Atari Mutineer Doors Programmers Guide

Door games are separate Atari BASIC programs that can be distributed apart from the main BBS ATR. Mutineer launches them from DOORS using DOORS.CFG.

For the door catalog file format, see Data And File Formats. For door ATR packaging, see Build And Packaging.

Door Package Layout

Use this source layout for a door game:

source/doorgames/<GAME>/
  <GAME>.cfg
  <GAME>.bas
  <GAME1>.ovl
  <GAME>.dat
  TEXT/<FILENAME>.asc
  TEXT/<FILENAME>.ata

Only the main .bas file is required. Overlays, data files, and text files are optional.

Build the Arena example:

make door-arena-atr

The package is written under source/atr/doors/.

Door Catalog

The main BBS reads DOORS.CFG rows:

id, door name, filename, path, access level

Example:

1, Arena, ARENA, D3:>DOORS>ARENA>, 2

DOORS builds the run path by appending filename to path:

D3:>DOORS>ARENA> + ARENA

The path must end in >. Filenames should be SDX-compatible 8.3 names.

Runtime Contract

A door program must:

Restore MMS state on entry if it needs caller I/O.
Use normal CIO devices (E: and K:) for caller text and input.
Check carrier at prompt boundaries.
Preserve the current message base byte at SS+97.
Return to the door menu with RUN "D1:>CORE>DOORS" in the current packaged ATR.

Door programs should not clear the MMS handoff unless they are intentionally logging the caller off.

MMS Session Rules

The caller identity, access level, user number, terminal modes, and session time live in the MMS handoff block. DOORS saves transient door information in reserved handoff bytes before launching a door. A door should avoid those bytes unless it owns and documents them.

For normal text:

OPEN #3,12,0,"E:"
OPEN #4,4,0,"K:"
PRINT #3;"WELCOME TO THE DOOR"
GET #3,X

For binary transfer behavior, use a dedicated transfer module or MMS raw mode. Do not mix terminal-translated I/O with binary payloads.

Missing Door Handling

If a configured door file is missing, DOORS traps the failed RUN, prints DOOR UNAVAILABLE., restores the BBS session, and returns to the door menu. A door package can therefore be optional for sysops.

Packaging Notes

Keep the door's own config and data files inside the door package. The main BBS only needs the DOORS.CFG row and any mounted disk/path required by that row.

The current door packager writes an install note explaining where to copy files and what catalog row to add.

The Arena example lives under source/doorgames/ARENA/ and is packaged with make door-arena-atr.