Memory Metadata ECC Layout Without Read-Modify-Write Delays
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Solution Overview
Problem
Existing semiconductor memory devices face inefficiencies in accessing and protecting metadata due to the need for read-modify-write operations when generating code words for metadata, which incur significant time penalties.
Innovation Solution
Combining data, metadata, and ECC data into a single code word for access, allowing a two-pass operation where metadata is accessed first and data/ECC data in a second pass, reducing the need for read-modify-write operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If read-modify-write operations are used to generate code words for metadata, then metadata protection is achieved, but access time increases significantly
Solution Approach 1:
The patent segments the code word into distinct portions: data bits, metadata bits, and ECC bits. By separating metadata from data at the bit level within the code word structure, the system can access and protect metadata independently without requiring full read-modify-write operations on the entire data block, thus reducing access time while maintaining protection.
Solution Approach 2:
The patent performs preliminary organization of metadata and data into a combined code word structure with designated bit positions before access operations. This preliminary arrangement allows the system to directly access metadata bits without needing to read, modify, and rewrite entire data blocks, eliminating the time-consuming read-modify-write cycle while preserving ECC protection capabilities.
2Reliability
If separate ECC protection is implemented for metadata, then metadata reliability improves, but additional ECC data bits are required
Solution Approach 1:
The patent merges metadata and data into a single unified code word structure where both types of information share the same ECC protection mechanism. The ECC bits are calculated to protect the entire code word including both data and metadata portions, eliminating the need for separate ECC schemes and reducing the total number of ECC bits required compared to independent protection of each component.
Solution Approach 2:
The patent implements a universal ECC protection scheme that serves multiple functions simultaneously: it protects both data and metadata within the code word, provides error detection and correction for the entire structure, and maintains compatibility with existing memory interfaces. This multi-functional approach avoids the overhead of implementing separate specialized ECC systems for metadata.
3Productivity
If metadata is accessed independently from data, then access efficiency improves, but column firing increases
Solution Approach 1:
The patent segments the code word into distinct bit fields for data, metadata, and ECC within a unified structure. This segmentation allows the system to identify and access specific metadata bits through precise column selection without activating all columns, thereby improving access efficiency while controlling the number of columns fired compared to accessing entire data blocks.
Data Source
AI summary
A bank of a memory device is divided into column planes. Each column plane is associated with column selects. A portion of a column plane associated with one column select used to store metadata associated with data of the remaining column selects. Both the metadata and the data are provided to an error correction code circuit as a combined code word that provides error correction for both the data and the metadata.