Mixing 8 and 16/24/32 bit displays in Linux (Redhat)

Problem

• Older display software, such as WEB, does not support displays higher than 8-bit
• Usually people use 24 or 32 bit "truecolour" displays, since 8-bit is limited to 255 colours
• This solution allows normal use of 24/32 bit display, plus an extra 8-bit display
• When running, press CTRL-ALT-F8 to switch to 8- bit display. Press CTRL-ALT-F7 to go back to normal display

Assumptions

• Tested in Redhat Linux 7,8,9 and Fedore Core 3
• Probably will work in other distribtions as well
• Will work in KDE or GNOME
• uses a "minimal" window manager, either twm or icewm, for the 8-bit display

Setting up

• Edit the file /etc/X11/XF86Config (Redhat 7-9) or /etc/X11/xorg.conf (Fedore Core) as follows:
  Find the "Screen" section, and duplicate the 24-bit depth Subsection, changing 24-bit to 8-bit. Example:

Section "Screen"
        Identifier   "Screen0"
        Device       "ATI Mach64"
        Monitor      "Monitor0"
        DefaultDepth    24

        Subsection "Display"
                Depth       24
                Modes       "1280x1024" "1280x960" "1152x864" "1024x768" "800x600" "640x480"
        EndSubsection

        Subsection "Display"
                Depth       8
                Modes       "1280x1024" "1280x960" "1152x864" "1024x768" "800x600" "640x480"
        EndSubsection

EndSection

• Edit /etc/X11/xdm/Xservers to add a new screen, and tell it where to put the screens. It should look like this when done:

# $Xorg: Xserv.ws.cpp,v 1.3 2000/08/17 19:54:17 cpqbld Exp $
#
# Xservers file, workstation prototype
#
# This file should contain an entry to start the server on the
# local display; if you have more than one display (not screen),
# you can add entries to the list (one per line).  If you also
# have some X terminals connected which do not support XDMCP,
# you can add them here as well.  Each X terminal line should
# look like:
#       XTerminalName:0 foreign
#
:0 local /usr/X11R6/bin/X vt7
:1 local /usr/X11R6/bin/X -depth 8 vt8

• Optional : Install icewm using yum
  yum install icewm
• Place the file "startx8.com" in your home directory.
  

#!/bin/csh

if (-e $home/.Xclients) mv $home/.Xclients $home/.Xclients-orig

# starts an 8-bit display in window 2 using fluxbox
#echo exec /usr/local/bin/fluxbox > $home/.Xclients

# start an xwindow display using twm (installed with redhat)
echo exec /usr/X11R6/bin/twm > $home/.Xclients

# start an xwindow display using icewm
#echo exec /usr/bin/icewm > $home/.Xclients

chmod a+x $home/.Xclients
startx -- :1 -depth 8

rm  -f $home/.Xclients
if (-e $home/.Xclients-orig) mv $home/.Xclients-orig $home/.Xclients

• Uncomment the appropriate command (twm, icewm or fluxbox) depending on the window manager installed. twm is already installed by Redhat.
• Make the file executable:
  

Running the program

• After you already have your normal X-display started, press CTRL-ALT-F2 to go to a new text login window
• Log in, then run the command
  

• A new X-window should start up.
• To switch back to your old window, press CTRL-ALT-F7. This one is accessed by CTRL-ALT-F8

twm instructions

• twm is a VERY MINIMAL X display
• To run a program, hold down left-click -- a menu will pop up
• Select xterm to run an x-terminal
• When new windows open, they open as hollow boxes. Move the box where you want the window, then click
• To resize the window, click and hold the box in the upper right corner
• To close a window (twm does not have a close button) , click the desktop until the menu comes up, then select kill
  • Move the skull and crossbones cursor over the window, click and it will be closed

Problems running web in recent Redhat (Fedora core 8)

• FC8 does not contain the correct libraries to run web -- it needs libXm.so.3, part of openmotif
• Download the proper openmotif2.3.0 rpm from http://www.motifzone.net/index.php
• It has a dependency: libXP.so.6
  • The rpm for this can be found at
    http://rpmfind.net/linux/rpm2html/search.php?query=libXp.so.6
    
• install both rpms: in FC8,

     rpm -ivh libXp-1.0.0-8.fc8.i386.rpm openmotif-2.3.0-1.fc8.i386.rpm
  

• Be sure to set LD_LIBRARY_PATH variable to include /usr/X11R6/lib
• Also, web needs an older version of openmotif, but can make a soft link to the version web wants:
  

sudo ln -s /usr/X11R6/lib/libXm.so.4.0.0 /usr/X11R6/lib/libXm.so.3

A second way to get an 8-bit display

• from instructions on Wadsworth site
• Use vnc (Virtual Network Computing) to create a virtual display.
• Most GNU/Linux distributions include vnc in their default installation which can be used to create a virtual display in a window on your current desktop.
• If it is not installed, try

      > yum install vnc vnc-server

• When vnc is installed:

       > vncserver -cc 3 -depth 8

• To run the display:

        vncviewer :1

• Opens new desktop within a window
• Here you can start web_linux normally or you can start it automatically by editing your vnc viewer startup file: ~/.vnc/xstartup

        
vncserver -kill :1

• Kills the vnc server.

• Can also simply close the window. When you reopen, you will be in the same place
• Set ALLOWTOPICVIEW =

-- BillRice - 22 Aug 2006