CHECKSUM
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● TOOL 02 · GAME BOY
YELLOW LEGACY
SAVE EDITOR
A browser save editor for Pokémon Yellow Legacy, covering the trainer block: your name, trainer ID, money, Game Corner coins, gym badges and the towns Fly can reach. Drop a save in, change what you need, download it back. The checksum is repaired for you.
Your save never leaves this tab. Everything runs in your browser, no upload, no server.
SAVE EDITOR
WAITING FOR FILE
PLAYER DATA
32 KiB
0 – 65535 · shown as the ID on your trainer card
max 999,999
max 9,999
GYM BADGES
FLY DESTINATIONS
Fly only lists towns you have visited. Ticking a town here makes it selectable on the town map. You still need the HM and a Pokémon that can learn it.
PENDING CHANGES
| OFFSET | FIELD | CHANGE |
|---|
SAVE STATE
LOADED TRAINER
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REQUIREMENTS
- A save from Pokémon Yellow Legacy (any version)
- A raw .sav file of exactly 32,768 bytes
- Not supported: vanilla Red/Blue/Yellow, save states (.st, .sgm, .ss1), archives, Gen 2 saves
HOW TO USE ▸ 4 STEPS
From save file to edited trainer
01
Get your save file
On an emulator the .sav sits next to your ROM (mGBA, BGB, SameBoy). On a flash cart or real cartridge, dump it with a GB Operator, GBxCart RW or similar.
02
Drop it in
The file is read locally and checked: exact size, a readable trainer and rival name, a sane bag and valid BCD wallet fields. The checksum is reported, not enforced, and a broken one gets fixed on the way out.
03
Edit the player block
Name, ID, money, coins, the eight badge bits and the eleven town-visited bits. Every pending change is listed with its offset before you download anything.
04
Put it back
Download the edited file, keep your original as a backup, and swap it in. Next boot the game loads it without the "file data is destroyed" screen.
WHY THIS EXISTS
Built for Yellow Legacy, not for vanilla
PKHeX is excellent, but it targets the official games. A romhack save is not what it was written for, and Yellow Legacy genuinely moves things: its bag holds 59 items instead of 20, which pushes money, badges, the trainer ID and coins 78 bytes further into the file. Point a vanilla editor at one and it writes confidently to the wrong address.
So these offsets were derived from the Yellow Legacy source itself — assembled and linked to a symbol file, not copied from a Gen 1 reference. Right now it covers the player block. The goal is the kind of coverage you would expect from PKHeX: party and box Pokémon, items and the rest, added one verified field at a time rather than all at once and half-checked.
UNDER THE HOOD
Every byte this editor can touch, and nothing else:
| OFFSET | WHAT IT IS | FORMAT |
|---|---|---|
| 0x2598 | player name (Gen 1 text) | 11 B |
| 0x2641 | money, 3 bytes BCD | BCD |
| 0x2650 | badges, bit 0 = Boulder | bits |
| 0x2653 | trainer ID | u16 BE |
| 0x289E | Game Corner coins | BCD |
| 0x29B7 | towns visited (Fly) | bits |
| 0x3523 | bank 1 checksum | auto |
The four gold offsets are the ones Yellow Legacy shifts; the towns, the gym mirror and the checksum sit where vanilla keeps them, because the hack reclaims 78 bytes of filler further down. The badge mask is also mirrored to 0x29D6 (wBeatGymFlags), which the game reads for gym statues and NPC text. Box banks 2 and 3 and their checksums are never touched.
GOOD TO KNOW
Will this corrupt my save?
It writes six fields and one checksum byte, nothing else. Still: the download is a separate file, so keep your original until you have booted the edited one.
Does it work on vanilla Yellow, Red or Blue?
No, and it refuses them on purpose rather than quietly writing to the wrong offsets. For the official games use PKHeX, which is built and tested for them.
Why is my checksum already wrong?
Usually because another tool edited the save and did not fix it, or the dump is partial. This editor recomputes it on download either way, which repairs the "file data is destroyed" screen.
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