Chapter 23 - Logic gates Flashcards
1
Q
summarise a NOT gate
A
- triangle with a circle at the end
- if input is 0, input is 1
- if input is 1, output is 0
- reverses the output
2
Q
what are all the logic gates
A
- AND
- OR
- NOT
- XOR
- NAND
- NOR
3
Q
Booleon expression for NOT gate
A
line over the letter(s)
4
Q
summarise an AND (conjunction) gate
A
- buzzer shape (two inputs one output)
- if both inputs are 1, output is 1, otherwise output is 0
- booleon expression is dot between letters
5
Q
summarise OR gate (disjunction)
A
- if either input is 1 then output is 1, otherwise output is 0
- 2 inputs and one output
- curved arrow
- booleon expression is +
6
Q
summarise XOR gate
A
- if one, but not both of the inputs is 1, output is 1, otherwise, output is 0
- curved arrow with line going through
- booleon expression is plus in a circle
7
Q
summarise NAND gate
A
- if both A and B are 1 , output 0, else output 1
- buzzer shape with circle at the end
- booleon expression is a line over with a dot separating
8
Q
benefits of NAND gate
A
- a single type of a NAND gate can perform two separate functions, reducing development costs
- cheaper than separate gates
9
Q
summarise a NOR gate
A
- gate only produces an output of 1 if both inputs are 0
- booleon expression is A + B with line over it
- curved arrow with circle at the end
10
Q
NOT is also known as
A
negation
11
Q
how can de morgan’s law be remembered
A
“change the sign break the bar”, or “change the sign build a bar”
12
Q
why is NAND known as a universal gate
A
because all the other gates are created by using this gate
13
Q
If a logic gate expression is A.B + C, how do you know how to draw it?
A
In logic gate expressions, AND (·) operations are performed before OR (+) operations unless parentheses specify otherwise. For A.B + C, the expression is equivalent to (A.B) + C
