How to Install and Initially Configure TimeDX & DMDX

1. Download DMDX.zip from http://www.u.arizona.edu/~jforster/dmdx/ . This will be the most up-to-date version of the software. All other files labeled DMDX***.zip are older archived versions of the software. Once downloaded, unzip the archive and run Setup.exe file which will guide you through the installation of DMDX and TimeDX. [NOTE: We do not recommend updating DMDX every time there is a new minor version change. There is always the possibility that this version change might introduce some, as yet, undetected bug. The only times we upgrade is when the version change added a feature we need or the version change corrected a known bug.]

2. Prior to using DMDX, TimeDX is used to set-up video, audio and timing parameters for stimulus output and data collection. This step must be performed before the first time you run DMDX. After opening TimeDX for the first time, you will be prompted to select hardware/software specifications for sound driver. You may have to indicate the video and sound drivers to use. In each instance, do NOT select the default but instead the second option which will typically be a specific video or sound driver based on the hardware you have installed in the computer.

3. The next step is to setup the video mode resolution and color specifications to test stimulus display using the computer’s video card. You will need to perform this step and step 4 for every video mode you intend to use with DMDX. Under the main File menu, highlight “Select Video Mode”. In this menu, you will need to select a video mode that is supported by your PCI card. We typically use:1024x768 (60hz) 16 bit (65536 color) RGB. You must also run a test to check whether your hardware can support this selection. Select “Do Test”. The text “TimeDX” should be displayed on your monitor. Hit “Escape” to return to the Video Mode menu and select “Done”.

4. Now that you have selected a specific video mode, you must time it to determine the refresh interval (i.e., tick duration). From the main File menu, highlight “Time Video Mode”. The program will then determine the refresh interval for this video mode by conducting the “Vertical Retrace Sync Test”. The refresh interval is the length of time it will take to fully redraw the screen from top to bottom. This is also referred to as a “tick”. If you have selected 60Hz refresh rate for the video mode, the refresh interval will be approximately 16.67 ms. After performing the test, it is important that you save the value to the registry by pressing the button: “Saved Last Used Values in Registry”.

5. While still in “Time Video Mode”, you can check that TimeDX determined the appropriate refresh interval by selecting “Enh. Retrace”. When selected, this will display a red box in the center of the screen with the text “Refresh Rate x” inside (x is the refresh rate designated during the Vertical Retrace Sync Test). The red box should stay relatively still (i.e., It may flicker but it should not systematically drift up or down) on your screen if the correct refresh rate has been set. If it does drift, use the + and – keys to slightly adjust the refresh rate until the red box remains still. If you make any changes during this test, you should again select Saved Last Used Values in Registry” to save this new value. Another way to test the refresh rate is to go into the Basic Tests menu and select “Refresh Rate” and “Do Test”. When this test is completed, there will be a refresh rate number inside the box. This number should be the same as the refresh rate that was originally determined when the Vertical Retrace Sync Test was run.

6. Finally, to test the millisecond timer that monitors and records the timing of stimulus display and response data, go into the Basic Tests menu and select “Millisecond Timer Test” and “Start”. This test begins a timer that verifies the timing resolution. The lowest timing resolution provided by DMDX is 1ms. The mean interval should be 1.0 with and SD less the .30. In addition, the majority of the data points should fall between 0.9 and 1.1. ms. If not, you may have problems with timing on this computer.

Page created by Rebecca Gloria

Last edited 11-09-2005