GNUSim8085 alternative: a browser 8085 simulator, or build the CPU
GNUSim8085 is a free, open-source (GPL-2.0) graphical simulator, assembler and debugger for the Intel 8085 microprocessor, originally written by Sridhar Ratnakumar. It runs on Linux and Windows and offers an editor with syntax highlighting, a keypad for entering instructions with their arguments, views of the registers, flags, stack, memory and I/O, breakpoints, stepwise execution and one-click conversion of a program to an opcode listing. Its latest release on GitHub is 1.4.1, from July 30, 2018, with Linux packages and a Windows installer, and the repository's description now says it needs a maintainer. If you want an 8085 simulator that runs in the browser, Sim8085 is the closest alternative; if you want to know what the processor is made of, digiwleea has you build one.
What GNUSim8085 is good at
A complete, classic 8085 lab on the desktop: write a program, step through it with breakpoints, and watch every register, flag and memory location, with the opcode listing a lab report needs. It works offline, with no account or network needed. (digiwleea is an independent project, not affiliated with GNUSim8085 or its authors.)
Alternatives, and how digiwleea is different
For the same job in a browser, Sim8085 is an open-source 8085 editor, assembler and debugger that keeps working offline once loaded; our comparison page has the details and a program we ran in it. digiwleea is something else: it does not run 8085 code, but it shows the hardware underneath. In the browser you build NOT and NAND from CMOS transistors, then adders, an ALU, registers, RAM, a program counter and a control unit, through a 40+ level course where every part is checked against its truth table, with an AI tutor (Wleea). The CPU you finish with is a small 8-bit accumulator machine whose capstone runs a stored LOAD, ADD, STORE, HALT program.
| GNUSim8085 | digiwleea | |
|---|---|---|
| Focus | Programming the Intel 8085 | Digital logic from transistors to a simple CPU |
| Runs on | Linux and Windows desktop | Any modern browser |
| Latest release | 1.4.1 (2018); repository needs a maintainer | Actively developed |
| The CPU | A given 8085, with registers and flags shown | Built by you: a small 8-bit accumulator machine |
| Price | Free, GPL-2.0 | Free lab and Act I; Premium for the full course |
No sign-up is needed to start: open the lab and place your first transistor, or read the free theory course. The account (and the AI tutor) are optional.
More comparisons: CPU and assembly simulators
See for yourself: build a logic gate from transistors in the simulator, then follow the path from sand to an 8-bit CPU.
Open the digiwleea lab →Frequently asked
Where can I download GNUSim8085?
From the GNUSim8085 project's GitHub releases. The latest release, 1.4.1 from 2018, has Linux packages and a Windows installer.
Is there an online alternative to GNUSim8085?
Yes. Sim8085 is an open-source 8085 simulator, assembler and debugger that runs in the browser and works offline once loaded.
Is GNUSim8085 still maintained?
Its GitHub repository describes the project as needing a maintainer, and its latest release is from 2018.