In one embodiment, an apparatus comprises a sense unit and a drive unit. In one embodiment, the apparatus includes a plurality of laser beam sources, each to produce a modulated optical beam. Said side beam is one of the two side beams generated by the reflected \xb1first order beams and fed back through the optical system returning towards the header portion to strike the side beam incident region. Predecoding is performed in parallel with translation of the linear address to a physical address by translation lookaside buffer logic.