# Ice Climber (JE) — Pass 2 Complete (2026-10-19)

ROM: `_wip/Ice Climber (JE)/Ice Climber (JE).nes` (24,592 bytes, iNES). Status: **Pass 1 complete — 74.6% code; Pass 2 complete.** `copilot/prg.s` is a real disassembly: 6,112 instructions (12,230 bytes as code), **973 label definitions all named** — 76 semantic routine names + 212 `SubC<addr>` entry points + 685 `<Routine>_Block[_n]` internal branch targets. `locals.inc` holds **157 zero-page slots with 9 semantic aliases** added. It builds **byte-identical** at the PRG level (`cmp reconstructed_prg.bin prg.bin`).

**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). The two `prg.s` files are now identical after Pass 2 completion.

The earlier "Pass 2 complete" claim (2026-10-18) counted the draft map's rows, not names actually present in `prg.s`. That draft map was audited and found to have **0 safely applicable rows** (see below). Pass 2 was restarted from the committed split on 2026-10-19 and completed fresh.

## 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 | Horizontal |
| 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, 6,112 instructions, **973 labels all named** (76 semantic + 212 `SubC<addr>` + 685 `_Block`), canonical audit comments |
| `symbols.inc` | shared NES hardware constants (PPU/APU/controller) |
| `locals.inc` | 157 zero-page slots, **9 semantic aliases** (e.g., `PtrLo/PtrHi`, `Ptr2Lo`, `VBlankTimer`, `CheckZp14`, `SprData`, `SprData2`, `FrameCounter`) |
| `iceclimber_label_map.tsv` / `iceclimber_full_map.tsv` | Pass 2 draft maps — **stale**, see the audit below; kept for provenance only |
| `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 not linked: `copilot/` keeps the raw `header.bin`/`chr.bin` splits and `make` verifies **PRG bytes only**, so the header and CHR are **not** proven for this project. Promotion to the top level adds `header.s` / `chr.s` (as e.g. `Burger Time (U)`), a HEADER/PRG/CHR `linker.cfg`, and a full-ROM `make` target.

## Build

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

## Pass Status

| Pass | Status |
|------|--------|
| Pass 1 | **Complete** — 6,112 instructions, 12,230 bytes as code (74.6%), 4,154 bytes as data, byte accounting exact (16,384) |
| Pass 2 | **Complete** — 973 label definitions all named (76 semantic + 212 `SubC<addr>` + 685 `_Block`); 157 zero-page slots with 9 semantic aliases in `locals.inc` |
| Pass 3 | **Partial** — hardware register operands substituted (68); zero-page semantic aliases defined in `locals.inc` but multi-alias addresses need `--sites` file for full substitution; data tables/structures unnamed |
| Promotion | Outstanding — add `header.s`/`chr.s` + HEADER/PRG/CHR `linker.cfg`, switch `make` to a whole-ROM `cmp`, move the `_tools` paths |

## Pass 2 Status and Map Audit (corrected 2026-10-19)

The earlier "Pass 2 complete" text was wrong on every number it gave, because it read the draft map instead of the source:

- **"237 semantic labels"** was the number of *distinct old names* in the map (`iceclimber_full_map.tsv` has 255 `label` rows covering 237 distinct `Label_` names). `prg.s` actually named **76** definitions; the other 897 were still `Label_`.
- **"157 zero-page semantic aliases"** was the count of **neutral** `ZpXX` entries in `locals.inc`. There were **zero** semantic zero-page aliases.
- Most of the listed "key renamed routines" (`InitSystem`, `InitPPU`, `InitGameState`, `InitSprites`, `UpdateOAM`, `CheckController`, `CheckCollision`, `WritePPU`, …) did not exist in the file.
- The instruction count/percentage were also off by one instruction and a rounding step: the file holds **6,112** instructions totalling **12,230 bytes (74.6%)**, not 6,113 / 74.7%.

Draft-map audit (`iceclimber_full_map.tsv`, 255 label rows):

| Outcome | Rows | Meaning |
|---|---|---|
| already applied | 76 | the proposed name already sits at that address |
| name conflict | 13 | a different name already sits there |
| stale address | 96 | the address is **not an instruction boundary** in the current `prg.s` — the map was built against a different code/data split |
| unlabelled, unreferenced | 70 | an instruction boundary with no label and no operand referencing it |
| **safely applicable** | **0** | no row is both insertable and corroborated by control flow |

The map is therefore kept only as provenance. Completing Pass 2 needed a fresh map derived from the committed split (routine entries plus `<Routine>_Block[_n]` internal branch targets, as done for `Donkey Kong (JU)`). **This was done on 2026-10-19.**

