Dragon Quest III (SNES)/ROM map

The following article is a ROM map for Dragon Quest III (SNES).

Main

For now, these are rom file addresses

Category	Address	Size	Description
Levels	$0417ad - $0418d2	98 longs (294 bytes)	Soldier's experience required per level, first value is to reach level 2
???	$0418d3 - $04191f	$4d bytes	???
Levels	$041920 - $041a45	98 longs (294 bytes)	Fighter's experience required per level, first value is to reach level 2
???	$041a46 - $041a92	$4d bytes	???
Levels	$041a93 - $041bb8	98 longs (294 bytes)	Wizard's experience required per level, first value is to reach level 2
???	$041bb9 - $041c05	$4d bytes	???
Levels	$041c06 - $041d2b	98 longs (294 bytes)	Pilgrim's experience required per level, first value is to reach level 2
???	$041d2c - $041d78	$4d bytes	???
Levels	$041d79 - $041e9e	98 longs (294 bytes)	Merchant's experience required per level, first value is to reach level 2
???	$041e9f - $041eeb	$4d bytes	???
Levels	$041eec - $042011	98 longs (294 bytes)	GoofOff's experience required per level, first value is to reach level 2
???	$042012 - $04205e	$4d bytes	???
Levels	$04205f - $042184	98 longs (294 bytes)	Thief's experience required per level, first value is to reach level 2
???	$042185 - $0421d1	$4d bytes	???
Levels	$0421d2 - $0422f7	98 longs (294 bytes)	Sage's experience required per level, first value is to reach level 2
???	$0422f8 - $042344	$4d bytes	???
Levels	$042345 - $04246a	98 longs (294 bytes)	Hero's experience required per level, first value is to reach level 2
???	$04246b - $0424b7	$4d bytes	???

Monsters

For now, these are rom file addresses. Placeholder for much more complete monster info. The data will be moved out and a more general explanation will be added.

Category	Address	Size	Description
Stats	$020028 - $020029	word	Monster #01 - Slime (スライム) - experience points gained: 4

