A computer system unaffected by memory module instability. The magnetic element includes a first pinned layer, a first spacer layer, a free layer, a second spacer layer, and a second pinned layer. Various embodiments allow a needle to be passed from the magnetic detection sensing device outside the patient toward a magnetic gastrostomy tube inside the patient or, alternatively, from the magnetic gastrostomy tube inside the patient toward the magnetic detection sensing device outside the patient. In such an alternative embodiment, the vision head is a parabolic mirror mounted on the extension arm for reflecting images, for example, from behind the distal end of the endoscope to the vision chip in the distal end of the endoscope to permit, for example, a retrograde view of the surgical site entrance.