# Lode Runner (U) — Pass 1 Disassembly

ROM: `_wip/Lode Runner (U)/Lode Runner (U).nes` (24,592 bytes, iNES). Status: **Pass 1 complete — 52.6% code.** `copilot/prg.s` is a real disassembly, not a skeleton: 11,057 lines with 627 address-based `Label_` definitions and canonical `; CPU:$xxxx PRG:xxxx  AA BB` audit comments. It builds **byte-identical** at the PRG level (`cmp reconstructed_prg.bin prg.bin`).


## 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 | `fab50c2e96710ca620710e719c72bbd2ef71cd854f8b2ae1348314bc10d421d9` |
| PRG SHA-256 | `9a52bea695d8ae2947341d9562927c00fd350a94d170cc9c2400fa5fd78e8613` |

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

| Vector | Target | Note |
|--------|--------|------|
| NMI | `$C02C` | per-frame heartbeat |
| RESET | `$C000` | cold start at $C000 — the usual pattern in this repo |
| IRQ | `$FFF9` | lands in the vector-page padding — unused placeholder |

## `copilot/` Contents

| File | Purpose |
|------|---------|
| `Lode Runner (U).nes` | original ROM image (reference) |
| `prg.bin` / `header.bin` / `chr.bin` | split image, produced by `_tools/splitnes.py` |
| `prg.s` | Pass-1 disassembly: 11,057 lines, 627 address-based `Label_` labels, canonical audit comments |
| `symbols.inc` | shared NES hardware constants (PPU/APU/controller) |
| `locals.inc` | project-local zero-page aliases |
| `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/Lode Runner (U)/copilot"
make        # → cmp reconstructed_prg.bin prg.bin → "BYTE-IDENTICAL"
```

## Pass Status

| Pass | Status |
|------|--------|
| Pass 1 | **Complete** — 11,057 lines of `prg.s`, 627 address-based `Label_` definitions, canonical audit comments; 52.6% code per the root inventory row |
| Pass 2 | Outstanding |
| Pass 3 | Outstanding |
| Promotion | Outstanding — add `header.s`/`chr.s` + HEADER/PRG/CHR `linker.cfg`, switch `make` to a whole-ROM `cmp`, move the `_tools` paths |

**Still owed:** a real power-on flow analysis (RESET/NMI/main-loop walk) in the style of the top-level project `OVERVIEW.md`s. This file was retitled and restatused in the 2026-10-19 doc-drift sweep to match the actual `prg.s`; the original skeleton-era text is superseded.