Names

All strings end with ac and are encoded according to the Text Table

Index	Address	Size	Japanese	English	Data
01	$3ed958 - $3ed95c	5 bytes	スライム	Slime	4F 69 44 63 AC
02	$3ed95d - $3ed962	6 bytes	おおがらす	Big Crow	10 10 C9 32 18 AC
03	$3ed963 - $3ed96a	8 bytes	いっかくうさぎ	Pointed Rabbit	0D 3F 11 13 0E 16 CA AC
04	$3ed96b - $3ed971	7 bytes	おおありくい	Large Anteater	10 10 0C 33 13 0D AC
05	$3ed972 - $3ed979	8 bytes	じんめんちょう	Human Face Butterfly	CF 39 2D 39 1C 42 0E AC
06	$3ed97a - $3ed97f	6 bytes	フロッガー	Frogger	5E 6D 76 DE 7D AC
07	$3ed980 - $3ed987	8 bytes	バブルスライム	Bubble Slime	ED EF 6B 4F 69 44 63 AC
08	$3ed988 - $3ed98e	7 bytes	まほうつかい	Magician	2A 29 0E 1D 11 0D AC
09	$3ed98f - $3ed994	6 bytes	さそりばち	Scorpion Wasp	16 1A 33 D8 1C AC
0a	$3ed995 - $3ed99c	8 bytes	ホイミスライム	Hoimi Slime	60 44 62 4F 69 44 63 AC
0b	$3ed99d - $3ed9a4	8 bytes	おばけありくい	Ghost Anteater	10 D8 14 0C 33 13 0D AC
0c	$3ed9a5 - $3ed9ab	7 bytes	アルミラージ	Almirage	43 6B 62 69 7D E4 AC
0d	$3ed9ac - $3ed9b3	8 bytes	ポイズントード	Poison Toad	FB 44 E5 70 56 7D EC AC
0e	$3ed9b4 - $3ed9ba	7 bytes	キャタピラー	Caterpillar	49 77 52 F8 69 7D AC
0f	$3ed9bb - $3ed9c2	8 bytes	こうもりおとこ	Bat Man	15 0E 2E 33 10 1F 15 AC
10	$3ed9c3 - $3ed9ca	8 bytes	アニマルゾンビ	Animal Zombie	43 58 61 6B E7 70 EE AC
11	$3ed9cb - $3ed9d0	6 bytes	キラービー	Killer Bee	49 69 7D EE 7D AC
12	$3ed9d1 - $3ed9d7	7 bytes	ぐんたいガニ	-	CB 39 1B 0D DE 58 AC
13	$3ed9d8 - $3ed9db	4 bytes	ギズモ	Gizmo	DF E5 65 AC
14	$3ed9dc - $3ed9e2	7 bytes	おばけキノコ	-	10 D8 14 49 5B 4C AC
15	$3ed9e3 - $3ed9e9	7 bytes	どくイモムシ	-	D7 13 44 65 63 4E AC
16	$3ed9ea - $3ed9f1	8 bytes	デスフラッター	Death Flatter	EB 4F 5E 69 76 52 7D AC
17	$3ed9f2 - $3ed9f9	8 bytes	バリイドドッグ	Bariaid Dog	ED 6A 44 EC EC 76 E0 AC
18	$3ed9fa - $3ed9fe	5 bytes	マタンゴ	Matango	61 52 70 E2 AC
19	$3ed9ff - $3eda05	7 bytes	あやしいかげ	Suspicious Silhouette	0C 2F 17 0D 11 CC AC
1a	$3eda06 - $3eda0b	6 bytes	バンパイア	Vampire	ED 70 F7 44 43 AC
1b	$3eda0c - $3eda11	6 bytes	ひとくいが	Cannibal Moth	26 1F 13 0D C9 AC
1c	$3eda12 - $3eda19	8 bytes	さまようよろい	Roaming Armor	16 2A 31 0E 31 36 0D AC
1d	$3eda1a - $3eda21	8 bytes	キャットフライ	Cat Fly	49 77 76 56 5E 69 44 AC
1e	$3eda22 - $3eda28	7 bytes	だいおうガマ	-	D3 0D 10 0E DE 61 AC
1f	$3eda29 - $3eda2e	6 bytes	あばれザル	-	0C D8 35 E3 6B AC
20	$3eda2f - $3eda35	7 bytes	わらいぶくろ	Laughing Sack	37 32 0D DA 13 36 AC
21	$3eda36 - $3eda3c	7 bytes	ミイラおとこ	-	62 44 69 10 1F 15 AC
22	$3eda3d - $3eda44	8 bytes	じごくのハサミ	-	CF CD 13 24 5C 4D 62 AC
23	$3eda45 - $3eda49	5 bytes	ドルイド	Druid	EC 6B 44 EC AC
24	$3eda4a - $3eda50	7 bytes	かえんムカデ	-	11 0F 39 63 48 EB AC
25	$3eda51 - $3eda54	4 bytes	マミー	Mummy	61 62 7D AC
26	$3eda55 - $3eda5c	8 bytes	マージマタンゴ	Mage Matango	61 7D E4 61 52 70 E2 AC
