View source for Nem s2

{{HistoricalArticle|equivalent=SCHG:Sonic the Hedgehog 2 (16-bit)}}
==Introduction==
Here are my hacking notes on the Sonic 2 rom. If you use these notes I'd appreciate it if you would mention it with your hack or your utility, so that other people can find their way here. For hex editing I recommend you use a hex utility called Hex workshop, and for emulators I recommend you get both Gens and Genecyst. Genecyst may be old and kinda crap, but it has a whole heap of debug outputs that really help when it comes to seeing exactly what it's doing and when.<P><br>
First of all it's very important that you understand the basics. All data stored on a computer is in the form of 1's and 0's. On a CD for example, a laser hits the surface, and if the laser bounces back and hits the lens it's a 1, and if it doesn’t it's a zero. Each 1 or 0 is called a bit, and a bit cannot have any other characters in it other that a 1 or a 0. Now the computer deals with bits in groups of 4. There are 16 possible combinations for a group of four 1's and 0's, so to make it simpler it deals with it as one value, rather than 4 (Eg. 0110 becomes 6). Now as there are 16 possible combinations for a group of 4 bits, this value to represent their values must have 16 values itself, so rather than a simple 0-9, this value is 0-F (0123456789ABCDEF). This value is called a hexadecimal value (hex value for short). Each hex value is dealt with in groups of 2, called a byte, each byte having 128 possible combinations. Now on a final output level the byte may be looked up on an ASCII table, which will convert that value into a recognisable character (Eg. a byte value of 73 becomes a lowercase s on an English ASCII table). You will practically never touch the ASCII version of the code in hacking though.</P><br><P>
Now one important thing to realise is that as one character of hex has 16 values and a decimal (real) value only has 10, it may be necessary to convert the numbers between them from time to time. This is done with the use of a base converter (included in hex workshop). Let's say you wanted to give Sonic 50 rings. If you enter 50 as the value, you will in fact end up with 80, because that value you are entering is actually a hex value, but if you use the base converter to convert it first, you merely enter the value of 50 into the decimal box, and it will spit out a hex value of 32, which will in fact give you 50 rings in the game. Another useful utility that you will need is a hex calculator (also included in hex workshop). A hex calculator is the same as a normal calculator, but it deals with hex values rather than decimal values.</P><br><P>
Another thing you need to know is that each level in Sonic 2 has a value assigned to it, but this value does not correspond with each level's final position in the game. Here is a list of the level values in Sonic 2:</P><BR>
{|align="center" border="1"
|00||Emerald Hill zone
|-
|04||Metropolis zone
|-
|05||Metropolis zone act 3
|-
|06||Wing fortress zone
|-
|07||Hill Top zone
|-
|08||Hidden Palace zone
|-
|0A||Oil Ocean zone
|-
|0B||Mystic Cave zone
|-
|0C||Casino Night zone
|-
|0D||Chemical Plant zone
|-
|0E||Death Egg zone
|-
|0F||Aquatic Ruin zone
|-
|10||Sky Chase zone
|}
<br>
<P>One other thing you need to know is the way that the Mega Drive stores all the art. All the art that is used in the game is stored in the form of 8x8 pixel blocks. These blocks do not actually store colours at all, they actually only have one hex value per pixel. That value specifies what point on the palette line the pixel will get its colour from. The palette has 4 lines, each with 16 colours on them. Now the colours on the palette can be changed at any point during play, and some palette colours may even automatically change colour each couple of frames to make it look like the colour is flashing.</P><br>
<P>Now these 8x8 blocks are not what make up the level directly. 4 8x8 blocks are grouped together to form a 16x16 block, and it is at this point that the palette line to use for that 16x16 block is specified. The 8x8 patterns can also have their x, y, or x and y values reversed when placing them in a 16x16 block. Also it's at the 16x16 level that the collision definitions are specified. Now finally we get to a 128x128 block, and these are the things that the actual level info loads. It is made up of 64 16x16 blocks, and each block inside them can use a different palette line. You cannot place anything except a sprite or a 128x128 block directly into a level.</P><br>
<P>Now that you know all the basics, here's my breakdown:</P><br>

==Address listing==
For the most part, there are no breaks in this list. If one address follows on directly from another on this list, it does so in the rom, with the exception of data that comes before 40000. All the compiled code that is used in the game is stored in this section, and that's a pain in the ass to sort through, so there will be many breaks there. The column on the left lists it's file location, the column in the middle contains it's name and description, and the column on the right will contain any special notes about it, such as compression format used if applicable, and number of blocks an art tile uses. The right column will also contain a link with the text further info, if that particular block requires it. That link will jump to a detailed explanation of that thing. Anything linked like that will also be listed in the contents at the top of the page.<br>

