1. Digital Circuit Why Digital Circuit? – Digital signals ( 0 and 1) are very easy to handle with electronic circuits only 2 states needed: Switch ON or OFF, Circuit CLOSED or OPEN, Current FLOWING or NOT, Voltage HIGH or LOW Low error: accurate measurement of voltage in analog circuit vs. 0 (0-2V) and 1 (2.6 to 5 V).

2. Review of Decimal Counting Most familiar! "Place holders" are powers of 10 Power of 10:3210 Weight:1000 100 10 1 10 3 10 2 10 1 10 0 Ten symbols or characters needed: 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 1998 = (1 x 10 3 ) + (9 x 10 2 ) + (9 x 10) + 8 = 1000 + 900 + 90 + 8 Example

3. Binary Counting Base 10Base 2Base 10Base 2 0081000 1191001 201101010 311 1011 4100121100 5101131101 6110141110 7111151111 Digitizing a Signal

4. Binary Counting Power of 2:76543210 Decimal Weight:1286432168421 2 7 2 6 2 5 2 4 2 3 2 2 2 1 2 0 Example: convert 1100010 to decimal Binary Number:01100010 Decimal Weight of Placeholders: 128 64 32 16 8 4 2 1 Contributions to Decimal Number:0643200020 Answer: 64 + 32 + 2 = 98 "bit" is a contraction of "binary digit"

5. Addition of Binary number 1 + 0 = 1-- No surprise. 1 + 1 = 10-- Don't forget to carry! 1 + 1 + 1 = 11

6. Concept Check: Binary Counting In binary, which one of the following is not true? A: 10 + 10 = 110 B: 11 + 11 = 110 C: 101 + 1 = 110 Answer: A