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What emulegOS is

emulegOS is a legOS emulator. We assume that you know:

  1. what the RCX is (if you don't, follow this link to the Lego® Mindstorm page to know more);
  2. what legOS is (if you don't, look at the legOS home page)

We started this project because we like a lot legOS and the way it opens a broad range of possibilities for the RCX, but we felt the need of a more comfortable environment where to test and debug our programs.

In brief, emulegOS is C++ code you can compile and link together with your legOS code. The resulting application emulates the behavior of your code as it were running on the actual RCX.

The main features include:

What emulegOS is not

A full-featured bullet-proof commercial-like program. We made our best to make it bug free, but wrote it for our own use so please be tolerant. We decided to share it with other legOS users in the hope somebody else finds it useful and contributes to improve it.

If we had had more time we could have done a better product, but we were too much involved in playing with our Lego®...


Feel free to send us any comment, suggestion or even heavy criticism. Any feedback is welcome and important for us to understand whether to invest more time in further enhancements. Send an e-mail just to say “I use it” or “I had a look but I don't like it”.


You don't need to have legOS installed neither the RCX itself to use emulegOS, even if it's obvious that the main reason for the existence of emulegOS is to fine tune a program to use on an actual RCX

emulegOS is not a stand alone application. It is C/C++ code to link with your legOS code, so you need a C++ compiler to use it.

We currently have two versions:


emulegOS is “public domain”. Feel free to use, modify and spread its code as you prefer.

We would like very much to receive a copy of any correction, improvement or porting to new platforms. They will be published in this page crediting the contributors.

Using emulegOS

If you got used to legOS, emulegOS is quite easy to use.

Current documentation is the in README distributed with the release.

The old 0.1.7 compatible documentation is provided in HTML format: OLD emulegOS User's Guide. It is outdated but may still contain some usefull information.

Porting emulegOS

We did our best to make emulegOS easy to port:

There's a detailed porting documentation (in HTML format) that refers to the original Windows/C++Builder version: How to port emulegOS

We recommend that you send to us an e-mail if decide to port emulegOS: we'll give you all the assitance we can.


Here you can download the last versions of emulegOS:

emulegOS at SourceForge

Check CVS for the latest updates and bug fixes. Don't forget to download the documentation from the above section.