Author Topic: Changing Screen Resolution  (Read 538 times)

billy_gates

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Changing Screen Resolution
« on: 13 December 2001, 03:53 »
In Redhat linux v7.2 running Gnome, How do I change the screen resolution without reinstalling linux?

voidmain

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Changing Screen Resolution
« Reply #1 on: 13 December 2001, 04:38 »
quote:
Originally posted by Billy Gates:
In Redhat linux v7.2 running Gnome, How do I change the screen resolution without reinstalling linux?


Changing the screen resolution is not the function of the window manager (gnome, kde, etc) but the function of X itself.  X has to be configured for each mode (resolution) that you want to be able to view.  There can be many defined resolutions and a default resolution.  

In the old days you had to edit the /etc/X11/XF86Config file directly and manually calculate the horizontal/vertican sync for each resolution based on your monitor and the refresh rates it and your video card were capable of.  Luckily there are utilities that can probe and generate this file for you and you can select and test each mode your vidcard/monitor are capable of.  

In RedHat and others if you want to stop X (open a shell window and as root type "init 3" which will stop X and give you a text login).  Log into that text login window as root and type "setup", select the "Xconfigurator" or X setup or whatever, you will see it.  I think most distros if not all have the "Xconfigurator", you can run it directly if you do not have the setup.  It should detect your video card and monitor and if it does not you can select the appropriate ones.  Then based on the amount of memory you have on your video card you will be presented with a list of 8,16, and 32 bit screen resolutions.  You can select and test as many as you want/need.  

Once you select the modes you want and successfully generate the XF86Config using this utility start X back up. (you may want to just do a "startx" command in case a mode is messed up, <CNTRL><ALT><BACKSPACE> will kill X if necessary).

Assuming you've made it this far and X is up and running you can cycle through the different modes (resolutions) by pressing <CTRL><ALT><+> where <+> is the "+" on your numeric keypad (not the one on the row of number keys at the top of your keyboard.  You can also use the <-> to cycle backward through the different modes.

Hopefully this helps....
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voidmain

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Changing Screen Resolution
« Reply #2 on: 13 December 2001, 04:43 »
quote:
Originally posted by VoidMain:

There can be many defined resolutions and a default resolution.  



Just noticed something that may be confusing about the note I just sent.  You can't set the "default" resolution in the Xconfigurator (at least I don't believe you can).  To do this you must edit the XF86Config file directly.  After getting the modes you want with Xconfigurator edit the XF86Config.  Near the bottom you will see your resolutions listed in order under each depth mode (6,16, or 32).  The resolutions might be listed like"

"1280x1024 1024x768 800x600 640x480"

The default mode when you start X in this case would be "1280x1024" if you want it to start up in "800x600" just move that one to the front of the list.  The order of the list determines the order when cycling with <CTRL><ALT><KP+>
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voidmain

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Changing Screen Resolution
« Reply #3 on: 13 December 2001, 04:57 »
And one last thing.  I just noticed you are running RedHat 7.2.  You are probably using X v4 in which case the config file in question is XF86Config-4 not XF86Config.
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billy_gates

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Changing Screen Resolution
« Reply #4 on: 13 December 2001, 08:22 »
Thanks, That helped a lot