{|border="1"
|0-FF||Vector table||     
|-
|100-200||Header||     
|-
|14DE-????||Programming to do wih decompression of art tiles to VRAM||Compiled
|-
|2782-28C1||Palette pointers||     
|-
|28C2||Sega screen palette (00)||     
|-
|2942||Title screen palette (01)||     
|-
|2962||Unknown palette (02)||     
|-
|29E2||"Sonic and Miles" screen palette (03)||     
|-
|2A22||EHZ palette (04, 05, 07, 0D)||     
|-
|2A82||WZ palette (06)||     
|-
|2AE2||MTZ palette (08, 09)||     
|-
|2B42||WFZ palette (0A)||     
|-
|2BA2||HTZ palette (0B)||     
|-
|2C02||HPZ palette (0C)||     
|-
|2C62||HPZ underwater palette (15)||     
|-
|2CE2||OOZ palette (0E)||     
|-
|2D42||MCZ palette (0F)||     
|-
|2DA2||CNZ palette (10)||     
|-
|2E02||CPZ palette (11)||     
|-
|2E62||CPZ underwater palette (16)||     
|-
|2EE2||DEZ palette (12)||     
|-
|2F42||ARZ palette (13)||     
|-
|2FA2||ARZ underwater palette (17)||     
|-
|3022||SCZ palette (14)||     
|-
|3082||Unknown palette (19)||     
|-
|30A2||Unknown palette (1A)||     
|-
|30C2||OOZ boss palette (25)||     
|-
|30E2||Menu palette (26)||     
|-
|3162||Main special stage palette (18)||     
|-
|31C2||Special stage 1 palette (1B)||     
|-
|31E2||Special stage 2 palette (1C)||     
|-
|3202||Special stage 3 palette (1D)||     
|-
|3222||Special stage 4 palette (1E)||     
|-
|3242||Special stage 5 palette (1F)||     
|-
|3262||Special stage 6 palette (20)||     
|-
|3282||Special stage 7 palette (21)||     
|-
|32A2||Unknown palette (22)||     
|-
|32C2||Unknown palette (23)||     
|-
|32E2||Unknown palette (24)||     
|-
|3302||Unknown palette (27)||     
|-
|3EA0-3EB0||Music playlist for levels||[[#Music_playlist_for_levels|Further info]] 
|-
|4948-498B||Pointers to demo file to use for levels||     
|-
|49E8-4A70||Pointers to collision indexes||[[#Collision_definitions|Further info]]
|-
|6FC0||??????? (sprite)||     
|-
|70F0||??????? (sprite)||     
|-
|7356||??????? (sprite)||     
|-
|7A68||Continue text (sprite)||     
|-
|7B82||Sprite of sonic lying down from continue screen (sprite)||     
|-
|80BE||??????? (sprite)||     
|-
|9454-947B||Level select level order||[[#Level_order|Further info]]
|-
|A1D6||Cut scene at end of game (sprite)||     
|-
|A3C8||??????? (sprite)||     
|-
|A894||??????? (sprite)||     
|-
|A988||??????? (sprite)||     
|-
|A9F2||??????? (sprite)||     
|-
|AAAE||??????? (sprite)||     
|-
|C054-C14F||Level size array||[[#Level_size_array|Further info]] 
|-
|C150-C1CF||Code for initial character and screen placement||Compiled
|-
|C1D0-C257||Character start location array||[[#Character_start_location_array|Further info]] 
|-
|C4FC||Offset index of rasterised layer deformation||[[#Offset_indexes|Further info]] 
|-
|C51E||Unknown (possibly title screen)||[[#Rasterised_layer_deformation|Further info]] 
|-
|C57E||EHZ layer deformation info||
[[#Rasterised_layer_deformation|Further info]] 
|-
|C682||Unknown (splitscreen, EHZ?)||
[[#Rasterised_layer_deformation|Further info]]
|-
|C7F2||HTZ layer deformation info||
[[#Rasterised_layer_deformation|Further info]]
|-
|C7BA||Unknown (level value 02)||
[[#Rasterised_layer_deformation|Further info]]
|-
|C7F2||Unknown (identical to WFZ)||
[[#Rasterised_layer_deformation|Further info]]
|-
|C82A||WFZ layer deformation info||
[[#Rasterised_layer_deformation|Further info]]
|-
|C8CA||Unknown (identical to HTZ)||
[[#Rasterised_layer_deformation|Further info]]
|-
|C964||HTZ layer deformation info||
[[#Rasterised_layer_deformation|Further info]]
|-
|CA92||Unknown (background fixed)||
[[#Rasterised_layer_deformation|Further info]]
|-
|CB10||Unknown (splitscreen, background locked, no deformation)||
[[#Rasterised_layer_deformation|Further info]]
|-
|CBA0||HPZ layer deformation info||
[[#Rasterised_layer_deformation|Further info]]
|-
|CC66||OOZ layer deformation info||
[[#Rasterised_layer_deformation|Further info]]
|-
|CD2C||MCZ layer deformation info||
[[#Rasterised_layer_deformation|Further info]]
|-
|CE6C||Unknown (splitscreen, background free moving, but no alteration)||
[[#Rasterised_layer_deformation|Further info]]
|-
|D0C6||CNZ layer deformation info||
[[#Rasterised_layer_deformation|Further info]]
|-
|D194||CNZ 2 player splitscreen||
[[#Rasterised_layer_deformation|Further info]]
|-
|D27C||CPZ layer deformation info||
[[#Rasterised_layer_deformation|Further info]]
|-
|D382||DEZ layer deformation info||
[[#Rasterised_layer_deformation|Further info]]
|-
|D4AE||ARZ layer deformation info||
[[#Rasterised_layer_deformation|Further info]]
|-
|D5DE||SCZ layer deformation info||
[[#Rasterised_layer_deformation|Further info]]
|-
|D666||01, 03, 09 layer deformation info||
[[#Rasterised_layer_deformation|Further info]]
|-
|F66C||??????? (sprite)||     
|-
|FC98||Swinging platform from aquatic ruin zone (sprite)||     
|-
|10310||??????? (sprite)||     
|-
|104AC||Stationary floating platform from aquatic ruin zone (sprite)||     
|-
|108BC||Collapsing platform from either oil ocean zone or mystic cave zone (sprite)||     
|-
|10A08||Collapsing platform from aquatic ruin zone (sprite)||     
|-
|111D4||??????? (sprite)||     
|-
|112F0||??????? (sprite)||     
|-
|115C4||Stomper from MCZ (sprite)||     
|-
|1169A||One way barrier from chemical plant zone and DEZ (sprite)||     
|-
|1188C||An animal and the 100 that are given off from busting a badnick (sprite)||     
|-
|11DC6||100 points (sprite)||     
|-
|11F44||A ring (sprite)||     
|-
|12078||Sprite of rings spraying out from being hit by an enemy (sprite)||     
|-
|125E6||??????? (sprite)||     
|-
|12670||Monitor (sprite)||     
|-
|12854||Image of what was in monitor flying up like it does when you bust it (sprite)||     
|-
|12E18||Flashing stars from intro (sprite)||     
|-
|132F0||??????? (sprite)||     
|-
|13600||??????? (sprite)||     
|-
|13C48||Sprite for level title card (sprite)||     
|-
|13F74||??????? (sprite)||     
|-
|14086||End of level result screen (sprite)||     
|-
|142F8-1433B||Main game level order||
[[#Level_order|Further info]]
|-
|143C0||End of special stage result screen (sprite)||     
|-
|15900||Vertical spikes (sprite)||     
|-
|15CC8||??????? (sprite)||     
|-
|15D44||??????? (sprite)||     
|-
|1600C||Sprite programming pointers (one address per sprite value)||
[[#Sprite_programming|Further info]]
|-
|1637C||??????? (sprite)||     
|-
|18888||Red spring facing upwards (sprite)||     
|-
|191B8||??????? (sprite)||     
|-
|19F50||Sonic (sprite)||     
|-
|1B8A4||Tails (sprite)||     
|-
|1D200||??????? (sprite)||     
|-
|1D320||??????? (sprite)||     
|-
|1D8F2||??????? (sprite)||     
|-
|1D97E||??????? (sprite)||     
|-
|1DD20||??????? (sprite)||     
|-
|1E0F0||??????? (sprite)||     
|-
|1F0B0||Starpoll (sprite)||     
|-
|1F624||??????? (sprite)||     
|-
|1F730||Star ball that sonic bounces off from CNZ (sprite)||     
|-
|1F8A8||??????? (sprite)||     
|-
|1FCDC||??????? (sprite)||     
|-
|2009C||Section of pipe that tips you off from chemical plant zone (sprite)||     
|-
|20210||??????? (sprite)||     
|-
|2031C||Master emerald (sprite)||     
|-
|203AC||??????? (sprite)||     
|-
|208DC||??????? (sprite)||     
|-
|20B9E||??????? (sprite)||     
|-
|20DEC||??????? (sprite)||     
|-
|20FD2||Big pylon thing that's in the foreground in CPZ (sprite)||     
|-
|21088||An explosion of an enemy, giving off an animal and 100 points (sprite)||     
|-
|2115C||??????? (sprite)||     
|-
|21392||??????? (sprite)||     
|-
|214C4||Rotating cylinder in Metropolis zone (sprite)||     
|-
|21928||See saw thingy from hill top zone (sprite)||     
|-
|21DAC||Diagonally moving lift thing from hill top zone (sprite)||     
|-
|22018||??????? (sprite)||     
|-
|222AC||Booster things from chemical plant zone (sprite)||     
|-
|22408||??????? (sprite)||     
|-
|2259C||Spin tube from chemical plant zone (sprite)||     
|-
|22FF8||??????? (sprite)||     
|-
|23300||??????? (sprite)||     
|-
|2351A||??????? (sprite)||     
|-
|238DC||??????? (sprite)||     
|-
|23AF4||Platform that shoots up in the air from oil ocean zone (sprite)||     
|-
|23E40||Spiky ball from OOZ (sprite)||     
|-
|24020||Oil in OOZ (sprite)||     
|-
|240F8||Strange spring from OOZ facing vertically (sprite)||     
|-
|24A16||Ball sitting on strange spring from OOZ (sprite)||     
|-
|24DD0||Block thingy in OOZ that launches you into the round ball things (sprite)||     
|-
|25244||Thingy from oil ocean zone that you enter when flying as a ball, and it turns and throws you another direction (sprite)||     
|-
|25694||Arrow shooter from aquatic ruin (sprite)||     
|-
|2588C||Pillar that drops it's lower part from aquatic ruin zone (sprite)||     
|-
|25A5A||Raising pillar from ARZ (sprite)||     
|-
|26104||Sprite that makes leaves fly off when you hit it from ARZ (sprite)||     
|-
|26370||Weird lever like spring from chemical plant zone and ARZ (sprite)||     
|-
|26634||Thing that pops up and releases steam sideways from metropolis zone (sprite)||     
|-
|26920||Twin stompers from MTZ (sprite)||     
|-
|26AE0||??????? (sprite)||     
|-
|26F58||??????? (sprite)||     
|-
|2715C||One of the spin tubes from MTZ (sprite)||     
|-
|27594||Block that has a spike that comes out of each side sequentially from MTZ (sprite)||     
|-
|27794||Floor spike from MTZ (sprite)||     
|-
|27884||Nut from MTZ (sprite)||     
|-
|27AB0||??????? (sprite)||     
|-
|27D6C||??????? (sprite)||     
|-
|28034||??????? (sprite)||     
|-
|283AC||??????? (sprite)||     
|-
|285C0||??????? (sprite)||     
|-
|28BC8||??????? (sprite)||     
|-
|28DF8||Spike block thing from MCZ (sprite)||     
|-
|28FF8||??????? (sprite)||     
|-
|291CC||Stairs from CPZ that move down to open the way (sprite)||     
|-
|293A0||Platform that moves back and forth on top of chemicals in CPZ (sprite)||     
|-
|29590||??????? (sprite)||     
|-
|297E4||Vine switch that you hang off in MCZ (sprite)||     
|-
|2997C||Vine that you hang off and it moves down from MCZ (sprite)||     
|-
|2A000||??????? (sprite)||     
|-
|2A290||Platform that is usually swinging from ARZ (sprite)||     
|-
|2A4FC||3 adjoined platforms from ARZ that rotate in a circle (sprite)||     
|-
|2A7B0||Fan blowing to the left from OOZ (sprite)||     
|-
|2AB84||Vertical spring from CNZ that you hold down jump on to pull back further (sprite)||     
|-
|2B140||??????? (sprite)||     
|-
|2B528||Flashing blocks in CNZ that appear and disappear in a rectangular shape that you can walk across (sprite)||     
|-
|2B84C||??????? (sprite)||     
|-
|2B8EC||Big block from casino night zone that moves back and forth (sprite)||     
|-
|2BA08||Elevator going up from CNZ (sprite)||     
|-
|2BB6C||Poky that gives out points from CNZ (sprite)||     
|-
|2C448||??????? (sprite)||     
|-
|2C6AC||Block thingy in CNZ that changes colour when you hit it and gives you points, until it disappears) (sprite)||     
|-
|2C92C||A sprite that you can hold on to, like the rails in WFZ (sprite)||     
|-
|2CA14||Octopus badnick from OOZ (sprite)||     
|-
|2CCC8||Seahorse badnick from OOZ (sprite)||     
|-
|2D068||Buzz bomber from EHZ (sprite)||     
|-
|2D394||Shark badnick from EHZ (sprite)||     
|-
|2D494||??????? (sprite)||     
|-
|2D734||??????? (sprite)||     
|-
|2EF18||??????? (sprite)||     
|-
|2FC50||??????? (sprite)||     
|-
|2FCF4||Button (sprite)||     
|-
|30480||??????? (sprite)||     
|-
|30FA4||Earthquake (sprite)||     
|-
|318F0||??????? (sprite)||     
|-
|32288||??????? (sprite)||     
|-
|32940||??????? (sprite)||     
|-
|32F90||??????? (sprite)||     
|-
|338EC||??????? (sprite)||     
|-
|340A4||??????? (sprite)||     
|-
|347EC||??????? (sprite)||     
|-
|34A5C||??????? (sprite)||     
|-
|34EB0||??????? (sprite)||     
|-
|34FA0||??????? (sprite)||     
|-
|353FE||??????? (sprite)||     
|-
|35554||??????? (sprite)||     
|-
|35FBC||??????? (sprite)||     
|-
|36924||Blowfly enemy from ARZ (sprite)||     
|-
|36A76||??????? (sprite)||     
|-
|36B88||??????? (sprite)||     
|-
|36BD4||??????? (sprite)||     
|-
|36DAC||??????? (sprite)||     
|-
|36F0E||??????? (sprite)||     
|-
|36FE6||??????? (sprite)||     
|-
|370FE||Red circle dude from hill top zone that has lava balls circling around him that he throws at you. (sprite)||     
|-
|37322||Lava snake (sprite)||     
|-
|373D0||??????? (sprite)||     
|-
|376E8||??????? (sprite)||     
|-
|377C8||Bomber badnick from SCZ (sprite)||     
|-
|37936||Turtle thing on the back of another larger turtle thing from SCZ (sprite)||     
|-
|37A06||??????? (sprite)||     
|-
|37A82||??????? (sprite)||     
|-
|37BFA||Coconuts (the badnick) from EHZ (sprite)||     
|-
|37E16||Snake like badnick from MCZ that flies out from wall at you (sprite)||     
|-
|3800C||Crab like badnick from MTZ (sprite)||     
|-
|3815C||??????? (sprite)||     
|-
|383B4||Praying Mantis dude from MTZ (sprite)||     
|-
|384A2||??????? (sprite)||     
|-
|3873E||Glowbug from MCZ (sprite)||     
|-
|3899C||Exploding star from MTZ (sprite)||     
|-
|38AEA||??????? (sprite)||     
|-
|38B86||??????? (sprite)||     
|-
|38DBA||Spider badnick from CPZ (sprite)||     
|-
|38F66||??????? (sprite)||     
|-
|39032||??????? (sprite)||     
|-
|39066||??????? (sprite)||     
|-
|390A2||??????? (sprite)||     
|-
|3937A||Jet badnick from SCZ (sprite)||     
|-
|3941C||??????? (sprite)||     
|-
|39452||??????? (sprite)||     
|-
|3972C||??????? (sprite)||     
|-
|3A1DC||??????? (sprite)||     
|-
|3A3F8||??????? (sprite)||     
|-
|3A790||??????? (sprite)||     
|-
|3B2DE||??????? (sprite)||     
|-
|3B36A||??????? (sprite)||     
|-
|3B3FA||??????? (sprite)||     
|-
|3B5D0||Tilting platform from WFZ (sprite)||     
|-
|3B8A6||??????? (sprite)||     
|-
|3B968||Wall turret from WFZ (sprite)||     
|-
|3BABA||??????? (sprite)||     
|-
|3BB4C||??????? (sprite)||     
|-
|3BB7C||??????? (sprite)||     
|-
|3BBBC||??????? (sprite)||     
|-
|3BC1C||??????? (sprite)||     
|-
|3BD7A||Platform that pops in and out from WFZ (sprite)||     
|-
|3BEAA||??????? (sprite)||     
|-
|3BF04||??????? (sprite)||     
|-
|3C0AC||Sprite that sonic hangs onto on the back of Robotnic's getaway ship at the end of WFZ (sprite)||     
|-
|3C328||Rivet thing that you bust to get into the ship at the end of WFZ (sprite)||     
|-
|3C3D6||??????? (sprite)||     
|-
|3C442||Laser boss guy at end of WFZ (sprite)||     
|-
|3CED0||??????? (sprite)||     
|-
|3D23E||Bad guy in CNZ (sprite)||     
|-
|3D4C8||Death Egg (sprite)||     
|-
|3EAC8||??????? (sprite)||     
|-
|3F1E4||Egg prison (sprite)||     
|-
|3FCE0||Offset index of dynamic pattern and animated pattern load cue's||Double offset<BR> 
[[#Offset_indexes|Further info]]
|-
|3FD24||Dynamic pattern reloading for 01, 02, 03, WFZ, 09, MCZ, SCZ (empty)||
[[#Dynamic_pattern_reloading|Further info]]
|-
|3FD26||Dynamic pattern reloading for HTZ||
[[#Dynamic_pattern_reloading|Further info]]
|-
|3FF08||Dynamic pattern reloading for CNZ||
[[#Dynamic_pattern_reloading|Further info]]
|-
|3FF10||Dynamic pattern reloading for CNZ (not linked in offset index, but loads CNZ stuff)||
[[#Dynamic_pattern_reloading|Further info]]
|-
|3FF24||Dynamic pattern reloading for ARZ||
[[#Dynamic_pattern_reloading|Further info]]
|-
|3FF2C||Dynamic pattern reloading for EHZ, MTZ, MTZ3, HPZ, OOZ, CPZ, DEZ||
[[#Dynamic_pattern_reloading|Further info]]
|-
|3FF94||EHZ animated pattern load cue (4)||
[[#Animated_pattern_load_cue's|Further info]]
|-
|3FFF8||MTZ animated pattern load cue (3)||
[[#Animated_pattern_load_cue's|Further info]]
|-
|40038||HTZ animated pattern load cue (4)||
[[#Animated_pattern_load_cue's|Further info]]
|-
|4009C||HPZ animated pattern load cue (2)||
[[#Animated_pattern_load_cue's|Further info]]
|-
|400C8||OOZ animated pattern load cue (4)||
[[#Animated_pattern_load_cue's|Further info]]
|-
|4010E||CNZ animated pattern load cue (1)||
[[#Animated_pattern_load_cue's|Further info]]
|-
|40160||Unknown animated pattern load cue (1) (mirror of CNZ load cue, but not linked in offset index)||
[[#Animated_pattern_load_cue's|Further info]]
|-
|401B2||CPZ animated pattern load cue (0)||
[[#Animated_pattern_load_cue's|Further info]]
|-
|401C4||DEZ animated pattern load cue (0)||
[[#Animated_pattern_load_cue's|Further info]]
|-
|401D6-?????||ARZ animated pattern load cue (3)||
[[#Animated_pattern_load_cue's|Further info]]
|-
|40350||Offset index for mappings and properties of misc spites using animated patterns||
[[#Offset_indexes|Further info]]
|-
|40372||EHZ, HTZ misc sprite mappings||
[[#Misc_sprite_definitions|Further info]]
|-
|403EE||MTZ misc sprite mappings||
[[#Misc_sprite_definitions|Further info]]
|-
|404C2||HPZ misc sprite mappings||
[[#Misc_sprite_definitions|Further info]]
|-
|405B6||OOZ misc sprite mappings||
[[#Misc_sprite_definitions|Further info]]
|-
|4061A||CNZ misc sprite mappings||
[[#Misc_sprite_definitions|Further info]]
|-
|406BE||Unknown misc sprite mappings (that damn phantom group again)||
[[#Misc_sprite_definitions|Further info]]
|-
|40762||CPZ misc sprite mappings||
[[#Misc_sprite_definitions|Further info]]
|-
|4076E||DEZ misc sprite mappings||
[[#Misc_sprite_definitions|Further info]]
|-
|4077A||ARZ misc sprite mappings||
[[#Misc_sprite_definitions|Further info]]
|-
|407BE-407C0||01, 02, 03, WFZ, 09, MCZ, SCZ misc sprite mappings (empty)||
[[#Misc_sprite_definitions|Further info]]
|-
|4134C-41A6B||Big and small numbers used on counters in game||Uncompressed<BR> 
[[SCHG:Nem s2|Further info]]
|-
|41D0C-41D2D||Offset index of object debug lists||
[[#Object_debug_list|Further info]] 
|-
|41D2E||EHZ/01/02/03/DEZ object debug lists||
[[#Object_debug_list|Further info]] 
|-
|42AA8||MTZ/MTZ act 3 object debug lists||
[[#Object_debug_list|Further info]] 
|-
|41EEC||WFZ object debug lists||
[[#Object_debug_list|Further info]] 
|-
|41FEE||HTZ object debug lists||
[[#Object_debug_list|Further info]] 
|-
|420E8||HPZ/OOZ object debug lists||
[[#Object_debug_list|Further info]] 
|-
|421F2||MCZ object debug lists||
[[#Object_debug_list|Further info]] 
|-
|422B4||CNZ object debug list||
[[SCHG:Nem s2|Further info]]
|-
|42376||CPZ object debug list||
[[SCHG:Nem s2|Further info]]
|-
|42438||ARZ object debug list||
[[SCHG:Nem s2|Further info]]
|-
|42522||SCZ object debug list||
[[SCHG:Nem s2|Further info]]
|-
|42594-4265F||Main level load block pointers||
[[SCHG:Nem s2|Further info]]
|-
|42660-426E5||Offset index of pattern load cue's||
[[#Offset_indexes|Further info]]
|-
|426E6-42D4F||Pattern load cues||
[[#Pattern_load_cues|Further info]]
|-
|42D50||Curve and resistance mapping||
[[#Collision_definitions|Further info]]
|-
|42E50||Collision array||
[[#Collision_definitions|Further info]]
|-
|44E50||EHZ and HTZ primary 16x16 collision index||Compressed<BR> 
[[#Collision_definitions|Further info]]
|-
|44F40||EHZ and HTZ secondary 16x16 collision index||Compressed<BR> 
[[#Collision_definitions|Further info]]
|-
|45040||MTZ primary 16x16 collision index||Compressed<BR> 
[[#Collision_definitions|Further info]]
|-
|45100||OOZ primary 16x16 collision index||Compressed<BR> 
[[#Collision_definitions|Further info]]
|-
|45200||MCZ primary 16x16 collision index||Compressed<BR> 
[[#Collision_definitions|Further info]]
|-
|452A0||CNZ primary 16x16 collision index||Compressed<BR> 
[[#Collision_definitions|Further info]]
|-
|45330||CNZ secondary 16x16 collision index||Compressed<BR> 
[[#Collision_definitions|Further info]]
|-
|453C0||CPZ and DEZ primary 16x16 collision index||Compressed<BR> 
[[#Collision_definitions|Further info]]
|-
|454E0||CPZ and DEZ secondary 16x16 collision index||Compressed<BR> 
[[#Collision_definitions|Further info]]
|-
|45610||ARZ primary 16x16 collision index||Compressed<BR> 
[[#Collision_definitions|Further info]]
|-
|45760||ARZ secondary 16x16 collision index||Compressed<BR> 
[[#Collision_definitions|Further info]]
|-
|458C0||WFZ/SCZ primary 16x16 collision index||Compressed<BR> 
[[#Collision_definitions|Further info]]
|-
|459A0||WFZ/SCZ secondary 16x16 collision index||Compressed<BR> 
[[#Collision_definitions|Further info]]
|-
|45A80||Offset index of level layout's||
[[#offset_index|Further info]]
|-
|45AC4||EHZ act 1 level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|45C84||EHZ act 2 level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|45E74||MTZ act 1 level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|462A4||MTZ act 2 level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|46684||MTZ act 3 level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|46B04||WFZ level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|46DD4||HTZ act 1 level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|47044||HTZ act 2 level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|47404||OOZ act 1 level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|47784||OOZ act 2 level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|47B24||MCZ act 1 level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|47D24||MCZ act 2 level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|47FF4||CNZ act 1 level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|483C4||CNZ act 1 level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|48774||CPZ act 1 level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|48A84||CPZ act 2 level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|48DE4||DEZ level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|48E94||ARZ act 1 level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|49264||ARZ act 2 level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|49634||SCZ level layout||Level compression<BR> 
[[#Level_layout|Further info]]
|-
|49714||Animated flowers in EHZ and HTZ||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|49914||Pulsing thing against chequered backing from EHZ||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|49A14||Dynamically reloaded cliffs in background from HTZ||Art compression<BR>192 blocks
|-
|4A33E||Dynamically reloaded clouds in background from HTZ||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|4A73E||Spinning metal cylinder patterns in MTZ||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|4B73E||Lava patterns in MTZ and HTZ||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|4BD3E||Animated section of MTZ background||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|4BF7E||Pulsing ball in OOZ||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|4C0FE||Square rotating around ball in OOZ||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|4C4FE||Oil in OOZ||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|4D4FE||Flipping foreground section in CNZ||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|4EEFE||Bonus pictures for pokie in CNZ||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|4FAFE||Animated background section in CPZ and DEZ||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|4FCFE||Waterfall patterns from ARZ||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|50000||Patterns for Sonic||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|64180||Patterns for Tails||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|6FBE0||Unknown offset index||
