Zeffy, you've pretty much got it.
The SPS (Stall Protection System) does also include, however, such inputs as flaps, power, accel/decel trends, etc, to massage the trip points.
That's why the stick pusher may kick several seconds after onset of shake, or almost concurrently, depending on the situation.
There's also the Rad Alt, to disable the pusher when close to trees.
PTH, the IAS is derived from the DADC and is displayed as "raw" data. Further downstream in the computational course do we find the low speed cue and the trend indicator. The most likely IAS error would be from water accumulation in the pitot statics and would normally cause a IAS MISMATCH annunciation. And those usually happen shortly after takeoff, after having overnighted in heavy rain.
Because all this is digital data, what is displayed on the PFD is what gets sent on the ARINC 717 line to the DFDR. By definition, what is on one is on the other.
Stubs400
