Spend a few minutes at your local electronics store and it’s obvious — the mobile phone is a device that far surpasses its original intent. With respect to functionality, today’s mobile phone goes well beyond the ability to make calls and store phone numbers. It also synchs up with your desktop’s calendar and address book, it can take pictures, play and store music, and receive emails.

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This type of convergence comes in two very different packages: “easy to carry” and “easy to use.” Easy to carry packages are resource limited because the entire unit is portable and constrained in regards to footprint and power consumption. Conversely, easy to use packages are comparable to your desktop. They have an easy-to-use graphical user interface and are not constrained by power consumption or packaging.

The goal of the portable device developer is to create powerful, useful, and engaging devices that are both easy to use and have “acceptable” portability. As with the massive convergence mentioned above, the end user’s perceptions of acceptable portability is also stressing the manufacturers’ abilities to meet ever more demanding usage criteria. Manufacturers are increasingly pressured to put more functionality into smaller packages while trying to extend battery life further and further. The challenge for device manufacturers is how to balance the needs of the user with bleeding edge technology while maintaining a competitive price point.

This is where a full-featured operating system (OS) comes into play. A good OS provides the interface to the hardware and allows the device to be managed in the most efficient manner possible. If the OS is managing both hardware and software, how can it possibly stay responsive? The answer lies in the real-time capabilities of that particular OS (see figure). A real-time OS keeps responsiveness at the top of the requirements list.

We all know developing a real-time kernel is no great feat. But once you start adding on all the components that make a full-featured operating system, real-time responsiveness has the potential to get lost in the clutter if the system is not architected from the start to provide real-time performance. With that in mind, let’s take a look at a few examples of operating system components that comprise a full-featured OS and how the lack of real-time features can affect the overall responsiveness of a device.