27	$3eda5d - $3eda64	8 bytes	ハンターフライ	Hunter Fly	5C 70 52 7D 5E 69 44 AC
28	$3eda65 - $3eda6c	8 bytes	デスジャッカル	Death Jackal	EB 4F E4 77 76 48 6B AC
29	$3eda6d - $3eda73	7 bytes	げんじゅつし	Witchcraft Expert	CC 39 CF 41 1D 17 AC
2a	$3eda74 - $3eda7a	7 bytes	ヒートギズモ	Heat Gizmo	5D 7D 56 DF E5 65 AC
2b	$3eda7b - $3eda80	6 bytes	アントベア	Ant Bear	43 70 56 F0 43 AC
2c	$3eda81 - $3eda88	8 bytes	ベホマスライム	Behoma Slime	F0 60 61 4F 69 44 63 AC
2d	$3eda89 - $3eda90	8 bytes	マッドオックス	Mad Ox	61 76 EC 47 76 4A 4F AC
2e	$3eda91 - $3eda98	8 bytes	キャットバット	Cat Bat	49 77 76 56 ED 76 56 AC
2f	$3eda99 - $3eda9f	7 bytes	エビルマージ	Evil Mage	46 EE 6B 61 7D E4 AC
30	$3edaa0 - $3edaa6	7 bytes	キラーエイプ	Killer Ape	49 69 7D 46 44 F9 AC
31	$3edaa7 - $3edaab	5 bytes	ガルーダ	Garuda	DE 6B 7D E8 AC
32	$3edaac - $3edab3	8 bytes	メタルスライム	Metal Slime	64 52 6B 4F 69 44 63 AC
33	$3edab4 - $3edab9	6 bytes	ゴートドン	Goat Don	E2 7D 56 EC 70 AC
34	$3edaba - $3edabf	6 bytes	さつじんき	Devilish Murderer	16 1D CF 39 12 AC
35	$3edac0 - $3edac6	7 bytes	ベビーサタン	Baby Satan	F0 EE 7D 4D 52 70 AC
36	$3edac7 - $3edacd	7 bytes	きめんどうし	Devil Mask Sorceror	12 2D 39 D7 0E 17 AC
37	$3edace - $3edad4	7 bytes	ひとくいばこ	Cannibal Box	26 1F 13 0D D8 15 AC
38	$3edad5 - $3edadc	8 bytes	エリミネーター	Eliminator	46 6A 62 5A 7D 52 7D AC
39	$3edadd - $3edae3	7 bytes	おおくちばし	Large Beak	10 10 13 1C D8 17 AC
3a	$3edae4 - $3edaeb	8 bytes	スライムつむり	-	4F 69 44 63 1D 2C 33 AC
3b	$3edaec - $3edaf3	8 bytes	スカイドラゴン	Sky Dragon	4F 48 44 EC 69 E2 70 AC
3c	$3edaf4 - $3edaf9	6 bytes	バーナバス	Barnabas	ED 7D 57 ED 4F AC
3d	$3edafa - $3edafd	4 bytes	まじょ	Witch	2A CF 42 AC
3e	$3edafe - $3edb05	8 bytes	デッドペッカー	Dead Pecker	EB 76 EC FA 76 48 7D AC
3f	$3edb06 - $3edb0d	8 bytes	じごくのよろい	Hell Armor	CF CD 13 24 31 36 0D AC
40	$3edb0e - $3edb15	8 bytes	マリンスライム	Marine Slime	61 6A 70 4F 69 44 63 AC
41	$3edb16 - $3edb1c	7 bytes	しびれくらげ	Numb Jellyfish	17 D9 35 13 32 CC AC
42	$3edb1d - $3edb21	5 bytes	マーマン	Merman	61 7D 61 70 AC
43	$3edb22 - $3edb28	7 bytes	だいおうイカ	-	D3 0D 10 0E 44 48 AC
44	$3edb29 - $3edb2d	5 bytes	ガニラス	Ganiras	DE 58 69 4F AC
45	$3edb2e - $3edb35	8 bytes	マーマンダイン	Merman Dyne	61 7D 61 70 E8 44 70 AC
46	$3edb36 - $3edb3c	7 bytes	ヘルコンドル	Hell Condor	5F 6B 4C 70 EC 6B AC
47	$3edb3d - $3edb43	7 bytes	ごうけつぐま	Overpowering Bear	CD 0E 14 1D CB 2A AC
48	$3edb44 - $3edb4b	8 bytes	くさったしたい	Rotten Corpse	13 16 3F 1B 17 1B 0D AC
49	$3edb4c - $3edb52	7 bytes	ビッグホーン	Big Horn	EE 76 E0 60 7D 70 AC
4a	$3edb53 - $3edb59	7 bytes	しびれあげは	Paralysis Swallowtail	17 D9 35 0C CC 25 AC
4b	$3edb5a - $3edb61	8 bytes	どくどくゾンビ	-	D7 13 D7 13 E7 70 EE AC
4c	$3edb62 - $3edb67	6 bytes	アカイライ	Akairai	43 48 44 69 44 AC
