Semiconductor memory device
AssigneeSeiko Epson Corporation
InventorNoboru Asauchi
Life of this patent
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Abstract
A semiconductor device 10 sets a pass-through flag to ON when the top address of a write-prohibited area is passed. When a request to write data to a write-restricted area WRA is received, the semiconductor memory device 10 determines whether or not the pass-through flag is set to ON, and if the pass-through flag is not set to ON, the semiconductor memory device 10 executes writing of the data to the write-restricted area. On the other hand, if the pass-through flag is set to ON, the semiconductor memory device 10 does not execute writing of the data to the write-restricted area.
Claims14
A semiconductor memory device comprising:
- a memory array that is sequentially accessed starting with the top address and contains a rewritable area used for storage of rewritable data and a write-prohibited area that is used for storage of read-only data and follows the rewritable area;
- an access request receiving unit that receives access requests for access of a desired address in said memory array;
- a flag setting unit that sets a flag to ON when said write-prohibited area has been accessed;
- and
- a memory controller that controls access of said memory array and does not write data to said desired address if said desired address is included in said rewritable area and said flag is set to ON.
A control apparatus for a semiconductor memory device that includes a memory array that is accessed sequentially starting with the top address and that contains a rewritable area used for storage of rewritable data and a write-prohibited area that follows the rewritable area and is used for storage of read-only data, said control apparatus comprising:
- an access request receiving unit that receives access requests for access of a desired address in said memory array of said semiconductor memory device;
- a flag setting unit that sets a flag to ON when said write-prohibited area has been accessed;
- and
- an access controller that controls access of said memory array of said semiconductor memory device, and that does not write data to said desired address if the access controller determines said desired address is included in said rewritable area with reference to information specifying the write-prohibited area in said memory array and that said flag is set to ON.
An access control method for a semiconductor memory device that comprises a memory array that is accessed sequentially starting with the top address and that contains a rewritable area used for storage of rewritable data and a write-prohibited area that follows the rewritable area and is used for storage of read-only data, the method comprising:
- receiving an access request for access of a desired address in said memory array;
- referring to information that specifies the write-prohibited area in said memory array;
- and
- not writing data to said desired address if said desired address is included in said rewritable area and if a flag that is set to ON when said write-prohibited area has been accessed is set to ON.
Dependencies are inferred from the claim text.