What is Sim8085?

Sim8085 is a modern, graphical simulator, assembler, and debugger for the Intel 8085 microprocessor, designed for students, educators, and enthusiasts. It combines a clean user interface with deep technical accuracy, making it the most intuitive and reliable way to write, run, and debug 8085 assembly programs.

Unlike traditional desktop tools, Sim8085 runs directly in your browser — yet works fully offline, even in airplane mode, after the first visit.

🔧 Why Sim8085?

✅ Accurate Instruction Simulation
Every instruction, flag, and timing behavior is modeled with care — matching real-world 8085 behavior more closely than legacy tools.
✅ Near-Native Performance
The simulation engine is written in C and compiled with Emscripten, offering performance close to native desktop apps — all within your browser.
✅ 100% Offline Support
No internet required after your first visit. Sim8085 runs entirely offline — perfect for exams, travel, or classrooms without Wi-Fi.
✅ Modern UI, No Installation
Say goodbye to clunky desktop GUIs. Sim8085 offers a smooth, responsive interface in your browser with no setup needed.
✅ Install as an App
Use Sim8085 directly in your mobile browser, or install it to your home screen for an app-like experience — no app store needed.
✅ Mobile-Optimized Interface
Use Sim8085 on your phone or tablet. It adapts to smaller screens with a responsive layout built for touch.

🚀 Key Features

Visual Memory & I/O Inspection
Watch registers, flags, memory, and I/O ports in real time as your program runs.
Syntax-Highlighted Editor
Write clear, error-resistant code with a fast and helpful code editor.
Stepwise Debugging
Step through code, and see exactly how your program behaves.
One-Click Opcode Conversion
Instantly view opcode listings from your code — ideal for hardware preparation.
Interrupt Support
Toggle interrupt lines like TRAP, RST 5.5, 6.5, and 7.5, and simulate real 8085 masking and latch behavior.
Long Program Support
Infinite loops, delay routines, and hardware-like behavior are supported thanks to smart execution controls.
Automatic Code Formatting Clean up and align your code with a built-in formatter that preserves comments, blank lines, and label positioning.

Acknowlegements

Sim8085 is built with Emscripten, Peggy, CodeMirror, Astro, and SolidJS. A lot of inspiration has been drawn from GNUSim8085 and FRISCjs.

License

The application is licensed under the BSD-3-Clause license, and the source code is available on GitHub.

This documentation is under the CC BY-SA 4.0 license, unless otherwise stated.