Memory Controller Write Limiting for Data Integrity
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Solution Overview
Problem
SD memory cards lack the ability to ensure the non-erasability, non-modifiability, and readability of photographic data, making them unsuitable for applications requiring high file maintainability, such as official photographs.
Innovation Solution
A semiconductor device with a memory controller that implements a logical address space with specific write limiting conditions, including read-only areas, limited-overwrite permitted FAT and directory entry areas, and address-incremental write areas, preventing data deletion, modification, or falsification while allowing data recording and reading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SD memory cards allow free writing and overwriting of data, then data can be updated and modified, but data integrity and non-erasability cannot be ensured
Solution Approach 1:
The memory card's address space is segmented into multiple distinct areas with different write permissions: a first area that allows free reading and writing, and a second area that allows only reading after initial writing. This segmentation enables simultaneous support for both data flexibility (first area) and data integrity (second area), resolving the contradiction between write flexibility and data integrity.
Solution Approach 2:
Different regions of the memory card are assigned different quality characteristics regarding write operations. The first area has the quality of being writable and modifiable, while the second area has the quality of being read-only after writing. This local differentiation of write permissions allows the system to provide both data flexibility and integrity assurance in appropriate locations.
2Reliability
If SD memory cards prevent data overwriting to ensure authenticity, then data maintainability is improved, but the ability to update data is lost
Solution Approach 1:
The memory card is divided into functional segments: a first area for data that requires update capability, and a second area for data that requires maintainability. This segmentation allows the system to simultaneously support both data update operations and data protection, enabling users to choose appropriate areas based on their needs.
Solution Approach 2:
The memory card implements dynamic write permission management where the second area transitions from a writable state during initial data entry to a read-only state after writing. This dynamic change in write permissions ensures that data can be updated when needed (during the writable phase) and protected when authenticity is required (during the read-only phase).
3Reliability
If SD memory cards implement write protection mechanisms, then data falsification is prevented, but compatibility with conventional devices may be affected
Solution Approach 1:
The memory card implements multi-functionality by providing both a first area with full read/write access (maintaining compatibility with conventional devices) and a second area with read-only protection (ensuring data authenticity). This universal design allows the memory card to work with various devices while simultaneously providing both data flexibility and protection capabilities.
Data Source
AI summary
According to one embodiment, a semiconductor device includes a semiconductor memory device and a memory controller. The semiconductor memory device is capable of holding data. The memory controller controls write operation to write data received from a host unit into the semiconductor memory device. The memory controller includes a logical address space including a plurality of address areas each having a write limiting condition according to an address and a type of data to be written into the semiconductor memory device, permitting an adding a file and inhibiting a written file from being overwritten in a specific file format.