Difference between revisions of "Ashura"
From Sonic Retro
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== Getting Ashura == | == Getting Ashura == | ||
− | In order to reproduce the Ashura glitch, the [[Cheat_Codes:Sonic the Hedgehog 2 (16-bit)#Cheat_Codes|zone select and debug codes]] must be active. Upon activation, proceed to one of the two Acts of [[Emerald Hill Zone]], as it does not occur in any other level. When the Zone begins, press {{b}}. [[Sonic the Hedgehog|Sonic]] will be a [[Ring]], signifying that [[debug mode]] is active. Press {{A}} four times; Sonic should be an invisible object. Then, press {{C}} repeatedly to create a number of waterfall objects. Press {{b}} to change back into Sonic, who, if the glitch has been activated correctly, will emerge from behind the waterfalls with a green and black palette. | + | In order to reproduce the Ashura glitch, the [[Cheat_Codes:Sonic the Hedgehog 2 (16-bit)#Cheat_Codes|zone select and debug codes]] must be active. Upon activation, proceed to one of the two Acts of [[Emerald Hill Zone]], as it does not occur in any other level. When the [[Zone]] begins, press {{b}}. [[Sonic the Hedgehog|Sonic]] will be a [[Ring]], signifying that [[debug mode]] is active. Press {{A}} four times; Sonic should be an invisible object. Then, press {{C}} repeatedly to create a number of waterfall objects. Press {{b}} to change back into Sonic, who, if the glitch has been activated correctly, will emerge from behind the waterfalls with a green and black palette. |
==Explanation== | ==Explanation== |
Revision as of 03:35, 19 November 2019
It has been suggested that this page or section be merged with Sonic the Hedgehog 2 (16-bit)/Bugs. Please see the relevant discussion on the talk page. |
Ashura is the fan-atoned name of the glitched-palette phenomena found in Sonic the Hedgehog 2's Emerald Hill Zone.
Getting Ashura
In order to reproduce the Ashura glitch, the zone select and debug codes must be active. Upon activation, proceed to one of the two Acts of Emerald Hill Zone, as it does not occur in any other level. When the Zone begins, press . Sonic will be a Ring, signifying that debug mode is active. Press four times; Sonic should be an invisible object. Then, press repeatedly to create a number of waterfall objects. Press to change back into Sonic, who, if the glitch has been activated correctly, will emerge from behind the waterfalls with a green and black palette.
Explanation
The reason for the Ashura palette glitch is a result of several objects being loaded into the Sprite Status Table at a given point in time. Since RAM on the Mega Drive is in limited quantity, only so many objects can be loaded into the status table before it reaches its allotted limit. When a mass of waterfall objects are placed using debug mode, this overloads the SST to a point that exceeds the SST's reserved RAM area; since the palette cache used by the game to update CRAM is located after the SST in system memory, SST data becomes parsed as color data in the reserved palette cache area and is loaded into CRAM accordingly. Because of this, the green color is purely a coincidence--it is not intentional.
Similar palette errors can occur upon porting the Sonic 1 sound driver to Sonic 2; if Sonic loses rings whilst underwater, it will overload the SST and spill into the palette cache, corrupting the underwater character palette line.
Origin
Kushami, a member of the Sonic Retro forums and a veteran of the online Sonic scene, posted the following first person explanation of the origins of the Ashura glitch:
“ | This is the sordid, unimpressive tale of Ashura:
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„ |
— Kushami, Sonic Retro Forums[1] |