To reply on myself:
> On Fri Oct 18 16:46:51 1996, Greg Oster wrote:
> [..]
> > Where might he find the source so he could do this?  In fact, where might 
> > interested parties find sources for the old X11R5 server for the Retina Z2 
> > so they might begin building an X11R6.1 server for the Z2?  Or perhaps the 
> 
> Yes, it would be great to get the source for the Retina Z2 Xserver.
> Anyone who knows who made this ?
> I think it was someone from france.

No, it was not from france, it was from Andy Heffernan.

A X11R5 source can be found on
ftp://ftp.uni-regensburg.de:/pub/NetBSD-Amiga/contrib/X11/X11R5/bin10/

X11R5.patches-25Oct94.tar.gz

I now remember that I took a look into this source when Andy put it on ftp,
BUT decided no to work with it (its much to change it to R6 and then
understand how this cfb.banked source work).

Bernd