[[SCHG:Nem s2|Further info]]
|-
|6FD8C||Data that offset index is linking to (something to do with mappings for sonic)||
[[#Mappings_for_Sonic/Tails|Further info]] 
|-
|714E0||Unknown offset index||
[[#Offset_indexes|Further info]] 
|-
|7168C||Data that offset index is linking to (something to do with mappings for sonic)||
[[SCHG:Nem s2|Further info]] 
|-
|71D8E||Bubble||Art compression<BR>32 blocks
|-
|71F14||Invincibility stars||Art compression<BR>00, 34 blocks
|-
|71FFC||Splash in water||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|7287C||Smoke from dashing||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|7393C||Supersonic stars||Art compression<BR>00, 14 blocks
|-
|739E2||Unknown offset index||
[[#Offset_indexes|Further info]] 
|-
|73AF8||Data that offset index is linking to (something to do with mappings for tails)||
[[#Mappings_for_Sonic/Tails|Further info]]
|-
|7446C||Unknown offset index||
[[#Offset_indexes|Further info]] 
|-
|74582||Data that offset index is linking to (something to do with mappings for tails)||
[[#Mappings_for_Sonic/Tails|Further info]]
|-
|74876||SEGA patterns||Art compression<BR>127 blocks
|-
|74F6C||Main patterns from title screen||Art compression<BR>336 blocks
|-
|7667A||Sonic and tails from title screen ||Art compression<BR>674 blocks
|-
|78CBC||A few menu patterns||Art compression<BR>10 blocks
|-
|78DAC||Button ||Art compression<BR>16 blocks
|-
|78E84||Vertical spring ||Art compression<BR>00, 20 blocks
|-
|78FA0||Horizontal spring ||Art compression<BR>12 blocks
|-
|7906A||Diagonal spring ||Art compression<BR>00, 32 blocks
|-
|7923E||Score, Rings, Time patterns ||Art compression<BR>24 blocks
|-
|79346||Sonic lives counter ||Art compression<BR>12 blocks
|-
|7945C||Ring||Art compression<BR>00, 14 blocks
|-
|79550||Monitors and contents ||Art compression<BR>60 blocks
|-
|7995C||Spikes||Art compression<BR>8 blocks
|-
|799AC||Numbers||Art compression<BR>18 blocks
|-
|79A86||Starpoll||Art compression<BR>00, 16 blocks
|-
|79BDE||Signpost||Art compression<BR>78 blocks
|-
|7A1A0||Signpost||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|7AB4A||Strange spring from CPZ and ARZ ||Art compression<BR>00, 28 blocks
|-
|7AC9A||Long horizontal spike ||Art compression<BR>00, 8 blocks
|-
|7AD16||Bubble man, and bubbles from bubble man ||Art compression<BR>00, 37 blocks
|-
|7AEE2||Bubbles from character ||Art compression<BR>00, 10 blocks
|-
|7AF82||Countdown text for drowning ||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|7B400||Game/Time over text ||Art compression<BR>34 blocks
|-
|7B592||Explosion ||Art compression<BR>68 blocks
|-
|7B946||Miles life counter ||Art compression<BR>00, 12 blocks
|-
|7BA32||Egg prison ||Art compression<BR>49 blocks
|-
|7BDBE||Image of tails in plane when sonic is on final frame at end of game||Art compression<BR>00, 36 blocks
|-
|7C0AA||Sonic continue ||Art compression<BR>12 blocks
|-
|7C20C||Tails life counter ||Art compression<BR>12 blocks
|-
|7C2F2||Tails continue ||Art compression<BR>12 blocks
|-
|7C43E||ASCII characters used in game ||Art compression<BR>00, 88 blocks
|-
|7C9AE||1P/2P wins text from 2P mode||Art compression<BR>38 blocks
|-
|7CD30||Sonic/Miles animated background from options and level select menu||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|7D22C||Title card patterns||Art compression<BR>94 blocks
|-
|7D58A||Alphabet for font using large broken letters||Art compression<BR>92 blocks
|-
|7D990||A menu box with a shadow||Art compression<BR>21 blocks
|-
|7DA10||Pictures in level preview box in level select||Art compression<BR>170 blocks
|-
|7E86A||Unknown. More text I haven't figured out||Art compression<BR>68 blocks
|-
|7EB58||Text for end of special stage, along with patterns for 3 emeralds.||Art compression<BR>72 blocks
|-
|7EEBE||"Perfect" text||Art compression<BR>00, 14 blocks
|-
|7EF60||Bluebird||Art compression<BR>00, 16 blocks
|-
|7F0A2||Squirrel||Art compression<BR>00, 20 blocks
|-
|7F206||Mouse||Art compression<BR>00, 20 blocks
|-
|7F340||Chicken||Art compression<BR>16 blocks
|-
|7F4A2||Beaver||Art compression<BR>00, 20 blocks
|-
|7F5E2||Penguin||Art compression<BR>16 blocks
|-
|7F710||Pig||Art compression<BR>18 blocks
|-
|7F846||Seal||Art compression<BR>00, 14 blocks
|-
|7F962||Penguin||Art compression<BR>00, 18 blocks
|-
|7FADE||Turtle||Art compression<BR>00, 20 blocks
|-
|7FC90||Bears||Art compression<BR>00, 20 blocks
|-
|7FDD2||Rabbit||Art compression<BR>00, 18 blocks
|-
|7FF2A||Rivet thing that you bust to get inside ship at the end of WFZ||Art compression<BR>00, 4 blocks
|-
|7FF98||Breakaway panels in WFZ||Art compression<BR>15 blocks
|-
|8007C||Spiked ball from OOZ||Art compression<BR>00, 32 blocks
|-
|80274||Unknown. HPZ style shaded blocks||Art compression<BR>6 blocks
|-
|8030A||Striped blocks from CPZ||Art compression<BR>4 blocks
|-
|80376||Oil falling into oil in OOZ||Art compression<BR>16 blocks
|-
|804F2||Cascading oil from OOZ||Art compression<BR>13 blocks
|-
|805C0||Ball on spring from OOZ||Art compression<BR>20 blocks
|-
|806E0||Spinball from OOZ||Art compression<BR>53 blocks
|-
|809D0||Collapsing platform form OOZ||Art compression<BR>40 blocks
|-
|80C64||Diagonal and vertical weird spring from OOZ||Art compression<BR>30 blocks
|-
|80E26||Swinging platform from OOZ||Art compression<BR>28 blocks
|-
|81048||4 stripy blocks from OOZ||Art compression<BR>4 blocks
|-
|810B8||Raising platform in OOZ||Art compression<BR>24 blocks
|-
|81254||Fan in OOZ||Art compression<BR>30 blocks
|-
|81514||Green flame from thingy that shots platform up in OOZ||Art compression<BR>18 blocks
|-
|81600||Patterns for appearing and disappearing string of platforms in CNZ||Art compression<BR>00, 4 blocks
|-
|81668||Spiky ball from poky in CNZ||Art compression<BR>00, 04 blocks
|-
|816C8||Moving cube from either CNZ and CPZ||Art compression<BR>16 blocks
|-
|817B4||Elevator in CNZ||Art compression<BR>4 blocks
|-
|81826||Bars from pokies in CNZ||Art compression<BR>12 blocks
|-
|81894||Hexagonal bumper in CNZ||Art compression<BR>6 blocks
|-
|8191E||Normal round bumper from CNZ||Art compression<BR>24 blocks
|-
|81AB0||Diagonal spring from CNZ that you pull back on||Art compression<BR>32 blocks
|-
|81C96||Vertical red spring||Art compression<BR>18 blocks
|-
|81DCC||Weird blocks in CNZ that you hit 3 times to get rid of them||Art compression<BR>28 blocks
|-
|81EF2||Flippers from CNZ||Art compression<BR>52 blocks
|-
|82216||Large moving platform from CPZ||Art compression<BR>00, 10 blocks
|-
|82364||Top of water in HPZ and CPZ||Art compression<BR>00, 24 blocks
|-
|824D4||Booster things in CPZ||Art compression<BR>00, 4 blocks
|-
|8253C||CPZ enemy made up of a string of balls||Art compression<BR>00, 04 blocks
|-
|825AE||CPZ metal things||Art compression<BR>33 blocks
|-
|827B8||CPZ large moving platform blocks||Art compression<BR>4 blocks
|-
|827F8||Stripy blocks from CPZ||Art compression<BR>8 blocks
|-
|82864||Small yellow moving platform from CPZ||Art compression<BR>48 blocks
|-
|82A46||Moving block from CPZ||Art compression<BR>24 blocks
|-
|82C06||Spring that covers tube in CPZ||Art compression<BR>32 blocks
|-
|82E02||Top of water in ARZ||Art compression<BR>00, 16 blocks
|-
|82EE8||Leaves from ARZ||Art compression<BR>00, 07 blocks
|-
|82F74||Arrow shooter and arrow from ARZ||Art compression<BR>00, 17 blocks
|-
|830D2||One way barrier from ARZ||Art compression<BR>8 blocks
|-
|8316A||Buzz bomber||Art compression<BR>00, 28 blocks
|-
|8336A||Octopus badnick from OOZ||Art compression<BR>00, 58 blocks
|-
|8368A||Flying badnick from OOZ||Art compression<BR>00, 56 blocks
|-
|839EA||Fish badnick from EHZ||Art compression<BR>22 blocks
|-
|83BF6||Robotnic's main ship||Art compression<BR>96 blocks
|-
|84332||Robotnic enemy from CPZ||Art compression<BR>111 blocks
|-
|84890||Large explosion||Art compression<BR>00, 100 blocks
|-
|84F18||Mini explosion||Art compression<BR>00, 8 blocks
|-
|84F96||Unknown. Trail of smoke of some kind.||Art compression<BR>00, 16 blocks
|-
|8507C||EHZ boss||Art compression<BR>128 blocks
|-
|85868||Chopper blades for EHZ boss||Art compression<BR>00, 20 blocks
|-
|8595C||HTZ boss||Art compression<BR>00, 107 blocks
|-
|86128||ARZ boss||Art compression<BR>166 blocks
|-
|86B6E||MCZ boss||Art compression<BR>204 blocks
|-
|87AAC||CNZ boss||Art compression<BR>00, 133 blocks
|-
|882D6||OOZ boss||Art compression<BR>181 blocks
|-
|88DA6||MTZ boss||Art compression<BR>124 blocks
|-
|894E4||Unknown||Uncompressed<BR> 
[[#Uncompressed_art|Further info]]
|-
|89534||Blowfly from ARZ||Art compression<BR>00, 9 blocks
|-
|8970E||Grounder from ARZ||Art compression<BR>00, 50 blocks
|-
|89B9A||Fish from ARZ||Art compression<BR>24 blocks
|-
|89DEC||Lava snake from HTZ||Art compression<BR>00, 19 blocks
|-
|89FAA||Enemy with spike cone on top form HTZ||Art compression<BR>20 blocks
|-
|8A142||Circular badnick from SCZ||Art compression<BR>28 blocks
|-
|8A362||Turtle badnick from SCZ||Art compression<BR>00, 57 blocks
|-
|8A87A||Coconuts from EHZ||Art compression<BR>38 blocks
|-
|8AB36||Snake like badnick from MCZ||Art compression<BR>10 blocks
|-
|8AC5E||Firefly from MCZ||Art compression<BR>00, 20 blocks
|-
|8AD80||Praying mantis badnick from MTZ||Art compression<BR>00, 32 blocks
|-
|8B058||Crab badnick from MCZ||Art compression<BR>00, 36 blocks
|-
|8B300||Exploding star badnick from MTZ||Art compression<BR>00, 15 blocks
|-
|8B430||Weird crawling badnick from CPZ||Art compression<BR>00, 32 blocks
|-
|8B6B4||Spider badnick in CPZ||Art compression<BR>00, 45 blocks
|-
|8B9DC||Scratch from WFZ||Art compression<BR>26 blocks
|-
|8BC16||Jet like badnick from SCZ||Art compression<BR>00, 25 blocks
|-
|8BE12||Robotic sonic||Art compression<BR>00, 217 blocks
|-
|8CC44||The tornado||Art compression<BR>79 blocks
|-
|8D1A0||Wall turret from WFZ||Art compression<BR>24 blocks
|-
|8D388||Hook on chain in WFZ||Art compression<BR>00, 20 blocks
|-
|8D540||Retracting platform from WFZ||Art compression<BR>54 blocks
|-
|8D7D8||Wheel for belt in WFZ||Art compression<BR>00, 16 blocks
|-
|8D96E||Moving platform in WFZ||Art compression<BR>00, 12 blocks
|-
|8DA6E||Giant unused vertical red laser in WFZ||Art compression<BR>12 blocks
|-
|8DAFC||Clouds||Art compression<BR>00, 18 blocks
|-
|8DC42||Red horizontal laser in WFZ||Art compression<BR>10 blocks
|-
|8DCA2||Platform that shoots sonic across from WFZ||Art compression<BR>00, 05 blocks
|-
|8DD0C||Rising platforms on belt from WFZ||Art compression<BR>00, 12 blocks
|-
|8DDF6||Unused badnick in WFZ||Artcompression<BR>12 blocks
|-
|8DEB8||Vertical spinning blades from WFZ||Art compression<BR>4 blocks
|-
|8DEE8||Horizontal spinning blades from WFZ||Art compression<BR>00, 29 blocks
|-
|8E010||Platforms that tilt in WFZ||Art compression<BR>12 blocks
|-
|8E0C4||Thrust from Robotnic's getaway ship in WFZ||Art compression<BR>00, 8 blocks
|-
|8E138||Laser boss from WFZ||Art compression<BR>00, 117 blocks
|-
|8E886||Robotnic's head||Art compression<BR>00, 24 blocks
|-
|8EA5A||Robotnic||Art compression<BR>76 blocks
|-
|8EE52||Robotnic's lower half||Art compression<BR>28 blocks
|-
|8EF96||Window in back that Robotnic looks through in DEZ||Art compression<BR>00, 08 blocks
|-
|8F024||Death egg||Art compression<BR>327 blocks
|-
|901A4||Bouncer badnik from CPZ||Art compression<BR>42 blocks
|-
|90520||Rocket thruster for tornado||Art compression<BR>00, 26 blocks
|-
|906DE-90973||Mappings for movie sequence and images at end of game||     
|-
|90974||Movie sequence at end of game||Art compression<BR>00, 193 blocks
|-
|91F3C||Final image of tornado with it and sonic facing screen||Art compression<BR>00, 127 blocks
|-
|927E0||Mini pictures of tornado in final ending sequence||Art compression<BR>00, 109 blocks
|-
|92F0A||Mini pictures of sonic and final image of sonic||Art compression<BR>135 blocks
|-
|93848||Mini pictures of sonic and final image of sonic in supersonic mode||Art compression<BR>117 blocks
|-
|93F3C||Final image of Tails ||Art compression<BR>181 blocks
|-
|94B28||Sonic the hedgehog 2 image at end of credits||Art compression<BR>72 blocks
|-
|94E74||EHZ 16x16 block mappings||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|95C24||EHZ/HTZ main level patterns||Compressed<BR> 
[[#Main_level_pattern_blocks|Further info]] 
|-
|985A4||HTZ 16x16 block mappings||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|98AB4||HTZ pattern suppliment to EHZ level patterns||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|99D34||EHZ/HTZ 128x128 block mappings||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|9CFD4||MTZ 16x16 block mappings||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|9DB64||MTZ main level patterns||Compressed<BR> 
[[#Main_level_pattern_blocks|Further info]] 
|-
|A06C4||MTZ 128x128 block mappings||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|A3364||OOZ 16x16 block mappings||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|A4204||OOZ main level patterns||Compressed<BR> 
[[#Main_level_pattern_blocks|Further info]] 
|-
|A6834||OOZ 128x128 block mappings||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|A8D04||MCZ 16x16 block mappings||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|A9D74||MCZ main level patterns||Compressed<BR> 
[[#Main_level_pattern_blocks|Further info]] 
|-
|AD454||MCZ 128x128 block mappings||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|AFFC4||CNZ 16x16 block mappings||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|B0894||CNZ main level patterns||Compressed<BR> 
[[#Main_level_pattern_blocks|Further info]] 
|-
|B2CF4||CNZ 128x128 block mappings||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|B5234||CPZ/DEZ 16x16 block mappings||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|B6174||CPZ/DEZ main level patterns||Compressed<BR> 
[[#Main_level_pattern_blocks|Further info]] 
|-
|B90F4||CPZ/DEZ 128x128 block mappings||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|BB944||ARZ 16x16 block mappings||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|BCC24||ARZ main level patterns||Compressed<BR> 
[[#Main_level_pattern_blocks|Further info]] 
|-
|C1434||ARZ 128x128 block mappings||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|C4074||WFZ/SCZ 16x16 block mappings||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|C5004||WFZ/SCZ main level patterns||Compressed<BR> 
[[#Main_level_pattern_blocks|Further info]] 
|-
|C7EC4||WFZ pattern suppliment to SCZ tiles||Compressed<BR> 
[[#Main_level_block_mappings|Further info]] 
|-
|C85E4||WFZ/SCZ 128x128 block mappings||Compressed<BR> 
[[#Main_level_block_mappings|Further info]]
|-
|CA906-?????||????????? (Special stage stuff)||     
|-
|DCD68||Background patterns for special stage ||Art compression<BR>127 blocks
|-
|DD48A||Sonic/Miles and number text from special stage ||Art compression<BR>62 blocks
|-
|DD790||"Start" patterns in special stage ||Art compression<BR>48 blocks
|-
|DD8CE||Stars in special stage ||Art compression<BR>00, 37 blocks
|-
|DD9C8||Unknown. Text in special stage. ||Art compression<BR>13 blocks
|-
|DDA7E||Ring patterns in special stage ||Art compression<BR>104 blocks
|-
|DDFA4||Horizontal shadow patterns in special stage ||Art compression<BR>38 blocks
|-
|DE05A||Diagonal shadow patterns from special stage ||Art compression<BR>58 blocks
|-
|DE120||Vertical shadow patterns in special stage ||Art compression<BR>25 blocks
|-
|DE188||Explosion patterns in special stage ||Art compression<BR>00, 48 blocks
|-
|DE4BC||Bomb patterns in special stage ||Art compression<BR>80 blocks
|-
|DE8AC||Emerald patterns in special stage ||Art compression<BR>46 blocks
|-
|DEAF4||Unknown. Text in special stage. ||Art compression<BR>99 blocks
|-
|DEEAE||Sonic and tails' animation frames from special stage ||Art compression<BR>851 blocks
|-
|E247E||"Tails" Patterns from special stage ||Art compression<BR>5 blocks
|-
|E24FE||?????????? (affected sprites in special stage)||     
|-
|E34EE||Unknown. looks like a really crap falling water thing. ||Art compression<BR>00, 12 blocks
|-
|E35F2||?????????? (compressed block of data to do with sprites for special stage)||Compressed<BR>
|-
|E427C||Data block acting as seperator||     
|-
|E4300||Offset index of ring location lists ||
[[#Offset_indexes|Further info]]
|-
|E4344||EHZ act 1 ring locations||
[[#Ring_placement|Further info]]  
|-
|E456A||EHZ act 2 ring locations||
[[#Ring_placement|Further info]] 
|-
|E47AC||Unknown (empty)||
[[#Ring_placement|Further info]] 
|-
|E47AE||Unknown (empty)||
[[#Ring_placement|Further info]] 
|-
|E47B0||Unknown (empty)||
[[#Ring_placement|Further info]] 
|-
|E47B2||Unknown (empty)||
[[#Ring_placement|Further info]] 
|-
|E47B4||Unknown (empty)||
[[#Ring_placement|Further info]] 
|-
|E47B6||Unknown (empty)||
[[#Ring_placement|Further info]] 
|-
|E47B8||MTZ act 1 ring locations||
[[#Ring_placement|Further info]] 
|-
|E4A2A||MTZ act 2 ring locations||
[[#Ring_placement|Further info]] 
|-
|E4C48||MTZ act 3 ring locations||
[[#Ring_placement|Further info]] 
|-
|E4D72||MTZ act 4 ring locations (empty)||
[[#Ring_placement|Further info]] 
|-
|E4D74||HTZ act 1 ring locations||
[[#Ring_placement|Further info]] 
|-
|E4EAA||HTZ act 2 ring locations||
[[#Ring_placement|Further info]] 
|-
|E50E8||HPZ act 1 ring locations||
[[#Ring_placement|Further info]] 
|-
|E525A||HPZ act 2 ring locations (empty)||
[[#Ring_placement|Further info]] 
|-
|E525C||Unknown (empty)||
[[#Ring_placement|Further info]] 
|-
|E525E||Unknown (empty)||
[[#Ring_placement|Further info]] 
|-
|E5260||OOZ act 1 ring locations||
[[#Ring_placement|Further info]] 
|-
|E5422||OOZ act 2 ring locations||
[[#Ring_placement|Further info]] 
|-
|E5598||MCZ act 1 ring locations||
[[#Ring_placement|Further info]] 
|-
|E570E||MCZ act 2 ring locations||
[[#Ring_placement|Further info]] 
|-
|E5944||CNZ act 1 ring locations||
[[#Ring_placement|Further info]] 
|-
|E5B7E||CNZ act 2 ring locations||
[[#Ring_placement|Further info]] 
|-
|E5E2C||CPZ act 1 ring locations||
[[#Ring_placement|Further info]] 
|-
|E5F9E||CPZ act 2 ring locations||
[[#Ring_placement|Further info]] 
|-
|E6150||DEZ act 1 ring locations (empty)||
[[#Ring_placement|Further info]] 
|-
|E6152||DEZ act 2 ring locations (empty)||
[[#Ring_placement|Further info]] 
|-
|E6154||WFZ act 1 ring locations||
[[#Ring_placement|Further info]] 
|-
|E6292||WFZ act 2 ring locations||
[[#Ring_placement|Further info]] 
|-
|E6294||ARZ act 1 ring locations||
[[#Ring_placement|Further info]] 
|-
|E642E||ARZ act 2 ring locations||
[[#Ring_placement|Further info]] 
|-
|E6684||SCZ act 1 ring locations||
[[#Ring_placement|Further info]] 
|-
|E66D6||SCZ act 2 ring locations (empty)||
[[#Ring_placement|Further info]] 
|-
|E66D8||Data block acting as seperator||
[[#Ring_placement|Further info]] 
|-
|E6800||Offset index of sprite lists||
[[#Offset_indexes|Further info]]
|-
|E684A||EHZ act 1 sprite locations||
[[#Sprite_placement|Further info]]
|-
|E6B7A||EHZ act 2 sprite locations||
[[#Sprite_placement|Further info]]
|-
|E6F34||MTZ act 1 sprite locations||
[[#Sprite_placement|Further info]]
|-
|E73C0||MTZ act 2 sprite locations||
[[#Sprite_placement|Further info]]
|-
|E78EE||MTZ act 3 sprite locations||
[[#Sprite_placement|Further info]]
|-
|E7F48||WFZ act 1 sprite locations||
[[#Sprite_placement|Further info]]
|-
|E82FC||WFZ act 2 sprite locations (empty)||
[[#Sprite_placement|Further info]]
|-
|E8302||HTZ act 1 sprite locations||
[[#Sprite_placement|Further info]]
|-
|E8668||HTZ act 2 sprite locations||
[[#Sprite_placement|Further info]]
|-
|E8C80||HPZ act 1 sprite locations||
[[#Sprite_placement|Further info]]
|-
|E8D94||HPZ act 2 sprite locations (empty)||
[[#Sprite_placement|Further info]]
|-
|E8D9A||Unknown (empty)||
[[#Sprite_placement|Further info]]
|-
|E8DA0||OOZ act 1 sprite locations||
[[#Sprite_placement|Further info]]
|-
|E9214||OOZ act 2 sprite locations||
[[#Sprite_placement|Further info]]
|-
|E968E||MCZ act 1 sprite locations||
[[#Sprite_placement|Further info]]
|-
|E99A0||MCZ act 2 sprite locations||
[[#Sprite_placement|Further info]]
|-
|E9D1E||CNZ act 1 sprite locations||
[[#Sprite_placement|Further info]]
|-
|EA3D8||CNZ act 2 sprite locations||
[[#Sprite_placement|Further info]]
|-
|EA9D2||CPZ act 1 sprite locations||
[[#Sprite_placement|Further info]]
|-
|EAD6E||CPZ act 2 sprite locations||
[[#Sprite_placement|Further info]]
|-
|EB230||DEZ act 1 sprite locations||
[[#Sprite_placement|Further info]]
|-
|EB254||DEZ act 2 sprite locations (empty)||
[[#Sprite_placement|Further info]]
|-
|EB25A||ARZ act 1 sprite locations||
[[#Sprite_placement|Further info]]
|-
|EB6A4||ARZ act 2 sprite locations||
[[#Sprite_placement|Further info]]
|-
|EBBDE||SCZ act 1 sprite locations||
[[#Sprite_placement|Further info]]
|-
|EBD4C||SCZ act 2 sprite locations (empty)||
[[#Sprite_placement|Further info]]
|-
|EBD52||Unknown (empty)||
[[#Sprite_placement|Further info]]
|-
|EBD58||Unknown (empty)||
[[#Sprite_placement|Further info]]
|-
|EBD5E||Unknown (empty)||
[[#Sprite_placement|Further info]]
|-
|EBD64||Unknown (empty)||
[[#Sprite_placement|Further info]]
|-
|EBD66||Data block acting as seperator||     
|-
|EC000||????????? (Sound effects?)||     
|-
|ED100||????????? (instruments?)||     
|-
|F0160||Fireball from EHZ||Art compression<BR>20 blocks
|-
|F02D6||Waterfall tiles ||Art compression<BR>24 blocks
|-
|F03DC||Another fireball ||Art compression<BR>00,16 blocks
|-
|F052A||Bridge in EHZ ||Art compression<BR>00, 8 blocks
|-
|F0602||Diagonally moving lift in HTZ ||Art compression<BR>48 blocks
|-
|F08F6||One way barrier from HTZ ||Art compression<BR>4 blocks
|-
|F096E||See-saw in HTZ ||Art compression<BR>24 blocks
|-
|F0B06||Fireball from HTZ ||Art compression<BR>24 blocks
|-
|F0C14||Rock from HTZ ||Art compression<BR>20 blocks
|-
|F0D4A||Badnick from HTZ with 4 balls of fire spinning around him||Art compression<BR>4 blocks
|-
|F0DB6||Large spinning wheel from MTZ ||Art compression<BR>120 blocks
|-
|F120E||Indent in large spinning wheel from MTZ ||Art compression<BR>9 blocks
|-
|F12B6||Unknown. MTZ block.||Art compression<BR>00, 8 blocks
|-
|F1384||Steam from MTZ||Art compression<BR>00, 15 blocks
|-
|F148E||Spike from MTZ||Art compression<BR>00, 8 blocks
|-
|F1550||Similarly shaded blocks from MTZ||Art compression<BR>54 blocks
|-
|F15C6||Lava bubble from MTZ ||Art compression<BR>00, 9 blocks
|-
|F167C||Unknown. A steam vent? ||Art compression<BR>00, 4 blocks
|-
|F16EC||Things from MTZ ||Art compression<BR>8 blocks
|-
|F178E||Small cog from MTZ ||Art compression<BR>00, 12 blocks
|-
|F1870||Unknown. Four blocks that are all the same colour from MTZ. ||Art compression<BR>00, 4 blocks
|-
|F187E||Large wooden box from MCZ ||Art compression<BR>32 blocks
|-
|F1ABA||Collapsing platform from MCZ ||Art compression<BR>00, 26 blocks
|-
|F1C64||Switch that you pull on from MCZ ||Art compression<BR>16 blocks
|-
|F1D5C||Vine that lowers in MCZ ||Art compression<BR>10 blocks
|-
|F1E06||Unknown. A log viewed from the end ||Art compression<BR>00, 4 blocks
|-
|F1E8C||SEGA intro sound||16000Hz mono<BR>8-bit unsigned<BR>PCM raw audio<BR> 
[[#Sega_intro_sound|Further info]] 
|-
|F8000-?????||????????? (Midis?)||     
|}

