1. Design a special-purpose unit using single-bit full adders for adding
(a) 12 singlebit numbers and
(b) 19 single-bit numbers.
2. Design a half subtracter circuit using
(a) only NOR gates and (b) only MUXs.
3. Design a 1-bit full subtracter module using only NOR gates and then obtain a 4-bit full subtracter using these modules.