And if you feel like to research how Oberon was implemented, the language, the kernel level GC and all the rest, there are lots of information available here,
http://www.inf.ethz.ch/personal/wirth/
The book "Project Oberon" describes the system.
For the Native Oberon's sucessors, EthOS and Blue Bottle, you can additionally read
http://research.microsoft.com/en-us/um/people/cszypers/books...
and
http://e-collection.library.ethz.ch/eserv/eth:26082/eth-2608...