address of a branch instruction itself or as an exception of the instruction extraction of this branch instruction. CONSTITUTION:An instruction unit 1 is an advanced control part which prefetches an instruction and includes an exception detection part 11 which detects an exception regarding the operated extraction of this instruction and a branch decision part 12 which decides a success or failure in branching with respect to the branch instruction. The exception control circuit 4 controls an execution unit 3 by limiting the execution of an instruction whose exception is detected by the execution unit 3 on the basis of the exception detection signal ex detected by the exception detection part 11 of the instruction unit 1, a branch instruction identification signal br and a branch decision signal go decided by the branch decision part 12 of the instruction unit 1, and a mask signal mk as a flag for determining an exception interruption system of the branch instruction held by the exception control circuit 4 and then starting a specific microprogram stored in a control storage unit 2, thereby realizing two kinds of exception interruption systems. |