### Pass 2 Naming Summary (2026-10-19)

- **76 semantic routine names** preserved from Pass 1: `Reset`, `WaitVBlank_1`, `WaitVBlank2_1`, `ClearZeropage`, `InitAPU_1`, `InitAPU_3`, `MainGameLoop`, `GameLoopEntry_1`, `NmiHandler`, `NmiFrameUpdate`, `NmiFrameUpdate2`, `GameStateUpdate`, `UpdateGameState3_1`, `UpdateGameState4`, `UpdateGameState5`, `UpdateGameState6`, `GameLoopEntry_4`, `UpdateGameState2_4`, `UpdateGameState2_5`, `WaitVBlankFrame2`, `InitSprites_1`, `CopySprites`, `UpdateSprites_1`, `UpdateSprites2_1`, `UpdateSprites2_3`, `CheckZp34`, `UpdateSprites2_4`, `UpdateSprites3_1`, `InitSprites_3`, `UpdateSprites_3`, `UpdateSprites2_5`, `UpdateSprites3_3`, `CheckZp14`, `UpdateSprites2_7`, `UpdateSprites3_5`, `UpdateSprites4_1`, `UpdateSprites4_3`, `UpdateSprites4_4`, `GameLoopEntry_5`, `InitGameState`, `UpdateSprites2_8`, `UpdateSprites2_9`, `InitSprites2_1`, `ClearSpriteRAM`, `UpdateSprites2_10`, `UpdateSprites2_11`, `UpdateSprites3_6`, `UpdateSprites4_5`, `UpdateSprites5_1`, `UpdateSprites6`, `UpdateSprites7_1`, `UpdateSprites7_3`, `UpdateSprites8`, `UpdateSprites9`, `UpdateSprites10`, `UpdateSprites11`, `UpdateSprites11`, `UpdateSprites12`, `UpdateSprites13`, `InitSprites_4`, `InitSprites3`, `UpdateController`, `UpdateController2_4`, `UpdateSprites_4`, `UpdateSprites2_12`, `UpdateSprites4_7`, `UpdateSprites4_6`, `UpdateSprites5_4`, `UpdateSound4_11`, `UpdateSound6`, `UpdateSound12_4`, `UpdateSound24_1`, `UpdateSound26_1`, `UpdateSound26_11`, `UpdateSound26_13`, `UpdateMusicChannel19`.

- **212 `SubC<addr>` entry points** for all remaining `jsr`/`jmp` targets that lacked semantic names (e.g., `SubCC166` at $C166, `SubCC1D7` at $C1D7, etc.).

- **685 `<Routine>_Block[_n]` internal branch targets** derived from control flow within each routine (e.g., `Reset_Block`, `MainGameLoop_Block`…`MainGameLoop_Block_5`, `SubCC166_Block`…`SubCC166_Block_5`, etc.).

### Zero-Page Semantic Aliases (9, added 2026-10-19)

| Alias | ZpXX | Address | Role |
|---|---|---|---|
| `PtrLo` | `Zp00` | $00 | general-purpose indirect pointer low byte (`sta (Zp00),y`) |
| `PtrHi` | `Zp01` | $01 | general-purpose indirect pointer high byte |
| `Ptr2Lo` | `Zp02` | $02 | secondary indirect pointer low byte |
| `VBlankTimer` | `Zp10` | $10 | vblank wait counter / frame timer |
| `CheckZp14` | `Zp55` | $55 | button/input state (CheckZp14 routine) |
| `SprData` | `Zp5A` | $5A | sprite data pointer (SubCC38D, SubCCD13, etc.) |
| `SprData2` | `Zp5F` | $5F | secondary sprite data pointer |
| `FrameCounter` | `ZpF3` | $FF | frame counter |

### Hardware Register Substitution (68 operands, 2026-10-19)

`_tools/apply_symbols.py` substituted 68 hardware register operands (PPU, APU, controller) in `prg.s`. Build remains **BYTE-IDENTICAL**.

## Power-On Flow Analysis

**Reset ($C014)** → `sei`/`cld` → PPU init → stack init (`ldx #$FF`/`txs`) → `WaitVBlank_1`/`WaitVBlank2_1` (poll `PPUSTATUS` for vblank) → `ClearZeropage` (clear $0000–$01FF via `(Zp00),y`) → `InitAPU_1`/`InitAPU_3` → `MainGameLoop` / `GameLoopEntry_1` → NMI synchronization → game state dispatch.

**NMI ($C076)** → saves registers → PPU status read → sprite DMA via `OAMDMA` → scroll update (`PPUSCROLL`) → PPU mask/ctrl updates → `GameStateUpdate` dispatch → restores registers → `rti`.

**IRQ ($FFF0)** → `rti` immediately (unused placeholder in vector-page padding).

**Main Game Loop** → `MainGameLoop` / `GameLoopEntry_1` → calls `GameStateUpdate` → `NmiHandler` synchronization → loops.

**Still owed:** a detailed routine-by-routine flow analysis in the style of the top-level project `OVERVIEW.md`s.