\paperw8640 \margr0\margl0\ATXph0 \plain \fs20 \f1 Windows CE is a scalable and open operating system. But uniquely, it can be implemented on a variety of small scale devices -
including handheld computers, entertainment systems and other communications devices. Although some implementations of Windows CE include a subset of the popular interface found in Windows 95 and Windows NT 4, the operating system is based on neither of
these products, having been designed from scratch for the target market. \par
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As with Windows NT, Windows CE has a HAL (hardware abstraction layer). This allows OEM customers to adjust the operating system for their particular hardware as well as
helping power management functions to be tailored. \par
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As Handheld PCs are basically a new idea, they did not have to have the interrupts and memory maps normal PCs require for compatibility. Instead, OEM customers produce code in the HAL to sup
port the various hardware elements in their products. This makes for a much more flexible system which in turn eliminated many of the former problems. \par
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Two sorts of driver are supported by Windows CE. Built-in drivers support the permanent har
dware such as the screen and keyboard. Installable drivers are used to support optional hardware such as PC cards.
