I have a Toshiba Satellite laptop with a Mobility Radeon x200 IGP and a dual boot system of Ubuntu 8.04 and Windows XP MCE. I have it attached to a CRT that's capable of 1600x1200 at 75 Hz, and in XP I can use the two screens fine. In Ubuntu it will only run at 1280x800 at 60Hz (the same as the LCD on the laptop), and only as a cloned screen, not an additional display.
I've found sites telling me to edit my sys.conf file (or something along those lines) but that pretty much shoots straight over my head in terms of the information required. Does anyone have any advice?
Generally these days you can use the xrandr tool to change display settings without restarting Xorg or editing your xorg.conf. However, it's possible you may need to initially set some parameters in your xorg.conf that will override the display cloning. Also, this depends on whether you are using the ATI free or binary driver.
xrandr -q should give you a list of displays. After that, you will know the port name for your external VGA connection (probably VGA-0 or VGA) and your laptop's built-in screen (probably LVDS or TMDS or something like that). Then you can use xrandr to manipulate the resolution of each display and "xrandr --output VGA-0 --mode (whatever) --left-of LVDS" (that's a very rough approximation: just type xrandr --help to see all options). Also, depending on your video drivers, there may be a graphical display configuration tool (e.g. aticonfig for ATI's binary drivers or nvidia-settings for nVidia's).
Try System->Preferences->Screen Resolution and hit the Detect Displays button to see if it finds the other display. You shouldn't need to mess with xrandr directly from the comand line, the Screen Resolution GUI tool should drive it fine.
The detect displays doesn't work. I think it's because my monitor's ancient enough that it doesn't have the chip that says what it's capable of (the name won't come to me). Is the screen resolution GUI tool the same as xrandr? When I did xrandr -q it said:
Screen 0: minimum 320 x 200, current 1280 x 800, maximum 1280 x 1200 VGA-0 disconnected (normal left inverted right x axis y axis) LVDS connected 1280x800+0+0 (normal left inverted right x axis y axis) 0mm x 0mm 1280x800 60.0*+ 60.0 1280x768 60.0 1024x768 60.0 800x600 60.3 640x480 59.9
So "VGA-0 disconnected" means that it doesn't see the CRT?
bump/update: yep, I'm back. I gave up on the non-proprietary driver, so now I'm on Catalyst 8.10 for Linux.
Quick recap: I have a 1280x800 LCD on my laptop and a 1600x1200 CRT attached via the laptop's VGA port. I'd like to run the CRT as the primary (have the menu on it, for example), be able to run the CRT at 85Hz (if not, it's a deal-breaker), and be able to drag things from one window to the other. Is that possible?
Try this .. good thing you are running 8.04. Envy for beginners is wonderful. However, once you get comfortable with Ubuntu/Linux you'll want to ditch it. However this is good to get you up and running.
One thing I find nice on it is the ability to turn a monitor off to Ubuntu. At work I have a laptop and I run with it plugged in to my desk monitor for most of my work but I leave the laptop lid open and dump my email and stuff over on the laptop LCD screen. This means that the taskbar and such are on the main monitor. When I go to undock, I pop open the Display tool, select the monitor and turn it off, now the taskbar and such are on the laptop and I can go to a meeting. Come back to my desk and dock, select the monitor back on and to the left of my laptop LCD and it all works again.
It would be nice it if was tied in to the dock / undock sequence, but it works well enough for me like this - I don't go to too many meetings!