Ultima IV internal formats

Introduction

This is a reference to the various files comprising the DOS version of Ultima IV.

EGA Files

These files contain the graphics used in the game. They can be uncompressed, run-length encoded, or LZW encoded. When uncompressed, each pixel value is represented by a 4-bit value indicating one of 16 colors:

Default EGA 16-color palette (set up to match the standard CGA colors)
Color	rgbRGB	Decimal
0 – black (#000000)	000000	0
1 – blue (#0000AA)	000001	1
2 – green (#00AA00)	000010	2
3 – cyan (#00AAAA)	000011	3
4 – red (#AA0000)	000100	4
5 – magenta (#AA00AA)	000101	5
6 – brown (#AA5500)	010100	20
7 – white / light gray (#AAAAAA)	000111	7
8 – dark gray / bright black (#555555)	111000	56
9 – bright blue (#5555FF)	111001	57
10 – bright green (#55FF55)	111010	58
11 – bright cyan (#55FFFF)	111011	59
12 – bright red (#FF5555)	111100	60
13 – bright magenta (#FF55FF)	111101	61
14 – bright yellow (#FFFF55)	111110	62
15 – bright white (#FFFFFF)	111111	63

SHAPES.EGA

This file contains the bitmaps for all 256 tiles and is 32,768 bytes long. Each tile is 16x16 pixels, and each byte represents two pixels. Therefore, each tile is 128 bytes. In other words, the first 8 bytes represent the 16 pixels on the first row of the first tile (read left to right), and the next 8 bytes represent the 16 pixels on the second row of the first tile, and so on.

The EGA Tile set is :

Offset	Tile #	Notes
0x0000	0	Deep Water
0x0080	1	Medium Water
0x0100	2	Shallow Water
0x0180	3	Swamp
0x0200	4	Grasslands
0x0280	5	Scrubland
0x0300	6	Forest
0x0380	7	Hills
0x0400	8	Mountains
0x0480	9	Dungeon Entrance
0x0500	10	Town
0x0580	11	Castle
0x0600	12	Village
0x0680	13	Lord British's Caste West
0x0700	14	Lord British's Castle Entrance
0x0780	15	Lord British's Castle East
0x0800	16	Ship West
0x0880	17	Ship North
0x0900	18	Ship East
0x0980	19	Ship South
0x0a00	20	Horse West
0x0a80	21	Horse East
0x0b00	22	Tile Floor
0x0b80	23	Bridge
0x0c00	24	Balloon
0x0c80	25	Bridge North
0x0d00	26	Bridge South
0x0d80	27	Ladder Up
0x0e00	28	Ladder Down
0x0e80	29	Ruins
0x0f00	30	Shrine
0x0f80	31	Avatar
0x1000	32	Mage 1
0x1080	33	Mage 2
0x1100	34	Bard 1
0x1180	35	Bard 2
0x1200	36	Fighter 1
0x1280	37	Fighter 2
0x1300	38	Druid 1
0x1380	39	Druid 2
0x1400	40	Tinker 1
0x1480	41	Tinker 2
0x1500	42	Paladin 1
0x1580	43	Paladin 2
0x1600	44	Ranger 1
0x1680	45	Ranger 2
0x1700	46	Shepherd 1
0x1780	47	Shepherd 2
0x1800	48	Column
0x1880	49	White SW
0x1900	50	White SE
0x1980	51	White NW
0x1a00	52	White NE
0x1a80	53	Mast
0x1b00	54	Ship's Wheel
0x1b80	55	Rocks
0x1c00	56	Lyin Down
0x1c80	57	Stone Wall
0x1d00	58	Locked Door
0x1d80	59	Unlocked Door
0x1e00	60	Chest
0x1e80	61	Ankh
0x1f00	62	Brick Floor
0x1f80	63	Wooden Planks
0x2000	64	Moongate 1
0x2080	65	Moongate 2
0x2100	66	Moongate 3
0x2180	67	Moongate 4
0x2200	68	Poison Field
0x2280	69	Energy Field
0x2300	70	Fire Field
0x2380	71	Sleep Field
0x2400	72	Solid Barrier
0x2480	73	Hidden Passage
0x2500	74	Altar
0x2580	75	Spit
0x2600	76	Lava Flow
0x2680	77	Missile
0x2700	78	Magic Sphere
0x2780	79	Attack Flash
0x2800	80	Guard 1
0x2880	81	Guard 2
0x2900	82	Citizen 1
0x2980	83	Citizen 2
0x2a00	84	Singing Bard 1
0x2a80	85	Singing Bard 2
0x2b00	86	Jester 1
0x2b80	87	Jester 2
0x2c00	88	Beggar 1
0x2c80	89	Beggar 2
0x2d00	90	Child 1
0x2d80	91	Child 2
0x2e00	92	Bull 1
0x2e80	93	Bull 2
0x2f00	94	Lord British 1
0x2f80	95	Lord British 2
0x3000	96	A
0x3080	97	B
0x3100	98	C
0x3180	99	D
0x3200	100	E
0x3280	101	F
0x3300	102	G
0x3380	103	H
0x3400	104	I
0x3480	105	J
0x3500	106	K
0x3580	107	L
0x3600	108	M
0x3680	109	N
0x3700	110	O
0x3780	111	P
0x3800	112	Q
0x3880	113	R
0x3900	114	S
0x3980	115	T
0x3a00	116	U
0x3a80	117	V
0x3b00	118	W
0x3b80	119	X
0x3c00	120	Y
0x3c80	121	Z
0x3d00	122	Space
0x3d80	123	Right
0x3e00	124	Left
0x3e80	125	Window
0x3f00	126	Blank
0x3f80	127	Brick Wall
0x4000	128	Pirate Ship West
0x4080	129	Pirate Ship North
0x4100	130	Pirate Ship East
0x4180	131	Pirate Ship South
0x4200	132	Nixie 1
0x4280	133	Nixie 2
0x4300	134	Giant Squid 1
0x4380	135	Giant Squid 2
0x4400	136	Sea Serpent 1
0x4480	137	Sea Serpent 2
0x4500	138	Seahorse 1
0x4580	139	Seahorse 2
0x4600	140	Whirlpool 1
0x4680	141	Whirlpool 2
0x4700	142	Storm 1
0x4780	143	Storm 2
0x4800	144	Rat 1
0x4880	145	Rat 2
0x4900	146	Rat 3
0x4980	147	Rat 4
0x4a00	148	Bat 1
0x4a80	149	Bat 2
0x4b00	150	Bat 3
0x4b80	151	Bat 4
0x4c00	152	Giant Spider 1
0x4c80	153	Giant Spider 2
0x4d00	154	Giant Spider 3
0x4d80	155	Giant Spider 4
0x4e00	156	Ghost 1
0x4e80	157	Ghost 2
0x4f00	158	Ghost 3
0x4f80	159	Ghost 4
0x5000	160	Slime 1
0x5080	161	Slime 2
0x5100	162	Slime 3
0x5180	163	Slime 4
0x5200	164	Troll 1
0x5280	165	Troll 2
0x5300	166	Troll 3
0x5380	167	Troll 4
0x5400	168	Gremlin 1
0x5480	169	Gremlin 2
0x5500	170	Gremlin 3
0x5580	171	Gremlin 4
0x5600	172	Mimic 1
0x5680	173	Mimic 2
0x5700	174	Mimic 3
0x5780	175	Mimic 4
0x5800	176	Reaper 1
0x5880	177	Reaper 2
0x5900	178	Reaper 3
0x5980	179	Reaper 4
0x5a00	180	Insect Swarm 1
0x5a80	181	Insect Swarm 2
0x5b00	182	Insect Swarm 3
0x5b80	183	Insect Swarm 4
0x5c00	184	Gazer 1
0x5c80	185	Gazer 2
0x5d00	186	Gazer 3
0x5d80	187	Gazer 4
0x5e00	188	Phantom 1
0x5e80	189	Phantom 2
0x5f00	190	Phantom 3
0x5f80	191	Phantom 4
0x6000	192	Orc 1
0x6080	193	Orc 2
0x6100	194	Orc 3
0x6180	195	Orc 4
0x6200	196	Skeleton 1
0x6280	197	Skeleton 2
0x6300	198	Skeleton 3
0x6380	199	Skeleton 4
0x6400	200	Rogue 1
0x6480	201	Rogue 2
0x6500	202	Rogue 3
0x6580	203	Rogue 4
0x6600	204	Python 1
0x6680	205	Python 2
0x6700	206	Python 3
0x6780	207	Python 4
0x6800	208	Ettin 1
0x6880	209	Ettin 2
0x6900	210	Ettin 3
0x6980	211	Ettin 4
0x6a00	212	Headless 1
0x6a80	213	Headless 2
0x6b00	214	Headless 3
0x6b80	215	Headless 4
0x6c00	216	Cyclops 1
0x6c80	217	Cyclops 2
0x6d00	218	Cyclops 3
0x6d80	219	Cyclops 4
0x6e00	220	Wisp 1
0x6e80	221	Wisp 2
0x6f00	222	Wisp 3
0x6f80	223	Wisp 4
0x7000	224	Evil Mage 1
0x7080	225	Evil Mage 2
0x7100	226	Evil Mage 3
0x7180	227	Evil Mage 4
0x7200	228	Lich 1
0x7280	229	Lich 2
0x7300	230	Lich 3
0x7380	231	Lich 4
0x7400	232	Lava Lizard 1
0x7480	233	Lava Lizard 2
0x7500	234	Lava Lizard 3
0x7580	235	Lava Lizard 4
0x7600	236	Zorn 1
0x7680	237	Zorn 2
0x7700	238	Zorn 3
0x7780	239	Zorn 4
0x7800	240	Daemon 1
0x7880	241	Daemon 2
0x7900	242	Daemon 3
0x7980	243	Daemon 4
0x7a00	244	Hydra 1
0x7a80	245	Hydra 2
0x7b00	246	Hydra 3
0x7b80	247	Hydra 4
0x7c00	248	Dragon 1
0x7c80	249	Dragon 2
0x7d00	250	Dragon 3
0x7d80	251	Dragon 4
0x7e00	252	Balron 1
0x7e80	253	Balron 2
0x7f00	254	Balron 3
0x7f80	255	Balron 4