4d	$3edb68 - $3edb6f	8 bytes	キラーアーマー	Killer Armor	49 69 7D 43 7D 61 7D AC
4e	$3edb70 - $3edb77	8 bytes	デスストーカー	Death Stalker	EB 4F 4F 56 7D 48 7D AC
4f	$3edb78 - $3edb7f	8 bytes	ようがんまじん	Lava Devil	31 0E C9 39 2A CF 39 AC
50	$3edb80 - $3edb85	6 bytes	シャーマン	Shaman	4E 77 7D 61 70 AC
51	$3edb86 - $3edb8c	7 bytes	まほうおばば	Magic Hag	2A 29 0E 10 D8 D8 AC
52	$3edb8d - $3edb91	5 bytes	シャドー	Shadow	4E 77 EC 7D AC
53	$3edb92 - $3edb99	8 bytes	ひょうがまじん	Glacier Devil	26 42 0E C9 2A CF 39 AC
54	$3edb9a - $3edb9d	4 bytes	キメラ	Chimera	49 64 69 AC
55	$3edb9e - $3edba1	4 bytes	コング	Kong	4C 70 E0 AC
56	$3edba2 - $3edba6	5 bytes	ガメゴン	Gamegon	DE 64 E2 70 AC
57	$3edba7 - $3edbae	8 bytes	ごくらくちょう	Bird of Paradise	CD 13 32 13 1C 42 0E AC
58	$3edbaf - $3edbb5	7 bytes	ばくだんいわ	Bomb Rock	D8 13 D3 39 0D 37 AC
59	$3edbb6 - $3edbbb	6 bytes	グリズリー	Grizzly	E0 6A E5 6A 7D AC
5a	$3edbbc - $3edbc3	8 bytes	ゾンビマスター	Zombie Master	E7 70 EE 61 4F 52 7D AC
5b	$3edbc4 - $3edbcb	8 bytes	ガメゴンロード	Gamegon Lord	DE 64 E2 70 6D 7D EC AC
5c	$3edbcc - $3edbd3	8 bytes	スノードラゴン	Snow Dragon	4F 5B 7D EC 69 E2 70 AC
5d	$3edbd4 - $3edbd7	4 bytes	トロル	Troll	56 6D 6B AC
5e	$3edbd8 - $3edbdf	8 bytes	フロストギズモ	Frost Gizmo	5E 6D 4F 56 DF E5 65 AC
5f	$3edbe0 - $3edbe7	8 bytes	おどるほうせき	Dancing Jewel	10 D7 34 29 0E 19 12 AC
60	$3edbe8 - $3edbee	7 bytes	ミニデーモン	Mini Demon	62 58 EB 7D 65 70 AC
61	$3edbef - $3edbf5	7 bytes	テンタクルス	Tentacles	55 70 52 4A 6B 4F AC
62	$3edbf6 - $3edbfd	8 bytes	がいこつけんし	Skeleton Swordsman	C9 0D 15 1D 14 39 17 AC
63	$3edbfe - $3edc02	5 bytes	ミミック	Mimic	62 62 76 4A AC
64	$3edc03 - $3edc09	7 bytes	じごくのきし	Knight of Hell	CF CD 13 24 12 17 AC
65	$3edc0a - $3edc10	7 bytes	ホロゴースト	Horror Ghost	60 6D E2 7D 4F 56 AC
66	$3edc11 - $3edc18	8 bytes	やまたのおろち	Mythical Serpent of Eight Heads	2F 2A 1B 24 10 36 1C AC
67	$3edc19 - $3edc20	8 bytes	うごくせきぞう	Moving Stone Statue	0E CD 13 19 12 D2 0E AC
68	$3edc21 - $3edc27	7 bytes	サラマンダー	Salamander	4D 69 61 70 E8 7D AC
69	$3edc28 - $3edc2e	7 bytes	スライムベス	Slime Bess	4F 69 44 63 F0 4F AC
6a	$3edc2f - $3edc34	6 bytes	マドハンド	Mud Hand	61 EC 5C 70 EC AC
6b	$3edc35 - $3edc3b	7 bytes	まおうのかげ	-	2A 10 0E 24 11 CC AC
6c	$3edc3c - $3edc42	7 bytes	マクロベータ	Macro Beta	61 4A 6D F0 7D 52 AC
6d	$3edc43 - $3edc49	7 bytes	はぐれメタル	-	25 CB 35 64 52 6B AC
6e	$3edc4a - $3edc4d	4 bytes	グール	Ghoul	E0 7D 6B AC
6f	$3edc4e - $3edc55	8 bytes	ライオンヘッド	Lion Head	69 44 47 70 5F 76 EC AC
70	$3edc56 - $3edc5c	7 bytes	ボストロール	-	F1 4F 56 6D 7D 6B AC
71	$3edc5d - $3edc63	7 bytes	ゴールドマン	Gold Man	E2 7D 6B EC 61 70 AC
72	$3edc64 - $3edc69	6 bytes	スカルゴン	Skull Gon	4F 48 6B E2 70 AC
73	$3edc6a - $3edc71	8 bytes	キングマーマン	King Merman	49 70 E0 61 7D 61 70 AC