==Offset indexes==
<P>An offset index is a handy way of keeping a block of data grouped together, and also replacing a whole heap of pointers. The way it works is there is a list of two byte values, and depending on the block of data the game wants to load, it will take one of those values and add it to the starting address of the offset index. The most common usage is for every act of every level value, there is an offset that acts as the pointer to the block of data to use for it. Lets look at an example:</P><br>
<P>REV00:</P><br>

<P>E6600: 004A 037A 5552 5552 5552 5552 5552 5552 0734 0BC0 10EE 10EE 1748 1AFC</P><br>

<P>REV01:</P><br>

<P>E6800: 004A 037A 5552 5552 5552 5552 5552 5552 0734 0BC0 10EE 10EE 1748 1AFC</P><br>

<P>Now this is the beginning of the offset index for the sprite locations. Now, can you see which values are the offset for MTZ act 2? They're 0BC0. All you had to do to get that was to take the level value for MTZ, which is 04, and count across four bytes for every value it is above 00, then across another two because it's the second act. Now we take that value and using a hex calculator, add it to the address of the offset table, which is E6800. That will give us a value of E73C0, which is the address in the rom of the MTZ act 2 sprite locations.</P><br>
<P>Also notice those 5552 values in there? Well those are for the unused level values in the game. You'll see some damn weird values put in for them in many places, and that's what causes the game to lockup in the final build of sonic 2 if you try and enter one of those levels.</P><br>
<P>There are other forms of an offset index such as the one where there's just one offset per level value, and another type that actually uses a double offset index. The first is easy enough, but a double offset index will specify two values per level, but that's not for act one and two, but rather two blocks of data to use for both acts.</P><br>