CHARSET.EGA

This contains the bitmaps for each character in the font. Each character is 8x8 pixels, and each byte represents two pixels. In other words, the first 4 bytes represent the 8 pixels on the first row of the first character.

The EGA Character Set is:

Offset	Length	Notes
0x0	32	character 0
0x20	32	character 1
0x40	32	character 2
...	...	...
0x1FC0	32	character 255

The order is the standard ASCII mapping; 'A' is character 65, 'z' is character 122. The lowest 32 characters have the following glyphs:

#	Name
0	Ankh
1	Symbol for horn effect
2	Brick wall 1
3	Brick wall 2
4	Updown arrow
5	Down arrow
6	Up arrow
7	Partial ankh
8	Filled circle
9	Copyright
10	Registered trademark
11	Male symbol
12	Female symbol
13	Border bar
14	Hollow square
15	?
16	Border endpiece (right)
17	Border endpiece (left)
18	?
19	Ellipsis
20	Moon phase 0
21	Moon phase 1
22	Moon phase 2
23	Moon phase 3
24	Moon phase 4
25	Moon phase 5
26	Moon phase 6
27	Moon phase 7
28	Cursor image 1
29	Cursor image 2
30	Cursor image 3
31	Cursor image 4

Run-Length Encoded EGA Files

The following .EGA files are RLE encoded: START.EGA, KEY7.EGA, RUNE_x.EGA (where x is between 0 and 5), STONCRCL.EGA, HONESTY.EGA, COMPASSN.EGA, VALOR.EGA, JUSTICE.EGA, SACRIFIC.EGA, HONOR.EGA, SPIRIT.EGA, HUMILITY.EGA, TRUTH.EGA, LOVE.EGA, and COURAGE.EGA. Each of these files represents a 16 color 320x200 bitmap. Each pixel is encoded in 4 bits, like SHAPES.EGA and CHARSET.EGA. However, runs of identical *bytes* (not pixels) are encoded with a special run indicator value (0x02) followed by a one byte count and a one byte value. This allows a single run of up to 255 bytes (510 pixels) to be represented as three bytes. For example, the byte values "28 28 28 28" could be represented as "02 04 28". If the value 0x02 needs to be represented, it *must* be encoded in a run ("02 01 02").