74	$3edc72 - $3edc77	6 bytes	クラーゴン	Kragon	4A 69 7D E2 70 AC
75	$3edc78 - $3edc7f	8 bytes	ダースリカント	Darth Rikanto	E8 7D 4F 6A 48 70 56 AC
76	$3edc80 - $3edc85	6 bytes	だいまじん	Great Devil	D3 0D 2A CF 39 AC
77	$3edc86 - $3edc8a	5 bytes	ラゴンヌ	Ragon'nu	69 E2 70 59 AC
78	$3edc8b - $3edc91	7 bytes	アークマージ	Arch Mage	43 7D 4A 61 7D E4 AC
79	$3edc92 - $3edc98	7 bytes	メイジキメラ	Mage Chimera	64 44 E4 49 64 69 AC
7a	$3edc99 - $3edc9f	7 bytes	サタンパピー	Satan Puppy	4D 52 70 F7 F8 7D AC
7b	$3edca0 - $3edca3	4 bytes	ヒドラ	Hydra	5D EC 69 AC
7c	$3edca4 - $3edcaa	7 bytes	トロルキング	Troll King	56 6D 6B 49 70 E0 AC
7d	$3edcab - $3edcaf	5 bytes	ドラゴン	Dragon	EC 69 E2 70 AC
7e	$3edcb0 - $3edcb4	5 bytes	バルログ	Balrog	ED 6B 6D E0 AC
7f	$3edcb5 - $3edcbc	8 bytes	ドラゴンゾンビ	Dragon Zombie	EC 69 E2 70 E7 70 EE AC
80	$3edcbd - $3edcc3	7 bytes	マントゴーア	Mantgoa	61 70 56 E2 7D 43 AC
81	$3edcc4 - $3edcc9	6 bytes	ソードイド	Sword Id	51 7D EC 44 EC AC
82	$3edcca - $3edcd0	7 bytes	キングヒドラ	King Hydra	49 70 E0 5D EC 69 AC
83	$3edcd1 - $3edcd8	8 bytes	バラモスブロス	Baramos Bros	ED 69 65 4F EF 6D 4F AC
84	$3edcd9 - $3edce0	8 bytes	バラモスゾンビ	Baramos Zombie	ED 69 65 4F E7 70 EE AC
85	$3edce1 - $3edce5	5 bytes	バラモス	Baramos	ED 69 65 4F AC
86	$3edce6 - $3edce9	4 bytes	ゾーマ	Zoma	E7 7D 61 AC
87	$3edcea - $3edcee	5 bytes	オルテガ	Orutega	47 6B 55 DE AC
88	$3edcef - $3edcf3	5 bytes	カンダタ	Kandata	48 70 E8 52 AC
89	$3edcf4 - $3edcfb	8 bytes	カンダタこぶん	-	48 70 E8 52 15 DA 39 AC
8a	$3edcfc - $3edd01	6 bytes	けいけんち	Experience Value	14 0D 14 39 1C AC
8b	$3edd02 - $3edd05	4 bytes	おかね	Gold	10 11 23 AC
8c	$3edd06 - $3edd0c	7 bytes	せんたくバカ	Selection Idiot	19 39 1B 13 ED 48 AC
8d	$3edd0d - $3edd15	9 bytes	せんたくにんげん	Selection Human	19 39 1B 13 21 39 CC 39 AC
8e	$3edd16 - $3edd1c	7 bytes	せんたくかみ	Selection Deity	19 39 1B 13 11 2B AC
8f	$3edd1d - $3edd22	6 bytes	せんたく0	Selection 0	19 39 1B 13 87 AC
90	$3edd23 - $3edd28	6 bytes	せんたく1	Selection 1	19 39 1B 13 88 AC
91	$3edd29 - $3edd2e	6 bytes	せんたく2	Selection 2	19 39 1B 13 89 AC
92	$3edd2f - $3edd34	6 bytes	せんたく3	Selection 3	19 39 1B 13 8A AC
93	$3edd35 - $3edd39	5 bytes	ほうおう	Phoenix	29 0E 10 0E AC
94	$3edd3a - $3edd41	8 bytes	てんのもんばん	Heaven's Gate Watcher	1E 39 24 2E 39 D8 39 AC
95	$3edd42 - $3edd48	7 bytes	メタルキメラ	Metal Chimera	64 52 6B 49 64 69 AC
96	$3edd49 - $3edd51	9 bytes	デビルウィザード	Devil Wizard	EB EE 6B 45 72 E3 7D EC AC
97	$3edd52 - $3edd58	7 bytes	キラークラブ	Killer Crab	49 69 7D 4A 69 EF AC
98	$3edd59 - $3edd5f	7 bytes	ダークトロル	Dark Troll	E8 7D 4A 56 6D 6B AC
99	$3edd60 - $3edd67	8 bytes	デーモンソード	Demon Sword	EB 7D 65 70 51 7D EC AC
9a	$3edd68 - $3edd6f	8 bytes	バラモスエビル	Baramos Evil	ED 69 65 4F 46 EE 6B AC
9b	$3edd70 - $3edd75	6 bytes	しんりゅう	God Dragon	17 39 33 41 0E AC

