How does the home position work on a Prusa i3 RepRap Printer? By what process does the Prusa i3 determine it's home position?  

I have a feeling that it works like this, but I'm not entirely sure about it:


If none of the end stops are activated; assume you are somewhere between Max-X, Max-Y, Max-Z and the point 0,0,0.
do


For axis in Axies


If axis endstop not signaling


subtract 100 steps from axis.



while endstops are not signaling, or if point 0,0,0 not reached;
It works like you describe, but it does not move all axes at the same time. It first moves the X-axis, subtracting steps while the X endstop is not pressed. When the X-axis is is homed (the X-endstop is gets pressed) it repeats the procedure for the Y-axis and finally the Z-axis.