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Promote Joypad Test Cartridge (U) from _wip to top-level project

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Moves Joypad Test Cartridge (U) from _wip/ to Joypad Test Cartridge (U)/ with full ROM build:
- Adds header.s, chr.s, linker.cfg (HEADER+PRG+CHR segments)
- Updates Makefile to build and verify reconstructed.nes vs rom.nes
- Adds rom.nes copy + copilot/rom.nes symlink per repo convention
- Verified byte-identical build

Pass 1 complete: full code/data classification (~3.5% code / ~96.5% data)
Pass 2 complete: routine headers for all labels, semantic naming for key
routines (Reset, NmiHandler, VramWrite, PpuScrollLatch, VramPtrWrite,
RetAddrUpdate, etc.), zero-page aliases in locals.inc

Root OVERVIEW.md updated:
- Removes Joypad Test Cartridge from _wip skeleton table (22 -> 21 skeletons)
- Adds Joypad Test Cartridge as #14 in numbered inventory (BYTE-IDENTICAL, Pass 2)
- Updates summary count from 13 to 14 projects
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tmerritt committed 2026-10-16 19:01:42 -04:00
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OVERVIEW.md
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@@ -154,11 +154,21 @@ This document provides a consolidated overview of all NES disassembly projects i
- **Build fix:** None needed; byte-identical out of the box (`make` in `copilot/`). Pass 1 complete — full code/data classification (~20% code / ~80% data); Pass 2 partial — routine headers and semantic naming for key routines (`Reset`, `NmiHandler`, `MainStateDispatch`, `MainLoopBody`, etc.); zero-page aliases in `locals.inc` (`GameMode`=$30, `NmiPhase`=$20, `NmiFlag`=$22, `Timer2F`=$2F, etc.)
- **Details:** `Wild Gunman (U)/OVERVIEW.md`
### 14. Joypad Test Cartridge (U)
- **Folder:** `Joypad Test Cartridge (U)/`
- **ROM:** `rom.nes` (24,592 bytes)
- **Source:** `copilot/prg.s` (~1,360 lines with routine headers)
- **Linker:** HEADER at $0000 (16 bytes), PRG at $C000 (16 KB), CHR at $0000 (8 KB)
- **Vectors:** NMI → $CCF7 (`NmiHandler`), RESET → $C000 (`Reset`), IRQ → $C000 (reuses `Reset`)
- **Key subsystems:** NMI-driven frame loop — main loop spins waiting on NMI phase; NMI handler does OAM DMA ($4014), PPU scroll/control latch, and burst VRAM writes from table at $0302; `VramPtrWrite` ($CD3F) uses a return-address modification trick at `RetAddrUpdate` ($CDC8) for runtime-computed dispatch; `VramWrite` ($CDEE) sets PPU address and writes data to PPUDATA; reset clears RAM, initializes PPU ($2000=$10, $2001=$00), triggers OAM DMA, and enters main loop
- **Build fix:** None needed; byte-identical out of the box (`make` in `copilot/`). Pass 1 complete — full code/data classification (~3.5% code / ~96.5% data); Pass 2 complete — routine headers for all labels, semantic naming for key routines, zero-page aliases in `locals.inc` (`VramPtrLo`=$00, `PpuCtrlShadow`=$EF, `FrameCounterLo`=$53, etc.)
- **Details:** `Joypad Test Cartridge (U)/OVERVIEW.md`
---
## Skeleton Projects (under `_wip/`)
22 additional ROMs awaiting full disassembly. Each is set up as a Pass-0 skeleton (`default_project.tar.gz`): `copilot/` contains the split `prg.bin`/`header.bin`/`chr.bin`, a symbolic skeleton `prg.s`, and builds **BYTE-IDENTICAL** at the PRG level. Mapper 0 / 16 KB PRG / 8 KB CHR for all.
