i have something weird going on or i am misunderstanding something. i put a function gererator on pin three of the 74ls05 and a logic probe on pin four. pin four just stays low. i changed the 74ls05 and got the same thing. i took it out of the circuit and mocked it up on a breadboard by itselt and get the same results. all of the inverters do the same ( one and two , five and six ...)but if i put the input on four three works as an output. is that supposed to be like that?