Lab # 5 Adder / Subtractor

Objective

In this experiment the student will design and implement a 4-bit adder / subtractor circuit.

  1. Design a full adder using EWB.
  2. Implement the full adder on a breadboard and have it signed off by your instructor or your TA.
  3. Using EWB, create an hierarchical design by cascading 4 full adders and additional circuitry to create a 4-bit adder / subtractor as indicated below.
Label one set of inputs as A3A2A1A0 and the other set as B3B2B1B0.
Label the outputs as S3S2S1S0.
Additional input X selects the circuit function:
If X = 0, S3S2S1S0 = A3A2A1A0 + B3B2B1B0
If X = 1, S3S2S1S0 = A3A2A1A0 - B3B2B1B0

    4. Verify the circuit and have it signed off by your instructor or your TA.