1. Digital Logic & Design
Dr. Waseem Ikram
Lecture No. 16

2. Recap

3. Carry Propagation Delay between 4-bit ALU units

4. Carry Propagation Delay eliminated by using Group Carry

5. 16-bit ALU S0 S1 S2 Cin G P P0 74X381 A2 B2 A3 B3 ALU0 A0 B0 A1 B1 F0

6. Parallel Comparators

7. Implementation of A>B

8. Implementation of A=B

9. Implementation of A<B

10. Comparison of numbers by Cascaded 4-bit Comparator
Comparator M
Comparator L
1101
0111
A>B
0110
1011
A<B
0011
0010
A=B
0100
0101
1001

11. Implementation of 4-bit Comparator by Cascading two 2-bit Comparators

12. Iterative Circuit Implementation of A=B function

13. Iterative Circuit Implementation of A>B function

14. 12-bit Comparator

15. Electronic Door Lock

16. Function Table of a 2-to-4 Binary Decoder
Input
Output I1 I0 O0 O1 O2 O3 1

17. 2-to-4 Decoder

18. Function Table of 74LS139, 2-to-4 Decoder
Input
Output B A 1 X

19. 74LS139, 2-to-4 Decoder

20. Decoders