LOGIC DESIGN LABORATORY MANUAL - VTU e-Learning Centre

Logic Design Laboratory Manual 13
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PROCEDURE:
• Check all the components for their working.
• Insert the appropriate IC into the IC base.
• Make connections as shown in the circuit diagram.
• Apply augend and addend bits on A and B and cin=0.
• Verify the results and observe the outputs.
ii)
4-BIT BINARY SUBTRACTOR.
Subtraction is carried out by adding 2’s complement of the subtrahend.
Example: 8 – 3 = 5 (0101)
• 8 is realized at A 3 A 2 A 1 A 0 = 1000
• 3 is realized at B 3 B 2 B 1 B 0 through X-OR gates = 0011
• Output of X-OR gate is 1’s complement of 3 = 1100
• 2’s Complement can be obtained by adding Cin = 1
Therefore
Cin = 1
A 3 A 2 A 1 A 0 = 1 0 0 0
B 3 B 2 B 1 B 0 = 1 1 0 0
S 3 S2 S1 S 0 = 0 1 0 1
Cout = 1 (Ignored)