National Semiconductor Corporation

Catalyst Semiconductor, Inc.

Fred Leung

Dumitru G Cioaca

Gelu Voicu

Paul J Patchen

Hon C Fung

Radu Vanco

Steven McGinness

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.

Intermediate size non-volatile electrically alterable semiconductor

An architecture is described for a single chip microcontroller wherein the microcode stored in the microcontroller's program memory may be easily modified without refabrication or removal of the microcontroller from its target environment. This is made possible by the utilization of a RAM based architecture for program memory instead of the traditional ROM based architecture.

Microcontroller with in-circuit user programmable microcode

Growing community of inventors

Cupertino, CA, United States of America

Fred Leung