EPROM silicon chip. Scanning electron micrograph (SEM) of the surface architecture of part of an EPROM (Eraseable Programmable Read- Only Memory) silicon microchip. The narrow tracks that have been deposited on the substrate (dark grey) form part of the chip's micro-circuitry. The pits in the tracks are connection points, where connections are made to circuit elements on the other side of the substrate. Image of an AMD AM27C512- 155DC chip. Magnification: x420 at 4x11cm size.