• 

  START.EGA

• 

  KEY7.EGA

• 

  RUNE_0.EGA

• 

  RUNE_1.EGA

• 

  RUNE_2.EGA

• 

  RUNE_3.EGA

• 

  RUNE_4.EGA

• 

  RUNE_5.EGA

• 

  _STONCRCL.EGA

• 

  HONESTY.EGA

• 

  COMPASSN.EGA

• 

  VALOR.EGA

• 

  JUSTICE.EGA

• 

  SACRIFIC.EGA

• 

  HONOR.EGA

• 

  SPIRIT.EGA

• 

  HUMILITY.EGA

• 

  TRUTH.EGA

• 

  LOVE.EGA

• 

  COURAGE.EGA

File	Purpose
START.EGA	The basic game borders
KEY7.EGA	Shown when the key is used
RUNE_0.EGA	Vision shown after meditating on valor
RUNE_1.EGA	Vision shown after meditating on honesty, justice, and honor
RUNE_2.EGA	Vision shown after meditating on compassion and sacrifice
RUNE_3.EGA	Vision shown after meditating on spirituality
RUNE_4.EGA	Vision shown after meditating on humility
RUNE_5.EGA	Vision after answering the final riddle in the Stygian Abyss
STONCRCL.EGA	Shown when game completed
HONESTY.EGA	Shown during questioning in abyss
COMPASSN.EGA	Shown during questioning in abyss
VALOR.EGA	Shown during questioning in abyss
JUSTICE.EGA	Shown during questioning in abyss
SACRIFIC.EGA	Shown during questioning in abyss
HONOR.EGA	Shown during questioning in abyss
SPIRIT.EGA	Shown during questioning in abyss
HUMILITY.EGA	Shown during questioning in abyss
TRUTH.EGA	Shown during questioning in abyss
LOVE.EGA	Shown during questioning in abyss
COURAGE.EGA	Shown during questioning in abyss

LZW Encoded EGA Files

The remaining .EGA files are LZW encoded: ABACUS.EGA, ANIMATE.EGA, GYPSY.EGA, INSIDE.EGA, OUTSIDE.EGA, PORTAL.EGA, TREE.EGA, WAGON.EGA, HONCOM.EGA, SACHONOR.EGA, SPIRHUM.EGA, VALJUS.EGA, and TITLE.EGA. Also, the file SHAPES.EGZ is a LZW compressed version of SHAPES.EGA. Like the RLE encoded files, each of these files represents a 16 color 320x200 bitmap. LZW encoded files only seem to be used in the introduction sequence (i.e. in TITLE.EXE); the images used by AVATAR.EXE are RLE encoded instead.

For more details on the LZW algorithm: Lempel-Ziv-Welch

• 

  ABACUS.EGA

• 

  ANIMATE.EGA

• 

  GYPSY.EGA

• 

  HONCOM.EGA

• 

  INSIDE.EGA

• 

  OUTSIDE.EGA

• 

  PORTAL.EGA

• 

  SACHONOR.EGA

• 

  SPIRHUM.EGA

• 

  TITLE.EGA

• 

  TREE.EGA

• 

  VALJUS.EGA

• 

  WAGON.EGA

File	Purpose
ABACUS.EGA	The abacus that serves as the background while the questions are asked
ANIMATE.EGA	The frames for the little critters in the upper corners of the intro screen
GYPSY.EGA	The gypsy herself
HONCOM.EGA	The cards for honor and compassion
INSIDE.EGA	Inside the fair
OUTSIDE.EGA	The fair from outside
PORTAL.EGA	Closeup of the moongate
SACHONOR.EGA	The cards for sacrifice and honor
SPIRHUM.EGA	The cards for spirituality and humility
TITLE.EGA	The background for the inital screen, including the large Ultima IV and the border for the map/menu
TREE.EGA	Initial graphic for character creation sequence (has animated moongate)
VALJUS.EGA	The cards for valor and justice
WAGON.EGA	The gyspy's wagon

WORLD.MAP

This is the map of Britannia. It is 256x256 tiles in total and broken up into 64 32x32 chunks; the total file is 65,536 bytes long. The first chunk is in the top left corner; the next is just to the right of it, and so on. The last chunk is in the bottom right corner. Each tile is stored as a byte that maps to a tile in SHAPES.EGA. The chunks are stored in the same way as the overall map: left to right and top to bottom.

The "chunked" layout is an artifact of the limited memory on the original machines that ran Ultima IV. The whole map would take 64kb, too much for a C64 or an Apple II, so the game would keep a limited number of 1k chunks in memory at a time. As the player moved around, old chunks were thrown out as new ones were swapped in.

Offset	Length (in bytes)	Notes
0x0	1024	32x32 map matrix for chunk 0
0x400	1024	32x32 map matrix for chunk 1
...	...	...
0xFC00	1024	32x32 map matrix for chunk 63

ULT files

These contain town information. Specifically, a 32x32 map, plus the starting position, movement behavior, and conversation index of each NPC. The conversation index gives the starting position of the NPC's dialog block in the corresponding .TLK file. I'm not sure why some of the data is duplicated.

Offset	Length (in bytes)	Notes
0x0	1024	32x32 Town Map Matrix
0x400	32	Tile index for NPCs 0-31
0x420	32	Start_x for NPCs 0-31
0x440	32	Start_y for NPCs 0-31
0x460	32	Unused? - Same structure as monster.sav so previous tile?
0x480	32	Unused? - Same structure as monster.sav so previous x?
0x4A0	32	Unused? - Same structure as monster.sav so previous y?
0x4C0	32	Movement Behavior for NPCs 0-31
0x4E0	32	1-based conversation index (in the corresponding tlk file) for NPCs 0-31. 0 indicates no tlk record.