21 additional ROMs awaiting full disassembly. Each is set up as a Pass-0 skeleton (`default_project.tar.gz`): `copilot/` contains the split `prg.bin`/`header.bin`/`chr.bin`, a symbolic skeleton `prg.s`, and builds **BYTE-IDENTICAL** at the PRG level. Mapper 0 / 16 KB PRG / 8 KB CHR for all.
| Project | Vectors (NMI/RESET/IRQ) | Mir. | Status |
|---------|--------------------------|------|--------|
@@ -169,7 +179,6 @@ This document provides a consolidated overview of all NES disassembly projects i
| `Hogan's Alley (JU)` | $C088 / $C000 / $C000 | H | BYTE-IDENTICAL |
| `Ice Climber (JE)` | $C076 / $C014 / $FFF0 | V | BYTE-IDENTICAL |
| `Ice Climber (U)` | $C076 / $C014 / $FFF0 | V | BYTE-IDENTICAL |
| `Joypad Test Cartridge (U)` | $CCF7 / $C000 / $C000 | H | BYTE-IDENTICAL |
| `Lode Runner (U)` | $C02C / $C000 / $FFF9 | H | BYTE-IDENTICAL |
| `Lunar Pool (U)` | $FF65 / $E80C / $FF64 | H | BYTE-IDENTICAL |
| `MUSCLE (U)` | $86CB / $8000 / $8764 | H | BYTE-IDENTICAL |
@@ -196,6 +205,7 @@ Notable vector/header observations for Pass 1 work:
- **Raid on Bungeling Bay (U) vs [a2]**: `[a2]` differs in mirroring only per header, but PRGs differ — separate builds.
- **Pyramid (U)** — *already at Pass 1*: interesting unlicensed Sachen boot ($4100 mapper pokes, "AV" stack-byte check, two queued-event dispatchers). See its `OVERVIEW.md`.
- **CIRCUS** — *at Pass 2/3*: full recursive disassembly complete. NMI-driven frame state machine (main loop is a spin loop at $C057). Menu text at $C763 ("CONTINUE", "STAGE", "SELECT", "PLAY"). Object state machine at $DC3F–$FE7B. Audio sequence data at $FABB–$FFFB. See `_wip/CIRCUS/OVERVIEW.md`.
- **Joypad Test Cartridge (U)** — *at Pass 2*: minimal code (~3.5%), data-heavy test cartridge. NMI handler drives per-frame PPU/OAM updates. Uses return-address modification trick at `RetAddrUpdate` ($CDC8) with `VramPtrWrite` ($CD3F) for runtime-computed dispatch. See `Joypad Test Cartridge (U)/OVERVIEW.md`.
## Common Patterns Across All Projects
@@ -249,7 +259,7 @@ make verify # (where supported by the Makefile)
## Summary
All 13 projects in this repository rebuild **byte-identical** to their original ROMs:
All 14 projects in this repository rebuild **byte-identical** to their original ROMs:
| # | Project | Build Status |
|---|---------|--------------|
@@ -266,7 +276,8 @@ All 13 projects in this repository rebuild **byte-identical** to their original
| 11 | Donkey Kong Jr. (JU) | BYTE-IDENTICAL (Pass 1) |
| 12 | CIRCUS | BYTE-IDENTICAL (Pass 2/3) |
| 13 | Wild Gunman (U) | BYTE-IDENTICAL (Pass 2) |
| 14 | Joypad Test Cartridge (U) | BYTE-IDENTICAL (Pass 2) |
Every project builds successfully with `make` in the `copilot/` folder, and every reconstructed ROM matches the original byte-for-byte. Donkey Kong Jr. shares the same byte-identical build guarantee; its remaining Pass 2/3 work is semantic renaming and table decoding, not build-correctness.
The 23 `_wip/` skeleton projects above also all rebuild byte-identical (PRG level); all Pass 1 work and promotion to this index's numbered inventory is future work.
The 21 `_wip/` skeleton projects above also all rebuild byte-identical (PRG level); all Pass 1 work and promotion to this index's numbered inventory is future work.