Block devices can be closely integrated with Windows CE, providing the following functionality:
Block devices can extend the Windows CE object store beyond the size of the system’s physical RAM. Block devices appear as folders within Windows CE Explorer. Users can perform many ordinary operations on block devices, such as drag-and-drop operations. Users can also create and delete files and directories, retrieve file and directory information, and even reformat the devices. These operations are all transparent to the user, who does not need to know that the underlying device is not the same as the system’s physical RAM. Because block device drivers interface seamlessly with Windows CE, it is the operating system’s file system code that performs these operations on the block device for the user.
Users can store both application code and data files on a block device. In Windows CE 2.10 and later, the operating system can use demand paging to load applications into memory, as needed. Versions of Windows CE prior to 2.10 did not load applications from external block devices, using this demand paging mechanism; instead, they loaded the entire application into RAM when it was launched.
Data on block devices such as linear flash memory cards transfers seamlessly between Windows CE, Windows 95, Windows NT, and MS-DOS. All these operating systems provide support for these block devices, using their own driver layers.
Windows CE versions 2.10 and later can store registry data on block devices, although it cannot be accessed directly from those devices. Windows CE 2.10 introduced APIs for saving and loading registry information from block devices. Registry data must first be copied to the RAM-based registry before it can be used. For more information, see Persistent Registry Storage on Block Devices.
Databases on Windows CE, such as Contacts or Tasks, can be stored and used in place on block devices. Windows CE 2.10 supports new APIs for mounting database volumes from locations other than RAM and ROM. For more information, see Persistent Database Storage on Block Devices.