What is the reason why an accelerometer shows -1g value when it's flips?

jremington:
Flip the accelerometer over and the sign changes, because the force holding the chip up is coming from the other side. -1 g is reported.

I don't understand so well this idea that you try to explain me, can you give me some image maybe? , for what I imagine, the force holding the chip AND the gravity come from the other side is It?