A browser-based Microsoft BASIC-80 (version 5.21) interpreter compiled to WebAssembly. Run classic BASIC programs directly in your web browser with a retro terminal-style interface.

This project takes the mbasicc C++ interpreter and compiles it to WebAssembly using Emscripten. It provides a complete BASIC programming environment in the browser with:

• Interactive command mode (type commands directly)
• Program editor with syntax highlighting
• Virtual file system for saving/loading programs
• Terminal-style output with classic green-on-black aesthetics

• Emscripten SDK - C++ to WebAssembly compiler (installation guide)
• mbasicc library - Must be located at ../mbasicc relative to this directory
• Make - Build tool
• Python 3 - For the development server (optional)

• Modern web browser with WebAssembly support (Chrome, Firefox, Safari, Edge)

1. Ensure Emscripten SDK is installed and activated:

   source /path/to/emsdk/emsdk_env.sh

2. Clone the mbasicc library (if not already present):

   cd ..
   git clone https://github.com/avwohl/mbasicc.git
   cd mbasicc_web

3. Build the project:

   make

This produces:

• web/mbasic.js - JavaScript WebAssembly loader
• web/mbasic.wasm - Compiled WebAssembly binary

Start the development server:

make serve

Then open http://localhost:8080 in your browser.

Alternatively, run manually:

cd web
python3 -m http.server 8080

Copy the contents of the web/ directory to any static web server:

web/
├── index.html      # Main page
├── style.css       # Styling
├── mbasic-ui.js    # UI controller
├── mbasic.js       # WASM loader (generated)
└── mbasic.wasm     # WebAssembly binary (generated)

Important: Your web server must serve .wasm files with the correct MIME type:

Content-Type: application/wasm

Most modern web servers handle this automatically. If you encounter issues, configure your server to add this MIME type.

Type commands directly in the terminal input:

• Write or paste BASIC code in the editor panel
• Click Run to execute (or press the Run button)
• Click Stop to halt a running program
• Use Load/Save buttons to manage files

10 PRINT "Hello, World!"
20 FOR I = 1 TO 10
30   PRINT I; " squared is "; I * I
40 NEXT I
50 INPUT "Enter your name: "; N$
60 PRINT "Hello, "; N$; "!"

mbasicc_web/
├── makefile                 # Build configuration
├── include/
│   ├── wasm_io.hpp         # Browser I/O interface
│   └── wasm_filesystem.hpp # Virtual filesystem interface
├── src/
│   ├── wasm_io.cpp         # Terminal I/O implementation
│   ├── wasm_filesystem.cpp # Virtual filesystem implementation
│   └── wasm_bindings.cpp   # Emscripten/JavaScript bindings
└── web/
    ├── index.html          # Main HTML page
    ├── style.css           # Terminal styling
    ├── mbasic-ui.js        # UI controller
    ├── mbasic.js           # Generated WASM loader
    └── mbasic.wasm         # Compiled interpreter

• C++ Layer: Wraps the mbasicc interpreter with custom I/O handlers for browser environments
• Emscripten Embind: Exposes C++ classes and functions to JavaScript
• ASYNCIFY: Enables blocking I/O operations (like INPUT) in WebAssembly by transforming them into async/await patterns
• Virtual Filesystem: In-memory file storage implemented in JavaScript

• No persistent storage: Files are lost on page reload (use download to save)
• Text-only: No graphics or sound support
• Single-threaded: One program runs at a time
• Memory-bound: Limited by browser available memory

See the mbasicc repository for license information.

• 80un - Unpacker for CP/M compression and archive formats (LBR, ARC, squeeze, crunch, CrLZH)
• cpmdroid - Z80/CP/M emulator for Android with RomWBW HBIOS compatibility and VT100 terminal
• cpmemu - CP/M 2.2 emulator with Z80/8080 CPU emulation and BDOS/BIOS translation to Unix filesystem
• ioscpm - Z80/CP/M emulator for iOS and macOS with RomWBW HBIOS compatibility
• learn-ada-z80 - Ada programming examples for the uada80 compiler targeting Z80/CP/M
• mbasic - Modern MBASIC 5.21 Interpreter & Compilers
• mbasic2025 - MBASIC 5.21 source code reconstruction - byte-for-byte match with original binary
• mbasicc - C++ implementation of MBASIC 5.21
• mpm2 - MP/M II multi-user CP/M emulator with SSH terminal access and SFTP file transfer
• romwbw_emu - Hardware-level Z80 emulator for RomWBW with 512KB ROM + 512KB RAM banking and HBIOS support
• scelbal - SCELBAL BASIC interpreter - 8008 to 8080 translation
• uada80 - Ada compiler targeting Z80 processor and CP/M 2.2 operating system
• uc80 - ANSI C compiler targeting Z80 processor and CP/M 2.2 operating system
• ucow - Unix/Linux Cowgol to Z80 compiler
• um80_and_friends - Microsoft MACRO-80 compatible toolchain for Linux: assembler, linker, librarian, disassembler
• upeepz80 - Universal peephole optimizer for Z80 compilers
• uplm80 - PL/M-80 compiler targeting Intel 8080 and Zilog Z80 assembly language
• z80cpmw - Z80 CP/M emulator for Windows (RomWBW)