procedure SetDisplayResolution() ;
var dm:TDeviceMode ;
sdc:HDC ;
w,h,c,f:Integer ;
begin
sdc := GetDC(0);
w:=GetDeviceCaps(sdc,HORZRES) ;
h:=GetDeviceCaps(sdc,VERTRES) ;
c:=GetDeviceCaps(sdc,BITSPIXEL) ;
f:=GetDeviceCaps(sdc,VREFRESH) ;
dm.dmPelsWidth :=800 ;
dm.dmPelsHeight :=600 ;
dm.dmBitsPerPel :=c ;
dm.dmDisplayFrequency :=75;
dm.dmFields :=DM_BITSPERPEL or DM_PELSWIDTH or DM_PELSHEIGHT or DM_DISPLAYFREQUENCY ;
ChangeDisplaySettings(dm,CDS_UPDATEREGISTRY) ;
end;