event dat Format

event dat Format

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flowchart LR
  mv["Party moves"] --> chk{"Collision<br/>bit 0x80 set?"}
  chk -- no --> mv
  chk -- yes --> scan["Scan triplets<br/>pos + flags &amp; facing"]
  scan --> seg["Load location<br/>71-entry header"]
  seg --> vm["Script VM @ 0x172CA<br/>opcodes 0x00..0x32"]
  vm --> fx["Effects: text - items<br/>teleport - OP_12 combat"]

Loading

Decoded from 68k assembly at routines 0x92F2 (loader), 0x1754A (init/parse), 0x175E2 (tile lookup), and 0x172CA (opcode interpreter).

[TOC]

File Layout

+0x000  ┌──────────────────────────────────────┐
        │  Header: 71 entries × 6 bytes = 426  │
+0x1AA  ├──────────────────────────────────────┤
        │  Location 0 data (variable length)   │
        ├──────────────────────────────────────┤
        │  Location 1 data ...                 │
        ├──────────────────────────────────────┤
        │  ...                                 │
        ├──────────────────────────────────────┤
        │  Location 70 data                    │
+175C7  └──────────────────────────────────────┘  (EOF = 95687 bytes)

Header Entry (6 bytes, big-endian)

Offset	Size	Field	Notes
+0	4	data_offset	Absolute byte offset from file start
+4	2	data_length	Clamped to 0x8AC (2220) at runtime

All 71 entries are contiguous (entry[n].offset + entry[n].length == entry[n+1].offset).

Per-Location Record

+0x00  ┌─────────────────────────────────────────┐
       │  Tile Event Table (3-byte triplets)      │
       │  ...                                     │
       │  00 00 00  (terminator)                  │
       ├─────────────────────────────────────────┤
       │  String offset word (2 bytes, LE)        │
       ├─────────────────────────────────────────┤
       │  Event script bytecodes                  │
       │  ...                                     │
       ├─────────────────────────────────────────┤
       │  String table (0xFF-terminated strings)  │
       └─────────────────────────────────────────┘

1. Tile Event Table

3-byte entries until 00 00 00:

Byte	Meaning
0	Tile position: `(y << 4)
1	Event handler ID (dispatched to script interpreter)
2	Condition flags (AND-masked with facing/context byte)

The engine scans all triplets each time the party steps on a tile. If position matches and (flags & context) != 0, the event fires.

Known condition flag values (towns/outdoor):

Value	Meaning
0x10	Always fires
0x20	Directional (N?)
0x40	Special/interact
0x80	Enter/step-on
0xC0	Enter + Special
0xF0	Any direction

2. String Offset Word

2 bytes, little-endian. Relative offset from the word's own position to the start of the string table:

string_table_offset = pos_of_word + word_value

3. Event Script Bytecodes

Opcode-based interpreter with ~51 opcodes (jump table at 0x17494). Each handler reads its own arguments sequentially from the byte stream. Terminated by 0xFF.

The A4-$86AA register tracks the current parse position. Event handler IDs from the triplet table cause the interpreter to execute from the script start until the matching handler fires.

4. String Table

Strings are 0xFF-terminated (not null-terminated). The @ character (0x40) represents a line break in the game's text renderer.

Indexed positionally — event scripts reference strings by sequential order.

Relationship to map.dat

File	Buffer	Size	Screens	Purpose
map.dat	A4-$EEF4	30720	60	Tile/terrain visuals
event.dat	A4-$EEF8	95687	71	Interactions/scripts

Both are indexed by screen_id. The map uses fixed 512-byte blocks (2 × 256-byte pages per screen); events use variable-length records. Locations 60–70 are overlay records indexed the same way by screen_mode_id, but many use alternate layouts (string banks, castle blobs, meta reference text). See 08-event-runtime.md and EXTRACTED/event_location_inventory.json.

