## Display Device Driver Reference for OS/2

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### Process PMI File

If this method is employed, the file must be read at this time. This is a once-only operation. Again, this cannot be performed during virtual video device driver initialization because the virtual device helper (VDH) services required to read the file are available only at DOS session task time.

The sections of the file required by the virtual video device driver are AdapterType, ChipSet, TrapRegs, Cleanup, and Lock and UnLock. A check against the adapter/chip set entries is used to confirm that the file is valid for the current configuration.

The list of entries in the TrapRegs section specifies the I/O port addresses and indexed ports that are to be saved and restored by the virtual video device driver. A bit mask for indexed registers is created and used for this purpose.

The Cleanup, Lock, and UnLock sections literally are used to perform the specified functions. Cleanup is required to put the adapter into a default clean state.