Fred Man Leung

US Patent:

57645868, Jun 9, 1998

Filed:

Oct 10, 1996

Appl. No.:

8/729009

Inventors:

Radu Vanco - Monte Sereno CA
Gelu Voicu - San Jose CA
Dumitru Cioaca - Cupertino CA
Fred Leung - Cupertino CA

Assignee:

Catalyst Semiconductor, Inc. - Sunnyvale CA

International Classification:

G11C 800

US Classification:

36523006

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.