Electronics and Communication Engineering - Digital Electronics - Discussion

Full adder has three input bits with two bits as output and remember, hail adder sum= a xor b and carry is ab and full adder the sum is a xor b xor c and carry is ab+bc+ca and for half subtractor, the difference is AXOR, BXOR, C and output is by taking side by side and seen above one is less than lower then we can find that borrow exists or not.