The + sign means OR. Don't confuse it with the maths symbol.
The . sign neans AND. Don't confuse it with the maths symbol.
A line above a letter or expression means NOT.
A 
sign means XOR.
Gate |
Expression |
Explanation |
|
NOT |
|
Q is not A. If A is 0 then Q is 1. If A is 1 then Q is 0. |
|
OR |
Q = A + B |
Q is output from this operation A or B |
|
AND |
Q = A . B |
Q is the output from this operation A and B |
|
NOR |
|
Q is the output from this operation A nor B |
|
NAND |
|
Q is the output from this operation A nand B |
De Morgan's Theorem
Wikipedia on De Morgan - Wikipedia uses different symbols for AND, OR and NOT.
De Morgan descovered some logical relationships that come in useful.
Here are some circuits and the matching Boolean expressions that are exactly equivalent to each other as discovered by De Morgan. These relationships still work if there are more than two inputs.
