You are correct in implying that total pressure is static plus dynamic pressure.

In a pitot-static system, the difference in pressure between the ram side of the diaphragm and the static side is what moves the diaphragm and in turn, the needle of the airspeed indicator. When the pressures on both sides of the diaphragm are equal, dynamic pressure is zero, and the airspeed is zero. While it’s true that dynamic pressure is added to static pressure on the ram side to create the difference, the diaphragm doesn’t know the total pressure (ambient pressure can be very high or very low – it makes no difference). It only moves in response to the difference in pressure between the two sides, so my wording was off.

From aerospace web (I don’t have my engineering books with me as I am at work):

http://www.aerospaceweb.org/question...ts/q0251.shtml

"The difference between the dynamic and static pressures is used to determine the indicated airspeed (IAS) that is displayed to the pilot on the airspeed indicator in the cockpit."

I suppose this statement isn't entirely correct, depending on how you look at it, since dynamic pressure is only the component of pressure resulting from motion. It must be added to static before static is subtracted again.

So we are left with the airspeed indicator measuring only dynamic pressure, and it doesn't have any way of knowing total pressure like the altimeter does.

<edit> added quotation marks, and wording.