Flash Memory Sector Management for EEPROM Compatibility
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Solution Overview
Problem
Flash memories, due to their sector-based erasure granularity and potential for write errors, cannot be directly replaced with EEPROM memories in existing systems, leading to issues with data reliability and the inability to handle defective sectors effectively.
Innovation Solution
A memory management method that writes data in sectors with administrative blocks containing identification and check information, allowing for flexible placement of administrative data and redundant writing to ensure data reliability and detect defective sectors, enabling the use of flash memory in systems designed for EEPROM.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If flash memory is used to replace EEPROM memory in existing systems, then cost is reduced and storage capacity is increased, but data reliability deteriorates due to sector-based erasure granularity and write errors affecting multiple cells
Solution Approach 1:
The memory system is segmented into multiple sectors, with each sector independently manageable. Administrative blocks are placed at specific locations within sectors to track and manage data reliability at the sector level, allowing defective sectors to be identified and isolated without affecting the entire memory system.
Solution Approach 2:
Administrative blocks serve as intermediary structures between the flash memory physical structure and the logical data storage. These blocks contain check information and counters that mediate the reliability issues by providing a layer of abstraction that handles sector-level error detection and management.
2Ease of operation
If administrative blocks are written at fixed locations in sectors, then data management is simplified, but reliability deteriorates when those fixed locations become defective
Solution Approach 1:
The location of administrative blocks within sectors is made dynamic rather than fixed. The system can relocate administrative blocks to different positions within a sector based on availability, allowing the memory system to adapt when fixed locations become defective while maintaining simplified data management through consistent logical access methods.
3Reliability
If check information is written with each data block, then data integrity verification is improved, but device complexity increases due to additional writing operations and storage requirements
Solution Approach 1:
Check information is merged with administrative blocks rather than being separate from data blocks. This combining approach provides data integrity verification while reducing overall complexity by consolidating metadata structures and reducing the number of separate operations needed for integrity checking.
Data Source
AI summary
A method of managing a rewritable mass memory subdivided into sectors within which data pages are recorded, and data periodically updated, where data erasure in a sector erases all previously written data therein. The method includes:writing pieces of data in a sector, each piece being associated with a first block containing at least one information for identifying the data piece,writing information data in an administrative block for managing the data of the sector concerned in the sector, each block being written among other data of the sector and being associated with a second block including one information piece and one check information piece,a block including a first part giving general indications and a second part including a counter being incremented at each writing of an administrative block in a new sector, each first block including a check number which is based on the corresponding administrative block counter.