A long time ago there was some sort of a computer from Commodore, which was called the Amiga. It was one of the best computers at that time and was able to give you some rocking feelings with music, games, multimedia and more....

Now Amiga has released a new OS version of their AmigaOS. This time it's version 4 and it contains some really cool features and enhancements.

Exec is the AmigaOS kernel and was written in 68K assembly for AmigaOS 3.1. It has been rewritten in C, as ExecSG, for AmigaOS 4.

Hardware abstraction layer (HAL)
Virtual addressing (for automatic stack enlargement etc.)
Page-based memory handling (less fragmentation and more efficient)
Virtual memory
New library interface
Resource tracking and management
Optional memory protection
WarpOS backwards compatibility
More info and features from over here.
_http://os.amiga.com/os4/OS4Features.php