Here's how to run savage.c on Linux with 8-bit colour:

1. Compile the program with "gcc display.c -L/usr/X11R6/lib -lXt"

2. Start the X server on an alternate display, in 8-bit mode:

 On, say, virtual screen 5, hit "ctrl-alt-F5" to get the login.
 Run "xinit -- :1 -depth 8"  A default (non-gnome) session starts.
 Run "./a.out" to run savage, which will now run through to completion.
 Exit from the shell to terminate X, and then log out.