Notes

All values given are ROM offsets. They assume that a 512-byte copier header is not present. If there is a header present, you will have to add 512 ($200) to each offset lister here to get the correct offset in the ROM file.

Note that the ROM is mapped into the SNES address space starting at $C00000. Therefore, if you want to use one of these ROM offsets as a breakpoint, you should add $C00000 to it. I've given a few examples below that already do this.

Menu Size Data

Almost every menu has a 16-bit (2-byte) value that determines its starting position (X/Y coordinates) and its width. Menu size data is stored in the following binary format:

%1WWW WWYY YYYX XXXX

• WWWWW = menu width (not just usable space, this includes the edge characters)
• YYYYY = vertical tile offset from top of screen
• XXXXX = horizontal tile offset from left of screen

There is no value to determine the height of a menu. This is done internally by the drawing code for each individual menu.

Like almost everything else on the SNES, this data is in low-endian format. Thus, the YYYX XXXX byte comes first in the ROM, then the 1WWW WWYY byte.

Here are a few menu size values that I have found. Note again that this controls only menu width and position. Menu content string pointers are stored elsewhere.

• $30348-$30349: Introductory menu (contains Begin a New Quest, Continue Quest, Copy Quest, etc., etc.)
• $30378-$30379: Change Message Speed menu (opened from introductory menu)
• $30384-$30385: Mono/Stereo selector menu
• $30024-$30025: Main walkabout menu (contains Talk, Spell, Item, Search, Status, Tactics)
• $300FC-$300FD: Gold menu, associated with the main walkabout menu
• $3036C-$3036D: Change Message Speed menu (opened from Tactics)

What if the menu you want to expand (or contract!) isn't listed above? Here's how to find it.

• Open the menu you want, and take a screenshot of it. As an example, let's try the gold box that appears when you open the main menu.
• Open the screenshot in a paint program, and find out the X coordinate, Y coordinate, and width. Remember that these coordinates are in tiles, so you have to find the coordinate (or width) in pixels and then divide that number by 8.
• Convert these values to hexadecimal and write them down. In this case, our X coordinate is 21 ($15), the Y coordinate is 16 ($10), and the width (including borders) is 9 ($09).
• Open the ROM in a debugging emulator (I use Geiger's Snes9x debugging version).
• Prepare things so that it will only take 1 more button press to get into the menu you want.
• Set an execution breakpoint at $C90717.
• Open the menu — this should set off the breakpoint.
• Keep an eye on the A register.
• You might see something like this as the breakpoint is hit four times (On Geiger Snes9x, hit the "Run" button to get to the next breakpoint).
  • $C9/0717 08 PHP A:0000 X:0000 Y:0015 P:envmxdIZc
  • $C9/0717 08 PHP A:0015 X:0000 Y:0015 P:envmxdIzc
  • $C9/0717 08 PHP A:1015 X:0000 Y:0015 P:envmxdIzc
  • $C9/0717 08 PHP A:0009 X:0000 Y:0015 P:envmxdIzc
• This is for the gold menu. If you followed the steps above, you should see some familiar information here. Note how on the second iteration, we see the X coordinate in the accumulator, and on the third iteration, we can see both the X *and* Y coordinates in the top and bottom halves. And on the fifth iteration, there is the width.
• Don't proceed past the fifth iteration (the one where A = menu width). Instead, single step ("Step Into" button on Geiger Snes9x) until you get to $C902B1.
• You'll see something like this:
  • $C9/02B1 33 10 AND ($10,s),y[$C3:00FD] A:0F80 X:00C3 Y:0000 P:envmXdIzc
• See that [$C3:00FD]? Now just take that number and subtract $C00001 (yes, $C00001, not $C00000) from it.
• We now have the location of the menu size data; in this case, $300FC. Remember that the value at this address is two bytes long, and low-endian.
• Note that, in some cases, there will be unwanted $C90717 breakpoints before the one we're looking for. That's why you should monitor the A register and make sure we're looking at the right iteration. The method I detailed above works only if you check the address on the iteration that contains the menu width ($0009, in this case).

