Define graphic drivers
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                             Detect    = 0;
                             CGA       = 1;
                             MCGA      = 2;
                             EGA       = 3;
                             EGA64     = 4;
                             EGAMono   = 5;
                             Reserved  = 6;
                             HercMono  = 7;
                             ATT400    = 8;
                             VGA       = 9;
                             PC3270    = 10;