Digital Systems Testing And Testable Design Solution High Quality [portable] Jun 2026

This was the ancient war of digital testing: controllability and observability . You needed to force a node to a specific state (controllability) and then watch its effect on the outside world (observability). Athena was failing both.

The signature readout was not 0x3F7A_2C91 . It was 0x3F7A_2C90 . A single bit error. The stuck-at '1' had reared its head. This was the ancient war of digital testing:

Methods for creating optimal test vectors to detect faults. The signature readout was not 0x3F7A_2C91

| Aspect | Low Quality | | | :--- | :--- | :--- | | Fault model | Stuck-at only | Stuck-at, delay, bridging, open | | DFT | None / ad hoc | Full scan + BIST + JTAG | | ATPG | Random patterns | Deterministic + fault simulation | | Coverage | <95% | ≥99% stuck-at, ≥95% timing | | Test time | >10 sec | <100 ms | | Diagnosis | Fail/pass only | Silicon debug support (scan dump) | The stuck-at '1' had reared its head