VAR CheckSnow : Boolean;

            When DirectVideo is set to true and a color text mode
            is selected then direct video can enable or disable
            "Snow-Checking" when characters are being stored to
            memory.  When CheckSnow is set to TRUE (its default
            value) characters will only be written to video memory
            during periods of horizontal retrace, thus preventing
            "snow" on older CGA adapters.  When CheckSnow is set to
            true it will result in slightly slower screen writes.
            Using the procedure TEXTMODE will reset this to its
            default state.