Logic Gates Flashcards
What are Logic Gates?
They are circuits used to perform logical operations
What is a Truth Table?
A Truth Table is a diagram that shows all possible logical inputs and their associated outputs.
Name the 6 logic gates.
AND OR NOT XOR NAND NOR
what does a NOT gate do and what does it look like and how is it represented in an expression?
- The output is the inverse of the input
- Has a triangle and a little circle
- represented by an overbar, Q = ‾A
what does a AND gate do and what does it look like and how is it represented in an expression?
- Two or more inputs where the output is true if all inputs are true
- Has a D shape
- represented by a dot, Q = A . B
what does an OR gate do and what does it look like and how is it represented in an expression?
- Two or more inputs where the output is true if either or both inputs are true
- Has a crescent shape
- represented by a plus, Q = A + B
what does an XOR gate do and what does it look like and how is it represented in an expression?
- Takes two or more inputs where the output is true if one input is exclusively true
- Has a crescent shape with an extra curved line
- represented by a circle with a plus inside, Q = A⊕B
what does a NAND gate do and what does it look like and how is it represented in an expression?
- It inverts the output of an AND gate
- Has a D shape and a little circle
- represented by an overbar over A . B
what does a NOR gate do and what does it look like and how is it represented in an expression?
- Takes two or more inputs where the output is true when all inputs are false
- Has a crescent shape with a little circle
- represented by an overbar over A + B
How do you know how many rows to fill in in a logic table?
Do 2 to the power of the number of inputs
2^2 inputs = 4 rows
2^3 inputs = 8 rows