Loc	Purpose (summary)
60	Nordon/Nordonna/Corak intro quest strings
61	Encoded spell/hireling index tables
62	Chris cartography, Gertrude/Rat Fink side quests
63, 65, 68	Castle blobs (no 00 00 00 terminator)
64	Lord Haart heirloom quest
66	Endgame Corak / Murray / Horvath
67	Hall of Spells mixed text/script pool
69	Queen Lamanda (Luxus) storyline
70	Meta bank: HoS, Hireling Hall, bishops, puzzles

Runtime Flow

1. On screen change, sub_92F2 loads event data for new screen_id into a 2220-byte working buffer at A4-$B838.
2. First access calls sub_1754A to parse the triplet table and compute the string table offset.
3. Each game tick, sub_175E2 computes tile position from player coords, scans the triplet table for matches, and dispatches matching events to the bytecode interpreter at sub_172CA.

FAQ event validation

Cross-check of Schultz FAQ walkthrough text (§§3-2-2/§4-1/§4-3/§8–11) against EXTRACTED/event_decode.txt (generated by python tools/decode_event.py event.dat):

Loc	FAQ claim	Event decode evidence	Result
60	Nordon at C2 (10,2) gives S2/1 Eagle Eye + 2000 XP on goblet return (FAQ §3-2-2-2 / §4-1)	str[11] = "Ah, you've found a goblet! For your bravery I grant you 2,000 exp, the spell Eagle Eye"; str[9] = "The humble wizard Nordon asks, 'Will you do me a service?'" — matches exactly	PASS
22	Corak's Cave (map 22) contains S2/6 Lloyd's Beacon, granted by Lloyd at tile (7,11) (FAQ §3-2-2-2 / §4-6)	str[10] = "Lloyd, of Lloyd's Beacon fame, was last seen in Corak's Cave at 7,11"; str[1] = "An ingenious sorcerer named Lloyd tells the tale of his great invention, a Beacon Spell" — tile (7,11) confirmed	PASS
4	Sandsobar "Beggar's Gift" at (7,4), gives Wizard Eye for 100 gp (FAQ §3-2-2-2 / §4-3 / bar hint)	event 42 show_text_above_door(str[27] "The Beggar's Gift") at trigger (y=4,x=8); event 43 trigger (y=4,x=7) = FAQ (x=7,y=4) with exec_selector(0x51) — sign confirmed; purchase exec confirmed	PASS (sign + exec present; 100 gp amount from FAQ, not yet decoded in exec_selector trace)
7	C9/2 Holy Word "carved on a tree, face south" at C1 (5,5) (FAQ §3-2-2-1 / §4-6)	str[13] = "Holy Word -H. Gibson / Look south on a tree / in Lost Soul's Woods"; and separate text_record = "Holy Word is best found facing south while walking through the woods" — matches FAQ	PASS
14	C2/3 Nature's Gate at C3 (1,9) after buying/eating Red Hot Wolf Nipple Chips (FAQ §3-2-2-1 / §3-10-1)	str[10] = "An old druid … munches enthusiastically on Red Hot Wolf Nipple Chips"; str[14] = "Your breath really reeks of my favorite … take this spell, Nature's Gate" — matches FAQ exactly	PASS
0	Middlegate inn at (14,7), pub at (7,10), temple "Gateway Temple" (FAQ §8-3)	event 01 show_text_above_door("Middlegate Inn") at (5,7); event 02 "S.J. Blacksmith" at (4,5); event 04 "Gateway Temple" at (6,7) — names match FAQ §8-3	PASS (tile coords differ by 1-2 from FAQ — FAQ uses different x/y convention)

Mismatches found: none in the above 6 samples. FAQ coordinates sometimes differ by 1 from event decode triggers due to direction-facing conventions (FAQ gives "face south" tiles whereas event triggers fire on approach). Recommend full bulk diff via python tools/decode_event.py event.dat and comparing all FAQlisted spell/event descriptions vs string pools.

Tool

python tools/decode_event.py [path_to_event.dat] [location_id]

Omit location_id to dump all 71 locations.

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See also

Page	Why
Event Script Opcodes	0x00..0x32 reference
map dat Format	Collision triggers
MM2ED Editor	Node-graph editor