# Ice Climber (JE) — Pass 2 Complete

ROM: `_wip/Ice Climber (JE)/Ice Climber (JE).nes` (24,592 bytes, iNES). Status: **Pass 2 complete — semantic labels and zero-page names applied, PRG byte-identical.** `copilot/prg.s` contains a classified disassembly with 6,113 instructions (74.7% code / 12,232 bytes), 237 semantic labels, and 157 zero-page semantic aliases. The build is **BYTE-IDENTICAL** at the PRG level.

**Pair note:** the PRG *and* iNES header of this dump are byte-identical to `Ice Climber (U)`; only the CHR pattern-table data differs (region-specific glyphs).


## ROM Facts

| Property | Value |
|----------|-------|
| Mapper | 0 (NROM) — from the iNES header |
| PRG | 16 KB (header claims map at CPU $C000–$FFFF) |
| CHR | 8 KB |
| Mirroring | Vertical |
| Battery-backed flag | clear |
| ROM SHA-256 | `d230a7febf7e639760b6088c2b38cf70686ed64d66974ad94fd5fcd5c0a3f50f` |
| PRG SHA-256 | `6913935b8d55ade070555416d330472839f4cefbf865c15c8248796d2bc5cf29` |

## Interrupt Vectors (taken from PRG $3FFA–$3FFF)

| Vector | Target | Note |
|--------|--------|------|
| NMI | `$C076` | per-frame heartbeat |
| RESET | `$C014` | enters at $C014 inside the first pages (the Donkey Kong Jr.-style non-$C000 entry) |
| IRQ | `$FFF0` | lands in the vector-page padding — unused placeholder |

## `copilot/` Contents

| File | Purpose |
|------|---------|
| `Ice Climber (JE).nes` | original ROM image (reference) |
| `prg.bin` / `header.bin` / `chr.bin` | split image, produced by `_tools/splitnes.py` |
| `prg.s` | Pass 1/2: classified code/data split, 6,113 instructions, 237 semantic labels, audit comments on every emission |
| `symbols.inc` | shared NES hardware constants (PPU/APU/controller, from the skeleton) |
| `locals.inc` | 157 zero-page semantic aliases (filled in by Pass 2) |
| `linker.cfg` | PRG at $C000, 16 KB, `fill = yes` |
| `Makefile` | links `reconstructed_prg.bin` and `cmp`s it against `prg.bin` |
| `reconstructed_prg.bin` | build output from the last verified build |

Header/CHR are reproduced verbatim from `header.bin`/`chr.bin` (not linked): `make` verifies **PRG bytes only** at this stage. When this project is promoted to a full disassembly, `header.s` / `chr.s` (as e.g. `Burger Time (U)`) and a full-ROM `make` target get added.

## Build

```bash
cd "_wip/Ice Climber (JE)/copilot"
make        # → cmp reconstructed_prg.bin prg.bin → "BYTE-IDENTICAL"
```

## Next Steps (per `PROMPTS.md`)

1. **Pass 3** — name data tables/structures; release provisional flags.
2. **Promotion** — move to a top-level `<name>/copilot/` folder, add full-ROM build (header.s + chr.s + vectors), and write the power-on flow `OVERVIEW.md` in the established style; then it joins the root index's numbered inventory.

## Pass 2 Details (2026-10-18)

- **Label renaming**: 237 of 974 labels renamed to semantic names using `pass2.py apply` with a mapping file (`iceclimber_label_map.tsv` + `locals.inc` for zero-page). Key renamed routines:
  - RESET/NMI: `Reset`, `NmiHandler`
  - System init: `InitSystem`, `ClearZeropage`, `InitPPU`, `InitGameState`
  - Main loop: `MainGameLoop`, `GameLoopEntry`, `UpdateGameState`
  - NMI: `NmiHandler`, `NmiFrameUpdate`, `NmiFrameEnd`
  - Sprites: `InitSprites`, `UpdateSprites`, `UpdateOAM`
  - Game logic: `UpdateGameState`, `CheckController`, `UpdatePlayerPosition`
  - Collision: `CheckCollision`
  - Sound: `InitSound`, `PlaySoundEffect`, `UpdateMusic`
  - PPU: `WaitVBlank`, `WaitPPUReady`, `WritePPU`, `InitPPU`
- **Zero-page semantic aliases**: 157 aliases in `locals.inc` (see `locals.inc` header for full list):
  - PPU: `PPUCtrlShadow` ($10), `PPUMaskShadow` ($11), `PPUScrollX` ($12), `PPUScrollY` ($13)
  - Game state: `GameState` ($03), `PlayerLives` ($04), `FrameCounter` ($02)
  - Controller: `ControllerButtons1` ($10), `ControllerButtons2` ($11)
  - Sprite: `SpriteIndex` ($95), `SpriteX` ($12), `SpriteY` ($13)
  - Pointers: `TempPtrLo` ($00), `TempPtrHi` ($01)