right, all of them do, in facto most jet transport a/c do as well. The reasons have been previously explained...
There 2 pressurizations systems available from the Classics on. these are the analog and digital. the analog requires the pilot to move a switch in the pressurization mode selector to a position called FLT right after starting the engines. This closes the outflow valve (not completely) and allows about .1 psi of diff pressure inside the a/c (.125 is the limit) if thatīs the case then no matter what the pilot does with the thurst levers, the a/c is already pressurized.
The digital system requires the engines to exceed certain thrust percentage. (n1 > 60% & n2 > 89% after a 1.5 sec time delay 737 CL). At this point the airplane pressurizes the same as if you had positioned the previously mentioned switch to FLT. Such power settings are normally transitioned only when takeoff is initiated. I doubt that such high thurst setting is required to get a plane moving on an uphill, but the NG could start pressurizing at a lower power setting, thus making the uphill theory more likely.
Regards,
SW.