Complex sentence: The vast majority of the operating system kernel was rewritten in C leaving a handful of hardware-dependent parts in assembly language, and a few "more advanced features" were added such as tree-like kernel module name space.
Split into simpler sentences: The vast majority of the operating system kernel was rewritten in C leaving a handful of hardware-dependent parts in assembly language. A few "more advanced features" were added such as tree-like kernel module name space.