Date: Tue, 21 Feb 1995 09:13:01 -0800 From: Dave Tweten <tweten@gilmore.nas.nasa.gov> To: johnb@mailserver.aixssc.uk.ibm.com Cc: freebsd-questions@FreeBSD.org Subject: Re: XF86Config HTimings Message-ID: <199502211713.JAA08987@gilmore.nas.nasa.gov>
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John Buxton writes: >I hope I've got the correct mailing list for this one. >If there's a specific list for XFree86, please let me know. Your best bet for XFree86 questions like this is probably the comp.windows.x.i386unix Usenet news group. >I am trying to setup my XF86Config file so that I can use 1024x768 with >256 colours. I've setup a corresponding mode in the "Monitor" section of >the file and I'm referencing it from the "Display" subsection of my "Screen" >section, however I think I'm coming unstuck with the HTimings of my mode. >I've currently got them set to :- > HTimings 1024 1048 1208 1264 >but I suspect this is wrong because when I run startx I get an error >message which says :- > (--) SVGA: Mode "1024x768i" needs hsync freq of 28.16 kHz. Deleted. >and so the mode can't be used and the X server doesn't start. Your monitor section gives HorizSync 30-37 indicating that for the sake of your monitor's health, the horizontal sync frequency must be kept between 30 and 37 kilohertz, inclusive. 28.16 kHz is clearly outside that range, so X did you the favor of not stressing your monitor. To really solve this problem right, you need to read VideoModes.doc, which came with the XFree86 distribution. It's entitled "The Hitchhiker's Guide to X386/XFree86 Video Timing". On my machine it's in the directory named /usr/src/X11R6/xc/programs/Xserver/hw/xfree86/doc. As the bottom line, it will help you decide to do one (or both) of two things. The first is to increase your dot-clock frequency. The second is to carefully nibble away at the rightmost three numbers of your HorizSync specification. To keep the same dot-clock frequency, you would have to nibble the rightmost number down to 1184, and make other required changes to the middle two numbers. "The Hitchhiker's Guide" will tell you all you need to know to decide if that's what you want to do, and if you do, how to. >I don't know what the HTimings mean and the XF86Config man page doesn't >really explain them, so I'm a bit lost. The place to find this information is "The Hitchhiker's Guide". >I've tried other values, but I'm worried that I might damage my monitor. So long as your HorizSync and VertRefresh specifications in the Monitor section are accurate, X won't let you damage your monitor. Instead, it will do exactly what it did to you, refuse to use the dangerous mode. >Section "Monitor" ... > Mode "1024x768i" ... > #HTimings 1024 1000 1000 1000 # SENDS SCREEN FUNNY!! "The Hitchhiker's Guide" will make it really obvious to you why this happened, too. When it comes to questions of video setup in your XF86Config file, "The Hitchhiker's Guide" is definitely "TFM". Anyone who wants to set up a monitor/graphics card combination should definitely "R" it.
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