==Main level load block==
This 
pointer table is what is used to load up the block mappings and main level 
patterns for every level in the game. Here's a breakdown of the pointer table in 
the S2 rom:
<P>
<BLOCKQUOTE>42594-42660: Indexed main level load block 
  (patterns/16x16/128x128)<BR>
  <BLOCKQUOTE>42594-425A0: Emerald hill zone (00)<BR>
    <BLOCKQUOTE>42594: EHZ/HTZ main level patterns (95C24) [04]<BR>42598: EHZ/HTZ 16x16 block mappings (94E74) [05]<BR>4259C: EHZ/HTZ 128x128 block 
 mappings (99D34) [04]<BR></BLOCKQUOTE>425A0-425AC: Unknown (01)<BR>
    <BLOCKQUOTE>425A0: EHZ/HTZ main level patterns (95C24) [06]<BR>425A4: EHZ/HTZ 16x16 block mappings (94E74) [07]<BR>425A8: EHZ/HTZ 128x128 block 
 mappings (99D34) [05]<BR></BLOCKQUOTE>425AC-425B8: Unknown (02)<BR>
 <BLOCKQUOTE>425AC: EHZ/HTZ main level patterns (95C24) [08]<BR>425B0: EHZ/HTZ 16x16 block mappings (94E74) [09]<BR>425B4: EHZ/HTZ 128x128 block 
 mappings (99D34) [06]<BR></BLOCKQUOTE>425B8-425C4: Unknown (03)<BR>
 <BLOCKQUOTE>425B8: EHZ/HTZ main level patterns (95C24) [0A]<BR>425BC: EHZ/HTZ 16x16 block mappings (94E74) [0B]<BR>425C0: EHZ/HTZ 128x128 block 
 mappings (99D34) [07]<BR></BLOCKQUOTE>425C4-425D0: Metropolis zone (04)<BR>
 <BLOCKQUOTE>425C4: MTZ main level patterns (9DB64) [0C]<BR>425C8: MTZ 16x16 block mappings (9CFD4) [0D]<BR>425CC: MTZ 128x128 block mappings 
 (A06C4) [08]<BR></BLOCKQUOTE>425D0-425DC: Metropolis zone act 3 (05)<BR>
 <BLOCKQUOTE>425E0: MTZ main level patterns (9DB64) [0C]<BR>425E4: MTZ 16x16 block mappings (9CFD4) [0D]<BR>425E8: MTZ 128x128 block mappings 
 (A06C4) [08]<BR></BLOCKQUOTE>425DC-425E8: Wing fortress zone (06)<BR>
 <BLOCKQUOTE>425DC: WFZ/SCZ main level patterns [10]<BR>425E0: WFZ/SCZ 16x16 block mappings [11]<BR>425E4: WFZ/SCZ 128x128 block mappings 
 [0A]<BR></BLOCKQUOTE>425E8-425F4: Hill top zone (07)<BR>
 <BLOCKQUOTE>425E8: EHZ/HTZ main level patterns (95C24) [12]<BR>425EC: EHZ/HTZ 16x16 block mappings (94E74) [13]<BR>425F0: EHZ/HTZ 128x128 block 
 mappings (99D34) [0B]<BR></BLOCKQUOTE>425F4-42600: Hidden Palace zone (08)<BR>
 <BLOCKQUOTE>425F4: OOZ 16x16 block mappings (A3364) [14]<BR>425F8: OOZ 16x16 block mappings (A3364) [15]<BR>425FC: OOZ 16x16 block mappings 
 (A3364) [0C]<BR></BLOCKQUOTE>42600-4260C: Unknown (09)<BR>
 <BLOCKQUOTE>42600: EHZ/HTZ main level patterns (95C24) [16]<BR>42604: 
 EHZ/HTZ 16x16 block mappings (94E74) [17]<BR>42608: EHZ/HTZ 128x128 block 
 mappings (99D34) [0D]<BR></BLOCKQUOTE>4260C-42618: Oil ocean zone (0A)<BR>
 <BLOCKQUOTE>4260C: OOZ main level patterns (A4204) [18]<BR>42610: OOZ 
 16x16 block mappings (A3364) [19]<BR>42614: OOZ 128x128 block mappings 
 (A6834) [0E]<BR></BLOCKQUOTE>42618-42624: Mystic cave zone (0B)<BR>
 <BLOCKQUOTE>42618: MCZ main level patterns (A9D74) [1A]<BR>4261C: MCZ 
 16x16 block mappings (A8D04) [1B]<BR>42620: MCZ 128x128 block mappings 
 (AD454) [0F]<BR></BLOCKQUOTE>42624-42630: Casino night zone (0C)<BR>
 <BLOCKQUOTE>42624: CNZ main level patterns (B0894) [1C]<BR>42628: CNZ 
 16x16 block mappings (AFFC4) [1D]<BR>4262C: CNZ 128x128 block mappings 
 (B2CF4) [10]<BR></BLOCKQUOTE>42630-4263C: Chemical plant zone (0D)<BR>
 <BLOCKQUOTE>42630: CPZ/DEZ main level patterns (B6174) [1E]<BR>42634: 
 CPZ/DEZ 16x16 block mappings (B5234) [1F]<BR>42638: CPZ/DEZ 128x128 block 
 mappings (B90F4) [11]<BR></BLOCKQUOTE>4263C-42648: Death egg zone (0E)<BR>
 <BLOCKQUOTE>4263C: CPZ/DEZ main level patterns (B6174) [20]<BR>42640: 
 CPZ/DEZ 16x16 block mappings (B5234) [21]<BR>42644: CPZ/DEZ 128x128 block 
 mappings (B90F4) [12]<BR></BLOCKQUOTE>42648-42654: Aquatic ruin zone (0F)<BR>
 <BLOCKQUOTE>42648: CPZ/DEZ main level patterns (BCC24) [22]<BR>4264C: 
 CPZ/DEZ 16x16 block mappings (BB944) [23]<BR>42650: CPZ/DEZ 128x128 block 
mappings (C1434) [13]<BR></BLOCKQUOTE>42654-42660: Sky chase zone (10)<BR>
 <BLOCKQUOTE>42654: WFZ/SCZ main level patterns (C5004) [24]<BR>42658: 
WFZ/SCZ 16x16 block mappings (C4074) [25]<BR>4265C: WFZ/SCZ 128x128 block 
mappings (C85E4) [14]<BR></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE>

Now as you can see, these pointers specify the loading addresses in the rom for the 16x16 and 128x128 block mappings, as well as the main pattern block for that level. The main pattern block will always be loaded into the VRAM at address 0000. These loading addresses are all preceeded by a one byte value, so the address pointer only uses three bytes rather than the standard four. The value that proceeds the 128x128 block mappings specifies a value on the palette index to load for that level. For more information on the palette system, go [[#Palettes|here]]. The values preceeding the main level pattern and 16x16 block mapping pointers give the index numbers of the pattern load cue's to use for that level. For more information on that go [[#Pattern_load_cue's|here]].

==Pattern load cues==
The pattern load cues are what loads all the pieces of art into the VRAM that are not in the main level load block. Here's a breakdown of the pattern load cues in the S2 rom:<br><br>

{|border="1"
|00||426E6||Standard block 1 (score\time\rings/lives/ring/numbers)||(3)
|-
|01||42700||Standard block 2 (starpoll/monitor/stars/bubbles)||(3)
|-
|02||4271A||pattern block for level with water (explosion/stars/bubbles)||(2)
|-
|03||4272E||game/time over (game\time over text)||(0)
|-
|04||42736||EHZ (waterfall/bridge/fireball/buzz bomber/coconuts/fish)||(6)
|-
|05||4275C||EHZ (spikes/diagonal spring/horizontal\vertical spring)||(3)
|-
|06||42776||Miles 1up patch (Miles lives counter)||(0)
|-
|07||4277E||Miles life counter (Miles lives counter)||(0)
|-
|08||42786||Tails 1up patch (Tails lives counter)||(0)
|-
|09||4278E||Tails life counter (Tails lives counter)||(0)
|-
|0A||42796||MTZ (Wheel/Unknown/Unknown/MSC from MTZ/steam/Unknown/MTZ spike/Badnick/starbomb)||(8)
|-
|0B||427CE||MTZ (Button/spikes/Mantis/vertical spring/horizontal spring/Unknown/Lava bubble/Cog/Unknown)||(8)
|-
|0C||42806||WFZ (Tornado/clouds/vertical blades/horizontal blades/jet badnick/unknown/scratch/tilting platforms/tornado/clouds)||(9)
|-
|0D||42844||WFZ (vertical blades/ horizontal blades/ unknown/ turret/ unknown/ unknown/ unknown/ unknown/ belt/ platforms/ retracting platform/ unknown/ trolley/ rivet/ unknown)||(D)
|-
|0E||4289A||HTZ (fireball/rock/conveyor/orbit badnick/unknown badnick/unknown badnick/spikes/diagonal spring/vertical spring/horizontal spring)||(9)
|-
|0F||428D8||HTZ (lift/fireball/unknown)||(2)
|-
|10||428EC||OOZ (green flame/raising platform/spikeball/unknown/unknown/cascading oil/unknown/unknown)||(8)
|-
|11||42924||OOZ (unknown/ unknown/ swinging platform/ unknown/ fan/ button/ spikes/ diagonal spring/ vertical spring/ horizontal spring/ seahorse/ octopus)||(B)
|-
|12||4296E||MCZ (box/collapsing platform/vine switch/lowering vine/firefly/unknown badnick)||(5)
|-
|13||42994||MCZ (long horizontal spike/ spikes/ unknown/ other spring/ vertical spring/ horizontal spring)||(5)
|-
|14||429BA||CNZ (unknown badnick/ moving cube/ unknown/ unknown/ unknown/ unknown/ unknown/ unknown/ unknown/ destroyable blocks)||(9)
|-
|15||429F8||CNZ (poky spring/vertical red spring/spikes/diagonal spring/vertical spring/horizontal spring)||(5)
|-
|16||42A1E||CPZ (CPZ stuff/CPZ stuff/booster/moving platform/small moving platform/spring cap/water surface/moving block/CPZ platform blocks)||(8)
|-
|17||42A56||CPZ (unknown badnick/unknown badnick/spikes/unknown/other spring/vertical spring/horizontal spring)||(6)
|-
|18||42A82||DEZ (stripy blocks from CPZ)||(0)
|-
|19||42A8A||DEZ (robotic sonic/unknown/Robotnic/Robotnic's head/Robotnic's lower half)||(4)
|-
|1A||42AAA||ARZ (one way barrier/water surface/leaves/arrow shooter)||(3)
|-
|1B||42AC4||ARZ (shark/blowfly/grounder/bubbles/spikes/other spring/vertical spring/horizontal spring)||(7)
|-
|1C||42AF6||SCZ (tornado)||(0)
|-
|1D||42AFE||SCZ (clouds/vertical blades/horizontal blades/jet badnick/turtle badnick/bomber)||(5)
|-
|1E||42B24||Sonic end of level results screen (title card patterns/unknown/sonic continue/perfect text)||(3)
|-
|1F||42B3E||End of level signpost (signpost)||(0)
|-
|20||42B46||CPZ boss (Robotnic's main ship/CPZ boss/mini explosion/unknown/large explosion)||(4)
|-
|21||42B66||EHZ boss (Robotnic's main ship/EHZ boss/chopper blades/large explosion)||(3)
|-
|22||42B80||HTZ boss (Robotnic's main ship/HTZ boss/large explosion/unknown)||(3)
|-
|23||42B9A||ARZ boss (Robotnic's main ship/ARZ boss/large explosion)||(2)
|-
|24||42BAE||MCZ boss (Robtnic's main ship/MCZ boss/large explosion)||(2)
|-
|25||42BC2||CNZ boss (Robotnic's main ship/CNZ boss/large explosion)||(2)
|-
|26||42BD6||MTZ boss (Robotnic's main ship/MTZ boss/mini explosion/large explosion)||(3)
|-
|27||42BF0||OOZ boss (OOZ boss/large explosion)||(1)
|-
|28||42BFE||Unknown (large explosion)||(0)
|-
|29||42C06||Death egg (Death egg)||(0)
|-
|2A||42C0E||EHZ animals (squirrel/blue bird)||(1)
|-
|2B||42C1C||MCZ animals (rat/chicken)||(1)
|-
|2C||42C2A||HTZ/MTZ/WFZ animals (beaver/penguin)||(1)
|-
|2D||42C38||DEZ animals (pig/chicken)||(1)
|-
|2E||42C46||Unknown (HPZ animals) (rat/seal)||(1)
|-
|2F||42C54||OOZ animals (penguin/seal)||(1)
|-
|30||42C62||SCZ animals (turtle/chicken)||(1)
|-
|31||42C70||CNZ animals (bears/blue bird)||(1)
|-
|32||42C7E||CPZ animals (rabbit/penguin)||(1)
|-
|33||42C8C||ARZ animals (penguin/blue bird)||(1)
|-
|34||42C9A||Special stage (emerald/unknown/special stage text/horizontal shadow/diagonal shadow/vertical shadow/explosion patterns/special stage ring/"Start"/unknown/special stage background/stars/"Tails")||(C)
|-
|35||42CDE||Unknown (Unknown)||(0)
|-
|36||42CF4||Boss at end of WFZ (Laser boss from WFZ/Robotnic/Robotnic's head/Robotnic's lower half/explosion)||(4)
|-
|37||42D12||Tornado at end of WFZ (tornado/rocket thruster from tornado/clouds)||(2)
|-
|38||42D26||Egg prison (egg prison)||(0)
|-
|39||42D2E||Normal explosion (explosion)||(0)
|-
|3A||42D36||Tails end of level results screen (title card patterns/unknown/tails continue/perfect text)||(3)
|}
<br>
This pointer list has an offset index to locate the correct cue. Go [[#Offset_indexes|here]] for an explanation of how this works. Now, each load cue has a two byte value before it that specifies how many addresses are in the cue, to avoid it reading too far, and going into the next cue. This value is dead simple, just enter the number of patterns on the cue in hex between the first two bytes, but you have to count 00 as 1, so if there was 16 loading addresses in the cue, you'd have 000F preceding it. After that, there are 6 bytes per load request. The first four bytes are a pointer to the art block to use, and the two bytes after that are the location in the VRAM to load them into.To change the pattern load cue's being loaded for a level, you need to change the values in the main level load block. For more information on that go [[#Main_level_load_block|here]].<br>

