Bad sprite: Difference between revisions

A bad sprite that causes a [[glitch battle]] is typically due to bad sprite dimensions. A dimension of x0 (apparently it is effectively x256) in width or height will result in the game unpacking a huge sprite. DataAs part of unpacking the sprite, data is temporarily stored [https://github.com/pret/pokeyellow/blob/05925cba37019d93f1c847015f4fbc1de110c200/sram.asm in bankless portions of SRAM] but it is possible for a buffer overflow when later areas of SRAM are touched (the reason encountering [[MissingNo.]] corrupts the Hall of Fame/results in a saving message on Stadium Game Boy Tower etc.). Furthermore, glitch Pokémon withsprites of both width 0 and height 0 will typically corrupt the memory even further; exceeding the end of SRAM in the memory map (SRAM ranges from A000-BFFF) and touching C000 and beyond; the beginning of WRAM.

Certain glitch Pokémon including Yellow [[MissingNo.]], {{gdex|Y:191|4 4 (hex:BF)}} and {{gdex|Y:237|4(h4? (hex:ED)}} can corrupt the current battle (an effect known as a [[glitch battle]] not to be confused with a [[glitch encounter system]]) in ways such as corrupting what is on the screen or causing [[glitch audio|glitch music]]. Occasionally, they will corrupt bytes in memory that will lead to freezes; such as C0EF/C0EF (the audio ROM bank and the saved copy of it, where the only valid sound banks are 02, 08, 1F, 20 (Yellow only)/28 (Japanese Yellow) and any other sound bank will lead to [[glitch sound command]]s which typically freeze the game; though some corruption is possible with bank 20 as well).