| 摘要 |
PURPOSE:To detect that all outputs of a PLA are false, by providing a means which generates all AND of NOT of OR as the output of an OR face. CONSTITUTION:An off-cover line 30 is precharged at the same timing as product term lines 24a-24c and OR face output lines 25a-25c. Inputs 01-03 and OIL of an output latch 29 are obtained by logically negating OR face output lines 25a-25c and the off-cover line by inverters 34a-34c and 37. The off-sover line 30 is discharged only when all output lines 25a-25c are not discharged at all, and all product term lines 24a-24c are discharged in this case. This case corresponds to the fact that outputs of all data output terminals 26a-26c are false. Thus, it is detected that all data outputs are false. |
