A leadless optical electronic package includes a lead frame having a die-attach pad and a plurality of leadless connection pads encapsulated in and extending through an encapsulation defining a planar mounting surface that can be soldered directly to a circuit board. A printed board having three board portions is carried onto an XY table from a supply conveyer and positioned by positioning means. The gate insulating film has the discrete traps for storing information charge, can locally inject carriers, and one memory cell constitutes a multi-storage cell for storing at least information of 2 bits.