Cost is obviously a major deciding factor when selecting an embedded operating system. Since there is essentially no cost of goods with software, vendors can adjust their pricing model to generate revenue from various sources. Vendors can charge for an initial license fee, development seats per engineer, development tools, per-unit royalties, continuing support, or major upgrades. To fairly compare prices, the overall cost of ownership must be computed for each OS being considered. The calculation must include the number of units planned for delivery over the life of the product. Although a commercial OS can be expensive, cost savings is an important reason to purchase embedded computer. If you can purchase and therefore eliminate the coding, debug, and documentation of the most complicated portion of the software, you should give it careful consideration. Vendors promote product technical support as a major benefit of a commercial OS. They are able to provide continuous support for the operating system portion of the software by spreading the cost over all customers.
refer to: http://embedded-computing.com/articles/choose-right-embedded-operating-system/
