Memory Address Filter Emulating Legacy Overrun Behavior
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Solution Overview
Problem
Newer automatic test equipment (ATE) may not emulate the memory overrun behavior of legacy ATEs, leading to compatibility issues with existing test programs that depend on the performance characteristics of older systems, which had scarce memory and different bus standards.
Innovation Solution
The implementation of a memory-address filter with a legacy-memory emulator that receives a target-address value and determines if it exceeds the maximum legacy-address value, allowing for emulation of legacy memory behavior by inhibiting or adjusting memory transactions to mimic the legacy memory, including wrap-around or overwrite scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If newer ATE uses larger memory capacity, then memory capacity is improved, but compatibility with legacy test programs is worsened
Solution Approach 1:
A memory controller is introduced as an intermediary between the legacy test program and the modern memory subsystem. The controller emulates legacy memory behavior by intercepting memory transactions, checking addresses against a maximum legacy address threshold, and selectively inhibiting or wrapping addresses to present legacy-compatible memory characteristics to the program while allowing the actual larger memory capacity to remain available.
2Quantity of substance
If memory size is increased, then data storage capability is improved, but memory overrun behavior becomes less predictable
Solution Approach 1:
The memory controller changes the effective address space parameter presented to legacy programs by implementing address wrapping or inhibition when the target address exceeds the maximum legacy address value. This transforms the unpredictable overrun behavior of larger memory into predictable legacy-compatible behavior, where addresses naturally wrap around or are blocked at the legacy memory boundary, ensuring reliable and consistent memory access patterns for legacy test programs.
Data Source
AI summary
A memory address filter is configurable to emulate memory overrun performance of a legacy memory using an electronic memory of equal or greater capacity. The address filter includes a comparator configured to determine whether a target address is greater than a maximum legacy-address. Memory emulation at target address values greater than the maximum legacy-address value includes one or more of inhibiting the memory transaction; accomplishing the requested memory transaction at the maximum legacy-address value; and accomplishing the requested memory transaction at an address equivalent to the target address wrapped according to the maximum legacy-address value. In some embodiments, the address filter accepts one or more configuration parameters, such as memory depth, wrap-around, and overwrite enable.