Movement Behavior

Byte Value	Type
0x00	Fixed
0x01	Wander
0x80	Follow
0xFF	Attack

TLK files

These files contain the dialogue for up to 16 NPCs in a given area. Each NPC has a 288 (0x120) byte block containing his or her dialogues, followed by the keywords that trigger his or her responses. Most of the fields are null-terminated, variable length strings, with the following field starting immediately after. The blocks are then padded with zero bytes to 288 bytes. See also Ultima IV transcript.

Offset	Length (in bytes)	Purpose
0x0	1	Question Flag (3=JOB, 4=HEALTH, 5=KEYWORD1, 6=KEYWORD2)
0x1	1	Does Response Affect Humility? (0=No, 1=Yes)
0x2	1	Probability of Turning Away (out of 256)
0x3	Varies	Name
Varies	Varies	Pronoun (He, She or It)
Varies	Varies	LOOK Description
Varies	Varies	JOB Response
Varies	Varies	HEALTH Response
Varies	Varies	KEYWORD 1 Response
Varies	Varies	KEYWORD 2 Response
Varies	Varies	Yes/No Question
Varies	Varies	YES Response
Varies	Varies	NO Response
Varies	Varies	KEYWORD 1
Varies	Varies	KEYWORD 2
Varies-0x119	Varies	00000....

CON files

These files contain the 11x11 battleground maps shown when combat starts. It has the map itself plus starting positions for up to 16 monsters and 8 party members.

Offset	Length (in bytes)	Purpose
0x0	16	start_x for monsters 0-15
0x10	16	start_y for monsters 0-15
0x20	8	start_x for party members 0-7
0x28	8	start_y for party members 0-7
0x30	16	Purpose unknown; seems to be a constant: 08 AD 83 C0 AD 83 C0 AD 83 C0 A0 00 B9 A6 08 F0
0x40	121	11x11 Map Matrix
0xB9	7	Purpose unknown; seems to be a constant: 8D 00 00 00 00 47 09

DNG files

These files define each of the dungeons. The standard file size is 4,608 bytes. ABYSS.DNG is 16,896 bytes.

3D Dungeon Map

The first 512 bytes are the 8x8 maps for each of the 8 levels. These are used for the dungeons in 3D mode. They are read, as usual, from left to right and then top to bottom.

Offset	Length (in bytes)	Purpose
0x0	64	Level 1 Map Matrix
0x40	64	Level 2 Map Matrix
0x80	64	Level 3 Map Matrix
0xC0	64	Level 4 Map Matrix
0x100	64	Level 5 Map Matrix
0x140	64	Level 6 Map Matrix
0x180	64	Level 7 Map Matrix
0x1C0	64	Level 8 Map Matrix

Dungeon Floor Tiles

Each point on the grid can be one of several types.

Value	Type
00	Nothing
10	Ladder Up
20	Ladder Down
30	Laddr Up & Down
40	Treasure Chest
50	Ceiling Hole
60	Floor Hole (unused)
70	Magic Orb
80	Winds/Darknes Trap
81	Falling Rock Trap
8E	Pit Trap
90	Plain Fountain
91	Healing Fountain
92	Acid Fountain
93	Cure Fountain
94	Poison Fountain
A0	Poison Field
A1	Energy Field
A2	Fire Field
A3	Sleep Field
B0	Altar
C0	Door
D0-DF	Dungeon Rooms 0-15
E0	Secret Door
F0	Wall

ABYSS.DNG Map Format

The Stygian Abyss also follows the same format with one important caveat: since it has 64 rooms instead of 16, several levels share D# values. Levels 1&2 each have eight rooms. Levels 3&4 each have eight rooms. Level 5 has 5 rooms, and Level 6 has 11 rooms. Level 7 has 4 rooms, and Level 8 has 12 rooms. The D# values still define the order the rooms appear; they simply reset every two dungeon levels.

Dungeon Rooms

The rest of the file is a set of 16 (64 in the case of the ABYSS.DNG) 256 byte blocks that define the dungeon rooms.

Offset	Length (in bytes)	Purpose
0x200	256	Room 0 Data
0x300	256	Room 1 Data
0x400	256	Room 2 Data
0x500	256	Room 3 Data
0x600	256	Room 4 Data
...	...	...
0x1100	256	Room 15 Data

ABYSS.DNG only

Offset	Length (in bytes)	Purpose
0x200	256	Room 0 Data
0x300	256	Room 1 Data
0x400	256	Room 2 Data
0x500	256	Room 3 Data
0x600	256	Room 4 Data
...	...	...
0x1100	256	Room 15 Data
0x1200	256	Room 16 Data
0x1300	256	Room 17 Data
...	...	...
0x4100	256	Room 63 Data

Dungeon Room Format

Offset	Length (in bytes)	Purpose
0x0	16	floor triggers (4 bytes each X 4 triggers possible)
0x10	16	tile for monsters 0-15 (0 means no monster and 0's come FIRST)
0x20	16	start_x for monsters 0-15
0x30	16	start_y for monsters 0-15
0x40	8	start_x for party member 0-7 (north entry)
0x48	8	start_y for party member 0-7 (north entry)
0x50	8	start_x for party member 0-7 (east entry)
0x58	8	start_y for party member 0-7 (east entry)
0x60	8	start_x for party member 0-7 (south entry)
0x68	8	start_y for party member 0-7 (south entry)
0x70	8	start_x for party member 0-7 (west entry)
0x78	8	start_y for party member 0-7 (west entry)
0x80	121	11x11 map matrix for room
0xF9	7	buffer

Trigger format

Offset	Length (in bytes)	Purpose
0x0	1	tile to be placed
0x1	1	2 nibbles indicating the (x,y) coords of trigger
0x2	1	2 nibbles indicating the (x,y) coords of 1st tile to change
0x3	1	2 nibbles indicating the (x,y) coords of 2nd tile to change

All 0's indicate no trigger. "No trigger" records come last.

TRIGGER EXAMPLE: 0x45 0x85 0x75 0x65 - Places a Lightning Field (tile #69) at locations (7, 5) and (6, 5) when you step on location (8, 5).

SAV Files

These files save the state of the program between sessions.

