Mask-programmed read-only memory with reserved space

摘要

The present invention discloses a mask-ROM with reserved space (mask-ROMRS). 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.

主权项

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.