Learn the Full Subtractor with interactive circuit diagrams, truth tables, Boolean expressions, Difference and Borrow logic, logic gate implementation, and digital logic examples.
A full subtractor extends the half subtractor with a borrow-in (Bin) from the previous stage, so bits can be chained to subtract multi-bit numbers. Diff = A ⊕ B ⊕ Bin. Bout is set whenever a borrow is needed either from the A/B stage or from the Bin stage: Bout = (A′·B) + (A′·Bin) + (B·Bin). It's built from two half subtractors and an OR gate, the same way a full adder is built from two half adders.
| A | B | Bin | Diff | Bout |
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