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Running QBASIC in a Browser – My Nostalgic Trip Back to the 1990s

Extracurricular Activities
by: Jordan Nelson

Recently, I saw Windows 95 running under Electron. The project definitely brought up some old memories from when I was young and new to computers in the mid-1990s. Back then, I spent all of my time outside of school learning how to write code in BASIC.

I discovered that the Windows 95 under Electron project uses a v86, x86 emulator running in JavaScript, and I decided that it would be fun to experiment with the emulator and get QBASIC up and running in a browser. Maybe I could recreate my programming experience from my childhood, all in a browser!

I was able to get QBASIC running under an MS-DOS 6.22 image by doing the following.

  1. Clone the v86 repository using Git. 
    $ git clone https://github.com/copy/v86.git
  2. Download a copy of MS-DOS 6.22. 
    $ curl https://i.copy.sh/images/msdos.img > msdos.img
  3. Build the emulator code. 
    $ cd v86 && make build/libv86.js
  4. Create a simple HTML page with some basic configuration for the emulator based on the examples provided by the v86 emulator. 
    <script src="v86/build/libv86.js"></script>
<script>
"use strict";

window.onload = function()
{
    var emulator = window.emulator = new V86Starter({
        memory_size: 32 * 1024 * 1024,
        vga_memory_size: 2 * 1024 * 1024,
        screen_container: document.getElementById("screen_container"),
        boot_order: 0x312,
        bios: {
            url: "v86/bios/seabios.bin",
        },
        vga_bios: {
            url: "v86/bios/vgabios.bin",
        },
        hda: {
            url: "images/msdos.img",
            size: 8 * 1024 * 1024
        },
        autostart: true,
    });
}
</script>

<body style="background: black;">

  <div id="screen_container">
    <div style="white-space: pre; font: 18px monospace; line-height: 18px"></div>
    <canvas style="display: none"></canvas>
</div>
</body>
  5. Use a the Python SimpleHTTPServer to serve the files. 
    $ python -m SimpleHTTPServer
  6. Open up the emulator in our browser, http://localhost:8000. The emulator automatically boots into DOS:
  7. Type QBASIC to enter:

    Then, we see my old friend:

  8. Let’s write a line of code:
  9. Let it run:

    10. I experimented with getting some of the SCREEN modes working so that I could do some graphics programming, but I received ILLEGAL FUNCTIONAL CALL errors. Maybe with some more experimentation, I can get that working. In the meantime, it was nice to have a nostalgic trip back to the origins of my programming experience.

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