# Sqoon (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: 18,471 / 32,768 bytes (56.4%).
`make` assembles and verifies byte-identical to `rom.nes`.

## ROM

| Property | Value |
|----------|-------|
| Format | iNES |
| Mapper | 0 (NROM) |
| PRG | 32 KB |
| CHR | 8 KB |
| Mirroring | Vertical |
| NMI vector | $8014 |
| RESET vector | $8000 |
| IRQ vector | $80F1 |

## Power-on flow

RESET enters at `$8000`:

    ldx #$FF                       ; CPU:$8000 PRG:0000  A2 FF
    txs                            ; CPU:$8002 PRG:0002  9A
    stx NmiFrameFlag                       ; CPU:$8003 PRG:0003  86 FE
    jsr Sub_82B2                   ; CPU:$8005 PRG:0005  20 B2 82
    jsr Sub_817B                   ; CPU:$8008 PRG:0008  20 7B 81
    lda #$00                       ; CPU:$800B PRG:000B  A9 00
    sta NmiFrameFlag                       ; CPU:$800D PRG:000D  85 FE
    sta Zp9A                       ; CPU:$800F PRG:000F  85 9A
    jmp Sub_80EE                   ; CPU:$8011 PRG:0011  4C EE 80
    pha                            ; CPU:$8014 PRG:0014  48
    lda NmiFrameFlag                       ; CPU:$8015 PRG:0015  A5 FE
    beq NmiHandler_Loop            ; CPU:$8017 PRG:0017  F0 03

NMI handler at `$8014`:

    pha                            ; CPU:$8014 PRG:0014  48
    lda NmiFrameFlag                       ; CPU:$8015 PRG:0015  A5 FE
    beq NmiHandler_Loop            ; CPU:$8017 PRG:0017  F0 03
    jmp IrqHandler                 ; CPU:$8019 PRG:0019  4C F1 80
    inc NmiFrameFlag                       ; CPU:$801C PRG:001C  E6 FE
    inc FrameCounter                       ; CPU:$801E PRG:001E  E6 54
    jsr Sub_8158                   ; CPU:$8020 PRG:0020  20 58 81
    lda PpuCtrlShadow                       ; CPU:$8023 PRG:0023  A5 1D

## Data-table inventory (Pass 3)

- `$833A-$83A2` (105 bytes) - `EnemyAnimationScriptTable`
- `$83C2-$83D3` (18 bytes) - `RoutinePointerTable`
- `$84A0-$84AF` (16 bytes) - `EnemyPathDeltaTable`
- `$85F3-$8606` (20 bytes) - `GameOverText`
- `$8690-$86A9` (26 bytes) - `EnemyGraphicTileIndexTable`
- `$8814-$8825` (18 bytes) - `LevelObjectDefinitionTable`
- `$8AB4-$8AD7` (36 bytes) - `EnemyTileIndexTable`
- `$8B48-$8B55` (14 bytes) - `PhaseLeftText`
- `$8BBD-$8BC7` (11 bytes) - `LevelStartParameterTable`
- `$8C41-$8C60` (32 bytes) - `EnemyMovementParameterTable`
- `$B5D5-$B5DD` (9 bytes) - `HomeDataText`
- `$BB39-$DC18` (8416 bytes) - `LevelGraphicData`
- `$DC6E-$DC8A` (29 bytes) - `EnemySpeedParameterTable`
- `$DD1A-$E08A` (881 bytes) - `SpriteGraphicData`
- `$E134-$E238` (261 bytes) - `EnemyHandlerPointerTable`
- `$E4B7-$F5D3` (4381 bytes) - `LevelCollisionData`
- `$FFE8-$FFFF` (24 bytes) - `VectorTable`

## Build

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