1. CSCI 3 Chapter 1 Data Storage

2. Bits  Today’s computer information is encoded as patterns of 0s and 1s.  These digits are called “bits” (binary digits)

3. Bits  The bit 0 represents the value of false  The bit 1 represents the value of true

4. Boolean Operations  The operations that manipulate true/false value are called “Boolean operations.”  Four of the basic Boolean operations are ANDAND OROR XOR (exclusive or)XOR (exclusive or) NOT {has only one input}NOT {has only one input}

5. Operation AND  Is designed to reflect the truth or falseness of a statement formed by two statements with operation AND. P AND Q This AND statement output is true only when both of its components are true.

6. Boolean Operations  The AND operation ABA AND B 000 010 100 111

7. Boolean Operations  The OR operation ABA OR B 000 011 111

8. Boolean Operations  The XOR operation P XOR Q means “either P or Q but not both.”P XOR Q means “either P or Q but not both.” ABA XOR B 000 011 101 110

9. Boolean Operations  The NOT operation It is different from AND, OR, and XOR operationIt is different from AND, OR, and XOR operation It has only one inputIt has only one input A NOT A 01 10

10. Exercise  Please write down the answers of the questions on the screen. Write down how you get the answers too, without this part, you won’t get the credit for the question.  NOTE, it will include AND, OR, XOR, NOT

11. Homework #2  A=1, B=1, C=0, D=0 1.NOT A 2.A AND B 3.B AND C 4.D XOR C 5.A XOR B 6.C AND A 7.A OR D

12. Homework #2 (cont.) 8. B AND (C OR D) 9. (NOT A)XOR(NOT B) 10. A AND (NOT D) 11. B XOR (NOT D) 12. C OR ((NOT A) AND (B OR C)) 13. NOT ((A AND B) OR (C AND D)) 14. (NOT C) AND ((B AND D) AND (C AND D))

13. Gates and Flip-Flops  A device that produces the output of a Boolean operation when given the operation’s input values is called a “gate.”  Gates can be constructed from a variety of technologies such as gears, relays, etc.

14. Gates and Flip-Flops  A flip-flop is a circuit that produces an output value of 0 or 1, which remains constant until a temporary pulse from another circuit causes it to shift to the other value.

15. Gates and Flip-Flops  AND gates:

16. Gates and Flip-Flops  OR gates:

17. Gates and Flip-Flops  XOR gates:

18. Gates and Flip-Flops  NOT gates:

19. A simple circuit  How it works.

20. A simple circuit  How it works.

21. A simple circuit  How it works.

22. A simple circuit  How it works.

23. A simple circuit  How it works.

24. Another way of constructing a flip-flop

25. Homework #3 (cont.)  Question #1 on Page 24 What input bit patterns will cause the following circuit to produce an output of 1?What input bit patterns will cause the following circuit to produce an output of 1?