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Sonic the Hedgehog (16-bit)/Object Editing

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SCHG: Sonic the Hedgehog

Object Pointer List

This is the pointer list for every object in Sonic 1, including all zone objects, unused objects, etc. The offsets for the code and mappings are based on where they are found in a clean HG disassembly. These offsets may change even in a clean disassembly, however, due to the Revision variable. Changing this to either the REV 00 or REV JP1 version can result in slightly different offsets for the code, and mappings. The offsets shown on this table reflect the REV 00 version.

NOTE: Code offsets were originally taken from the Nemesis guides, and do not all appear to be accurate. Object pointers are currently in a process of being checked and verified. Mappings offsets are currently 100% accurate, and reflect the point in the ROM where the mapping pointers start, rather than where the code for the pieces themselves start. This is also analogous to the data found in RAM at an objects obMap OST byte.

ID # Description Code Mappings Subparameters
01 Sonic $12BD8 $211E2
02 ???? $D5B2 N/A All of these point to ObjectFall, the subroutine directly after the object table; apparently a label for a null object was made but code was never added.
03 ???? $D5B2 N/A
04 ???? $D5B2 N/A
05 ???? $D5B2 N/A
06 ???? $D5B2 N/A
07 ???? $D5B2 N/A
08 LZ water splash $142F0 $145CC
09 Sonic in Special Stage $1B984 $211E2
0A Drowning countdown numbers $13C98 $129CC
0B LZ vertical pole $11206 $11322
  • $00 - Unbreakable
  • $0x - Pole breaks in xx seconds.
0C LZ Flapping doors $11346 $113F2 $0x - Door flaps open/shut in xx seconds.
0D End of level signpost $EB28 $ED38
0E Sonic on the title screen $A61C $A888
0F "PRESS START BUTTON" and "TM" from title screen $A69C $A7C4
10 Blank object $1C022 N/A
11 GHZ Bridge $7328 $7934 Subtype dictates # of logs
12 Spinning light behind glass from SYZ $E90C $E982
13 Fireball Maker (MZ/SLZ) $E296 N/A Subtype determines # of frames a fireball is spawned (30, 60, 90, 120, 150, 180)
14 Fireball from MZ/SLZ $E304 $B36E
  • $17 - Goes left to right
  • $25 - Goes top to bottom
  • $30-31, 35, 40-42 - Goes up, then comes down
  • $36 - Goes right to left
15 GHZ and MZ swinging platforms
Spiked ball on a chain (SBZ)
SLZ swinging platforms
$7952
  • $7C48 (GHZ & MZ)
  • $7C66 (SLZ)
  • $10AA0 (SBZ)
16 Spear from LZ $11F04 $11F9A
  • $00 - Horizontal spear
  • $02 - Vertical spear
17 Helix of spikes on a pole from GHZ $7CA2 $7DF8 $10
18 GHZ platforms
SLZ platforms
SYZ platforms
$7E32
  • $80FA (Unused)
  • $813C (GHZ)
  • $8188 (SYZ)
  • $819A (SLZ)
  • x0: Doesn't move
  • x1: Moves side to side
  • x2: Moves up and down
  • x3: Falls when stood on
  • x4: Falls immediately
  • x5: Moves side to side
  • x6: Moves up and down
  • x7: Rises when switch in high nybble is pressed
  • x8: Rises immediately
  • x9: Doesn't move
  • xA: Large - moves up and down
  • xB: Moves up and down slowly
  • xC: Moves up and down slowly
19 Blank object $81A8 N/A
1A Collapsing ledge from GHZ $8210 $85A0
  • $00 - Style 1
  • $01 - Style 2
1B Water surface from LZ $110C6 $1116C
1C Zone Scenery object $87CA $7934
  • $00 - Fireball launcher (SLZ)
  • $03 - Bridge stump (GHZ)
1D Unused Switch object $885E $891C
1E Ballhog $8B4C $8E62
1F Crabmeat $94F0 $9750
20 Cannonball that Ball Hog throws $8C1C $8E62
21 SCORE, TIME, RINGS $1C548 $1C5B4
22 Buzz Bomber $97DE $9A36
23 Missile that Buzz Bomber throws $9932 $9B06
24 Buzz Bomber Missile's Dissolve Effect $8CF2 $8EA6
25 Ring $9B26 $9F92
26 Monitor $A118 $A58A
  • $00 - Blank
  • $01 - Robotnik
  • $02 - 1-Up
  • $03 - Speed Up
  • $04 - Shield
  • $05 - Invincible
  • $06 - Super Ring
  • $07 - S Monitor
  • $08 - Goggles
27 Standard explosion $8D62 $8EC6
28 Freed animals $8F22
  • $9466 (Rabbit & Penguin)
  • $947E (Chicken, Seal & Flicky)
  • $9496 (Pig & Squirrel)
29 Points upon destroying $9412 $94AE
2A One way barrier from SBZ $8934 $89EC
2B Chopper enemy $AB20 $ABCA
2C Jaws enemy $ABDA $AC70
2D Burrobot enemy $ACA4 $AE5C
2E Contents of monitor flying up from monitor being busted $A302 $A58A
2F Large platforms from MZ $AEB8 $B2D4
  • $01 - Large oscillating platform
  • $15 - Platform that sinks upon being walked on
  • $20-$29 - Smaller oscillating platform
    (Speed from 0 to 9, with 0 being fastest)
30 Large glassy blocks from MZ $B39E $B5FA
  • $01 - Oscillating block
  • $04 - Block moves down when switch 0 pressed
  • $14 - Moves down when switch 1 pressed
31 Metal stomping blocks on chains $B67C $BB4E
  • $02, $12 - Large with spikes, short chain
  • $11 - Large with spikes, long chain
  • $23 - Small with metal head
  • $80-$85: Large with spikes, raises when switch 0-5 is pressed
32 Switch $BD2E $BEA4
  • $00-$0F: Switches 0-F
33 Moveable block in MZ and LZ $BED2 $C2E6
34 Title card $C306 $C9E6
35 Fireball that sits on the floor (MZ)
(appears when you walk on sinking platforms)
$B1DC $B36E
36 Spikes $CE28 $CFE8 First nybble - mappings frame (0-5)

