Troubleshooting and quickly isolating faults is of tremendous value for reducing the time to redesign or repair failing boards.  This paper describes how using an interpreter that allows the execution of a full test suite for verifying a design or an individual test for fault isolation can dramatically improve quality and reliability with In-System Diagnostics.  It describes how memory errors can be isolated to ECC, single-bit, row, column, and correlated to a part’s reference designator.  Also how the debug engineer can have control over the test parameters and environment variables without recompiling.