Lites was a Unix-like

Unix-like

A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....

 operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

, based on 4.4BSD

Berkeley Software Distribution

Berkeley Software Distribution is a Unix operating system derivative developed and distributed by the Computer Systems Research Group of the University of California, Berkeley, from 1977 to 1995...

 and the Mach microkernel

Microkernel

In computer science, a microkernel is the near-minimum amount of software that can provide the mechanisms needed to implement an operating system . These mechanisms include low-level address space management, thread management, and inter-process communication...

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Specifically, Lites was a multi-threaded server and emulation library that provided unix functionality to a Mach based system. At the time of its release Lites provided binary compatibility with 4.4BSD, NetBSD, FreeBSD, 386BSD, UX (4.3BSD) and Linux.http://web.archive.org/web/19970716001117/www.cs.hut.fi/~jvh/lites-1.0-announcement.html

Lites was originally written by Johannes Helander at Helsinki University of
Technology, and was further developed by The Flux Research Group at the University of Utah

University of Utah

The University of Utah, also known as the U or the U of U, is a public, coeducational research university in Salt Lake City, Utah, United States. The university was established in 1850 as the University of Deseret by the General Assembly of the provisional State of Deseret, making it Utah's oldest...

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http://www.cs.utah.edu/flux/lites/html/lites-info.html