Second nybble - movement type:

  • 0 - Still
  • 1 - Vertical
  • 2 - Horizontal
37 Rings flying out from being hit $9CB6 $9F92
38 Shield and invincibility stars $14158 $143B2
39 "Game over"/"Time over" sprite $C4B8 $CBA4
3A End of level results screen $C572 $CBD8
3B GHZ purple rock $D050 $D10E
3C Breakable walls in GHZ, SLZ $D11C $D2B6
  • $00 - Left edge
  • $01 - Main part of wall
  • $02 - Right edge
3D Eggman (GHZ) $17700 $17D0C
3E Egg prison $1AB22 $1AD74
3F Large explosion $8DF6 $8F0C
40 Motobug $F61A $F7A0
41 Springs $DABE $DD1A
  • $00 - Red vertical spring
  • $02 - Yellow vertical spring
  • $10 - Red spring facing left
  • $12 - Yellow spring facing left
42 Newtron enemy (GHZ) $DD68 $D4F2
  • $00 - Flies along the ground
  • $01 - Fires missile, then disappears
43 Roller enemy (SYZ) $DFFA $E1A2
44 Wall barrier from GHZ $E1D4 $E250
  • $00 - Type 1 (shading at top)
  • $01 - Type 2 (regular pattern)
  • $02 - Type 3 (fully shaded)
45 Spiked metal block from beta version (MZ) $B99A $BC5A
46 Solid blocks and blocks that fall from the ceiling (MZ) $E7D0 $E904
  • $00 - Solid block
  • $01 - Wobbling block, doesn't fall
  • $02 - Wobbling block, falls
47 Pinball bumper (SYZ) $E9D0 $EB00
48 Swinging ball on a chain from GHZ boss $17AE4 $17DD4 (Boss Item)
$7C48 (Chain link)
$81AA (Ball)
49 Waterfall sound effect $D0BE N/A
4A Special stage entry from beta $14254 $1446C
4B Giant ring $9E06 $9FD2
4C Lava geyser / lava that falls from the ceiling trigger (MZ) $ED84 $F24A
  • $01 - Falls from ceiling
  • Called by object $33 for use as geyser
4D Lava geyser / lava that falls from ceiling $EE70 $F24A Triggered by object $4C
4E Advancing wall of lava (MZ) $F05E $F52E
4F Blank object used for object $50 ??? N/A
50 Yadrin enemy (SYZ) $F83A $F92E
51 Smashable green block (MZ) $FC92 $FDD4
52 Moving blocks (MZ, LZ, SBZ) $FDF8 $1004A (MZ & SBZ)
$100A0 (LZ)
  • $01 - MZ block that moves back and forth
  • $02 - MZ block that moves right when stood on
  • $07 - LZ platform that appears when switch 2 is pressed
  • $28 - SBZ platform that moves up and down
  • $39 - SBZ platform that slides away
  • $41 - MZ platform that moves side to side
53 Collapsing floors (MZ, SLZ, SBZ) $8320 $8746
  • $01 - MZ/SBZ collapsing blocks
  • $81 - SLZ collapsing blocks
54 Invisible lava tag (MZ) $F1B8 $F210
55 Basaran enemy (MZ) $100A8 $1023E
56 Moving blocks (SYZ/SLZ/LZ) $10286 $10700
  • $00 - SYZ Block
  • $01, 02 - SYZ Block that moves side to side
  • $13 - SYZ Block that moves up and down
  • $58-5B - SLZ Block that moves in a circle,
    moving up in circumference
57 Spiked ball on a chain $10782 $10956 (SYZ)
$1095E (LZ)
Subparameters are set so the first half of the nybble sets the speed (lower is faster) and the second half determines the amount of links on the chain, starting with 2 at the 3 value.
58 Spikeball $10976 $10AA0
  • $01 - Moves side to side
  • $02 - Moves up and down
  • $C3 - Moves in a circle
59 Raising platforms (SLZ) $10AD2 $10D48
  • $00 - Rises when stood on
  • $01 - Rises higher when stood on
  • $03 - Falls when stood on
  • $0C - Rises diagonally when stood on
  • $8A - Series of platforms that rise and vanish
5A Platforms that move in circles (SLZ) $10D5A $10E82
  • $00-03 - First through fourth platforms moving clockwise
  • $04-07 - First through fourth platforms moving counterclockwise
5B Blocks that form a staircase (SLZ) $10E90 $1103C
  • $00 - Regular staircase
  • $02 - Staircase you need to knock down
5C Metal girders in foreground (SLZ) $11044 $11096
