I am tempted to be difficult, but I won't.
In manual mode, (lathe) push the jog arrows back and up, when it stops it at home position. (mill) push the jog button up until it stops, then you are home.
When you program it, at the end of a block of code have the machine rapid far past the limits and it will always stop and be in home postition, (unless the limits are set wrong). lathe example G0 X400.Z400.-- mill example G0 Z100.
The easy answer is that "home position" is silly and for other controls, not OSP. There is no "home" only soft limit switches, which double as a toolchange position. Yer days of over travel are over my friend.