==Collision definitions==
Ok, I’m going to explain how collision works on objects that are not sprites in the sonic games. First of all forget the image that the block contains. The image has absolutely nothing to do with the collision. There's basically in invisible collision box on top of every 16x16 block that sets what's solid and what's not. This collision box has two parts to it. The main part of it is the collision array (an array is basically a table of values). The collision array stores the actual data that says that is a block is solid in certain places. It does that through 16 bytes per collision box. To understand how those 16 bytes set what's solid, imagine a 16x16 block. Now imagine that 16x16 block with the numbers 1-10 (hex) down the side starting from the bottom and going up to the top, and starting from the left and going up as it moves right along the top, so that you can give an exact location of each pixel. (eg, the top left pixel would be 10,00) Now, in this array the first two bytes define what's solid for the row of pixels on the left side of that 16x16 block. Basically the first of those two bytes says where to start making things solid, and the second byte says where to stop making them solid. So if you entered the value 0010, the first row would be solid from the very bottom of the block all the way up to the top. If you were to enter the value 020E, there would be two pixels on either side of the block that are not solid, and everything in the middle would be. The next two bytes after that are for the next row, etc. After 16 bytes the definitions for the next collision box begin.</P><br>
<P>Now, to specify which blocks use which collision boxes, there are collision indexes, which give an array location for each 16x16 block. If you look at the space used by the collision array, you can divide that by 16 (the number of bytes used by each entry into the array) to give a one byte value, which represents the maximum number of collision boxes that the array can hold in the S2 platform, which is FF. Now, for each level there is at least one 16x16 collision index, and that index consists of a whole heap of array locations, one for each 16x16 block. If for example you wanted the 9th 16x16 block to use the collision box with an array location of 3E, you would give the 9th byte of the collision index for that level a value of 3E.</P><br>
<P>It is through collision indexes that the loops work in the game. It's commonly believed that there are layers, and that the sprite represented by 4 rings changes between them. This is partly true. For any levels that use multiple layers like that, there is a secondary 16x16 collision index. That object switches the 16x16 collision index in use. The pointers to these 16x16 collision indexes are stored at 49E8-4A70. The first set of pointers in this group specify the location of the primary collision index to use for each level, and the second set specify the location of the secondary collision index to use for each level.</P><br>
<P>Now just setting something as solid, doesn't give it the effect of having a slope. There's an index in the rom, which has one byte in it for each collision array location. To understand how this value works, think of two lines running parallel to each other, both with the value 0-F along them. Now, the first value of the byte gives a point on the right line, and the second value gives a point on the left line. Now imagine drawing a line between these to points. If the points are different, the resulting gradient will be taken to create the effect of a slope and the resistance going up it on the box in the corresponding collision array location.</P><br>

==Level layout==
The level data in the S2 rom is compressed. Editing compressed data is extremely impractical, so you can either extract it first using an extraction program such as ChaoSaX-Extract, and once it's in that form refer to my savestate hacking info for information on how to edit it. Once you've finished editing it you can then use the soon to be added compression routine in ChaoSax-Extract to recompress it, and then you can place it back into the rom. If it is a larger size than the original, you will need to fiddle around with the locations and the offset index to get it back in.<br>

==Ring placement==
The data for ring placement has an offset index to locate the correct group. Go [[#Offset_indexes|here]] for an explanation of how this works. Now, in the rom each ring does not have to be stored individually. Instead you can place one ring, and specify that a certain number of rings come after it. The definitions for one ring takes up 4 bytes in the rom. Let's look at an example:<br>
1234 5678<br>
Now, in this example the ring will be placed at an x location of 1234, and a y location of 678. With that value where the 5 was entered, if the value entered is below 8, an additional ring will be placed next to the one before it for every unit that the value entered is above 0. Entering a value above 8 will place an additional ring below the one before it for each unit that the value entered is above 8. When specifying a position as the start of a group of rings, if the group is horizontal, the rings will go across to the right of that point, and if the group is vertical the rings will go down from that point. The value FFFF closes the group of ring locations, and it is essential that this is at the end of the ring locations list, or else the game will keep on reading past that point until it hits that value.<br>

==Sprite placement==
Sprites are quite simple to define. It takes six bytes to define one sprite. The first two bytes are the x location of the sprite, and the next two bytes are the y location of the sprite. The 5th byte is the number on the sprite array to lookup to get the location for the function to use for the programming of that sprite, and the 6th byte is an optional declaration to use with the function for that sprite. Go [[#Sprite_programming|here]] for more info on what exactly that means, and a list of all the sprites in the S2 rom.<br>

==Main level block mappings==
The block mappings in the S2 final rom are compressed. If you want to edit them you need to extract them first, edit them, and then recompress them afterwards. For more information on exactly what the block mappings do, and how to edit them, refer to the sonic 2 savestate breakdown. Note that the 16x16 block mappings in the S2 beta rom are not compressed, so if any port from the beta to the final is to be successful, those mappings will need to be compressed first.<br>

==Main level pattern blocks==
Unlike the beta, the main pattern block for the levels do not use the standard art compression format, but a less complex one to allow the patterns to be loaded faster into the VRAM, and hence cut down on loading times for levels significantly. Also unlike the standard art compression format, this one has been cracked. A decompression utility such as ChaoSaX-Extract is capable of decompressing these patterns. If a port is to be done from the beta, it will be necessary to either allow the game to decompress the main pattern block into the VRAM, and then recompressing the appropriate blocks manually and putting them into the rom, or just cheat and stick these patterns on the pattern load cue. That is rather sloppy though. For information on how to edit extracted patterns, refer to the Sonic 2 savestate breakdown.<br>

==Uncompressed art==
Any art that needs to be updated on the fly will not be compressed in the rom. This is because the game can't work with compressed data, and needs to extract any data it wants to use to the ram. This decompression process takes a fair bit of computation, and because of that it wouldn't be possible to create the appearance of a smooth animation using compressed data. The same reason is true as to why any data that is not loaded into the ram will always be uncompressed, because otherwise they would have to load it into the ram just to read it.<br>
<P>Now, for example all of the blocks for Sonic and Tails are uncompressed, because they of course need to be updated quickly. You can use basically any editing utility to edit them, but you can only change what each block looks like through this. In order to edit what blocks are placed where in each of Sonic's animation frames, you need to edit the mappings for them, and for more information on that go [[#Mappings_for_Sonic/Tails|here]]. Now in their uncompressed form, you can edit them just like you would in the VRAM, so for more information on that check the sonic 2 savestate breakdown.</P><br>

==Mappings for Sonic/Tails==
What the mappings do is they tell the game what patterns to display, and where to put them for each of the frames that the sprite has. The mappings for most sprites are contained within their function (go [[#Sprite_programming|here]] for more details), but with the Sonic and Tails sprites, to allow the programmers to add a new frame easily without having to recompile the function, and hence the whole game because of the size difference, they created a separate array containing the mapping data for each frame. I haven't examined this to see how it works yet, but when I do I’ll explain the format here.<br>

==Sega intro sound==
The Sega intro sound is just a 16000HZ wav sound. Opening up the rom in any sound editing program that supports raw audio with the settings listed next to the location on the list will enable you to playback the sound effect. You could also insert your own sound in the same place as long as it's at the same bitrate. The bitrate is to do with the quality of the sound. The lower it is the crappier it will sound, because that's to do with how often the output is modified. Just think of the difference between long play and short play on a VCR. Stuff recorded in long play does save space, but the quality of the recording is worse.<br>

==Art compression format==
The art compression format is a very dense compression format. It's only used for art because the format relies on the data being in blocks of 64 bytes. This format is used for all the compressed art in sonic 1 and sonic 2 beta, and all the compressed art except for the main level pattern blocks in Sonic 2 and S3&K. As I said this format is very dense, and as such it requires a hell of a lot of computation to decompress. Because of this it also requires a hell of a lot of time and effort to crack. I've had a go at it, but the lightning has yet to strike. When I crack it I’ll post the format breakdown here, and create a simple program to decompress it, but until then it is impossible to directly edit any art using this format. The porting of a compressed block of art is simple though, so if you want to transfer beta art to the final, you can just tack it onto the end and enter the pointer into the pattern load cue of the level or event you want it to appear at, along with a VRAM location to load it into. Go [[#Pattern_load_cue's|here]] for more information on that.<br>

==Dynamic pattern reloading==
Dynamic pattern reloading is a method of loading patterns into the VRAM, but unlike the other methods, this one has no limitations, because it uses actual programmed code. Basically this is here for any effects to do with patterns changing in game that isn't posible using the normal load cue system, like the hills in the background of HTZ where the patterns to display are determined by the position of the screen. Because the programming for it is in the form of compiled code, direct editing of it is not possible.<br>

==Animated pattern load cue's==
Animated patterns require the art they are working with to be in an uncompressed form, so if you are attempting to make an animated pattern, make sure the art is uncompressed or it won't work. Now, the length of each load request on the cue varies depending on the animation. The first byte specifies a value that will determine how often to switch frames in the animation. If you use this value you will not be able to specify a frame as having a different duration to another. Setting this to FF will disable automatic frame control and allow the user to input a manual duration for each frame. This will mean that for every frame the user wants in the animation, they have to allow another byte at the end of the load request. If you want automatic pattern control, which you would use if you want all the animations frames to have the same duration. Just enter how many screen refreshes to wait until the next frame of the animation is displayed. Bytes 2,3, and 4 are the address in the rom to load the patterns from. Bytes 5 and 6 are the location in VRAM to load the patterns into. Byte 7 is the number of frames the animation has, and byte 8 is the number of spaces in VRAM to use for each frame. The function of the bytes beyond this point depend on whether or not automatic frame control is enabled, so refer to appropriate section below.<br><br>
<p>With automatic frame control:<br>
One byte per frame of animation. This byte simply specifies the image to use for each frame of the animation. Based on the loading address entered, this value is the offset in 8x8 blocks to load each frame from in the rom. So if for example you were dealing with an animation that had 4 8x8 blocks per frame, and there were 4 frames of that, and you wanted it to display each frame one by one, you would enter the value 0004 080C.</p><br>
<p>Without automatic frame control:<br>
Two bytes per frame of animation. The first byte is the offset of blocks in the file to load the animation frame from. This byte simply specifies the image to use for each frame of the animation. Based on the loading address entered, this value is the offset in 8x8 blocks to load each frame from in the rom. The second byte is the number of screen refreshes to keep that image loaded for, before going on to the next animation frame.<br>

==Misc sprite definitions==
It looks like there are some sprites that get thier mappings and whatnot from this index, so they can reuse just a couple of sprites for some of the the miscellaneous objects in a level that the character doesn't actually interact with, but those objects can be completely different from one level to the next. A handy way of avioding programming each one individually, and thus saving a hell of a lot of space. As for how to edit them, well I haven't looked at that yet, but when I do i'll post an explination of the format here.<br>

==Rasterised layer deformation==
Raster effects are simply effects to do with deformation of an image based on lines of pixels. In Sonic 2, these effects are used to create the movement effects for the backgrounds of all the levels, as well as the 2 player splitscreen effect. Because the programming for these effects are stored in the form of compiled code, you'll have to learn 68K ASM in order to edit them. Switching between levels is easy enough though, just change the corresponding value on the preceeding offset index to link to the effect you wish to use.<br>

==Palettes==
All the main palettes used in the game are linked in a pointer table at 294E. In this pointer table there are 8 bytes per palette. The first four simply give a location in the rom for the data to load. The fifth and sixth bytes give the location in the system ram to load the data into, and the seventh and eighth bytes give the number of bytes being loaded. Here's a palette pointer:<br><br>0000 2942 FB20 0007<br><br>Now in this case the palette is being loaded from 00002942 in the rom into the beginning of the second above water palette row (FB20), and it's loading 4 colours (0007). Here's a listing of the palette pointers in the S2 rom:<br><br>

