Chapter 3 Digital circuits

3.1 Logic signals - Gates Binary system : (binary bits or digits) - 0 & 1 - LOW & HIGH - Negated and Asserted.

3.1 Logic signals - Gates Different devices used to represent binary bits 01 Pneumatic Logiclow presurehigh Relay Logicopenclosed Fiber Opticslight onoff Read Only CDno pitpit (See table 3.1 of book)

3.2 How do we represent logic Y F1 Z F2 X Logic Circuit X Y Z F1 F N bits  2 n different values Example N=3 : 2 3 = 8 Black box view of logic circuit 3 inputs and 2 outputs Truth table Truth tables : it gives all combinaisons of input and corresponding Output values

3.3 Basic building blocks AND, OR, NOT

3.3 Basic building blocks … NAND, NOR NAND gate : combination of NOT and AND NOR gate : combination of NOT and OR Note that NAND produces the opposite results of AND NOR produces the opposite results of OR

3.4 Example: a logical circuit 1 2 F X Y Z X’ Y’ X.Y X’.Y’.Z F X Y Z X’ Y’ X.Y X’.Y’.Z

3.4 Example : …. Logic diagrams Truth table