Put the player on a real volume, and find the write window is the frame

ROADMAP K3. src/player/packed.s (2,898 B) brings up its own display, builds
its own 193-entry DMA chain, keeps its own frame clock off V-DISP and fetches
every record itself with READ(10) off a CZ-6BS1. The rig writes no picture
byte, no palette entry and no CRTC register.

120 of 120 frames pixel-exact, every one compared, in both palette orders --
the gate had to grow to do it, because a packed frame is a LITERAL and the
codec's recursion was what made one comparison audit 120.

And the write window turns out to be the frame. A packed write requires R20
bit 11, buffer mode blanks the layer, and a DMAC-direct player holds the
window open for the whole data phase, so

    dark fraction of a slot = record bytes / (DATA-PHASE rate x slot)

which is 1.0 at the container's own 582.0 KB/s: every frame delivered, on
time, pixel-exact, and none of them displayed. The rate in that expression is
the BURST rate, a third hardware number B1 has no test for. It reverses 61.5's
ranking -- a packed player that DMAs to RAM and paints with the measured 27.3%
blit is on screen 72.7% of every slot at any rate, and the two are equal only
at 2,131 KB/s = 3.7x the wire.

And a held channel costs the frame clock half its ticks without the clock
being able to tell: 487 of 1,038 V-DISP edges lost, zero late frames reported,
the player believing 12 fps while the screen ran at 6.37.

FINDINGS 64. ROADMAP K4 opened and fenced behind B2.
check.sh ALL GREEN before and after.

Claude-Session: https://claude.ai/code/session_01194oWYW8DQXK1SZ2DnChW6

tools/bench/check.sh

@@ -703,4 +703,36 @@ else
   echo "  SKIPPED: no px68k at $PX68K -- the container's bytes were not rendered"
 fi
 
+echo "--- session 32: the PACKED PLAYER, end to end off the disc (FINDINGS 64) ---"
+# ROADMAP K3. src/player/packed.s brings up its own display, builds its own
+# 193-entry DMA chain, keeps its own frame clock off V-DISP and fetches every
+# record itself with READ(10) off a CZ-6BS1. This script writes no picture byte
+# and no palette entry.
+#
+# WHY EVERY FRAME IS COMPARED AND THE CODEC'S GATE COMPARES ONE. The codec is
+# temporally recursive -- a SKIP block is a claim about the previous frame -- so
+# its last frame audits all 120. A packed frame is a LITERAL and frame 119 says
+# nothing about frame 60. The simplification that deleted the ring also deleted
+# the gate's free lunch.
+#
+# AND WHY IT IS PACED AT HALF RATE. The write window has to be OPEN for the
+# whole transfer and buffer mode blanks the graphics layer, so at the
+# container's own 12 fps there is no instant at which a complete frame is
+# displayable and there is nothing to snapshot (FINDINGS 64.2 -- that is the
+# session's finding, not a rig limitation being worked around). Half rate opens
+# a display interval without changing one byte of the transfer.
+#
+# GATE ONLY: runs 2-4 of packed_run.sh measure the apparatus rather than gate
+# it, and they are three more MAME jobs for numbers that cannot change unless
+# MAME does. tools/bench/packed_run.sh with no DLX_PK_GATE_ONLY runs all four.
+if [ -f "$HOME/mame/roms/x68000.zip" ] || [ -d "$HOME/mame/roms/x68000" ]; then
+  DLX_PK_GATE_ONLY=1 DLX_PK_NFR="$NF" bash tools/bench/packed_run.sh \
+    tmp/packed_singe.dlxp > tmp/packed_gate_stage.log 2>&1 \
+    || { cat tmp/packed_gate_stage.log; exit 1; }
+  grep -aE "^  (FLAG|array|chain|frame clock|late frames|WRITE WINDOW)|^OK " \
+    tmp/packed_gate_stage.log
+else
+  echo "  SKIPPED: no x68000 romset -- the player was not run"
+fi
+
 echo "ALL GREEN"