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US 5,359,569 AGranted
Semiconductor memory
AssigneeHitachi, Ltd.
InventorsKenji Fujita, Toshiyuki Nakao, Hirotsugu Yamagata, Nobuyuki Saze
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Abstract
A semiconductor storage including a main flash memory, a volatile write cache, a data control circuit, an alternate flash memory and a power supply. This arrangement permits the use of a smaller write cache in comparison with the use of a non-volatile memory, and also provides decreased capacity of the write cache, permitting high-speed access and long-life.
Claims14
A semiconductor storage comprising:
- a non-volatile semiconductor memory;
- a volatile semiconductor memory;
- a data control circuit, connected to said non-volatile semiconductor memory and said volatile semiconductor memory, for controlling read out of data from the non-volatile semiconductor memory and writing of data into the volatile semiconductor memory in response to an access instruction;
- a battery for supplying power to the non-volatile semiconductor memory and the volatile semiconductor memory for a period of time during which said power supply circuit is in failure,
- wherein said data control circuit has first writing means for writing the data written in the volatile semiconductor memory into the non-volatile semiconductor memory for a period of time during which the reading and writing operations responsive to said access instruction are not executed,
- wherein said non-volatile semiconductor memory has a redundant non-volatile semiconductor memory, and
- wherein said data control circuit has second writing means for detecting a predetermined condition in the non-volatile semiconductor memory and for writing the data written in the volatile semiconductor memory into said redundant non-volatile semiconductor memory into said redundant non-volatile semiconductor memory.
4 more elements
Dependencies are inferred from the claim text.