XImtool on 16-bit Displays

Having just purchased a new Compaq 1800T laptop with 16-bit colors and a nice 1400x1050 screen with the hope of working at home, I ran into a nasty problem with the NOAO/IRAF ximtool, which displays and analyzes astronomical images. I had installed the latest X11IRAF binaries for RedHat (I'm running 6.2) from tucana.noao.edu.

The error was
> X Error of failed request: BadMatch (invalid parameter attributes)
> Major opcode of failed request: 72 (X_PutImage)
> Serial number of failed request: 4262
> Current serial number in output stream: 4267

which the folks at NOAO informed me was caused by using more than 8-bits per pixel in the X visual. Ximtool only runs under 8-bit PseudoColor visuals. NOAO recommended running an 8-bit server and switching back when I didn't need ximtool. The command they suggested was % startx -- -bpp 8.

What I really wanted was to run 16-bit displays everywhere except in a window where I would pop open ximtool. The solution I found with some help from the computer gurus at Rice was to use something called vnc. You need two items, vncserver and vncviewer, both available from http://www.uk.research.att.com/vnc/start.html.

The idea is that in addition to your normal 16-bit Xserver and your normal windowing environment (I'm using enlightenment) you also run an 8-bit pseudocolor X-server with vncserver on DISPLAY :1, and then display it in a window with vncviewer. This keeps the 8-bit stuff all in one window, which is ideal. The vnc software seems to be developed primarily to view Windows in unix and vice-versa.

First, download vncviewer and vncserver for X from the vnc website (register and tell them thank you). When you install the software it will prompt you for a password. You can store this in a password file if you like, and then set
vncviewer*passwordFile: /home/wherever/password
in your .Xresources file. While you are at it, set
vncviewer*geometery: 1290x950+70+20
(for my screen) in .Xresources.

In the .vnc directory there is a file called xstartup. Mine looks like:
#!bin/sh
xrdb $HOME/.Xresources
xgterm -geometry 70x65+10+10 +sb &
ximtool-alt &
twm &

**NOTE** You *must* run twm and not an environment like enlightenment! If you do you'll end up with what I got, which was a false color display but a frozen screen with no windowing control. There went about a week. You should be all set to go. To run vnc type

vncserver -cc 3 :1
vncviewer :1

The -cc 3 is for pseudocolor, and the :1 is the display. You can run more of these (:2, :3, etc.) if you like. To kill the server type 'vncserver -kill :1'.

This works great for me. If you're interested, check out how to set up a dual boot Windows/Linux platform on a laptop.


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Patrick Hartigan
hartigan@sparky.rice.edu