An alloy suitable for use in a ball grid array or chip scale package comprising from 0. The movable unit is a lightweight construction seal beam. Further, alternating steps of reactive ion etching and ion beam etching are performed to isolate MTJ pillars and expose side surfaces of the MTJ layers. A bi-directional disc pusher is supported on a gantry between adjacent drawers and is positionable along the adjacent drawers proximate a selected target disc location corresponding to one of the plurality of disc locations. The compensating circuits are made of different combinations of resistor, transistor and current sink components.