The ARM family is the problem in that case. There's so much variation among the different versions that drivers are an issue. There is a version of the Oberon language, Astrobe, that runs on the a few of the smaller chips, created by CFB Software, but it's not a full operating system. http://www.astrobe.com/default.htm
I can't offer a URL but I thought Wirth ported Oberon to some sort of ARM processor (in the last ten years or so) to control an RC airplane or some such.
I suppose one could email Dr. Wirth asking for the source code but in reality, you'd be better off forking a newer version of Oberon. It should be as easy to port as a compiler can be.
