Memory access system

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United States of America Patent

PATENT NO 4803621
SERIAL NO

06890075

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ATTORNEY / AGENT: (SPONSORED)

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Abstract

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A memory architecture having particular application for use in computer systems employing virtual memory techniques. A processor provides row and column addresses to access data stored in a dynamic random access memory (DRAM). The virtual address supplied by the processor includes high and low order bits. In the present embodiment, the high order bits represent a virtual row address and the low order bits represent a real column address. The virtual row address is applied to a memory management unit (MMU) for translation into a real row address. The real column address need not be translated. A comparator compares the current virtual row address to the previous row address stored in a latch. If the current row and previous row addresses match, a cycle control circuit couples the real column address to the DRAM, and applies a strobe signal such that the desired data is accessed in the memory without the need to reapply the row address. If the row addresses do not match, the cycle control circuit initiates a complete memory fetch cycle and applies both row and column addresses to the DRAM, along with the respective strobe signals. By properly organizing data in the memory, the probability that sequential memory operations access the same row in the DRAM may be significantly increased. By using such an organization, the present invention provides data retrieval at speeds on the order of a cache based memory system for a subset of data stored.

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Patent Owner(s)

Patent OwnerAddress
SUN MICROSYSTEMS INC A DE CORP2550 GARCIA AVENUE MOUNTAIN VIEW CA 94043

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Inventor(s)

Inventor Name Address # of filed Patents Total Citations
Kelly, Edmund J San Jose, CA 18 929

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