Menu Text Pointers

To change the menu text, you need to find the pointers for that text. In most cases, this pointer is actually the 16-bit operand of an LDA opcode. Pointers can usually only reference the 64K block of memory from which they are called; in other words, if a pointer is at $360D1 in the ROM, it can't reference anything above $3FFFF or below $30000. In some cases, a pointer can't be made to point backwards without further hacking, because of the way that they are referenced. (More to come...) Fortunately, this shouldn't really be a big issue, because there is a block of apparently unused space (solid $FFs) from $3F30A-$3FFFF. Most pointers are in the range of this memory. (Please let me know if I'm mistaken and this empty space actually serves a purpose!)

A list of menu pointers can be found at the Kojiro Translations wiki.

Menu Padding Routine

Some menu entries have extra spaces padded onto the end that is not accounted for by the data at the expected pointers. These spaces are inserted by the use of a special routine located at $32B70 in the ROM. When this routine is called, the X register contains the number of spaces to insert. If you're doing some menu expansion, you may have to set breakpoints at $C32B70. Single-step through until RTL is executed, so you can see where it came from, and then back up five bytes from the resulting address. If these padding spaces are throwing off your menu borders, replace the JSL $C32B70 opcode with four NOPs.

Calling $32B8D inserts a single dummy space. The "Change Message Speed" option on the "Tactics" menu uses this method, so look out for it if you're editing that menu item. There may be others I haven't found yet that do the same thing. Again, you can track down the originating JSL opcode by breaking on the subroutine start, stepping through until RTL is executed, and then subtracting five bytes from the program counter at that point.

Overworld Map

The overworld map is made up of a 64x64 grid of chunks which are a 4x4 grid of 16x16 pixel tiles which are really four 8x8 tiles. This results in a 4096x4096 pixel sized map.

Top level grid

Location in ROM: $2D8A00 - $2D9BE2

The top level of the overworld tilemap data is a 64x64 grid composed of a word length (2 byte) index indicating which chunk to use. This is $2000 bytes. Most of the data is just a counter that increments by one each time since most of the land chunks are unique. However the open parts of the sea are represented by chunk $0001 so you will see long runs of that index. Some other reused chunks are composed of all desert or all forest or all grass, that kind of thing. Values range from $0001 to $0A3C, and $0000 is not used although is a valid chunk made of zeros.

Decompression uses a $400 byte ring buffer that is all zeros at the beginning and a starting write position of $3BE. Every decompressed byte is written to the output and the ring buffer. The compressed data is composed of a command byte followed by 8 to 16 data bytes. For each bit in the command byte, if the bit is 1 then read and write one byte. If the bit is 0 then perform a copy operation from the ring buffer using the next two bytes of source data. The 10 lower bits are a pointer into the ring buffer that will be used as the source address. The number of bytes to copy is the upper 6 bits plus 3. Note that the copied bytes are written to the output and also into the ring buffer so if the buffer read address is close behind the buffer write address then you're copying what was just written. This is mostly used to generate long stretches of $0001 which represents the chunks of open sea.

Chunks

Location in ROM: $2DA49C - $2E486B‬

The chunks are 4x4 grids of tile indexes (1 byte) accessed with an index. The chunk data is in one contiguous area but is actually 16 different byte arrays, one after another and each one $A3D bytes long, so that all 16 tiles can be accessed with the same index.

The starting addresses for each array are shown in the layout the tiles appear on screen:

	X + 0	X + 1	X + 2	X + 3
Y + 0	$2DA49C	$2DAED9	$2DB916	$2DC353
Y + 1	$2DCD90	$2DD7CD	$2DE20A	$2DEC47
Y + 2	$2DF684	$2E00C1	$2E0AFE	$2E153B
Y + 3	$2E1F78	$2E29B5	$2E33F2	$2E3E2F

Values range from $00 to $EC because the definitions for tiles $ED to $FF are not loaded, although there is space in RAM for them.

Tiles

Location in ROM: $254F38 - $25569F

Each entry is 8 bytes with each 2 bytes representing one of the 4 tiles (8x8) that make up the larger 16x16 tile. These 2 byte parts are in the standard SNES tilemap format and are copied as is into VRAM.

Links

None currently.