------------------------------------------- ModeLine-HOWTO by Rick Niles. niles@axp745.gsfc.nasa.gov ------------------------------------------- Version 1.0 2/11/95 ------------------------------------------- The file X11R6/lib/X11/doc/VideoModes.doc explains how to setup video timings for your video card / monitor combination, however I found this to be a long overly complicated explanation of something really not that complex. Please let no one take offense at this, since without this file I don't think I would ever have figured out how to configure my setup and I am therefore very thankful to the writers of that document. I just thought I would give my shortened explanation of how to setup your XF86Config file for XFree86 and in particular information about the Mach64 timings I've played with. There are three major sections of the XF86Config file that deal with the video card and monitor: the monitor section, the graphics device section and the screen section. Ironically the timings I'm discussing in this document concentrate on Monitor section even though I use many specs from the video card. In regard to the graphics device section I suggest commenting out any "Clocks" given in the file when setting up a new server and/or video card and let "X -probeonly" determine what Clocks are good for your card / server combination. I recommend this above just putting in the numbers given in the manual because exact timings on cards will vary. Redirect this information into a file and copy it into the XF86Config file. Now the hard part about setting up a XF86Config file is the definitions of the Modelines. For many non-ATI cards these number must be multiples of 8. For ATI cards they need NOT be. There are 10 arguments after each Modeline directive: Modeline
(name) Any name you'd like to assign to this mode, in double quotes. The most common name is of the form HRxVR (e.g. "640x480") However if you would like to have multiple Dot Clocks for a give resolution setting your might try HRxVRxDCL (e.g. "640x480x35.0") (DCL) Dot Clock: This should be one of the dot clocks listed in the manual or found in the Clocks section from the "X -probeonly" command. (HR & VR) Horizontal and Vertical Resolution: This also an easy one, it's the number pixels you want to see across and down the screen when you're in this mode. (HPS, HPE, VPS, VPE) Hortz. & Vertical Pulse Start and End: This controls where the image of the screen will be placed relative to the physical screen. These are the numbers to play with if the image is biased toward the edges of the physical screen. For starters just make them evenly spaced between the resolution numbers (HR,VR) and the field length numbers (HFL,VFL). If the image is biased toward the left (right), increase (decrease) the HPS and the HPE. If the image is biased toward the top (bottom), increase (decrease) the HPS and the HPE. (HFL,VFL) Horizontal & Vertical Field Length: Now these are the most important numbers of all. If you set these numbers too low or high for your monitor the XF86 server will reject your whole modeline. The KEY relation to remember is: --------------------------------------------- | DCL = HSF * HFL and DCL = RR * VFL * HFL | --------------------------------------------- where HSF = Horiz. Scan Freq. (kHz) RR = (Vert.) Refresh Rate (Hz) These two numbers are given as a valid range for a particular monitor. Try exceeding the specs and see how far you can go before funny things start happening. These two equations give you all the information you need to set up your Modelines for a particular set-up. They leave two degrees of freedom (i.e. two unknowns), for a chosen Dot Clock (DCL). As HFL and VFL get smaller, the screen will get wider and taller. However, you can not make these values arbitrarily close to the HR and VR since as they approach these values the HSF and RR will exceed your monitor's cabilities. Therefore one way of getting the maximum image size (hence using the most of your physical monitor's real-estate) for a particular Dot Clock (DCL) is to plug in the maximum HSF and RR your monitor is rated for. If the image is still too small your only option is to reduce the Dot Clock (DCL) (or try exceeding your monitor specs). This fact troubled me for sometime as it seems counter-intuitive, however try to get comfortable with it as it is true none-the-less. The other way I thought of to resolve the extra degrees of freedom is to use the video card table given in the manual of my Mach 64. The manual gave DCL, HSF, & RR, hence I could solve for VFL & HFL using the equations above. I thought this might be a good idea since perhaps in some way the card was "designed" to work at these frequencies, and hence they make work better in some way. (However, I now seriously doubt that assumption.) Here is that table: HFL and VFL values for XF86_Mach64 corresponding to ATI Mach64 Manual Display Screen Refresh Horizon. Pixel Horizon. Vertical Resolution Rate Freq. Clock Field Len. Field Len. (pixels) (Hz) (kHz) (MHz) (Pixels) (Pixels) (HRxVR) (RR) (HSF) (DCL) (HFL) (VFL) ----------------------------------------------------------------- 640x 480 60 31.5 25.2 800 525 640x 480 72 37.7 32.0 849 524 640x 480 75 37.5 35.0 933 500 640x 480 90 47.9 39.9 833 532 640x 480 100 53.0 44.9 847 530 800x 600 48 33.8 36.0 1065 704 800x 600 56 35.2 36.0 1023 629 800x 600 60 37.9 39.9 1053 632 800x 600 70 44.5 44.9 1009 636 800x 600 72 48.0 50.4 1050 667 800x 600 75 49.5 49.5 1000 660 800x 600 90 57.1 56.6 991 634 800x 600 100 62.5 67.5 1080 625 1024x 768 43 35.5 44.9 1265 826 1024x 768 60 48.3 65.0 1346 805 1024x 768 70 56.5 75.0 1327 807 1024x 768 72 58.2 75.0 1289 808 1024x 768 75 60.0 78.8 1313 800 1024x 768 90 76.2 100.0 1312 847 1024x 768 100 79.0 110.0 1392 790 1152x 864 43 45.9 65.0 1416 1067 1152x 864 60 59.0 80.0 1356 983 1152x 864 70 66.1 100.0 1513 944 1152x 864 75 75.1 110.0 1465 1001 1152x 864 80 80.0 126.0 1575 1000 1280x1024 43 50.0 80.0 1600 1163 1280x1024 47 50.0 80.0 1600 1064 1280x1024 60 64.0 110.0 1719 1067 1280x1024 70 74.0 126.0 1703 1057 1280x1024 75 80.0 135.0 1688 1067