From The KNOS Project:
KNOS is a revolutionary approach to internet security through the use of secure clients, networks small or as large as the cloud. Its unique system runs as a secondary operating system without touching the computer's hard drive. By its design, it cannot be written to, creating a special immunity from virus, spyware and malware infections so pervasive on the internet today. Malware can't run on KNOS so it won't be transmitted from KNOS clients to the server and network as a result, reducing the cost and resources necessary to keep your network clean. It offers a comprehensive application environment that can be customized to meet a particular purpose.
KNOS is a fully locked-down client system based upon BSD, the foundation of Macintosh OSX, secure military systems and secure servers in use by major entities. KNOS provides a "secure lockdown" because nothing can ever be written to its read-only memory filesystem. KNOS leaves the existing computer hard disk completely untouched and fully protected because the existing hard disk is no longer connected to the network. KNOS is perfect for use on unsecured networks. It provides military quality "high side" trust because it cannot be infected.
KNOS is intended for distribution by IT Departments for their network users, ISP's (KNOS is an excellent alternative "walled garden", encouraging and enabling customer retention while protecting the network), and other situations where a mass distribution of our disks with specific application sets and portals is desired. KNOS is an excellent front end for "cloud" computing, remote access to institutional sites, and portable computers in secure environments in a world of ever increasing "zero day attacks" from "trusted sources."