PARTY.SAV

This file stores the information that is stored when the game is saved. It includes party-wide information like gold and food, plus a 39 byte record for each character.

Offset	Length (in bytes)	Purpose
0x0	4	Counter (incremented regularly, probably every screen update)
0x4	2	Moves (low word)
0x6	2	Moves (high word)
0x8	39	Player 0 record
0x2F	39	Player 1 record
0x56	39	Player 2 record
0x7D	39	Player 3 record
0xA4	39	Player 4 record
0xCB	39	Player 5 record
0xF2	39	Player 6 record
0x119	39	Player 7 record
0x140	4	Food (in units of hundredths)
0x144	2	Gold
0x146	16	Karma (2 bytes each for honesty, compassion, valor, justice, sacrifice, honor, spirituality and humility; 0-partial avatar)
0x156	2	Torches
0x158	2	Gems
0x15A	2	Keys
0x15C	2	Sextants
0x15E	16	Armor (2 bytes each for none (unused), cloth, leather, chain, plate, magic chain, magic plate, mystic robes)
0x16E	32	Weapons (2 bytes each for none (unused), staves, daggers, slings, maces, axes, swords, bows, crossbows, oil, halberds, magic axes, magic swords, magic bows, magic wands, mystic swords)
0x18E	16	Reagents (2 bytes each for sulfurous ash, ginseng, garlic, spider silk, blood moss, black pearl, nightshade, mandrake)
0x19E	52	Mixtures (2 bytes each for awaken, blink, cure, dispel, energy, fireball, gate, heal, iceball, jinx, kill, light,magic missile, negate, open, protection, quickness, resurrect, sleep, tremor, undead, view, winds, x-it, y-up, z-down)
0x1D2	1	Items (1 bit each for skull, skull destroyed, candle, book, bell, key part C, key part L, key part T)
0x1D3	1	Items (1 bit each for horn, wheel, candle used at abyss entrance, book used at abyss entrance, bell used at abyss entrance, (3 bits unused))
0x1D4	1	X coordinate
0x1D5	1	Y coordinate
0x1D6	1	Stones (1 bit each for BYRGOPWB)
0x1D7	1	Runes (1 bit each for HCVJSHSH)
0x1D8	2	Number of characters in party
0x1DA	2	Transportation (0x10-ship facing west, 0x11-ship facing north, 0x12-ship facing east, 0x13-ship facing south, 0x14-horse facing west, 0x15-horse facing east, 0x18-balloon, 0x1f-on foot)
0x1DC	2	On surface: balloon status (0-on ground, 1-flying) in dungeon: current torch duration
0x1DE	2	Current phase of left moon (Trammel); range = 0-7
0x1E0	2	Current phase of right moon (Felucca); range = 0-7
0x1E2	2	Hull integrity of currently boarded ship if you x-it a ship, save, restart the game, and board the ship again, you will find that all damage to the ship has been mysteriously repaired.
0x1E4	2	Introduced to Lord British (0-haven't been introduced, 1-introduced)
0x1E6	2	Time of last successful hole up & camp. The game stores ((moves / 0x64) & 0xffff) in this field when you successfully hole up & camp. If (moves / 0x64) < 0x10000: You can only hole up & camp successfully if the current ((moves / 0x64) & 0xffff) is different from the value in this field. If (moves / 0x64) >= 0x10000: Hole up & camp is always successful.
0x1E8	2	Time of last mandrake/nightshade find. The game stores (moves & 0xf0) in this field when you find mandrake/nightshade. You can only find mandrake/nightshade if the current (moves & 0xf0) is different from the value in this field.
0x1EA	2	Time of last successful meditation at a shrine. The game stores ((moves / 0x64) & 0xffff) in this field when you successfully meditate at a shrine. If (moves / 0x64) < 0x10000: You can only meditate successfully if the current ((moves / 0x64) & 0xffff) is different from the value in this field. If (moves / 0x64) >= 0x10000: Meditating at a shrine is always successful.
0x1EC	2	Time of last virtue-related conversation. The game stores ((moves / 0x10) & 0xffff) in field when one of the following happens: (1) you give gold to a beggar, (2) you answer a yes/no question from an NPC (doesn't have to be a question where the answer affects your virtue). If ((moves / 0x10) & 0xffff) < 0x10000: Giving gold to a beggar or answering a virtue-related yes/no question only increases your karma if ((moves / 0x10) & 0xffff) is different from the value in this field. If ((moves / 0x10) & 0xffff) >= 0x10000: Giving gold or answering a virtue question always increases your karma.
0x1EE	2	If the party is in a dungeon: coordinates of this dungeon, if not: coordinates of the dungeon last entered by the party
0x1F0	2	Orientation in dungeon (0-west, 1-north, 2-east, 3-south)
0x1F2	2	Dungeon level (starting at zero, 0xffff = surface)
0x1F4	2	Current party location (see below)

Character Record Format

Offset	Length (in bytes)	Purpose
0x0	2	HP
0x2	2	Maximum HP
0x4	2	XP
0x6	2	Strength
0x8	2	Dexterity
0xA	2	Intelligence
0xC	2	MP
0xE	2	???
0x10	2	Weapon
0x12	2	Armor
0x14	16	Name
0x24	1	Sex (0xb-male, 0xc-female)
0x25	1	Class
0x26	1	Status ('G'-good, 'P'-poisoned, 'S'-sleeping, 'D'-dead)

Party Location

Since you can only save on the surface or in a dungeon, the only valid party locations are 0 and 0x11-0x18.

Value	Location
0x00	Surface
0x01	Lord British's castle
0x02	The Lycaeum
0x03	Empath Abbey
0x04	Serpent's Hold
0x05	Moonglow
0x06	Britain
0x07	Jhelom
0x08	Yew
0x09	Minoc
0x0A	Trinsic
0x0B	Skara Brae
0x0C	Magincia
0x0D	Paws
0x0E	Buccaneer's Den
0x0F	Vesper
0x10	Cove
0x11	Deceit
0x12	Despise
0x13	Destard
0x14	Wrong
0x15	Covetous
0x16	Shame
0x17	Hythloth
0x18	Abyss
0x19	Shrine of Honesty
0x1A	Shrine of Compassion
0x1B	Shrine of Valor
0x1C	Shrine of Justice
0x1D	Shrine of Sacrifice
0x1E	Shrine of Honor
0x1F	Shrine of Spirituality
0x20	Shrine of Humility

MONSTERS.SAV

Ultima IV maintains a structure (in memory) that I've decided to call the "monster table." When you Journey Onward, U4 loads MONSTERS.SAV into the monster table. When you Quit & Save, U4 writes the monster table to MONSTERS.SAV. The purpose of the monster table fields depends on the current party location (surface, dungeon, settlement).

