Mask-programmed read-only memory with reserved space
View Patent ↗The present invention discloses a mask-ROM with reserved space (mask-ROM RS ). For small content revision, the present invention salvages the original data-mask by writing the data-pattern of new content into a reserved mask-region which originally has no data-pattern.
1. A mask-programmed read-only memory (mask- ROM) family, comprising:
a first mask-ROM die comprising at least a first memory array; a second mask-ROM die comprising at least a second memory array; wherein said first and second memory arrays are same except for a reserved portion, said reserved portion comprising a same plurality of mask-ROM cells in said first and second memory arrays, wherein all mask-ROM cells in the reserved portion of said first memory array have a same structure, and the mask-ROM cells in the reserved portion of said second memory array have at least two structures.
2. The mask-ROM family according to claim 1 , wherein all mask-ROM cells in the reserved portion of said first memory array comprise a data layer.
3. The mask-ROM family according to claim 1 , wherein all mask-ROM cells in the reserved portion of said first memory array comprise no data layer.
4. The mask-ROM family according to claim 1 , wherein at least selected mask-ROM cells in the reserved portion of said second memory array comprise a data layer.
5. The mask-ROM family according to claim 1 , wherein at least selected mask-ROM cells in the reserved portion of said second memory array comprise no data layer.
6. The mask-ROM family according to claim 1 , wherein the total number of the mask-ROM cells in the reserved portion is more than 10% of the total number of the mask-ROM cells in said first memory array.
7. The mask-ROM family according to claim 1 , wherein the total number of the mask-ROM cells in the reserved portion is more than 10% of the total number of the mask-ROM cells in said second memory array.
8. The mask-ROM family according to claim 1 , wherein each of said first and second mask-ROM dice further comprises an address translator.
9. The mask-ROM family according to claim 8 , wherein said address translator comprises a non-volatile memory for storing an address-mapping table.
10. The mask-ROM family according to claim 9 , wherein said non-volatile memory is a re-writable memory.
11. The mask-ROM family according to claim 10 , wherein said re-writable memory is a flash memory.