Abstract: A programmable read only memory (PROM) includes a first plurality of conductive lines, a second plurality of conductive lines and polycrystalline silicon material therebetween. At the crossing points of the first and second plurality of lines doped regions are provided in the polycrystalline silicon in contact with a second line and which extend at least partially through the material. To provide a diode interconnect at any crossing point, the associated region is irradiated by a laser beam to either cause diffusion of dopant atoms to the underlaying conductive line or activate implanted ions, thereby electrically interconnecting the first and second lines through a diode. The PROM is readily fabricated as part of a monolithic integrated circuit or electrical array and can be programmed after completion of the fabrication process.