Ten lines of UNIX code were changed. No samples were lost, and UNIX happily ran on the same computer. Other Commercial Products Using Embedded Source Code UNIX Cobalt Networks Qube 2 is a low-cost server appliance that provides Internet connectivity, email, Web publishing, and other Web and network file services. The Whistle InterJet, using FreeBSD, provides email, Web access, and Web publishing for a small office. Whistle has been an active partner with the Open Source community, using and contributing to the Open Source projects.
Some RTOS vendors have extremely good products.
Their code might fit your problem like a glove. If your problem matches the features of an existing RTOS but doesn't fit the UNIX model, your choice is easy. Remember, many of the commercial vendors have a long history of serving particular areas in the market. Their mature product could be what you should use. At first, I was going to recommend against UNIX for the small, nonpaged systems, but a Source Code UNIX can be stripped down to fit many situations.