<TABLE align=center border=1>
  <TR>
 <TD>00</TD>
 <TD>2782</TD>
 <TD>SEGA screen palette (28C2)</TD></TR>
  <TR>
 <TD>01</TD>
 <TD>278A</TD>
 <TD>Title screen palette (2942)</TD></TR>
  <TR>
 <TD>02</TD>
 <TD>2792</TD>
 <TD>Unknown palette (2962)</TD></TR>
  <TR>
 <TD>03</TD>
 <TD>279A</TD>
 <TD>"Sonic and Miles" screen palette (29E2)</TD></TR>
  <TR>
 <TD>04</TD>
 <TD>27A2</TD>
 <TD>EHZ palete (2A22)</TD></TR>
  <TR>
 <TD>05</TD>
 <TD>27AA</TD>
 <TD>Level value 01 palette (2A22)</TD></TR>
  <TR>
 <TD>06</TD>
 <TD>27B2</TD>
 <TD>WZ palette (2A82)</TD></TR>
  <TR>
 <TD>07</TD>
 <TD>27BA</TD>
 <TD>Level value 03 palette (2A22)</TD></TR>
  <TR>
 <TD>08</TD>
 <TD>27C2</TD>
 <TD>MTZ palette (2AE2)</TD></TR>
  <TR>
 <TD>09</TD>
 <TD>27CA</TD>
 <TD>MTZ act 3 palette (2AE2)</TD></TR>
  <TR>
 <TD>0A</TD>
 <TD>27D2</TD>
 <TD>WFZ palette (2B42)</TD></TR>
  <TR>
 <TD>0B</TD>
 <TD>27DA</TD>
 <TD>HTZ palette (2BA2)</TD></TR>
  <TR>
 <TD>0C</TD>
 <TD>27E2</TD>
 <TD>HPZ palette (2C02)</TD></TR>
  <TR>
 <TD>0D</TD>
 <TD>27EA</TD>
 <TD>Level value 09 (2A22)</TD></TR>
  <TR>
 <TD>0E</TD>
 <TD>27F2</TD>
 <TD>OOZ palette (2CE2)</TD></TR>
  <TR>
 <TD>0F</TD>
 <TD>27FA</TD>
 <TD>MCZ palette (2D42)</TD></TR>
  <TR>
 <TD>10</TD>
 <TD>2802</TD>
 <TD>CNZ palette (2DA2)</TD></TR>
  <TR>
 <TD>11</TD>
 <TD>280A</TD>
 <TD>CPZ palette (2E02)</TD></TR>
  <TR>
 <TD>12</TD>
 <TD>2812</TD>
 <TD>DEZ palette (2EE2)</TD></TR>
  <TR>
 <TD>13</TD>
 <TD>281A</TD>
 <TD>ARZ palette (2F42)</TD></TR>
  <TR>
 <TD>14</TD>
 <TD>2822</TD>
 <TD>SCZ palette (3022)</TD></TR>
  <TR>
 <TD>15</TD>
 <TD>282A</TD>
 <TD>HPZ underwater palette (2C62)</TD></TR>
  <TR>
 <TD>16</TD>
 <TD>2832</TD>
 <TD>CPZ underwater palette (2E62)</TD></TR>
  <TR>
 <TD>17</TD>
 <TD>283A</TD>
 <TD>ARZ underwater palette (2FA2)</TD></TR>
  <TR>
 <TD>18</TD>
 <TD>2842</TD>
 <TD>Main special stage palette (3162)</TD></TR>
  <TR>
 <TD>19</TD>
 <TD>284A</TD>
 <TD>Unknown palette (3082)</TD></TR>
  <TR>
 <TD>1A</TD>
 <TD>2852</TD>
 <TD>Unknown palette (30A2)</TD></TR>
  <TR>
 <TD>1B</TD>
 <TD>285A</TD>
 <TD>Special stage 1 palette (31C2)</TD></TR>
  <TR>
 <TD>1C</TD>
 <TD>2862</TD>
 <TD>Special stage 2 palette (31E2)</TD></TR>
  <TR>
 <TD>1D</TD>
 <TD>286A</TD>
 <TD>Special stage 3 palette (3202)</TD></TR>
  <TR>
 <TD>1E</TD>
 <TD>2872</TD>
 <TD>Special stage 4 palette (3222)</TD></TR>
  <TR>
 <TD>1F</TD>
 <TD>287A</TD>
 <TD>Special stage 5 palette (3242)</TD></TR>
  <TR>
 <TD>20</TD>
 <TD>2882</TD>
 <TD>Special stage 6 palette (3262)</TD></TR>
  <TR>
 <TD>21</TD>
 <TD>288A</TD>
 <TD>Special stage 7 palette (3282)</TD></TR>
  <TR>
 <TD>22</TD>
 <TD>2892</TD>
 <TD>Unknown palette (32A2)</TD></TR>
  <TR>
 <TD>23</TD>
 <TD>289A</TD>
 <TD>Unknown palette (32C2)</TD></TR>
  <TR>
 <TD>24</TD>
 <TD>28A2</TD>
 <TD>Unknown palette (32E2)</TD></TR>
  <TR>
 <TD>25</TD>
 <TD>28AA</TD>
 <TD>OOZ boss palette (30C2)</TD></TR>
  <TR>
 <TD>26</TD>
 <TD>28B2</TD>
 <TD>Menu palette (30E2)</TD></TR>
  <TR>
 <TD>27</TD>
 <TD>28BA</TD>
 <TD>Unknown palette (3302)</TD></TR></TABLE><br>

To change the palette being loaded for each level, you need to change the palette index number in the main level load block. For more information on that go here. The palettes themeslves are very easy to modify as they are all uncompressed in the rom. Refer to the savestate hacking documents for information on how to edit palettes.<br>

==Level size array==
All the sizes of the levels are stored in a simple array, and can be easily modified to change the boundaries of the level. This array is located at C054, and for each act there are four values. The first gives the X start location of the level, and the second gives the X end location of the level. Likewise the third value gives the Y start location of the level, and the fourth gives the Y end location of the level.<br>

==Character start location array==
The start location for the characers and the camera for each level are stored in this array at address C1D0. It couldn't be any simpler to modify, there's just two values per act, the first being the X location, and the second being the Y location.<br>

==Music playlist for levels==
This is actually part of a sub in the code, but it's editable all the same. Pretty simple, just one byte per level. That one byte is the value of the song you wish to play. You must enter the value in the form in which it is displayed in the beta version, which is with 80 as the starting value, not 00 as it is displayed in the final. You'll notice with the value for death egg, it's 08 not 88, which is why there's no sound in the level.<br>

==Level order==
There are several different sections in the game to do with the order of levels. The first one is the one that determins which level the game loads when someone finishes a level. The second one is the one which determins which level to load when you select a level from the level select menu. The level select one is easy to modify, just enter the level value followed by an act number for each of the levels you want to load, in the order you want them to be loaded. For a list of the level values for all the different stages, look at the beginning of the introduction to this page. Note that if you load the same level into the level order twice, when you link to it via the level select, it will continue the sequence from the last one in the list, not the first.<br>
The second system for which level to load when one ends works slightly differently. There is a list of values, with two bytes allocated to each act of each level. That two byte value is simply the value of the level you wish to load when that level ends. So, if you wanted ARZ act 1 to load up when you finish MTZ act 2, you would take the location of the table, which in this case is 142F8, and you would add 18 bytes to that location, and then you would replace the next two bytes from that point with 0F00. That's becuase you add four bytes to the address for every level that comes before it, and in this case there are 4, and then you would add another 2 bytes becuase you want to alter the level to load when you finish the second act.</p>
<p>Also, note that when you want a level to be the last level in the game, you must enter the value FFFF as the stage to load when it finishes. This tells the game to end and return to the title screen.</p><br>

==Object debug list==
This list is what determins what sprites you can place in debug mode, and in what levels. An offset index is used to locate which object debug list to use for which level, so if you want further info on that go [[#Offset_indexes|here]]. Now, there is a 2 byte value at the start of each debug list. That 2 byte value is simply the number of sprites in the list. After that there are 8 bytes per sprite. Here's an object that's present in an object debug list from sonic 2:

<TABLE align=center border=1>
  <TR>
 <TD colSpan=2>2601</TD>
 <TD colSpan=2>2D36</TD>
 <TD colSpan=2>0800</TD>
 <TD colSpan=2>0680</TD></TR>
  <TR>
 <TD><FONT color=red>1</FONT></TD>
 <TD><FONT color=green>2</FONT></TD>
 <TD><FONT color=green>3</FONT></TD>
 <TD><FONT color=green>4</FONT></TD>
 <TD><FONT color=blue>5</FONT></TD>
 <TD><FONT color=yellow>6</FONT></TD>
 <TD><FONT color=pink>7</FONT></TD>
 <TD><FONT color=pink>8</FONT></TD></TR></TABLE><br><br>
And here's a quick referance sheet of what each byte does. For further info 
on each one, refer to information below.<br><br>
<TABLE align=center border=1>
  <TR>
 <TD><FONT color=red>1</FONT></TD>
 <TD>Object number</TD></TR>
  <TR>
 <TD><FONT color=green>2-4</FONT></TD>
 <TD>Sprite mappings</TD></TR>
  <TR>
 <TD><FONT color=blue>5</FONT></TD>
 <TD>Declaration</TD></TR>
  <TR>
 <TD><FONT color=yellow>6</FONT></TD>
 <TD>Frame to display</TD></TR>
  <TR>
 <TD><FONT color=pink>7 and 8</FONT></TD>
 <TD>flip/mirror/palette/VRAM location</TD></TR></TABLE><br><br>
Object number:<br>This value is what determins which object to use. For a list of all the sprites in the game, check out the sprite programming section of this document here. In the case of the above example the object number is 26, which is a monitor.<br><br>Sprite mappings:<br>This is a pointer to the location in the rom to load the mappings for that sprite. This will be located in the programming for the sprite itself. Do not change this unless porting between levels, or you're absolutely sure you know what you're doing, or the game will most likely hang. This only affects the preview picture, not the placed object itself. In this case, the sprite mappings are being loaded from the address 012D36 in the rom.<br><br>Declaration:<br>This is the declaration for the loading of the sprite. For information on exactly what that is, go here. In this example the declaration is 08, which switches the type of monitor it is in the case of this sprite.<br><br>Frame to display:<br>This is simply the frame of the sprite that will be displayed on the preview picture before you place an object. Right now it's set to 00, which is the first frame.<br><br>Flip/mirror/VRAM location:<br>The first hex value of the 7th byte is to do with flipping and mirroring of the sprite, as well as the palette line to use for it. Refer to the following table for an explination of what responce each value will create.<br>

<TABLE align=center border=1>
  <TR align=middle>
 <TD>Value</TD>
 <TD>palette line</TD>
 <TD>flipped horizntally</TD>
 <TD>flipped vertically</TD></TR>
  <TR align=middle>
 <TD>0</TD>
 <TD>1</TD>
 <TD>n</TD>
 <TD>n</TD></TR>
  <TR align=middle>
 <TD>1</TD>
 <TD>1</TD>
 <TD>n</TD>
 <TD>y</TD></TR>
  <TR align=middle>
 <TD>2</TD>
 <TD>2</TD>
 <TD>n</TD>
 <TD>n</TD></TR>
  <TR align=middle>
 <TD>3</TD>
 <TD>2</TD>
 <TD>n</TD>
 <TD>y</TD></TR>
  <TR align=middle>
 <TD>4</TD>
 <TD>3</TD>
 <TD>n</TD>
 <TD>n</TD></TR>
  <TR align=middle>
 <TD>5</TD>
 <TD>3</TD>
 <TD>n</TD>
 <TD>y</TD></TR>
  <TR align=middle>
 <TD>6</TD>
 <TD>4</TD>
 <TD>n</TD>
 <TD>n</TD></TR>
  <TR align=middle>
 <TD>7</TD>
 <TD>4</TD>
 <TD>n</TD>
 <TD>y</TD></TR>
  <TR align=middle>
 <TD>8</TD>
 <TD>1</TD>
 <TD>n</TD>
 <TD>n</TD></TR>
  <TR align=middle>
 <TD>9</TD>
 <TD>1</TD>
 <TD>y</TD>
 <TD>n</TD></TR>
  <TR align=middle>
 <TD>A</TD>
 <TD>2</TD>
 <TD>n</TD>
 <TD>n</TD></TR>
  <TR align=middle>
 <TD>B</TD>
 <TD>2</TD>
 <TD>y</TD>
 <TD>n</TD></TR>
  <TR align=middle>
 <TD>C</TD>
 <TD>3</TD>
 <TD>n</TD>
 <TD>n</TD></TR>
  <TR align=middle>
 <TD>D</TD>
 <TD>3</TD>
 <TD>y</TD>
 <TD>n</TD></TR>
  <TR align=middle>
 <TD>E</TD>
 <TD>4</TD>
 <TD>n</TD>
 <TD>n</TD></TR>
  <TR align=middle>
 <TD>F</TD>
 <TD>4</TD>
 <TD>y</TD>
 <TD>n</TD></TR></TABLE><br>

In the case of our example, the value of 0 is used, so the preview image will use the first palette line, and will not be flipped or mirrored. <br><br>The last hex value of the 7th byte, and all of the 8th byte in this block combine to give a starting location in the VRAM to find the patterns to use for that sprite when displaying the preview. This is not an actual location, but merely the number of blocks after which to load the patterns from. After the value of 800 is passed, the block number resets to zero but the image is mirrored. In this case, that block number is 680.<br><br>And that's about it. I've just realised that this is a rediculous amount of detail for such a small thing, but at least you're sure to get it.<br>

==Sprite programming==
The programming for a sprite in the sonic games are stored as a function, and that function can take one declaration. People often confuse this declaration with a subtype value, but it's not really. What that basically means for the non programmers out there is that when the game places a sprite, you can enter a value along with the sprite number that may alter something about that sprite, but what it does varies depending on what sprite you're working with. Now because these functions are now compiled, the only way you can effectively edit them is to find the code for it and decompile it into assembly, alter it as necessary, and then recompile it and enter it back into the rom. This document will contain all the info necessary to enter a new sprite or replace an old one, but when it comes to the ASM you're on your own. <br><br>Now, the value assigned to a sprite in the game is done by a pointer index at 1600C-1637C. It’s Pretty simple, just one pointer per address value. Here's the pointer list in Sonic 2. I've named all the ones I could at the time. I made this list quite a while ago though, and I think I could do a better job if I redid it now, but I can't be stuffed doing it at this point in time.<br>