5D Fans (SLZ) $114FC $11610 $00-$02
5E Seesaws (SLZ) $1163C $119A4 (Seesaw)
$119E6 (Spikeball)
5F Walking bomb enemy (SLZ, SBZ) $119F6 $11C28
60 Orbinaut enemy (LZ, SLZ, SBZ) $11CCE $11EE4
  • $00 - Attacking type
  • $02 - Nonattacking type
61 Blocks (LZ) $11FD4 $121C2
  • $01 - Block that falls when stood on
  • $05 - Pushable block
  • $13 - Platform that rises
  • $30 - Block
62 Gargoyle head (LZ) $121E8 $12318 $01-$04
63 Platforms on a conveyor belt (LZ) $1233C $1267C
  • $7F - Conveyor belt wheels
  • $80-85 - Tag for small platforms
64 Bubbles (LZ) $126A4 $129CC $80-82
65 Waterfalls (LZ) $12A9E $12B54
  • $00, $07 - Vertical water
  • $02-$04, $06 - Waterfall corner
  • $08 - Diagonal water
  • $09 - Waterfall splash
  • $49 - Waterfall splash that moves up and down with water
66 Rotating disc that grabs Sonic (SBZ) $1509A $15292
  • $00-$03 - Changes direction when switches 0 through 3 are pressed
67 Disc that you run around (SBZ)
(Small object; actual disc is in level tiles)
$154E2 $15686 $40
68 Conveyor belts (SBZ)
(Small object; actual belt is in level tiles)
$1568E N/A
  • $20 - Belt going left
  • $E0 - Belt going right
69 Spinning platforms and trapdoors (SBZ) $15730 $158E0 (Trapdoor)
$1593A (Spinning platform)
  • $01, $02 - Trapdoor
  • $80-$83 - Spinning platform
  • $90-$9F - Spinning platform
6A Ground and ceiling saws (SBZ) $1597C $15B98
  • $01 - Ceiling saw, moves sideways
  • $02 - Ceiling saw, moves up and down
  • $03 - Ground saw
6B Stomper and platforms (SBZ) $15C12 $15F68
  • $13, 24, 34 - Stomper
  • $80-88 - Doors opened by switches 0-8
6C Vanishing platforms (SBZ) $15FF8 $1612A $00, $40, $80, $C0, $C6, $E6
6D Flamethrower (SBZ) $E4E0 $E5F4 $43
6E Electrocution orbs (SBZ) $16146 $161E0
  • $02, $04, $06, $08 - Various speeds, lower is faster
6F Spinning platforms that move around a conveyor belt (SBZ) $1626A $1593A $80-$85
70 Large girder block (SBZ) $1652A $16628
71 Invisible solid blocks $1141A $114B6 Various
72 Teleporter (SBZ) $16668 N/A $00-$08
73 Eggman (MZ) $18230 $17D0C (Eggman)
$17DD4 (Boss Item)
74 Lava that Eggman drops (MZ) $186A4 $B36E
75 Eggman (SYZ) $190EE $17D0C (Eggman)
$17DD4 (Boss Item)
76 Blocks that Eggman picks up (SYZ) $19692 $197F8
77 Eggman (LZ) $17E36 $17D0C (Eggman)
78 Caterkiller enemy (MZ, SBZ) $16934 $16D6E
79 Lamppost $16E2E $170F8 $00-$09 - Posts 0 through 9
7A Eggman (SLZ) $188B8 $17D0C (Eggman)
$17DD4 (Boss Item)
7B Exploding spikeys that the SLZ boss drops $18CCE $190DE
7C Giant Ring Flash Effect $9ED6 $A074
7D Hidden points at the end of a level $1715E $17248
  • $01 - 1,000 points
  • $02 - 100 points
  • $03 - 10 points
7E Special stage results screen $C7AE $CC9A
7F Chaos Emeralds from the special stage results screen $C956 $CDF4
80 Continue screen $4E42 $5056
81 Sonic on the continue screen $4F5C $5056
82 Eggman (SBZ2) $19832 $1AA56 (Eggman)
$BEA4 (Button)
83 Blocks that disintegrate when Eggman presses a switch $19B60 $19D12
84 Cylinders Eggman hides in (FZ) $1A44E $1A676
85 Eggman (FZ) $19D58 $17D0C (Eggman)
$19A34 (SBZ Eggman)
$1A3DA (Damaged Eggmobile)
$1A41C (Eggmobile Legs)
$1A676 (Cylinder)
86 Energy balls/launcher (FZ) $1A7DA $1AA56 (Launcher)
$1AAA6 (Plasma Ball)
87 Sonic on the ending sequence $53E2 $5680
88 Chaos Emeralds on the ending sequence $553C $577A
89 "SONIC THE HEDGEHOG" text on the ending sequence $5616 $57B2
8A "SONIC TEAM PRESENTS" and credits $17264 $172E2
8B Robotnik on the "TRY AGAIN" and "END" screens $59E2 $5BCC
8C Chaos Emeralds on the "TRY AGAIN" screen $5AC2 $577A

