|PRAMA Initiative a également une page sur SRAM glitch.|
The SRAM glitch, also known as Save corruption glitch and Save abuse glitch, is a method of performing a partial save in Pokémon Red, Blue, and Yellow with a hard reset, such that the party data in the SRAM is carried into the new save file. It notably allows allows the player to perform the send party Pokémon to a new game or 255 Pokémon glitch immediately after starting a new game.
The glitch exploits a quirk in the code for saving the game to get a save file with a correct checksum. The necessary timing for the hard reset is very precise (less than 0.1 second), but it is still much easier than getting the correct checksum by chance.
- Start a new game.
- Play as much as you wish, without saving.
- Begin to save the game.
- At a very precise moment, power off or reset the console. The timing is version-dependent and is easier on Pokémon Yellow.
The cue is to power off or reset after the "Yes/No" dialog box has disappeared, but before the text changes to "Saving..."
Holding Start+Select+A+B will not work, as the game prevents soft resets while it is saving.
In Pokémon Red and Blue, the window of opportunity is a few frames only, located right after the box disappears, making the glitch rely more on luck than on timing.
In Pokémon Yellow, there are more frames where the glitch will be successful, and the window is further away from the Yes/No box disappearing, making the glitch more viable on console.
If the glitch was successful, a Continue option will be present when the game is started again, and the player will be able to access their Pokémon screen even if they never received the starter (unless the party data in the SRAM has 0 Pokémon).
There are two ways the glitch can fail: either when rebooting the game the message "The file data is destroyed!" will appear, which usually indicates the reset happened too early and will remove the Continue option, or a Continue option will appear but the Pokémon screen cannot be accessed, indicating that the reset happened too late.
255 Pokémon glitch
- Main article: 255 Pokémon glitch
By performing the SRAM glitch while the player has no save file, the party data will become whatever is in the SRAM, and is likely to be all 0xFF bytes (in particular, clearing the save file will set the SRAM to all 0xFF). As a result, the player will have 255 Pokémon in the party. When the player opens the party screen, it will appear to show nothing in the party, but the player will be able to scroll the cursor to any of the 255 slots and switch Pokémon around.
If the player wants to perform this glitch, but a save file exists (i.e. a Continue option exists on the title menu), it can be cleared by pressing Up+Select+B on the title screen (not the title menu; it is the screen with the "Pokémon" logo and version name, and can be reached from the title menu by pressing B), and choosing "Yes" to the "Clear all saved data?" prompt.
The expanded party can be exploited in many ways. For example:
- Warp to the Safari Zone: Swapping the 3rd Pokémon with the 36th can warp the player to the Safari Zone gate. (discovered by VaeporSage)
- Walk through walls: Swapping Pokémon 62 with 63 allows the player to walk through walls. (discovered by hibiki ganaha)
- Expanded item pack: Swap Pokémon 9 with Pokémon 10, and then with Pokémon 11. If you want to undo the effects of the 255 Pokémon glitch, stand on the right tile of the house's exit mat, and swap Pokémon 187 with Pokémon 178, wait a while[clarification needed], and press A.
Send party Pokémon to a new game
- Main article: Send party Pokémon to a new game
If the player starts a new game while a save file already exists, and successfully perform the SRAM glitch, then the party Pokémon from the old save file will appear in the new game.
If the glitch fails due to the reset happening too early, then the game will say "The file data is destroyed!", but the saved party Pokémon data is in fact not overwritten. Therefore, if the player starts a new game in this state and try again, they may still be able to retrieve those party Pokémon. (Of course, if the reset happens too late and the save was successful, then the party would be overwritten and unable to be retrieved.)
When saving the game in Generation I, the game calls three functions, each only saving a part of it, and the parts are in fact overlapping:
- The first function saves everything, except the party data.
- The second function only saves the current box data.
- The third function saves the party data, the Pokédex data, and (in Yellow) Pikachu's happiness and mood.
Besides being used for a full save, the third function is also used after trading a Pokémon in the Cable Club. Presumably at least one of the first two functions is also intended to be used somewhere else, but they don't seem to be in the final game.
The importance of having three functions is that all three functions will compute a checksum from the full save data on the SRAM, and write it to the SRAM. When performing a full save, the first function would result in an inconsistent save file, and checksum it. At this point, if the player resets the game, the save file would be considered valid by the game since the checksum is correct.
Furthermore, the second function would then save the current box data to the SRAM, which takes a significant number of frames, but actually does nothing because the current box data is already saved by the first function. Therefore, during this period, the checksum on the SRAM will remain valid, resulting in a relatively large time window for the hard reset.