This good question was recently brought to my attention by Jan Liband, director of marketing at ENCIRQ. Thanks, Jan.

And for the crime of tossing around the phrase "proprietary RTOS" as if I knew precisely what it meant, I must plead guilty. (See, for evidence, my recent blog, Proprietary RTOS, RIP? Not Yet.)

Truth is, in most of my discussions with software vendors and consultants, the term "proprietary" does not come up that often. And when it does, I am often less than 100 percent clear about what it means.

Thanks to Jan's prodding, it now seems to me that a much more useful distinction for an RTOS is commercial vs. in-house. For example, a quick look through my files turned up some recent Venture Development research that shows the DSO market comprising three main sectors: operating systems developed in-house, commercial Linux, and commercial RTOS. In other words, you have just three choices for a device OS:

• Your device can run on an OS your company developed in-house;
• Your device can run on a commercial RTOS your company bought from a software vendor (Wind River, Green Hills, Microsoft, etc.); or
• Your device can run on a commercial Linux distribution your company has licensed from an open-source vendor (Red Hat, Wind River, etc.).

Makes sense to me. So, is it time to chuck the term "proprietary" and stick instead with "commercial" or "in-house" when discussing RTOSes? My vote is a guilty yes.