{| width="100%" border=1
|-
| 1
| Sonic [19F50]
|-
| 2
| Tails [1B8A4]
|-
| 3
| ??????? [1FCDC]
|-
| 4
| ??????? [208DC]
|-
| 5
| ??????? [1D200]
|-
| 6
| Rotating cylinder in Metropolis zone [214C4]
|-
| 7
| Oil (stretches across entire map) [24020]
|-
| 8
| Unknown (some kind of vertical barrier, but barrier is not visible) [1DD20]
|-
| 9
| ??????? [338EC]
|-
| A
| ??????? [1D320]
|-
| B
| Section of pipe that tips you off from chemical plant zone [2009C]
|-
| C
| Unknown (some strange thing that bobs up and down. Possibly top of water in HPZ.) [20210]
|-
| D
| Unknown (hit it from left or right and get thrown back faster than should be possible) [191B8]
|-
| E
| Flashing stars from intro [12E18]
|-
| F
| ??????? [13600]
|-
| 10
| Unknown (tails won't move) [347EC]
|-
| 11
| ??????? [F66C]
|-
| 12
| Master emerald [2031C]
|-
| 13
| ??????? [203AC]
|-
| 14
| See saw thingy from hill top zone [21928]
|-
| 15
| Swinging platform from ARZ [FC9C]
|-
| 16
| Diagonally moving lift thing from HTZ [21DAC]
|-
| 17
| Unknown (looks like some sort of steam burst like from MTZ) [10310]
|-
| 18
| Stationary floating platform from ARZ [104AC]
|-
| 19
| Unknown (some kind of floating platform that moves back and forth, but not very far) [22018]
|-
| 1A
| Collapsing platform from either OOZ or MCZ [108BC]
|-
| 1B
| Booster things from CPZ [222AC]
|-
| 1C
| ??????? [111D4]
|-
| 1D
| Unknown (seemed to have a random area within a set distance from the sprite in which you could get hurt.) [22408]
|-
| 1E
| Spin tube from CPZ [2259C]
|-
| 1F
| Collapsing platform from OOZ [10A08]
|-
| 20
| Unknown (lava bomb that Robotnic drops in HTZ?) [22FF8]
|-
| 21
| Unknown (sprite just changes between two palette lines) [80BE]
|-
| 22
| Arrow shooter from ARZ [25694]
|-
| 23
| Pillar that drops it's lower part from ARZ [2588C]
|-
| 24
| ??????? [1F8A8]
|-
| 25
| A ring [11F44]
|-
| 26
| Monitor [12670]
|-
| 27
| An explosion of an enemy, giving off an animal and 100 points [21088]
|-
| 28
| An animal and the 100 that are given off from busting a badnick [1188C]
|-
| 29
| The 100 [11DC6]
|-
| 2A
| Stomper from MCZ [115C4]
|-
| 2B
| Raising pillar from ARZ [25A5A]
|-
| 2C
| Sprite that makes leaves fly off when you hit it from ARZ [26104]
|-
| 2D
| One way barrier from CPZ and DEZ [1169A]
|-
| 2E
| Image of what was in monitor flying up like it does when you bust it [12854]
|-
| 2F
| Unknown (a small block) [23300]
|-
| 30
| Unknown (something you can't see with a collision box the size of the whole damn screen) [238DC]
|-
| 31
| Lava collision marker [20DEC]
|-
| 32
| Unknown (A block that when you hit it from the top you get 100 points, and it then splits into six pieces which fly down off the screen) [2351A]
|-
| 33
| Platform that shoots up in the air from oil ocean zone [23AF4]
|-
| 34
| Sprite for level title card [13C48]
|-
| 35
| ??????? [1D97E]
|-
| 36
| Vertical spikes [15900]
|-
| 37
| Sprite of rings spraying out from being hit by an enemy [12078]
|-
| 38
| Shield that surrounds character [1D8F2]
|-
| 39
| Unknown (sprite comes from the left, and sits on the screen near the centre. If you press jump it will reset to Sega logo. Possibly game over sprite.) [13F74]
|-
| 3A
| End of level result screen [14086]
|-
| 3B
| Unknown (a block) [15CC8]
|-
| 3C
| Unknown (a barrier you can smash by dashing into. Like the rock barriers in Sonic 3.) [15D44]
|-
| 3D
| Block thingy in OOZ that launches you into the round ball things [24DD0]
|-
| 3E
| Egg prison [3F1E4]
|-
| 3F
| Fan blowing to the left from OOZ [2A7B0]
|-
| 40
| Weird lever like spring from CPZ and ARZ [26370]
|-
| 41
| Red spring facing upwards [18888]
|-
| 42
| Thing that pops up and releases steam sideways from metropolis zone [26634]
|-
| 43
| Spiky ball from OOZ [23E40]
|-
| 44
| Star ball that sonic bounces off from CNZ [1F730]
|-
| 45
| Strange spring from OOZ facing vertically [240F8]
|-
| 46
| Ball sitting on strange spring from OOZ [24A16]
|-
| 47
| Button [2FCF4]
|-
| 48
| Thingy from OOZ that you enter when flying as a ball, and it turns and throws you another direction [25244]
|-
| 49
| Unknown (Huge vertical laser from WFZ?) [20B9E]
|-
| 4A
| Octopus badnick from OOZ [2CA14]
|-
| 4B
| Buzz bomber from EHZ [2D068]
|-
| 4C
| ??????? [1637C]
|-
| 4D
| ??????? [1637C]
|-
| 4E
| ??????? [1637C]
|-
| 4F
| ??????? [1637C]
|-
| 50
| Seahorse badnick from OOZ [2CCC8]
|-
| 51
| CNZ boss [318F0]
|-
| 52
| HTZ boss [2FC50]
|-
| 53
| Things spinning around MTZ boss [32940]
|-
| 54
| MTZ boss [32288]
|-
| 55
| OOZ boss [32F90]
|-
| 56
| EHZ boss [2EF18]
|-
| 57
| MCZ boss and Earthquake [30FA4]
|-
| 58
| Unknown (some kind of really big explosion?) [2D494]
|-
| 59
| Unknown (alters the palette to put in some colours that look really awesome in ARZ, then teleports you back to x0 y0 and doesn't allow you to move) [35FBC]
|-
| 5A
| ??????? [35554]
|-
| 5B
| ??????? [353FE]
|-
| 5C
| Shark badnick from EHZ [2D394]
|-
| 5D
| CPZ boss [2D734]
|-
| 5E
| ??????? [6FC0]
|-
| 5F
| ??????? [70F0]
|-
| 60
| ??????? [34FA0]
|-
| 61
| ??????? [34EB0]
|-
| 62
| ??????? [1637C]
|-
| 63
| ??????? [340A4]
|-
| 64
| Twin stompers from MTZ [26920]
|-
| 65
| Unknown (a long platform) [26AE0]
|-
| 66
| Unknown (a tall bumper from CNZ, that I don't think was ever implemented in a level) [26F58]
|-
| 67
| One of the spin tubes from MTZ [2715C]
|-
| 68
| Block that has a spike that comes out of each side sequentially from MTZ [27594]
|-
| 69
| Nut from MTZ [27884]
|-
| 6A
| Unknown (jump on it and it's fine. Jump off it and it moves down) [27AB0]
|-
| 6B
| Unknown (Same type of block as above, but it doesn't move) [27D6C]
|-
| 6C
| Unknown (a block that moves up and to the left slowly)[28034]
|-
| 6D
| Floor spike from MTZ [27794]
|-
| 6E
| Unknown (a block that rotates round in a circle) [283AC]
|-
| 6F
| End of special stage result screen [143C0]
|-
| 70
| Unknown (Big circle of sprites rotating around, and changing their tiles depending on their position) [285C0]
|-
| 71
| Unknown (six vertical blocks that change patterns) [112F0]
|-
| 72
| ??????? [2893C]
|-
| 73
| Unknown (a small thing with a picture of a ring on it) [289D4]
|-
| 74
| Unknown (a small block with no patterns on it) [20EE0]
|-
| 75
| ??????? [28BC8]
|-
| 76
| Spike block thing from MCZ [28DF8]
|-
| 77
| Unknown (long block) [28F88]
|-
| 78
| Stairs from CPZ that move down to open the way [291CC]
|-
| 79
| Starpoll [1F0B0]
|-
| 7A
| Platform that moves back and forth on top of chemicals in CPZ [293A0]
|-
| 7B
| Unknown (acts exactly like a spring, but tries to use level specific patterns) [29590]
|-
| 7C
| Big pylon thing that's in the foreground in CPZ [20FD2]
|-
| 7D
| ??????? [1F624]
|-
| 7E
| ??????? [1E0F0]
|-
| 7F
| Vine switch that you hang off in MCZ [297E4]
|-
| 80
| Vine that you hang off and it moves down from MCZ [2997C]
|-
| 81
| Unknown (Long invisible vertical barrier. Suspect it's pasted over the force fields used in the boss at the end of WFZ.) [2A000]
|-
| 82
| Platform that is usually swinging from ARZ [2A290]
|-
| 83
| 3 adjoined platforms from ARZ that rotate in a circle [2A4FC]
|-
| 84
| ??????? [2115C]
|-
| 85
| Vertical spring from CNZ that you hold down jump on to pull back further [2AB84]
|-
| 86
| Flipper from CNZ [2B140]
|-
| 87
| ??????? [7356]
|-
| 88
| ??????? [34A5C]
|-
| 89
| ARZ boss [30480]
|-
| 8A
| Unknown (a line of text on the centre of the screen. Will have to put in correct tiles to see what it says.) [3EAC8]
|-
| 8B
| ??????? [21392]
|-
| 8C
| Blowfly enemy from ARZ [36924]
|-
| 8D
| Unknown (ummm, a blowfly behind a wall like grounder is, but not exactly behind it. When it busts out weird things happen.) [36A76]
|-
| 8E
| Unknown (Same as above) [36A76]
|-
| 8F
| Unknown (a thing that sits in one place and does nothing. You can bust it like a badnick.) [36B88]
|-
| 90
| Unknown (a sprite that launches up and to the left, then curves back down. You can bust it like a badnick.) [36BD4]
|-
| 91
| Unknown (heads towards you. Can be busted like a badnick.) [36DAC]
|-
| 92
| Unknown (when you pass it, it sends a large burst up which hurts you.) [36F0E]
|-
| 93
| Unknown (sprite rapidly reverses direction and spirals down.) [36FE6]
|-
| 94
| Lava snake [37322]
|-
| 95
| Red circle dude from hill top zone that has lava balls circling around him that he throws at you. [370FE]
|-
| 96
| Lava snake... again [37322]
|-
| 97
| Unknown (sprite accelerates down and to the right) [373D0]
|-
| 98
| ??????? [376E8]
|-
| 99
| Bomber badnick from SCZ [377C8]
|-
| 9A
| Turtle thing on the back of another larger turtle thing from SCZ [37936]
|-
| 9B
| ??????? [37A06]
|-
| 9C
| ??????? [37A82]
|-
| 9D
| Coconuts (the badnick) from EHZ [37BFA]
|-
| 9E
| Snake like badnick from MCZ that flies out from wall at you [37E16]
|-
| 9F
| Crab like badnick from MTZ [3800C]
|-
| A0
| Unknown (sprite falls down) [3815C]
|-
| A1
| Praying Mantis dude from MTZ [383B4]
|-
| A2
| Unknown (sprite falls down, then locks up emulator) [384A2]
|-
| A3
| Glowbug from MCZ [3873E]
|-
| A4
| Exploding star from MTZ [3899C]
|-
| A5
| Unknown (sprite moves back and forth, throwing something at you that curves up and back down) [38AEA]
|-
| A6
| Unknown (sprite moves up and down slowly, shooting a fast moving projectile down and to the left) [38B86]
|-
| A7
| Spider badnick from CPZ [38DBA]
|-
| A8
| ??????? [38F66]
|-
| A9
| ??????? [39032]
|-
| AA
| ??????? [39066]
|-
| AB
| Unknown (sprite sits there and does nothing. You can bust it like a badnick) [390A2]
|-
| AC
| Jet badnick from SCZ [3937A]
|-
| AD
| Unknown (appears to be a block and has no image, but if you hit it in the corner it busts like a badnick) [3941C]
|-
| AE
| ??????? [39452]
|-
| AF
| Unknown (block that laser beams shoot from to form barrier at end of WFZ? Just a hunch.) [3972C]
|-
| B0
| Unknown (weird sums it up. It alters the palette, 128x128 block mappings, and quickly moves to the left as a killable badnick. Destroying it interrupts the process of altering the block mappings data (among other things).) [3A1DC]
|-
| B1
| Unknown (appears across from it's actual position and does nothing. Can be busted like a badnick.) [3A3F8]
|-
| B2
| ??????? [3A790]
|-
| B3
| ??????? [3B2DE]
|-
| B4
| Unknown (sprite flashes between frames. Can be busted like a badnick.) [3B36A]
|-
| B5
| ??????? [3B3FA]
|-
| B6
| Tilting platform from WFZ [3B5D0]
|-
| B7
| Unknown (sprite flashes between there and not there really fast, then disappears completely) [3B8A6]
|-
| B8
| Wall turret from WFZ [3B968]
|-
| B9
| Unknown (sprite flies really fast to the left. I suspect it's the laser shot from wing fortress zone.) [3BABA]
|-
| BA
| Unknown (sprite sits there and does nothing. Can be busted like a badnick.) [3BB4C]
|-
| BB
| Unknown (refer to above) [3BB7C]
|-
| BC
| Unknown (sprite flashes present and not present really fast) [3BBBC]
|-
| BD
| Unknown (sprite keeps on dropping things that fall straight down) [3BC1C]
|-
| BE
| Platform that pops in and out from WFZ [3BD7A]
|-
| BF
| Unknown (sprite flashes between frames) [3BEAA]
|-
| C0
| Unknown (it appears to be a spring sort of thing that was cut from the final. It makes you bounce off to the left without gaining much height.) [3BF04]
|-
| C1
| Sprite that sonic hangs onto on the back of Robotnic's getaway ship at the end of WFZ [3C0AC]
|-
| C2
| Rivet thing that you bust to get into the ship at the end of WFZ [3C328]
|-
| C3
| Unknown (sprite moves up and to the left changing frames as it goes, then disappears completely.) [3C3D6]
|-
| C4
| Unknown (same as above) [3C3D6]
|-
| C5
| Laser boss guy at end of WFZ [3C442]
|-
| C6
| Unknown (sprite sits there and does nothing. Can be busted like a badnick) [3CED0]
|-
| C7
| Death Egg [3D4C8]
|-
| C8
| Bad guy in CNZ [3D23E]
|-
| C9
| Unknown (sprite changes palette) [132F0]
|-
| CA
| Movie sequence at end of game (will display the pictures, alter the block mappings, and after sequence is over will teleport Sonic to appropriate location on map.) [A1D6]
|-
| CB
| ??????? [A9F2]
|-
| CC
| Unknown (appears to be later trigger of above one. It will alter block mappings and teleport sonic.) [A3C8]
|-
| CD
| Unknown (sprite bobs up and down, then moves off to the left) [AAAE]
|-
| CE
| ??????? [A894]
|-
| CF
| ??????? [A988]
|-
| D0
| ??????? [1637C]
|-
| D1
| ??????? [1637C]
|-
| D2
| Flashing blocks in CNZ that appear and disappear in a rectangular shape that you can walk across [2B528]
|-
| D3
| ??????? [2B84C]
|-
| D4
| Big block from casino night zone that moves back and forth [2B8EC]
|-
| D5
| Elevator going up from CNZ [2BA08]
|-
| D6
| Poky that gives out points from CNZ [2BB6C]
|-
| D7
| Unknown (some kind of bumper) [2C448]
|-
| D8
| Block thingy in CNZ that changes colour when you hit it and gives you points, until it disappears) [2C6AC]
|-
| D9
| A sprite that you can hold on to, like the rails in WFZ [2C92C]
|-
| DA
| Continue text (kinda funny. It uses the rings variables to store the number of seconds you have left, so it's weird to see it in a level.) [7A68]
|-
| DB
| Sprite of sonic lying down from continue screen [7B82]
|-
| DC
| ??????? [125E6]
|}

==References==
<references />

{{SCHGuides}}