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US 8,266,366 B2Granted
Memory device operable in read-only and write-once, read-many (WORM) modes of operation
AssigneeSanDisk Technologies LLC
InventorsRichard Matthew Fruin, Christopher S. Moore, Samuel Y. Yu
Life of this patent
Estimating the term…
Abstract
One-time programmable (OTP) and write-once read-many (WORM) memory devices and methods for use therewith are provided. These embodiments can be used to provide compatibility between a memory device that uses an OTP (or few-time programmable (FTP)) memory array and host devices that use a file system, such as the DOS FAT file system, that expects to be able to rewrite to a memory address in the memory device. These embodiments can also be used to prevent accidental or deliberate overwrites, changes, or deletions to existing data in a WORM memory device.
Claims50
A memory device comprising:
- a memory;
- and
- a controller in communication with the memory, wherein the controller is operative to:
- power-up in read-only mode;
- receive a command from a host device to switch to a write-once, read-many (WORM) mode;
- in response to the command from the host device, switch from the read-only mode to the WORM mode;
- and
- while in the WORM mode:
- receive a write command from the host device;
- and
- determine if the write command should be performed.
8 more elements
A memory device comprising:
- a memory;
- and
- a controller in communication with the memory, wherein the controller is operable in first and second modes of operation, wherein in the first mode of operation, the memory device operates in a read-only mode, and wherein in the second mode of operation, the memory device operates in a write-once, read-many (WORM) mode;
- wherein the controller is operative to:
- receive a command from a host in communication with the memory device to write data to the memory;
- and
- analyze the write command to determine if the write command should be performed;
- wherein the memory comprises a user data area, and wherein the controller is operative to determine that the write command should not be performed if the write command attempts to write data to a 32-byte area that has at least one non-zero entry.
5 more elements
A memory device comprising:
- a memory;
- and
- a controller in communication with the memory, wherein the controller is operable in first and second modes of operation, wherein in the first mode of operation, the memory device operates in a read-only mode, and wherein in the second mode of operation, the memory device operates in a write-once, read-many (WORM) mode;
- wherein the controller is operative to:
- receive a command from a host in communication with the memory device to write data to the memory;
- and
- analyze the write command to determine if the write command should be performed;
- wherein the memory comprises a user data area, and wherein the controller is operative to determine that the write command should be performed if the write command is appending a 32-byte area to a previously-programmed 512-byte sector.
5 more elements
A method for using a memory device, the method comprising:
- performing the following in a controller of a memory device comprising a memory:
- powering-up in read-only mode;
- receiving a command from a host device to switch to a write-once, read-many (WORM) mode;
- in response to the command from the host device, switching from the read-only mode to the WORM mode;
- and
- while in the WORM mode:
- receiving a write command from the host device;
- and
- determining if the write command should be performed.
6 more elements
A method for using a memory device, the method comprising:
- performing the following in a controller of a memory device comprising a memory:
- operating the memory device in a read-only mode when the controller is in a first mode of operation;
- operating the memory device in a write-once, man WORM mode when the controller is in a second mode of operation;
- receiving a command from a host in communication with the memory device to write data to the memory;
- and
- analyzing the write command to determine if the write command should be performed;
- wherein the memory comprises a user data area, and wherein the method further comprises determining that the write command should not be performed if the write command attempts to write data to a 32-byte area that has at least one non-zero entry.
4 more elements
A method for using a memory device, the method comprising:
- performing the following in a controller of a memory device comprising a memory:
- operating the memory device in a read-only mode when the controller is in a first mode of operation;
- operating the memory device in a write-once, read-many (WORM) mode when the controller is in a second mode of operation;
- receiving a command from a host in communication with the memory device to write data to the memory;
- and
- analyzing the write command to determine if the write command should be performed;
- wherein the memory comprises a user data area, and wherein the method further comprises determining that the write command should be performed if the write command is appending a 32-byte area to a previously-programmed 512-byte sector.
4 more elements
Dependencies are inferred from the claim text.