Customising the Filesystem

Customising the Filesystem

The virtual filesystem lives in prompt/javascript/fs.js as a JS array called fs. Every directory and every file is an object in that tree. No server, no database — edit the file, hard-refresh, the prompt picks up the change.

What a node looks like

var fs = [{
  name: 'C',
  directories: [ ... ],
  files: [ ... ]
}];

A node is one of:

Shape	Means
{ name, directories, files }	a directory
{ name, link }	a "file" that opens a URL when executed
{ name, data }	a "file" whose data is run as a batch script when executed

hidden: true on a node hides it from dir output (still navigable via cd).

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Adding a link file

{ name: 'GITHUB.COM', link: 'https://github.com/yourname' }

Drop it into any directory's files array. The user can cd into the directory and type github.com to open it.

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Adding a batch file

{ name: 'HELLO.BAT',
  data: 'echo off\nsetcol 2e\necho Hello, world!\nsetcol 07\necho.' }

Lines are separated by \n. Supported batch commands: anything in Commands plus any filename present in the current directory.

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Adding a directory

{ name: 'MUSIC',
  directories: [],
  files: [
    { name: 'BANDCAMP.COM', link: 'https://yourname.bandcamp.com' }
  ]
}

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Adding a system menu (numbered list)

The standard pattern for a system with several titles is a directory whose menu.bat prints a box-drawn menu, plus numbered launcher .bat files that each run a named link .bat.

{ name: 'GAMES', directories: [], files: [
    { name: 'menu.bat', data: 'echo off\ncls\necho ╔═══...╗\n...echo.\n' },
    { name: '0.bat',    data: 'echo off\ncd ..\ncd ..\nmenu\n' },
    { name: '1.bat',    data: 'mario\n' },
    { name: '2.bat',    data: 'contra\n' },
    { name: 'mario.bat',  link: '../systems/jsnes/play.html?game=mario' },
    { name: 'contra.bat', link: '../systems/jsnes/play.html?game=contra' },
] }

The menu.bat data string renders rows like ║ 1. Super Mario Bros. (1985) MARIO ║ — title first, year column, code last is the project convention (see Menu box format below).

The flow: the user types a number → it runs the matching N.bat → which runs <key> → which resolves to <key>.bat (the link: entry) → which opens the emulator URL.

For a real example see the NES or C64 blocks in fs.js.

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Menu box format

Standard menus use double-rule CP437 borders with a 45-char inner width.

 ╔═════════════════════════════════════════════╗
 ║              CENTERED HEADER                ║ ◄── header (45 chars between ║)
 ╠─────────────────────────────────────────────╣
 ║                                             ║ ◄── blank spacer row
 ║   1.  Some Title           (1985)  CMDNAME  ║ ◄── 4-column: # Title (Year) CODE
 ║   2.  Another Title        (1986)  CMD2     ║
 ║                                             ║
 ║  11.  BASIC system prompt          BASIC    ║ ◄── BASIC/prompt rows skip the year column
 ║                                             ║
 ║   0.  Back                                  ║ ◄── always last
 ║                                             ║
 ╠─────────────────────────────────────────────╣
 ║        Type a number and press ENTER        ║
 ╚═════════════════════════════════════════════╝

Entry row layout (45 chars between borders): 4 columns — number, title, year, code. Games sorted by year ascending, alphabetical within year.

 ║   N.  Title field          (YYYY)  CMDNAME  ║
 ├──┤├──┤├─────────────────┤├──────┤├─┤├──────┤
  3   2.       21 chars        6     2    9
  spc ". "   title (left)    year   sp  code (left)

• Title field 21 chars left-justified; year column 6 chars (YYYY) or (home)-style marker; 2-char separator; code field 9 chars left-justified.
• BASIC / system-prompt rows have no year — title field extends through the year + separator slot.
• Double-digit numbers shift left one space: NN. vs N. — same 7-char prefix width.
• Blank line before the last entry in a group = visual separator (e.g. games vs system prompt).

Two things to remember:

• Apostrophes in titles must be escaped: K.C.\'s Krazy Chase! inside a '...' JS string.
• The on-screen rendering uses CP437 box-drawing glyphs (É, ═, ║, etc.) via the font sprite system — the Unicode equivalents shown above are for documentation readability only.

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Boot behaviour

autoexec.bat runs automatically on load. Its default data is just menu\n — which runs the root menu.bat. The root menu.bat in turn does cd emulators\nmenu\n, dropping the user straight into the EMULATOR LAUNCHER.

To boot to a different starting place, override menu.bat (or autoexec.bat):

{ name: 'autoexec.bat', data: 'cd emulators\\console\\nes\\games\ncls\ndir/w/o\n' }

To set colours at boot, prepend setcol:

{ name: 'autoexec.bat', data: 'echo off\nsetcol 02\nc:\ncls\nmenu\n' }

Common combos:

Code	bg / fg
07	black / light grey (default)
0f	black / white
17	dark blue / light grey
02	black / dark green
0a	black / green
0e	black / yellow

See Font System for the 16-colour palette.

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A few things we've learned the hard way

• Use absolute paths (cd\\games\\action) inside .bat files; relative cd only works if the target is a direct child.
• Files can only be executed from the directory they live in — there is no PATH.
• For menu generation it's much easier to write a small Python helper that emits the echo lines than to hand-craft the box-drawing characters.