retroDE_ps2/docs/ch368_audit_log.md

Ch368 Audit Log - Runtime CLUT Adjacent-Frame Motion

Scope

Add the adjacent SH3 capture frame to the established 24-draw runtime-CLUT path, then prove A/B motion with the same native-640x480 persistent-Z, board-versus-simulation, and replay-color gates used by Ch367.

Frame-B Capacity Measurement

• Frame B is the 24-draw shared-texture cluster from capture 20260624224121, emitted as zsrtb24: eight ordered 204-record epochs, one texture fill, seven CRC-verified reuses, and runtime palette staging before every epoch.
• At request depth 2048, epoch 3 saturated the request FIFO and dropped 151 fragments. This is a bounded-capacity failure, not a board candidate.
• A complete depth-4096 integration run passed all eight epochs with exact Z and color scoreboards: Z 0/307200, color 0/108435, zero drops, and 664,865 accepted fragments.
• Per-epoch request-FIFO high water: 1060, 1074, 1431, 2198, 68, 3610, 2993, and 3340. The measured maximum is 3610, leaving 486 entries of headroom at depth 4096.

Production Change

• The DE25 top changes only u_zc_emit request depth from 2048 to 4096. No clock, SDC, or protocol change is involved. The existing zc_g_drops counter remains the fail-closed board guard.
• Focused regressions pass after the source change: tb_gs_lpddr_zc_emit, tb_clut_stage_cdc, and tb_top_psmct32_runtime_clut. The complete zsrtb24 depth-4096 integration run is the capacity and exactness proof for this value.

First GUI Fit And Response-Ready Cut

• The first 4096-entry GUI fit failed setup only: WNS -0.063 ns, TNS -0.126 ns; hold and every other signoff class remained clean. The six failing paths terminated at the EMIF write-response FIFO.
• The two launch families were the Z-RMW bready and write-arbiter grant controls, both feeding the arbiter's live m_bready mux. The arbiter now registers response-ready from the final W handshake, removing that live grant/client-ready cone while retaining the selected transaction through B acceptance.
• The response-path regression is clean: tb_gs_lpddr_wr_arb passes its priority/transaction checks and tb_gs_lpddr_zc_emit passes three complete Z/color drains. The full zsrtb24 depth-4096 integration gate also passes after the cut: 664,865 accepted fragments, zero drops, Z 0/307200, and color 0/108435.
• At that point, the pending gate was one full Quartus 26.1 GUI compile; the board remained on the Ch367-proven RBF until STA was clean.

Corrective GUI Fit And Silicon Proof

• Quartus 26.1 STA completed at 15:53 with timing requirements met: setup +0.076 ns, hold 0.000 ns, recovery +1.045 ns, minimum pulse width +0.200 ns, and zero TNS. The fitted request FIFO is a 4096 x 74 dual-clock M20K implementation using 16 M20Ks. Core SHA-256: b146503317ba8268fee06a83b2650cdf57cb79e64da3b6b5aa6a22e9b356cf60.
• The RBF was SHA-verified on the DE25 and loaded through core_loader.sh; fpga0 reported operating.
• Frame B board gate passed all eight 204-record epochs: one texture fill plus seven resident CRC reuses, eight runtime palette copies, fresh drains, and zero drops. Its board framebuffer is byte-identical to integration simulation at SHA-256 3191d75983e72a158f91f15cc1f57b6ff7c5e40d5bbb4a49957db06db4e2fded; replay-color is exact at 307200/307200 pixels.

A/B Motion Closure

• The host ran A -> B -> A -> B with a fresh color/Z preclear, texture fill, runtime palette staging, and eight ordered drains for every frame. All 32 epochs reported zero drops.
• The four board boundary dumps alternate exactly: A dumps 0 and 2 hash to 6614d7211b9a668cfeda12e4fa2d6f469d3ee4d3a10bdf56c0119b35f93c7803; B dumps 1 and 3 hash to 3191d75983e72a158f91f15cc1f57b6ff7c5e40d5bbb4a49957db06db4e2fded. Each equals its matching integration framebuffer byte-for-byte.
• Independent replay-color checks are exact for both alternating frames: A is 307200/307200 over 346,425 fragments and B is 307200/307200 over 664,865 fragments.

Result

Ch368 is closed on silicon: native-640x480 persistent-Z runtime-CLUT motion between two adjacent authentic SH3 captures, with deterministic A/B/A/B board outputs, exact integration framebuffers, and exact replay-color evidence.