Session 1: hardware research, content measurement, codec decision, MAME harness

Verified GVRAM is one word-access per pixel in ALL color modes; chose 256-color
256x192 with movem.l bursts (page 1 sacrificed as double-buffer).

Measured 8 scenes from the Blu-ray source: blit costs under 8% of the 12fps
cycle budget, so I/O is the bottleneck, not CPU. Naive delta+RLE reaches only
3.2:1 (365 KB/s, 470MB) -> decision to use 4x4 vector quantization (~30 KB/s).

"Shot on twos" assumption failed: the transfer has zero duplicate frames, so
12fps requires explicit decimation.

Documents three false measurement results and their root causes (per-frame
Floyd-Steinberg dithering, temporal denoise, exact-match dedupe on noisy source).

MAME Lua injection harness works and is reusable for cycle-cost measurement;
the IOCS _B_READ disk benchmark is blocked returning -1.

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

tools/bench/bench.s

@@ -0,0 +1,36 @@
+FLAG    = $18000
+STAT    = $18004
+NREAD   = $18008
+BUF     = $20000
+CHUNK   = 65536          ; bytes per read
+RECS    = CHUNK/256      ; 256-byte records per read
+NCHUNK  = 16             ; 16 x 64KB = 1MB total
+
+        org     $10000
+start:
+        move.l  #1,FLAG.l              ; signal: started
+        move.l  #NCHUNK,d6
+        moveq   #0,d5                  ; record position
+        moveq   #0,d4                  ; completed count
+loop:
+        movem.l d4-d6,-(sp)
+        moveq   #$46,d0                ; _B_READ
+        move.l  #$80000000,d1          ; PDA=$80 (SASI unit0), mode=0
+        move.l  d5,d2                  ; position (records)
+        move.l  #CHUNK,d3              ; byte count
+        lea     BUF,a1
+        trap    #15
+        movem.l (sp)+,d4-d6
+        move.l  d0,STAT.l              ; last status
+        tst.l   d0
+        bmi.s   failed
+        addq.l  #1,d4
+        move.l  d4,NREAD.l
+        add.l   #RECS,d5
+        subq.l  #1,d6
+        bne.s   loop
+        move.l  #$FF,FLAG.l            ; signal: done OK
+stop:   bra.s   stop
+failed:
+        move.l  #$EE,FLAG.l            ; signal: error
+        bra.s   stop