Long time control question

Hi all,

Just looking for some help understanding time controls.  I am used to playing in tournaments with only one time control so I am not sure how the long time control works. 

The time control in question is this:  40/90, g30 and increment 30s

So my question is-

Does the clock just run it's course and it is up to the players to make sure all the moves have been made in the first time control or does the clock know and set off a flag if one player does make enough moves?  I am curious too if that depends entirely on the clock.

Also, I am assuming that if both players make all moves in the right amount of time the clock just rolls over to the last time control after the first time control ends.

Hope this makes sense - thanks for the help

Laser

Of course a clock doesn't know how many moves you have made. It doesn't even know that you are playing chess.