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
- 📝 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.
- Emscripten SDK
- Node.js ≥ 22.x and pnpm
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Install Emscripten (follow official instructions). You need this only if you are working on the instruction simulator code (
src/core/8085.c). -
Clone this repo and install dependencies:
pnpm install
-
Start the development server:
pnpm dev
If you make changes in src/core/8085.c:
-
Build the updated simulator:
pnpm build-emulator
-
Commit the modified JS file.
-
Make sure the emulator is built:
pnpm build-emulator
-
Build the frontend:
pnpm build
-
Final output will be in the
dist/directory.
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.
