Texas Instruments Corporation

Chein C Chen

Jerald G Leach

Joseph A Coomes

David E Francis

John C Cooper

A memory interface unit capable of coupling a microprocessor to memory external to the microprocessor, wherein the memory can be of at least two types differing in width, and where the data stored in such memory can be in different sizes, and wherein the memory can be formed in sections. The invention utilizes means for controlling at least two strobe signal lines and means for shifting the memory address lines, programmably, so as to accommodate the various combinations of memory width and data size.

Memory interface with address shift for different memory types

A memory interface unit for coupling a microprocessor to a memory external to the microprocessor, the memory being utilized for the storage of data therein and the retrieval of data therefrom, and the memory being provided in one or more memory banks, each of the banks being provided with a set of address lines and a byte enable line, data being transferring to and from each of the memory banks on a group of data lines, and the memory banks being provided in one or more banks whereby the group or groups of data lines, as the case may be, provide a memory data path having a physical transfer width for transfer of data to and from the memory, and the data being stored and retrieved over the memory data path in two or more data types, each type having a different size, the memory interface unit being provided with a set of address pins and a set of strobe pins, comprising. The unit includes a first element for providing an indication of a physical transfer width of a memory coupled to the memory interface unit. Also provided is a second element for providing an indication of a data type to be transferred to or from the memory. A third element, responsive to the first element and the second element, depending on the data type indication, provides to the address pins an address, shifted in position, with at least some of the address lines being for coupling to the address lines of the one or more banks of memory, as the case may be, and with one or more of the address pins being for activation of the byte enable line or lines, as the case may be, for data to be transferred, or, alternatively, providing to the address pins an address, unshifted in position, for coupling to the address lines of the one or more banks of memory, as the case may be, for addressing data to be transferred. Depending on the physical transfer width indication, the third element also causes one or more of the strobe pins to be used as additional address pins.

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Sugar Land, TX, United States of America

Chein C Chen