ItemDex/RB:000

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Name (transcribed): #j.

Identifier (HEX): 00
Identifier (DEC): 000
Effect pointer: 01D1
Unterminated name glitch item?: No
Tossable/Sellable?: Yes
Buy Price: 829850
Sell Price: 414925
Name bytes: {{{9}}}

(hex:00) is a glitch item in Pokémon Red and Blue.

Using will typically freeze the game both from inside and outside of battle.

It is a common item in the expanded item pack.

The inventory can also be filled with this glitch item with the j. (0x00) inventory filling map script glitch.

Advanced use

More accurately, this glitch item runs in the middle of two byte map header pointers (these begin at 01AE) at 01D1; misaligned in between Route 6 and Route 7's header pointer (executed as instructions; not followed). When the code is in between Route 10 and Route 11's header, it represents call nc,BE42. The carry flag is not set; hence BE42 is executed.

SRAM may be locked resulting in the typical "rst 38 freeze", but can be avoided if the player views the summary of a Pokémon from the party just before using the item, allowing for arbitrary code execution at 0:BE42. Using a pop hl at the end of the code, the stack can be manipulated to safely ret.

While theoretically possible, methods to write to 0:BE42 and use   with the corrupted values have not been published yet.