For the shown digital logic circuit with inputs A and B, select its truth table (diagram in source).
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Question

For the shown digital logic circuit with inputs A and B, select its truth table (diagram in source).

G1 Physics · Accepted Answer

From the original circuit, the upper NAND stage yields U = NOT(A·B). The lower NAND stage receives A̅ and B and yields L = NOT(A̅·B). Their outputs enter AND, so Y = U·L = NOT(A·B)·NOT(A̅·B). Using Boolean algebra, Y = (A̅ + B̅)(A + B̅) = B̅. Thus Y for (A,B)=00,01,10,11 is 1,0,1,0. Final answer: Option C.