Semiconductor Memory Card Dual-Access Storage Architecture
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Solution Overview
Problem
Conventional methods for writing data to semiconductor memory cards, such as those using the FAT file system, face inefficiencies in writing speed due to the large size difference between file system management information and file data, leading to low access speeds for small-sized data updates.
Innovation Solution
An information recording medium with separate recording areas for file system management information and file data, allowing data to be written in access units tailored to their respective sizes, utilizing a controller to manage access based on data type and a method for accessing the medium that specifies the data type with each write command.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data is written to semiconductor memory card using conventional file systems with unified access units, then file system management information can be updated, but writing speed decreases due to large size difference between file data and management information
Solution Approach 1:
The patent divides the recording medium into multiple recording areas with different access units: a first recording area for file system management information with small access units (e.g., 512 bytes), and a second recording area for file data with large access units (e.g., 16 KB or 64 KB). This segmentation allows each area to be optimized for its specific data characteristics, resolving the contradiction between writing speed and device complexity.
Solution Approach 2:
The patent applies different access unit sizes to different recording areas based on local requirements. The first recording area uses small access units suitable for frequent updates of management information, while the second recording area uses large access units suitable for bulk file data storage. This local quality approach optimizes writing speed for each specific purpose without compromising the other.
2Productivity
If cluster size is reduced to match erase block size, then writing speed improves for small data, but writing speed decreases for large file data due to frequent erase operations
Solution Approach 1:
The patent segments the storage into two distinct areas with different access unit sizes. The first recording area uses small access units that match the erase block size, enabling fast updates for management information. The second recording area uses large access units that minimize the number of erase operations required for file data. This segmentation resolves the time loss contradiction by optimizing each area independently.
Solution Approach 2:
The patent effectively copies the success of small access unit design from the first recording area to the second recording area by providing both areas with appropriate access unit sizes. Instead of using a single access unit size for both areas, the system copies the principle of matched access units to each area's specific needs, thereby achieving high writing speed for both small and large data.
3Reliability
If file system management information is updated frequently, then data integrity is maintained, but access speed decreases due to small data size and frequent writes
Solution Approach 1:
The patent segments the storage system to dedicate the first recording area specifically for file system management information with small access units. This allows frequent updates to management information without impacting the speed of file data access. The small access units enable rapid writes while the dedicated area ensures data integrity through consistent management information updates.
Solution Approach 2:
The patent applies local quality by providing the first recording area with small access units optimized for frequent updates of management information, while the second recording area uses large access units optimized for file data. This local optimization allows the system to maintain both reliability through frequent management information updates and high speed through appropriate access unit sizing for each area.
Data Source
AI summary
An information recording medium such as a semiconductor memory card includes a first semiconductor memory having a first recording area accessed by a relatively small access unit and storing file system management information, a second semiconductor memory having a second recording area accessed by a relatively large access unit and storing file data (file entity data), and a controller for controlling the first and second semiconductor memories. The information recording medium selects either one of recording areas of the first and second semiconductor memories depending on the data type, and writes data into the selected recording area.