Dynamic pattern load cues

In sonic 1 DPLCs are utilized exclusively for sonic's sprite but nevertheless an understanding of the format is useful to have.

The format starts out with relative pointers that are one word in length and stored with a big endian byte order. These pointers point to data signifying what to load and how much to load. The format for this is:

The first byte contains a count of how many entries there. Each entry follows this format:

One word is stored and is divided up into nybbles where the highest nybble stores how many tiles are to be loaded minus one.

The next three nybbles store the offset relative to the beginning of the tileset in tiles meaning to get an offset in bytes you will have to multiply this value by 32 (or shift to the left by 5).

Mappings Editing

Each mapping is 5 bytes long, taking the form TTTT TTTT 0000 WWHH PCCY XAAA AAAA AAAA LLLL LLLL.

  • LLLL LLLL is the left co-ordinate of where the mapping appears.
  • TTTT TTTT is the top co-ordinate of where the mapping appears.
  • WW is the width of the mapping, in tiles minus one. So 0 means 8 pixels wide, 1 means 16 pixels wide, 2 means 24 pixels wide and 3 means 32 pixels wide.
  • HH is the height of the mapping, in the same format as the width.
  • P is the priority-flag. If P is set, the mapping will appear above everything else.
  • CC is the palette line.
  • X is the x-flip-flag. If X is set, the mapping will be flipped horizontally.
  • Y is the y-flip-flag. If Y is set, the mapping will be flipped vertically.
  • AAA AAAA AAAA is the tile index.

The VRAM offset specified in an object's SST will be added to the PCCY XAAA AAAA AAAA word.

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