low resolution VGA monitors (640x480 or 480p) in Ubuntu

I want to do some emulation on an external display. I have a Sony PGM2950Q monitor. This monitor is only capable of displaying 480p (640 x 480) at 31Hz. So it should be great for Mame.

Plugging it in to my Thinkpad T-61 (intel graphics) with Ubuntu 14.04.3 with VGA (via BNC breakout cable) results in a garbled / overlapping display running at the lowest setting of 800x600 @ 60Hz. I know the monitor works as have tested it previously.

What would be the best way to fix this? Ideally I want it to recognise a configured display rather than have to set it up every time.

1 Answer

You can use xrandr:

The commands to be executed in order:

cvt 640 480
xrandr --newmode "640x480_31.00" 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync

The part of the line after xrandr --newmode is similar to the ouput you should get when using the cvt command, so copy the output from the "resolution_refreshRate" ("640x480_31.00" here) point to the +vsync point and add it to xrandr --newmode.

Then:

xrandr --addmode LVDS1 resolution_refreshRate (don't use speechmarks)
xrandr --output LVDS1 --mode resolution_refreshRate

If you want to make the changes permanent:

• Create a bash script, xrandr.sh for example, and place your xrandr commands into it:

  #!/bin/bash
  sudo xrandr --newmode ""640x480_31.00"" 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync
  sudo xrandr --addmode LVDS1 640x480_31.00
  xrandr --output LVDS1 --mode 640x480_31.00

• Make the script executable with chmod +x xrandr.sh

• Search for "Startup Applications" in the dash, run it, and add the script as a startup application.

The commands will now run every time you log into your account.

Note: I'm using LVDS1 as the supposed monitor name, but yours probably won't be the same. You can find your monitor name using:

xrandr | grep " connected " | awk '{ print$1 }'