Extender Card Routing Signals for ECC Memory Testing
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Solution Overview
Problem
Testing of memory modules with error-correction code (ECC) memory is problematic due to the standard memory module sockets on PC motherboards not being designed for frequent replacement and the need for more comprehensive testing of ECC memory modules.
Innovation Solution
A modified extender card with cross-over connections is used to route data from the ECC generator on the PC motherboard to one of the data DRAMs, allowing for full pattern-sensitivity testing of ECC DRAMs by swapping data signals with ECC signals, enabling the ECC DRAM to be fully exercised with desired test patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard memory module sockets on PC motherboard are used for testing, then test cost is reduced, but socket wear increases due to frequent replacement of memory modules
Solution Approach 1:
An extender card is introduced as an intermediary component between the PC motherboard and the memory module under test. The extender card contains a test socket that receives the memory module, while the extender card itself is inserted into the standard memory module socket on the motherboard. This intermediary structure protects the motherboard socket from wear by transferring all mechanical stress and insertion/removal cycles to the extender card's socket, which is specifically designed for frequent testing operations.
2Reliability
If extender card with test socket is used, then socket wear on motherboard is reduced, but device complexity increases
Solution Approach 1:
The extender card is designed with multi-functionality to reduce overall system complexity. It serves multiple purposes: (1) protects the motherboard socket from wear, (2) provides a test socket for receiving memory modules, (3) contains wiring traces to route signals between the motherboard and test socket, and (4) can be easily removed or replaced. This consolidation of multiple functions into a single component simplifies the testing system compared to modifying the motherboard directly or using multiple separate components.
3Device complexity
If standard extender card with direct connections is used, then simple signal routing is achieved, but ECC DRAM cannot be fully tested with desired test patterns
Solution Approach 1:
The extender card incorporates dynamic signal routing capability through a multiplexer or switch that can reconfigure the connection between data DRAMs and ECC DRAM. During normal operation, data signals are routed directly to data DRAMs. During ECC testing, the multiplexer dynamically switches to cross-over mode, routing data test patterns to ECC DRAM and ECC signals to data DRAMs. This dynamic reconfiguration enables comprehensive ECC testing without requiring a completely different wiring scheme.
Solution Approach 2:
The testing process uses periodic action by alternating between two testing modes: (1) normal testing mode where data signals go to data DRAMs and ECC signals go to ECC DRAM, and (2) cross-over testing mode where the connections are swapped to test ECC DRAM with data test patterns. The test program periodically switches between these modes to comprehensively test both data and ECC memory functions, ensuring thorough validation of the memory module's error correction capabilities.
Data Source
AI summary
Memory modules with an extra dynamic-random-access memory (DRAM) chip for storing error-correction code (ECC) are tested on a personal computer (PC) motherboard tester using a cross-over extender card inserted into a memory module socket on the motherboard. ECC code generated on the motherboard is normally stored in the extra ECC DRAM chip, preventing test patterns such as checkerboards and walking-ones to be written directly to the ECC DRAM chip. During testing, the cross-over extender card routes signals from the motherboard for one of the data DRAM chips to the ECC DRAM chip, while the ECC code is routed to one of the data DRAM chips. The checkerboard or other test pattern is thus written and read from the ECC DRAM chip that normally stores the ECC code. The cross-over extender card can be hardwired, or can have a switch to allow normal operation or testing of the ECC DRAM chip.