Windows CE is a variation of Microsoft's Windows operating system that is designed specifically for minimalistic computers and embedded systems. Windows CE is a distinctly different kernel and may run in under a megabyte of memory. It is supported on Intel x86 and lookalikes, MIPS, ARM, and Hitachi SuperH processors. Devices using Windows CE are often configured without disk storage. They may be configured as a "closed" system that does not allow for end user extension. Windows CE is a real-time operating system with a deterministic interrupt latency. It supports 256 priority levels and provides for priority inversion. Unlike UNIX-like operating systems, the fundamental unit of execution is the thread, which allows for simpler, faster concurrent programming.
Although Micorsoft denies that the initials "CE" are significant, many people believe that the letters stand for "Compact Edition" or "Consumer Electronics". Today Windows CE is no longer aimed only at handheld devices. Many platforms are based on the Windows CE operating system, including: Microsoft's AutoPC, Handheld PC, Pocket PC, Pocket PC 2002, Pocket PC 2003, Pocket PC 2003 SE, Smartphone 2002, Smartphone 2003, Windows Mobile 5.0, and more.