Memory device and method of controlling the same
AssigneeFujitsu Limited
InventorsHideaki Suzuki, Masaji Inami
Life of this patent
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Abstract
Provided is a memory device including a nonvolatile memory for storing data and a password in a designated address, a password comparison circuit for comparing an externally input first password with a second password stored in the nonvolatile memory, a volatile memory for storing authentication information indicating that access right establishment is authenticated, if the two passwords are found to be equal by the comparison, and an access control circuit for permitting external access to the nonvolatile memory only when the authentication information is stored in the volatile memory.
Claims17
A memory device comprising:
- a nonvolatile memory for storing data and a password in a designated address;
- a password comparison circuit for comparing an externally input first password with a second password stored in said nonvolatile memory;
- a volatile memory for storing authentication information indicating that access right establishment is authenticated, if the two passwords are found to be equal by the comparison;
- and
- an access control circuit for permitting external access to said nonvolatile memory only when the authentication information is stored in said volatile memory.
A memory device control method comprising the steps of:
- (a) when receiving an external instruction for writing a first password in a nonvolatile memory, holding the first password without writing it in the nonvolatile memory;
- (b) when receiving an external instruction for reading out a first address of the nonvolatile memory, reading out a second password from the first address in the nonvolatile memory, and holding the second password without outputting it to the outside;
- (c) comparing the first and second passwords;
- (d) if the two addresses are found to be equal by the comparison, storing, in a volatile memory, authentication information indicating that access right establishment is authenticated;
- and
- (e) permitting external access to the nonvolatile memory only when the authentication information is stored in the volatile memory.
Dependencies are inferred from the claim text.