Abstract: An electrically alterable semiconductor memory device having an array of memory cells formed by individual transistors. The structure of the memory cells is compact and facilitates high density memory devices and is particularly well suited for contactless, virtual ground arrays. The memory cells can be read and programmed a page at a time. The memory cells can also be programmed using source-side hot-electron injection with improved efficiency and lowered programming currents.

Abstract: A semiconductor memory device that operates as a normal memory device as long as existing memory is being addressed, but appears to external hardware and software to have a larger size (or standard size) memory array than is actually present in the semiconductor memory device is disclosed. To external hardware and software, the semiconductor memory device operates as if it has more addressable memory cells than in fact actually exist in the memory array. When addressing missing memory cells, the semiconductor memory device emulates or mimics their presence for the benefit of the external hardware or software. Preferably, the semiconductor memory device is a non-volatile electrically alterable semiconductor memory device. A method for emulating missing memory cells is also disclosed.