To write a 1 bit, toggle the select current from both X and Y axis to go over the magnetization threshold to flip the crossing core polarity
To read a bit, the direction of the current is opposite to the write current. Select the X and Y wires of the desired bit and note how the green sense wire detects a signal if the core's magenitic field direction changes. Reading flips the polarity to the direction of the current so reading resets the core state.