# Galaga (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: 11,319 / 32,768 bytes (34.5%).
`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 | $C0C8 |
| RESET vector | $C000 |
| IRQ vector | $C000 |

## Power-on flow

RESET enters at `$C000`:

    sei                            ; CPU:$C000 PRG:4000  78
    cld                            ; CPU:$C001 PRG:4001  D8
    ldx #$00                       ; CPU:$C002 PRG:4002  A2 00
    stx PPUCTRL                    ; CPU:$C004 PRG:4004  8E 00 20
    stx PPUMASK                    ; CPU:$C007 PRG:4007  8E 01 20
    lda PPUSTATUS                  ; CPU:$C00A PRG:400A  AD 02 20
    bpl Reset_OnNonnegative        ; CPU:$C00D PRG:400D  10 FB
    ldx #$BF                       ; CPU:$C00F PRG:400F  A2 BF
    txs                            ; CPU:$C011 PRG:4011  9A
    lda #$A5                       ; CPU:$C012 PRG:4012  A9 A5
    cmp ZpFF                       ; CPU:$C014 PRG:4014  C5 FF
    bne Reset_Loop                 ; CPU:$C016 PRG:4016  D0 04

NMI handler at `$C0C8`:

    pha                            ; CPU:$C0C8 PRG:40C8  48
    txa                            ; CPU:$C0C9 PRG:40C9  8A
    pha                            ; CPU:$C0CA PRG:40CA  48
    tya                            ; CPU:$C0CB PRG:40CB  98
    pha                            ; CPU:$C0CC PRG:40CC  48
    ldx Zp4A                       ; CPU:$C0CD PRG:40CD  A6 4A
    dex                            ; CPU:$C0CF PRG:40CF  CA
    bne NmiHandler_Loop            ; CPU:$C0D0 PRG:40D0  D0 19

## Data-table inventory (Pass 3)

- `$8000-$BDFF` (15872 bytes) - `UnreachedRomData`
- `$BE59-$BFFF` (423 bytes) - `UnreachedRomData2`
- `$C480-$C49F` (32 bytes) - `SpriteHeightTable`
- `$CC32-$CC37` (6 bytes) - `SpriteSpawnOffsetTable`
- `$D816-$D819` (4 bytes) - `SpriteStarCountTable`
- `$D9CA-$D9CF` (6 bytes) - `SpriteMovementParameterTable`
- `$E0F3-$E112` (32 bytes) - `ExplosionGraphicTable`
- `$E1E8-$E1E8` (1 bytes) - `UnreachedByte`
- `$E69A-$E69A` (1 bytes) - `UnreachedByte2`
- `$E7B1-$E7B5` (5 bytes) - `SpriteScoreTable`
- `$E9AA-$EAD9` (304 bytes) - `SpriteAttributeTable`
- `$EC7B-$EC84` (10 bytes) - `LevelStarPointerTable`
- `$ED8E-$F78F` (2562 bytes) - `LevelGraphicData`
- `$F7B4-$FFFF` (2124 bytes) - `SpriteGraphicData`

## Build

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