[DMDX] Re: Scan lines again I am trying to get my machine to run at the fastest refresh rate that I can  by altering the number of scan lines. I am running in 640x480, 8 bit colour  mode. When I use  it seems to work fine.  However, if I change the second value to anything but 400, I get the message: SetDisplayMode failed DDERR_INVALID MODE (88760078) Direct Draw does not support the requested mode. This seems odd, because Timedx will happily let me tune vertical retraces  for any number of lines I like (and shows very satisfying reductions in  refresh times). Can anyone suggest anything?  >If you have stored values in the registry for all possible modes you wish  to exploit you must be transposing the unaltered number of scan lines in  the video mode specification with the modified number of scan lines. I don't think that this is correct. The code I used first was: n1 f60  s6    $ 0 "Press the footswitch"; $ +1 *"Test"/; $ 0 "End"; $ This gives the following error message: SetDisplayMode failed DDERR_INVALID MODE (88760078) Direct Draw does not support the requested mode. Then I used this code: n1 f60  s6    $ 0 "Press the footswitch"; $ +1 *"Test"/; $ 0 "End"; $ This resulted in DMDX complaining that I had not tuned the relevant  vertical retrace values in Timedx, when in fact I had (I had selected  640x480, 8 bit, and entered 380 in the scan lines box). Note that the only difference between these two bits of code is the  VideoMode command, the first being , and the  second being . I think this addresses your point  regarding the transposition of unaltered and modified number of scan lines.  It seems that the first format is actually the correct one, because as I  pointed out in my first message,  does actually  work. However, if I use any value other than 400 in the second position, it  does not work, and produces the "SetDisplayMode failed" message. I have also tried to run these bits of code on 4 different machines, with  identical results on all of them. Michael =============================================== Dr Michael Johnston Research Fellow School of Psychological Science La Trobe University ph:    9479-1736 fax:   9479-1956 email: m.johnston@latrobe.edu.au School homepage: http://www.psy.latrobe.edu.au/