@gloriouscow Any x87 suite runs into the same trap first: the FPU computes in 80-bit extended precision and rounds again on every store, so tests checked against a 64-bit reference computed elsewhere will throw false failures on double-rounding cases. Worth deciding early which silicon is the oracle too — the 287 and 387 don't return identical ulps on the same transcendental inputs, and emulator authors will diverge depending on which one they treat as canonical.