DeviceID Identifies a virtual device. If this value is zero, then the ES:DI registers point to an 8 character space-padded case-sensitive device name (Windows 95).
The return value is the entry-point address contained in the ES:DI register pair if the function is supported. Otherwise, ES:DI contain zero.
Any virtual device can provide service functions to be used by MS-DOS programs. For example, the virtual-display device provides services that the Windows old application program uses to display MS-DOS programs in a window. It is the responsibility of the MS-DOS program to provide the appropriate virtual-device identifier. The function returns a valid address if the virtual device supports the entry point.
MS-DOS programs call the entry point using a far call instruction. The services provided by the virtual device depend on the device. It is the responsibility of the MS-DOS program to set registers to values that are appropriate to the specific virtual device.
For versions of Windows prior to version 3.0, the program must set the ES:DI register pair to zero before calling this function.
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