Surface

On the surface, the monster table contains information about monsters and inanimate objects (chests, horses, ships, balloon). A table entry is free if previousTile[i]==0. When u4dos deletes an entry, it sets both currentTile[i] and previousTile[i] to 0. Slots 0-7 are for monsters, while slots 8-31 are for inanimate objects. Non-empty entries don't have to be contiguous. Whirlpools and twisters are special cases; they must be placed in slot 0-3, or they won't swallow ships / damage the party. When you leave Hythloth, u4dos creates the balloon at (233 / 242). If there is more than one inanimate object on a tile, objects closer to the beginning of the table are drawn on top of those closer to the end. Monsters and the party are always drawn on top of inanimate objects. The current tile and previous tile values are used during runtime. However, when the game is saved, the previous tile must be set to the monster's base tile. The current tile can be any of the monster's tiles, except for pirate ships, where the current tile determines which direction the pirate ship is facing. If the previous tile is not set to the monster's base tile, it won't behave properly in u4dos: monsters with ranged attacks won't use them in combat, twisters and whirlpools will attack the party, and pirates will appear as pirate ships in battle. For transports with more than one tile (horse, ship), the previous tile determines which direction the transport is facing, while the current tile can be any of the transport's tiles.

Offset	Length (in bytes)	Purpose
0x0	32	Current Tile #s
0x20	32	X Coordinates For Current Turn
0x40	32	Y Coordinates For Current Turn
0x60	32	Tile #s For Previous Turn
0x80	32	X Coordinates For Previous Turn
0xA0	32	Y Coordinates For Previous Turn
0xC0	32	Unused
0xE0	32	Unused

Dungeons

In a dungeon, the monster table contains information about the monsters in the dungeon. A monster stored in the monster table is *also* stored in DNGMAP.SAV. Inanimate objects are not stored in the monster table; they are stored *only* in DNGMAP.SAV.

Offset	Length (in bytes)	Purpose
0x0	32	Unused
0x20	32	X Coordinate For Current Turn
0x40	32	Y Coordinate For Current Turn
0x60	32	Current Tile #
0x80	32	X Coordinate For Previous Turn
0xA0	32	Y Coordinate For Previous Turn
0xC0	32	Dungeon Level (Range: 0-7)
0xE0	32	Unused

Settlements

In a castle/town/village, the monster table is loaded from the settlements’ .ULT file, starting at offset 0x400. It contains information about the settlements’ NPCs.

Offset	Length (in bytes)	Purpose
0x0	32	Current Tile #
0x20	32	X Coordinate For Current Turn
0x40	32	Y Coordinate For Current Turn
0x60	32	Tile # For Previous Turn
0x80	32	X Coordinate For Previous Turn
0xA0	32	Y Coordinate For Previous Turn
0xC0	32	Movement Behavior For NPCs 0-31 (0x0-fixed, 0x1-wander, 0x80-follow, 0xFF-attack)
0xE0	32	Conversation Index (.tlk file) For NPCs 0-31

OUTMONST.SAV

OUTMONST.SAV is a backup of the monster table, created when you enter a dungeon or settlement. When you leave a dungeon or settlement, the monster table is reloaded from OUTMONST.SAV.

Exception: When you enter Hythloth through the ladder in LB's castle, the game does not write the current monster table to OUTMONST.SAV, because it already did that when you entered LB's castle.

DNGMAP.SAV

When you Quit & Save in a dungeon, the game saves objects (orbs, chests) and monsters in DNGMAP.SAV. DNGMAP.SAV contains the 8x8 maps for all 8 levels. Every tile is encoded as a byte. The upper nibble of a tile determines the tile type (see below). The lower nibble encodes the monster standing on the tile, except for tiles 0x80 0x90 0xA0 0xD0 (see below).

Value	Purpose
0x00	Nothing
0x10	Ladder Up
0x20	Ladder Down
0x30	Ladder Up/Down
0x40	Chest
0x50	Hole in Ceiling (unused)
0x60	Hole in Floor (unused)
0x70	Orb (see below)
0x80	Wind/Darkness Trap (magic winds)
0x81	Falling Rocks Trap (falling rocks)
0x8E	Pit Trap
0x90	Ordinary Fountain (no effect)
0x91	Healing Fountain (restores all HP)
0x92	Acid Fountain (100 HP damage)
0x93	Curing Fountain (cures poison)
0x94	Poisoned Fountain (poison and 100 HP damage)
0xA0	Poison Field
0xA1	Energy Field
0xA2	Fire Field
0xA3	Sleep Field
0xB0	Altar (stone color depends on dungeon)
0xC0	Door
0xD0-0xDF	Dungeon Rooms 0-15
0xE0	Hidden Door
0xF0	Wall

Monsters

Value	Purpose
0x0	None
0x1	Rat
0x2	Bat
0x3	Spider
0x4	Ghost
0x5	Slime
0x6	Troll
0x7	Gremlin
0x8	Mimic
0x9	Reaper
0xA	Insect Swarm
0xB	Gazer
0xC	Phantom
0xD	Orc
0xE	Skeleton
0xF	Rogue

Orbs

When a PC touches an orb, one or more attributes are raised by 5 points each. Which attributes are raised depends on the dungeon.

Dungeon	Attributes
Deceit	INT
Despise	DEX
Destard	STR
Wrong	INT,DEX
Covetous	DEX,STR
Shame	INT,DEX
Hythloth	INT,DEX,STR

EXE Files

These files are the executable programs that power the game. They also contain some data that does not fit elsewhere.

