Windows CE (Compact Embedded) is a real-time embedded operating system by Microsoft. Part of the Microsoft Windows Embedded platform, Windows CE is designed for use with handheld computers or systems with limited memory and resources.
The system kernel and libraries are used in Windows Mobile and its successor Windows Phone, which are used in smartphones and Pocket PCs, as well as a runtime library for the Sega Dreamcast. Windows Phone 8 abandoned the Windows CE architecture, opting to use the NT kernel as part of the MinWin architecture.
Early versions of Windows CE were inspired by Microsoft WinPad (1994), a scrapped mobile platform for handheld PCs, based on Windows for DOS. Versions of WinPad can still be found in early betas of Windows 95, as well as part of SDKs for Windows 3.1.
Windows CE version 1.0 (codename Pegasus) was released in 1996 for H/PC (Handheld PC) devices only. Later versions added support for more form factors.
Version 2.0 (codename Birch) was released in 1997 and added support for many device architectures and standard APIs. It was bundled with several handheld computer platforms, as with the earlier version.
Version 3.0 (codename Cedar) was released in 2000. This version increased priority levels from 8 to 256. This version also had a big recode that made Windows CE real time down to microseconds.