| 摘要 |
PURPOSE: To realize the self checking of high performance by providing a means for selecting one output in ripple adders, a means for storing variable carry inputs when they are equal to a first value and a second value and a means of emitting an error signal based on the output. CONSTITUTION: Ripple adders 31 and 32 add Ai-Aj to Bi-Bj. An output multiplexer STMUX 33 gives a correct addition value to a latch A01 through a signal line 33A when a variable signal CARRY=1, and gives the correct addition value to a latch A02 when CARRY=0. The addition values stored in the latches A01 and A02 are compared by a comparator 37. When the two addition values are not equal, the comparator 37 outputs the error signal. Thus, the error can be detected by comparing the latches A01 and A02 in the stage when even one error occurs in a ripple carry stage. |
