Method and apparatus for using a one-time or few-time programmable memory with a host device designed for erasable/rewritable memory
View Patent ↗The embodiments described herein can be used to enable one-time or few-time programmable memories to work with existing consumer electronic devices (such as those that work with flash—an erasable, non-volatile memory) without requiring a firmware upgrade, thereby providing backwards compatibility while minimizing user impact. As such, these embodiments are a viable way to bridge one-time or few-time programmable memories with existing consumer electronic devices that have flash card slots. These embodiments also allow future consumer electronic devices to be designed without updating firmware to include a file system customized for a one-time or few-time programmable memory.
1. A memory device comprising:
a memory array; and
a controller in communication with the memory array, wherein the controller is operative to:
(a) receive a request from a host device in communication with the memory device to write data to a first address in the memory array;
(b) compare the data requested to be written to the first address with data contained in the first address; and
(c) based on the comparison in (b), perform one of the following:
(c1) write the data to the first address;
(c2) without writing the data to the first address, inform the host device that the data was written to the first address; and
(c3) write the data to a second address instead of the first address.
2. The memory device of claim 1 , wherein the controller is operative to perform (c1) in response to the first address containing a set of un-programmed memory cells.
3. The memory device of claim 1 , wherein the controller is operative to perform (c1) if the data requested to be written to the first address appends data contained in the first address.
4. The memory device of claim 1 , wherein the data contained in the first address comprises a file system structure.
5. The memory device of claim 1 , wherein the controller is operative to perform (c2) in response to the host attempting to write, in a file allocation table, data that indicates a previously-allocated address is free.
6. The memory device of claim 1 , wherein the controller is operative to perform (c2) in response to the host attempting to write data only to a predetermined field in a file listing.
7. The memory device of claim 1 , wherein the controller is operative to perform (c2) in response to the host attempting to write data only to a last accessed date field.
8. The memory device of claim 1 , wherein the controller is operative to perform (c2) in response to the host attempting to write data only to a predetermined field in a directory listing.
9. The memory device of claim 1 , wherein the controller is operative to perform (c3) if the data requested to be written to the first address is different from the data contained in the first address.
10. The memory device of claim 1 , wherein the controller is operative to perform (c3) if the data requested to be written to the first address is different from the data contained in the first address and the difference is not located only in a predetermined field in a file listing.
11. The memory device of claim 1 , wherein the controller is operative to perform (c3) if the data requested to be written to the first address is different from the data contained in the first address and the difference is not located only in a predetermined field in a directory listing.
12. The memory device of claim 1 , wherein the controller is operative to generate an error in response to an attempt to format the memory device.
13. The memory device of claim 1 , wherein the controller is operative to generate an error in response to an attempt to write data to an address preceding an address of a file allocation table.
14. The memory device of claim 1 , wherein the controller is further operative to generate an error in response to an attempt to write data to a predetermined address in the memory array.
15. The memory device of claim 1 , wherein the controller is operative to generate an error in response to the memory array being full.
16. The memory device of claim 1 , wherein the controller is further operative to update a file allocation table in the memory array to indicate that the second address is no longer free when performing (c3).
17. The memory device of claim 1 , wherein the memory array is organized into logical units that can be partially written into, whereby multiple write operations can be performed to each logical unit before the logic unit is full, and wherein the controller is operative to write ECC data for a logical unit when a last write operation is made to the logical unit.
18. The memory device of claim 1 , wherein the controller comprises:
a first page register; and
a second page register;
wherein the data contained in the first address is written in the first page register while the data to be written to the first address is written in the second page register.
19. The memory device of claim 1 , wherein the memory array comprises a one-time programmable memory array.
20. The memory device of claim 1 , wherein the memory array comprises a few-time programmable memory array.
21. The memory device of claim 1 , wherein the memory array comprises a three-dimensional memory array.
22. The memory device of claim 1 , wherein the memory device comprises an electrical connector configured to mate with a corresponding electrical connector on the host device, and wherein the host device comprises a write-many file system.
23. A memory device comprising:
a memory array storing a file system structure; and
a controller in communication with the memory array, wherein the controller is operative to:
(a) receive a request from a host device in communication with the memory device to write, in the file system structure, data that indicates a previously-allocated address is free; and
(b) without writing the data in the file system structure, inform the host device that the data was written in the file system structure.
24. The memory device of claim 23 , wherein the file system structure comprises a file allocation table.
25. The memory device of claim 23 , wherein the data comprises us.
26. The memory device of claim 23 , wherein the memory array comprises a one-time programmable memory array.
27. The memory device of claim 23 , wherein the memory array comprises a few-time programmable memory array.
28. The memory device of claim 23 , wherein the memory array comprises a three-dimensional memory array.