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 — calls `menu`
├── menu.bat              `cd emulators\nmenu` (drops straight into the EMULATOR LAUNCHER)
└── EMULATORS\
    ├── DOS\              MS-DOS games (self-hosted, jsdos)
    │   ├── DUKE\         Duke Nukem 1, II, 3D
    │   └── KEEN\         Commander Keen 1-6 + Keen Dreams
    ├── CONSOLE\          ATARI (2600 / 7800) / NINTENDO (NES) / SEGA (GENESIS) /
    │                     MATTEL (INTV) / COLECO (CVISION) / MAGNAVOX (ODYSSEY2) /
    │                     SMITH-ENG (VECTREX)
    └── HOMECOMP\         ACORN (BBC / ARCHIMDS) /
                          COMMODRE (PET / VIC20 / MAX / C64 / C16 / PLUS4) /
                          ATARI (400 / 800XL / ST) / SINCLAIR (SPECTRUM / ZX81) /
                          TANDY (COCO) / MSX (MSX1 / MSX2)

Self-hosted vs placeholder systems

All 22 self-hosted sub-systems run their games locally — every byte of game data is on the same origin. The remaining 3 systems are placeholders without an emulator yet.

System	Backing emulator
DOS	jsdos (emulators/jsdos/)
CONSOLE → NINTENDO → NES	JSNES (emulators/jsnes/)
CONSOLE → SEGA → GENESIS	lrusso/Genesis (emulators/genesis/)
CONSOLE → ATARI → 2600	javatari.js (emulators/javatari/)
CONSOLE → ATARI → 7800	JS7800 (emulators/js7800/)
CONSOLE → SMITH-ENG → VECTREX	DrSnuggles/jsvecx (emulators/jsvecx/)
HOMECOMP → ACORN → BBC	jsbeeb (emulators/jsbeeb/)
HOMECOMP → ACORN → ARCHIMDS	archimedes-live (emulators/archimedes-live/)
HOMECOMP → ATARI → 400	atari800 v5.2.0 (emulators/atari800/, ?machine=atari → OS-B / AltirraOS-800)
HOMECOMP → ATARI → 800XL	atari800 v5.2.0 (emulators/atari800/, default → AltirraOS-XL)
HOMECOMP → ATARI → ST	EstyJS + EmuTOS (emulators/estyjs/)
HOMECOMP → SINCLAIR → SPECTRUM	JSSpeccy 3 (emulators/jsspeccy/)
HOMECOMP → SINCLAIR → ZX81	JtyOne (emulators/jtyone/)
HOMECOMP → TANDY → COCO	XRoar (emulators/xroar/)
HOMECOMP → MSX → MSX1 / MSX2	WebMSX (emulators/webmsx/)
HOMECOMP → COMMODRE → PET	EmulatorJS + VICE xpet (emulators/pet/) — default model 3032 (BASIC 2 chargen); per-game override to 4032 for PETSCII Robots; 9 .prg classics + the PETSCII Robots shareware .d64 (David Murray, 2022)
HOMECOMP → COMMODRE → VIC20	EmulatorJS + VICE xvic (emulators/vic20/) — 10 cartridge .prgs loading at $A000; vice_vic20_memory_expansions='all' gives the full 35K expansion
HOMECOMP → COMMODRE → MAX	EmulatorJS + VICE x64 in Ultimax mode (emulators/max/) — Japan-only 1982 console, 2 KB RAM + cart-only; 8 .crt carts (TOSEC + Internet Archive Slalom + Multimax-extracted) + MAX BASIC cart
HOMECOMP → COMMODRE → C64	EmulatorJS + VICE x64 (emulators/c64/) — 10 .d64 disk images; real-time IEC loading with authentic 1541 drive sounds during loads
HOMECOMP → COMMODRE → C16	EmulatorJS + VICE xplus4 in C16 mode (emulators/c16/) — vice_plus4_model='c16pal' for 16K RAM; 10 first-in-series C16 16K .prgs from plus4world.com
HOMECOMP → COMMODRE → PLUS4	EmulatorJS + VICE xplus4 (emulators/plus4/) — 10 first-in-series Plus/4 classics from plus4world.com
Placeholders (no emulator yet)	INTV, CVISION, ODYSSEY2

All six VICE-family bundles ship the same input config: keyboardInput: 'enabled' + altKeyboardInput: 'enabled' (typed keys → VICE keyboard callback) + vice_joyport_type: '1' for the five with a joystick port (PET excepted — no joystick). Numpad 8/4/6/2 drives joystick directions; 0 or 5 is fire; everything else types. A defensive UX banner (emulators/_shared/genx-numlock-warn.js) fires after the first keydown if NumLock is off.

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). Placeholder GAMES menus collapse to a single (No locally-hosted titles yet) line + Back option.

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:.

No .html files in the tree. The virtual filesystem only lists .bat files — game launchers, menu scripts, and the numbered shortcuts that route between them. Auxiliary HTML pages (each emulator's controls.html, future bezels, etc.) live on disk under emulators/<name>/ but are reached from inside the emulator's entry HTML (via a corner link), not from the DOS prompt. Period-correct: a DOS user typing dir shouldn't see .html.

See Customising the Filesystem for examples of adding entries.