tmerritt
9aef410424
Adds remaining NROM as _wip Update gitignore to not keep object files Adds AGENTS.md as this is an AI helped project
54 lines
2.8 KiB
Markdown
54 lines
2.8 KiB
Markdown
# Lode Runner (U) — Skeleton Project
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ROM: `_wip/Lode Runner (U)/Lode Runner (U).nes` (24,592 bytes, iNES). Status: **SKELETON — not yet disassembled.** The entire 16 KB PRG bank is a single unclassified block; `copilot/prg.s` is the default-project skeleton (`default_project.tar.gz`) that reproduces it as one `.incbin`. The skeleton build is **byte-identical** at the PRG level.
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## ROM Facts
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| Property | Value |
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|----------|-------|
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| Mapper | 0 (NROM) — from the iNES header |
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| PRG | 16 KB (header claims map at CPU $C000–$FFFF) |
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| CHR | 8 KB |
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| Mirroring | Horizontal |
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| Battery-backed flag | clear |
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| ROM SHA-256 | `fab50c2e96710ca620710e719c72bbd2ef71cd854f8b2ae1348314bc10d421d9` |
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| PRG SHA-256 | `9a52bea695d8ae2947341d9562927c00fd350a94d170cc9c2400fa5fd78e8613` |
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## Interrupt Vectors (taken from PRG $3FFA–$3FFF)
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| Vector | Target | Note |
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|--------|--------|------|
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| NMI | `$C02C` | per-frame heartbeat |
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| RESET | `$C000` | cold start at $C000 — the usual pattern in this repo |
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| IRQ | `$FFF9` | lands in the vector-page padding — unused placeholder |
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## `copilot/` Contents
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| File | Purpose |
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|------|---------|
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| `Lode Runner (U).nes` | original ROM image (reference) |
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| `prg.bin` / `header.bin` / `chr.bin` | split image, produced by `_tools/splitnes.py` |
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| `prg.s` | Pass-1 skeleton: `.incbin "prg.bin", $0000, $4000` (whole PRG) |
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| `symbols.inc` | shared NES hardware constants (PPU/APU/controller, from the skeleton) |
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| `locals.inc` | project-local zero-page aliases — empty for now (filled in Pass 2) |
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| `linker.cfg` | PRG at $C000, 16 KB, `fill = yes` |
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| `Makefile` | links `reconstructed_prg.bin` and `cmp`s it against `prg.bin` |
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| `reconstructed_prg.bin` | build output from the last verified build |
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Header/CHR are reproduced verbatim from `header.bin`/`chr.bin` (not linked): `make` verifies **PRG bytes only** at this stage, which is exactly what a skeleton proves. When this project is promoted to a full disassembly, `header.s` / `chr.s` (as e.g. `Burger Time (U)`) and a full-ROM `make` target get added.
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## Build
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```bash
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cd "_wip/Lode Runner (U)/copilot"
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make # → cmp reconstructed_prg.bin prg.bin → "BYTE-IDENTICAL"
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```
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## Next Steps (per `PROMPTS.md`)
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1. **Pass 1** — replace the blanket `.incbin` with classified code/data: trace reachability from RESET ($C000) and NMI ($C02C), emit per-instruction `; PRG:$xxxx AA BB` annotations, keep unreached bytes as explicit `.byte` blocks.
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2. **Pass 2** — replace `Label_`/`Sub_` names with semantic routine names; fill `locals.inc`.
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3. **Pass 3** — name data tables/structures; release provisional flags.
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4. **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.
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