1. Appendix B Digital Logic

2. Irvine, Kip R. Assembly Language for Intel-Based Computers, 2003. 2 NOT AND OR XOR NAND NOR Truth Tables Boolean Operators

3. Irvine, Kip R. Assembly Language for Intel-Based Computers, 2003. 3 NOT A = Ā A AND B = A  B A OR B = A + B A XOR B= 1 if and only if one of A or B is 1 A NAND B = NOT ( A AND B) NOR= NOT (A OR B) Truth Tables Boolean Operators

4. Irvine, Kip R. Assembly Language for Intel-Based Computers, 2003. 4 Boolean Algebra Based on symbolic logic, designed by George Boole Boolean expressions created from: – NOT, AND, OR

5. Irvine, Kip R. Assembly Language for Intel-Based Computers, 2003. 5 NOT Inverts (reverses) a boolean value Truth table for Boolean NOT operator: Digital gate diagram for NOT:

6. Irvine, Kip R. Assembly Language for Intel-Based Computers, 2003. 6 AND Truth table for Boolean AND operator: Digital gate diagram for AND:

7. Irvine, Kip R. Assembly Language for Intel-Based Computers, 2003. 7 OR Truth table for Boolean OR operator: Digital gate diagram for OR:

8. Irvine, Kip R. Assembly Language for Intel-Based Computers, 2003. 8 Operator Precedence Examples showing the order of operations:

9. Irvine, Kip R. Assembly Language for Intel-Based Computers, 2003. 9 Truth Tables (1 of 3) A Boolean function has one or more Boolean inputs, and returns a single Boolean output. A truth table shows all the inputs and outputs of a Boolean function Example:  X  Y

10. Irvine, Kip R. Assembly Language for Intel-Based Computers, 2003. 10 Truth Tables (2 of 3) Example: X   Y

11. Irvine, Kip R. Assembly Language for Intel-Based Computers, 2003. 11 Truth Tables (3 of 3) Example: (Y  S)  (X   S) Two-input multiplexer

12. Basic Identities

13. De Morgan’s Theorem A NOR B = (NOT A) AND (NOT B) A NAND B = (NOT A) OR (NOT B)

14. Basic Logic Gates

15. NAND Gates

16. NOR Gates

17. Sum of products F = ABC + ABC + ABC

18. Product of sums (X  Y  Z) = X + Y + Z (De Morgan) 

19. Product of sums

20. Simplification of Boolean expression Algebraic simplification Karnaugh maps Quine McKluskey Tables

21. Algebraic simplification Show how to simplify F = ABC + ABC + ABC To become F = AB + BC = B(A + C)

22. Simplified implementation of F = ABC + ABC + ABC = B(A + C)

23. Karnaugh Maps

24. The use of Karnaugh maps

25. Overlapping groups F = ABC + ABC + ABC = B(A + C)

26. The Quine-McKluskey Method

27. 2 nd stage All pairs that differ in one variable

28. Last stage

29. Final stage Circle each x that is alone in a column. Then place a square around each X in any row in which there is a circled X. If every column now has either a squared or a circled X, then we are done, and those row elements whose Xs have been marked constitute the minimal expression. ABC + ACD + ABC + ACD

30. NAND

31. Multiplexor S2S1F 00D0 01D1 10D2 11D3

32. Multiplexor implementation

33. Decoder

34. Use of decoders To address 1K byte memory using four 256 x 8 bit RAM chips

35. Small-scale integration Early integrated circuit provided from one to ten gates on a chip. The next slide shows a few examples of these SSI chips.

37. Programmable Logic Array (PLA)

38. Programmed PLA

39. Read-only memory

40. A 64 bit ROM

41. Adders

42. 4-Bit Adder

43. Implementation of an Adder

44. Multi-output adder The output from each adder depends on the output from the previous adder. Thus there is an increasing delay from the least significant to the most significant bit. For larger adders the accumulated delay can become unacceptably high.

45. 32-Bit Adder using 8-Bit Adders

46. Carry look ahead

47. Irvine, Kip R. Assembly Language for Intel-Based Computers, 2003. 47 Printing this Slide Show To print this slide show with black characters on a white background, do the following: Select Print... from the File menu. Select Handouts in the Print what drop-down box. Select 2 or 3 in the Slides per page drop-down box. Select the Pure black and white check box (optional) Click on OK to begin printing. Back to the title page