Virtual Filesystem

Virtual Filesystem

The simulated C: drive lives in prompt/javascript/fs.js as a JS object tree. Every directory and file in the prompt is defined here.

Top-level layout

C:\
├── AUTOEXEC.BAT          runs on boot — clears the screen and renders the root menu
├── menu.bat              the boot configuration table + EMULATOR LAUNCHER box
├── 1.bat                 cd emulators / menu
└── EMULATORS\
    ├── DOS\              MS-DOS games (self-hosted, jsdos)
    ├── CONSOLE\          ATARI (2600 / 5200 / 7800) / NINTENDO (NES) / SEGA (GENESIS) /
    │                     MATTEL (Intellivision) / COLECO (CVision) / MAGNAVOX (Odyssey 2)
    └── HOMECOMP\         ACORN (BBC / ARCHIMEDES) / COMMODORE (C64) /
                          ATARI (800XL / ST) / SINCLAIR (SPECTRUM / ZX81) /
                          TANDY (CoCo) / MSX (MSX1 / MSX2)

Self-hosted vs externally-linked systems

System	Status	Backing emulator
DOS	self-hosted	jsdos (emulators/jsdos/)
CONSOLE → NINTENDO → NES	self-hosted	JSNES (emulators/jsnes/)
CONSOLE → SEGA → GENESIS	self-hosted	lrusso/Genesis (emulators/genesis/)
CONSOLE → ATARI → 2600	self-hosted	javatari.js (emulators/javatari/)
HOMECOMP → ACORN → BBC	self-hosted	jsbeeb (emulators/jsbeeb/)
HOMECOMP → ACORN → ARCHIMEDES	self-hosted	archimedes-live (emulators/archimedes-live/)
HOMECOMP → MSX → MSX1 / MSX2	self-hosted	WebMSX (emulators/webmsx/)
All other CONSOLE / HOMECOMP systems	external link	game-specific URLs on third-party sites

Self-hosted systems have 10 games each plus a PROMPT (command-line systems) or DESKTOP (RISC OS) entry that boots a clean machine. MSX has 10 + 10 (MSX1 + MSX2 sub-menus).

See Emulators for the integration recipe and how to add more systems.

Per-system menu pattern

A typical <SYSTEM>\GAMES\ directory looks like:

GAMES\
├── menu.bat              numbered title list (45-char wide CP437 box)
├── 0.bat                 cd .. / cd .. / menu (back two levels)
├── 1.bat .. N.bat        each runs a named .bat
└── <key>.bat             one per title, with link: → emulator URL

Navigation (NES example):

1   → cd emulators / menu        (EMULATOR LAUNCHER → CONSOLE / HOMECOMP)
2   → cd console / menu          (CONSOLE SYSTEMS)
2   → cd nintendo / menu         (NINTENDO CONSOLES)
1   → cd nes / cd games / menu   (NES GAMES)
3   → contra                     (opens emulators/jsnes/play.html?game=contra)
0   → cd .. / cd .. / menu       (back to NINTENDO menu)

File object schema

A node in fs.js is { name, directories?, files? } for directories, or one of these for files:

Field on a file	Meaning
data: '<batch>'	Treats the "file" as a batch script — each \n-separated line is dispatched as a command
link: '<url>'	Treats the file as a launcher — window.open(link, "_blank")
hidden: true	Hidden from dir output (still navigable via cd)

Game .bat files use link: to the emulator wrapper. menu.bat and numbered launchers use data:.

See Customising the Filesystem for examples of adding entries.