What is NOR logical operator?

Question

Is nor:

!(a or b)
!a or !b
!(a and b)

something else?

Answer 1

!(a or b)

see http://en.wikipedia.org/wiki/Logical_NOR for more

Answer 2

your first alternative: !(a or b)

which happens to be equivalent to !a and !b

Answer 3

!(a or b)

Answer 4

NOR(a, b) is defined to be NOT(OR(a, b)) which is !(a or b) in infix notation. By De Morgan's Laws, this is also equivalent to (!a) and (!b).

Answer 5

((a NAND a) NAND (b NAND b)) NAND ((a NAND a) NAND (b NAND b)) if you want to be circuit fabrication friendly. :)