GP windows: What is it?

[news at clyde.concordia.ca]

I am having trouble trying to run a couple of the sun graphics demos that
are found in the /usr/demo/GP1 directory.  For example, when I try to run
a demo called 'flight', it says that it only runs in GP windows.  It seems
that GP stands for Graphics Processor, but what is it?  Are all Sun's
'equipped' with it (if it's hardware), or is it some software environment
that has to be called up, like Suntools?  

The same problem happens with the rotobj demo.  Strange thing is, when I
compiled both flight.c and rotobj.c, I didn't get any errors.  If this GP
window stuff is indeed optional hardware, it would have been better if the
compiler checked to see if it exists on the user's machine, and then warn
the user...

                                             Jean Goulet
                                             Electrical Engineering
                                             Class of '89
                                             Concordia University
                                             Montreal, Canada