# Elevator Action (U)

## Status

**Pass 3 complete; promoted.** `prg.s` is a traced disassembly with all
address-derived labels replaced, all `jsr`/`jmp` operands symbolic, hardware
registers named via `symbols.inc`, and `apply_symbols.py` reporting 0 residue.
Code coverage: 19,446 / 32,768 bytes (59.3%).
`make` assembles and verifies byte-identical to `rom.nes`.

## ROM

| Property | Value |
|----------|-------|
| Format | iNES |
| Mapper | 0 (NROM) |
| PRG | 32 KB |
| CHR | 8 KB |
| Mirroring | Horizontal |
| NMI vector | $8081 |
| RESET vector | $8000 |
| IRQ vector | $8000 |

## Power-on flow

RESET enters at `$8000`:

    sei                            ; CPU:$8000 PRG:0000  78
    cld                            ; CPU:$8001 PRG:0001  D8
    ldx #$FF                       ; CPU:$8002 PRG:0002  A2 FF
    txs                            ; CPU:$8004 PRG:0004  9A
    lda #$10                       ; CPU:$8005 PRG:0005  A9 10
    sta PPUCTRL                    ; CPU:$8007 PRG:0007  8D 00 20
    lda PPUSTATUS                  ; CPU:$800A PRG:000A  AD 02 20
    bpl Reset_OnNonnegative                 ; CPU:$800D PRG:000D  10 FB
    lda #$FF                       ; CPU:$800F PRG:000F  A9 FF
    ldy #$24                       ; CPU:$8011 PRG:0011  A0 24
    sta $0200,y                    ; CPU:$8013 PRG:0013  99 00 02
    dey                            ; CPU:$8016 PRG:0016  88

NMI handler at `$8081`:

    sta NmiSaveA                       ; CPU:$8081 PRG:0081  85 9A
    stx NmiSaveX                       ; CPU:$8083 PRG:0083  86 9B
    sty NmiSaveY                       ; CPU:$8085 PRG:0085  84 9C
    lda ZpFA                       ; CPU:$8087 PRG:0087  A5 FA
    beq NmiHandler_Loop                 ; CPU:$8089 PRG:0089  F0 03
    jmp Sub_81D6                      ; CPU:$808B PRG:008B  4C D6 81
    lda PpuCtrlShadow                       ; CPU:$808E PRG:008E  A5 88
    and #$7F                       ; CPU:$8090 PRG:0090  29 7F

## Data-table inventory (Pass 3)

- `$83CB-$844E` (132 bytes) - `EnemySpawnOffsetTable`
- `$8628-$973D` (4374 bytes) - `EnemyHandlerPointerTable`
- `$9CA1-$9D61` (193 bytes) - `EnemyAttributeMaskTable`
- `$A240-$A24F` (16 bytes) - `EnemySpriteXPositionTable`
- `$A281-$A284` (4 bytes) - `LevelDataPointerTable`
- `$A348-$A3E2` (155 bytes) - `EnemyMoveCodeTable`
- `$A3F9-$A46E` (118 bytes) - `EnemySpawnScriptTable`
- `$AA9B-$B50C` (2674 bytes) - `LevelTilemapData`
- `$B525-$B58C` (104 bytes) - `EnemySpritePatternTable`
- `$B599-$BB2A` (1426 bytes) - `EnemyTileGraphicData`
- `$BDB5-$BDC9` (21 bytes) - `EnemyScriptPointerTable`
- `$BE15-$BE1D` (9 bytes) - `EnemyScriptEntryTable`
- `$C2F1-$C320` (48 bytes) - `SpriteOamAttributeTable`
- `$C487-$C837` (945 bytes) - `SpriteOamEntryTable`
- `$D0DE-$D0ED` (16 bytes) - `EnemySpeedTable`
- `$D187-$D2B5` (303 bytes) - `LevelObjectPointerTable`
- `$D586-$D599` (20 bytes) - `EnemySpawnRecordTable`
- `$D6B4-$D73D` (138 bytes) - `EnemyPaletteRecordTable`
- `$E61D-$E79D` (385 bytes) - `EnemyMovementDeltaTable`
- `$F0E1-$F0E6` (6 bytes) - `EnemyFallingSpeedTable`
- `$F1E3-$F4DA` (760 bytes) - `LevelSceneryTileData`
- `$F6FC-$F703` (8 bytes) - `PpuBitMaskTable`
- `$F956-$F975` (32 bytes) - `LevelHandlerPointerTable`
- `$F9BB-$F9C2` (8 bytes) - `PpuInverseBitMaskTable`
- `$FA73-$FFFF` (1421 bytes) - `LevelSceneryLayoutData`

## Build

```
Byte-identical ROM verified.
```