Pokémon Jade Pikachu Analysis Report
Investigation of the crash at the end of Stage 1
About this site
This site documents the investigation of the crash that occurs at the end of Stage 1 in Pokémon Jade (Special Pikachu Edition), through to the creation of a corrective patch. The material is organized by purpose and covers isolation of the cause, static ROM analysis, dynamic verification in an emulator, and generation of an IPS patch.
Dynamic analysis identified the crash as occurring inside the second banked call at $241C. A corrected ROM that supplies DE=1400 successfully transitions from Stage 1 to Stage 2.
Within the scope of this repository, this game requires hhugboy or mGBA. Although the ROM header declares MBC1, the cartridge actually uses the unlicensed NT-new mapper to select ROM regions. A typical Game Boy emulator that does not support this arrangement may fetch instructions from the wrong ROM region, producing a white screen, corrupted graphics, or a crash.
The corrected ROM was verified with mGBA 0.10.3. An experimental conversion to standard MBC5 also failed in Gambatte and SameBoy under EmuHawk 2.11.1. See EmuHawk Compatibility Experiment for details.
This site primarily publishes explanatory text, numeric facts, the minimum instruction excerpts needed for verification, and original diagrams and tables. Game screenshots are limited to images essential for commenting on reproduction conditions and display corruption, with their source and purpose stated. ROMs, modified ROMs, patch binaries, videos, save files, save states, extracted assets, and extensive derived dumps are not published.
See Publication Policy and Rights Notice for details.
Choose a starting point
Learn what this game is and how it came about
Read the Game Background Report. It distinguishes this title from the Telefang-derived bootleg with the same name and summarizes its Makon Soft lineage, gameplay, language variants, known crash, unusual mapper, and unresolved questions. Claims drawn from online sources are separated from direct observations of the ROM.
Read the conclusion and evidence for the fix
Read the Investigation and Complete Fix Record. It follows the full investigation from reproducing and isolating the crash, through unsuccessful tests, to the DE=1400 correction and confirmation of the transition to Stage 2.
Understand the flow of the ROM code
Read Static Analysis of the Stage Transition. It explains the state variables, branch targets, level-number conversion, and placement of the corrective code in the order they run after a stage ends. The report includes only the instruction excerpts needed for independent verification.
Reproduce the investigation in mGBA
Read Emulator Verification. It gives a concise list of the state variables and breakpoints to watch, the values to record, and the expected execution path.
Understand and create the IPS patch
Read Creating the IPS Patch. It explains the 12 changed bytes, the IPS file structure, the dedicated generation script, and checks that prevent applying the modification to the wrong ROM.
View the physical cartridge
The 3D Cartridge Viewer presents a three-dimensional model made with three.js together with photographs of the cartridge.
Investigation status
| Item | Status | Details |
|---|---|---|
| Target ROM identification | Verified | Size and SHA-256 fixed |
| Static analysis of stage transition | Documented | State variables, primary routines, and corrective code mapped |
| Emulator reproduction | Verified | Execution goes astray inside $241C after reaching $240A |
| Root cause | Verified | NT-new mapper selector and failure to restore the overwritten E register |
| Corrective patch | Verified | Corrected ROM transitions from Stage 1 to Stage 2 |
Verified scope
- Size and SHA-256 of the target ROM
- Reproduction of the unmodified-ROM crash in mGBA 0.10.3
- Isolation of the failure to the second banked call at
$241C - Normal return from the destination selected by selector
14and operation00 - Transition from Stage 1 to Stage 2 with
DE=1400in the corrected ROM - Byte-for-byte agreement between the corrected ROM and a fresh application of the IPS to the source ROM
- Correct goal processing for Stages 1 through 5
Not yet verified
- Compatibility with hhugboy or versions of mGBA other than 0.10.3
- Byte-for-byte results from applying the IPS with other patching tools