TITLE.EXE

This executable is launched by ULTIMA.COM to display the introduction and create new characters. When "Journey Onward" is selected from the intro menu, it exits and ULTIMA.COM passes control off to AVATAR.EXE, the main game executable. AVATAR.EXE has lots of the data necessary for the intro screens embedded in it.

Offset	Length (in bytes)	Purpose
0x0	17445	???
0x4425	11088	Text for Introduction, Gypsy Dialog and Gyspy Questions (null-terminated strings)
0x6f75	1035	???
0x70dc	8	Starting x positions for a new game
0x70e4	8	Starting y positions for a new game
0x7380	184	List of Frames Sequences for Beasties on Intro Screen
0x7438	54	???
0x746e	532	266 X/Y Coordinates for the pixels that make up the Lord British signature on the introductory title screen
0x7682	1	Zero Terminating Byte
0x7683	95	Tile Values for the 19x5 map that appears on the introductory title screen
0x76e2	548	Script Data for the intro map animations
0x7906	...	???

AVATAR.EXE

This is the main game executable, launched from ultima.com (or run on its own to skip the intro). Lots of the special case data is embedded in it.

Offset	Length (in bytes)	Purpose
0x0	25123	???
0x06223	1	Everything this value and below can't be used in the Abyss
0x0	38719	???
0x0f963	1	volume on/off flag
0x0f964	27	13 two-byte code pointers to 13 sound generation routines plus one padding byte
0x0f97f	171	.ULT filenames; 16 zero terminated strings
0x0fa2a	48	stone colors; 8 zero terminated strings
0x0fa5a	91	.DNG filenames; 8 zero terminated strings
0x0fab5	28	???
0x0fad1	8	moongate x-coordinates (one byte for each moongate starting at Moonglow)
0x0fad9	8	moongate y-coordinates (one byte for each moongate starting at Moonglow)
0x0fae1	32	16 two-byte offsets to .ULT filenames (value + 62141 gives file offset)
0x0fb01	32	area x-coordinates (one byte for each town, city, castle, dungeon, shrine)
0x0fb21	32	area y-coordinates (one byte for each town, city, castle, dungeon, shrine)
0x0fb41	16	8 two-byte offsets to stone colors (value + 62141 gives file offset)
0x0fb51	16	8 two-byte offsets to .DNG filenames (value + 62141 gives file offset)
0x0fb61	72	???
0x0fba9	8	pirates cove ship x coordinates
0x0fbb1	8	pirates cove ship y coordinates
0x0fbb9	8	pirates cove ship tiles
0x0fbc1	37	zero terminated list of tiles that are walkable
0x0fbe6	149	14 zero-terminated navigation strings ("North", "Sail North", etc.)
0x0fc7b	539	Chamber of the Codex virtue questions
0x0fe96	78	???
0x0fee4	647	Chamber of the Codex dialog strings
0x1016b	28	???
0x10187	509	Chamber of the Codex dialog strings
0x10384	83	???
0x103d7	1280	abyss question dialog strings
0x108d7	22	11 two-byte offsets to abyss question answers (value + 62141 gives file offset)
0x108ed	80	???
0x1093d	169	.TLK filenames; 16 zero terminated strings
0x109e6	13	"OUTMONST.SAV" zero terminated string
0x109f3	32	16 two-byte offsets to .TLK filenames (value + 62139 gives file offset)
0x10a13	659	???
0x10ca6	246	monster names; 36 zero terminated strings
0x10d9c	129	weapon names; 16 zero terminated strings
0x10e1d	77	armor names; 8 zero terminated strings
0x10e6a	64	weapon abbreviations; 16 zero terminated strings
0x10eaa	55	character class names; 8 zero terminated strings
0x10ee1	58	npc type names; 8 zero terminated strings
0x10f1b	81	reagent names; 8 zero terminated strings
0x10f6c	434	spell names; 26 zero terminated strings
0x1101e	292	castle/city/town/dungeon/shrine names; 32 zero terminated strings
0x11142	11	???
0x1114d	72	36 two-byte offsets to monster names (value + 62131 gives file offset)
0x11195	32	16 two-byte offsets to weapon names (value + 62131 gives file offset)
0x111b5	16	8 two-byte offsets to armor names (value + 62131 gives file offset)
0x111c5	32	16 two-byte offsets to weapon abbreviations (value + 62131 gives file offset)
0x111e5	16	8 two-byte offsets to character class names (value + 62131 gives file offset)
0x111f5	330	???
0x1133f	26	mp required for each spell (one byte per spell)
0x11359	654	???
0x115e7	16	mask of which classes can use each weapon (one byte per weapon)
0x115f7	8	mask of which classes can use each type of armor (one byte per armor type)
0x115ff	134	???
0x11685	52	monster hp table
0x116b9	36	monster leader types (one byte per monster type)
0x116dd	36	monster encounter size table (one byte per monster type)
0x11701	2	???
0x11703	16	weapon damage list (one byte per weapon type)
0x11713	8	armor defense list (one byte per armor type)
0x1171b	16	weapon category list (one byte per weapon type; 0 = melee, 0xff = missile)
0x1172b	154	.CON filenames; 14 zero terminated strings
0x117c5	28	14 two-byte offsets to .CON filenames (value + 62131 gives file offset)
0x117e1	64	dungeon .CON filenames; 7 zero terminated strings
0x11821	164	???
0x118c5	12	altar room exit destinations 0-3 = truth (north, east, south, west), 4-7 = love, 8-11 = courage
0x118d1	146	???
0x11963	8	ambush monster types
0x1196b	190	miscellaneous text strings
0x11a29	26	spell reagent masks (one byte per spell)
0x11a43	364	miscellaneous text strings
0x11baf	16	city/runemask pairs (city id, corresponding rune bitmask)
0x11bbf	12	miscellaneous text string
0x11bcb	120	24 five-byte item location records (see below)
0x11c43	288	???
0x11d63	250	companion dialog text
0x11e5d	16	8 two-byte offsets to virtue adjectives for companion dialogs (value + 62123 gives file offset)
0x11e6d	1404	???
0x11f7f	128	16 entries of 8 bytes giving the y location of different shops (?,?,?,?,?,Healer,?,?)
0x123e9	3486	Hawkwind dialog text; the first 40 zero terminated strings are his responses for 5 levels times 8 virtues, plus some other miscellaneous dialog strings
