event dat Format

event dat Format

event.dat Format — Might & Magic II (Amiga)

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

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: `(x << 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 extra areas (quest zones, special dungeons) that may share map screens or use extended addressing.

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.

Tool

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

Omit location_id to dump all 71 locations.