## Physical Device Driver Reference

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### Replacing Character Device Drivers

OS/2 character device drivers can be replaced. For system character device drivers, the appropriate bits in the attribute field of the device driver header and the name of the character device driver must match.

When the new device driver is loaded, the attribute field and name are used to determine if the new device driver is attempting to replace a driver already installed. If so, the previously installed device driver is requested to uninstall the indicated device. If this driver refuses the uninstall command, the new device driver is not allowed to initialize. If the previously installed device driver performs the uninstall operation, the new device driver is initialized.

Note: The uninstall command is needed to allow a physical device driver to relinquish its interrupt vectors and its allocated physical memory.