- Run 5: syndrome pipeline with serial popcount (no improvement)
- Run 6: balanced popcount adder tree — TT timing MET at 50 MHz
- Run 7 series (8 attempts): LAYER_WRITE pipeline exploration
- LAYER_WRITE split not viable (cell explosion / PnR divergence)
- Yosys synthesis non-determinism documented
- Hold margin sensitivity (0.4/0.2 vs 0.5/0.3) identified
- Run 7h reproduces Run 6 by reusing golden synthesis netlist
Key finding: balanced_popcount synthesis netlist is the golden reference
for all future PnR iterations.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Documents 4 hardening runs with timing/area/DRC results. Identifies
SYNDROME state as critical path bottleneck (222 logic levels, 49 ns)
and proposes 2-stage pipeline fix to meet 50 MHz target.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