0x13187	80	40 two-byte offsets to Hawkwind dialog strings (value + 62075 gives file offset)
0x131d7	564	reagent vendor dialog text; x zero terminated strings
0x133eb	16	reagent vendor index for each city (one byte per castle/city/town)
0x133fb	8	4 two-byte offsets to reagent shop names (value + 62075 gives file offset)
0x13403	8	4 two-byte offsets to reagent shopkeeper names (value + 62075 gives file offset)
0x1340b	24	price for each of the first six reagents at Moonglow, Skara Brae, Paws, and Buccaneers Den respectively (one byte per price)
0x13423	1274	weapon vendor dialog text; 28 zero terminated strings
0x1391d	12	6 two-byte offsets to weapon shop names (value + 62075 gives file offset)
0x13929	12	6 two-byte offsets to weapon shopkeeper names (value + 62075 gives file offset)
0x13935	24	which four weapons each of the six weapons vendors can sell (one byte per weapon)
0x1394d	32	price of each weapon (two bytes for each price)
0x1396d	16	weapon vendor index for each city (one byte per castle/city/town)
0x1397d	28	14 two-byte offsets to weapon descriptions (value + 62075 gives file offset) for all weapons except hands and mystic
0x13999	522	more weapon vendor dialog text; 27 zero terminated strings
0x13ba3	646	armor vendor dialog text; 19 zero terminated strings
0x13e29	10	5 two-byte offsets to armor shop names (value + 62075 gives file offset)
0x13933	12	6 two-byte offsets to armor shopkeeper names (value + 62075 gives file offset)
0x13e3f	20	which four types of armor each of the five armor vendors can sell (one byte per armor type)
0x13e53	4	zero padding
0x13e57	16	price of each type of armor (two bytes for each price)
0x13e67	16	armor vendor index for each city (one byte per castle/city/town)
0x13e77	12	6 two-byte offsets to armor descriptions (value + 62075 gives file offset) for all armor types except skin and mystic
0x13e83	484	more armor vendor dialog text; 27 zero terminated strings
0x14067	318	horse vendor dialog text; 7 zero terminated strings
0x141a5	622	guild vendor dialog text; x zero terminated strings
0x14413	6	???
0x14419	8	price per unit of each guild item (two bytes for each price)
0x14521	8	quantity per unit of each guild item (two bytes for each quantity)
0x14429	4	2 two-byte offsets to guild shop names (value + 62075 gives file offset)
0x1442d	4	2 two-byte offsets to guild shopkeeper names (value + 62075 gives file offset)
0x14431	8	4 two-byte offsets to guild item inquiry responses (value + 62075 gives file offset) for torches, gems, keys, sextants
0x14439	702	inn dialog text; x zero terminated strings
0x146F7	16	inn index for each city (one byte per castle/city/town)
0x14707	8	inn sleep location x coordinate for seven inns plus zero pad
0x1470f	8	inn sleep location y coordinate for seven inns plus zero pad
0x14717	8	inn prices for seven inns plus zero pad
0x1471f	14	7 two-byte offsets to inn names (value + 62067 gives file offset)
0x1472d	14	7 two-byte offsets to inn names (value + 62067 gives file offset)
0x1473b	14	7 two-byte offsets to inn price dialogs (value + 62067 gives file offset)
0x14749	424	more inn dialog text; x zero terminated strings
0x148f1	266	healer dialog text; x zero terminated strings
0x149fb	16	healer index for each city (one byte per castle/city/town)
0x14a0b	20	10 two-byte offsets to healer shopkeeper names (value + 62067 gives file offset)
0x14a1f	20	10 two-byte offsets to healer shopkeeper names (value + 62067 gives file offset)
0x14b33	598	more healer dialog text; x zero terminated strings
0x14d89	978	tavern dialog text; x zero terminated strings
0x1515b	16	tavern index for each city (one byte per castle/city/town)
0x1516b	12	minimum price for information at each tavern (two bytes for each price)
0x15177	12	6 two-byte offsets to tavern shop names (value + 62067 gives file offset)
0x15183	12	6 two-byte offsets to tavern shopkeeper names (value + 62067 gives file offset)
0x1518f	12	6 two-byte offsets to tavern specialty names (value + 62067 gives file offset)
0x1519b	12	price for plate of food at each tavern (two bytes for each price)
0x151a7	12	7 two-byte offsets to tavern information topics (value + 62067 gives file offset) (??? why 7, not 6)
0x151b5	12	6 two-byte offsets to tavern information responses (value + 62067 gives file offset)
0x151c1	598	more tavern dialog text; x zero terminated strings
0x15417	456	food vendor dialog text; x zero terminated strings
0x155df	16	food vendor index for each city (one byte per castle/city/town)
0x155ef	10	price for 25 units of food at each vendor (two bytes for each price) for Moonglow, Britan, Yew, Skara Brae, and Paws, respectively
0x155f9	10	5 two-byte offsets to food shop names (value + 62067 gives file offset)
0x15603	10	5 two-byte offsets to food shopkeeper names (value + 62067 gives file offset)
0x1560d	189	Lord British dialog keywords; 27 zero terminated strings
0x156ca	2968	Lord British dialog text; 25 zero terminated strings ("He says", plus responses for last 24 of the above keywords)
0x16262	104	???
0x162ca	2037	Lord British "help" response dialog strings
0x16abf	...	???

Item Location Record

Each item location record has the following structure:

Offset	Length (in bytes)	Purpose
0x0	1	Item Location (same encoding as party location in PARTY.SAV, e.g. 0 for surface)
0x1	1	X Coordinate of Item
0x2	1	Y Coordinate of Item
0x3	2	pointer to function that handles picking up the item

External Links

• Xenerkes' Ultima website
• More technical information
• Original version of this article.

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Technical Details
Game	Ultima III ☥ Ultima IV ☥ Ultima V ☥ Ultima VI ☥ Ultima VII ☥ Ultima VIII ☥ Ultima IX ☥ Ultima Underworld