Microsoft Word - Digital Logic Design v_4_6a

• “NOT” symbol  Z= X =X’ (Also called the complement)


• “NOT” truth table
  X Z=X’
  0 1
  1 0


• Review the 74LS04 Data sheet on the website

 Order of Operation Precedence (Same as decimal arithmetic)

Highest to lowest order of Precedence for Binary Operator: “=”, “()”, “ ”, “.”, “+”

Note:

 Parentheses are used to force the operation order sequence much like decimal Algebra.

 The equal sign “=” is same as decimal algebra for assignment.

 An expression is a combination of variables and binary operators Z+ X Y + X

 The number of Literal is the total occurrences of all variables in an expression.

For example f(x,y,z) = x+ y.x.z + x’.y’.z is said to have 7 literals. The number of literals typically

used as a measure of implementation complexity.

 Additional standard logic gates:

 NOR is an OR gate with the output negated

Review the 74LS02 Data sheet on the website

 NAND is an AND gate with the output negated

Review the 74LS00 Data sheet on the website

 XOR (also called “Module 2 add” or “exclusive or”) X⊕Y=X.Y+X.Y

 “XOR” Symbol

 “XOR” Truth Table

Review the 74LS86 Data sheet on the website

X Y (^) X⊕Y
0 0 0
0 1 1
1 0 1
1 1 0

X

Y

Z

X Z