Q: My X server is set to only display 8-bit colour (256 colours). I quickly run out of colours in Netscape. How can I display more colours?
A: Here's what to do if your system is configured to use XFree86 (not one of the proprietary servers such as Accelerated X or Metro-X).
This info applies specifically to Red Hat 4.2 and XFree86 3.3. It may not be exactly correct on other configurations. (March 2001 comment: It definitely does not apply for XFree86 4.x, but should hold for any 3.x release.)
You can tell your X server to use greater colour depths (e.g. 16 bits per pixel instead of just 8). In this example, we'll use 16, but your hardware may also support 24-bit or 32-bit colour depths. The default X settings are configured in the file /etc/X11/XF86Config. In that file you can change the default colour depth by adding or editing a line in the section labeled "Screen". After the Device and Monitor listings, you can include a line that reads 'DefaultColorDepth 16' so that X starts with 16 bit colours by default.
You also need to have a "Subsection Display" entry under the "Screen" section that lists "Depth 16". This section lists the modes (screen resolutions) to enable when running 16 bit colour. You probably have Display sections for 8, 16, 24, and 32-bit colour depths in your XF86Config file. Not all modes may work with your hardware. Some hardware is only supported in 8 or 16-bit mode.
You can also set the colour depth manually when you start X by specifying an option on the command line. E.g., entering "startx -- -bpp 16" will launch X with 16-bit colour depth.