Question

1. Design a bit-sliced N-bit full subtractor from N one-bit ripple borrow full subtractors. Draw the block diagram of the full subtractor in the format given in question 3. Represent each gate with a square that is labeled with its type.

Answer 1

a 1-bit full subtractor is shown below:

now the borrow of state N will be given as input to stage n+1 hence giving us a ripple carry adder

here is the circuit for 4-bit ripple full subtractor

the blocks represent a 1-bit full subtractor as shown