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Fast, accurate, and offline-capable Intel 8085 simulator with assembler and debugger. Works on desktop and mobile, no installation needed.

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debjitbis08/sim8085

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Sim8085

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Sim8085 is a modern web-based development environment for the Intel 8085 microprocessor. It includes a graphical editor, assembler, and debugger designed to help students, educators, and enthusiasts explore 8085 assembly programming.

🖥️ Try it now at sim8085.com


✨ Features

  • 📝 Syntax-highlighted editor for writing 8085 assembly code.
  • 🐞 Interactive debugger with:
    • Step-by-step execution
    • Flag and register updates
    • Visual memory inspection
  • ⚙️ Assembler with smart error messages, help fix common problems quickly.
  • 🧠 Interrupt system that closely matches how the 8085 handles interrupts.
  • ♾️ Supports long-running programs (e.g., waveform generators or infinite loops), safely handled in-browser.
  • ⏱️ Instruction Timing Mode to simulate real-time delays.
  • 🧹 Built-in code formatter that aligns mnemonics, operands, and comments into neatly spaced columns.
  • 🚄 Near-native performance, powered by a C-based simulator compiled to highly optimized JavaScript via Emscripten.
  • 📱 Mobile-friendly and works great in modern mobile browsers.
  • 💾 Offline support: Once loaded, Sim8085 continues to work even without an internet connection thanks to full PWA support.
  • 📦 Installable as an app: Add Sim8085 to your home screen or desktop like a native app, no App Store needed.

🖼️ Screenshot

Sim8085 Screenshot


🛠️ Development Setup

📦 Requirements

🚧 Steps

  1. Install Emscripten (follow official instructions). You need this only if you are working on the instruction simulator code (src/core/8085.c).

  2. Clone this repo and install dependencies:

    pnpm install
  3. Start the development server:

    pnpm dev

🔧 Building the Emulator (C to JS)

If you make changes in src/core/8085.c:

  1. Build the updated simulator:

    pnpm build-emulator
  2. Commit the modified JS file.


🚀 Production Build

  1. Make sure the emulator is built:

    pnpm build-emulator
  2. Build the frontend:

    pnpm build
  3. Final output will be in the dist/ directory.


💖 Support Sim8085

Sim8085 is a free and open-source project built with care to help students and educators learn 8085 programming with ease. If you find it useful and would like to support its continued development, consider donating:

Your support helps cover hosting, development time, and the addition of new features. Every little bit counts!


© 2013-present Debjit Biswas. BSD-3-Clause License.