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Re: UX400S: a decent machine

  Date: Sat, 20 Jan 90 00:57:01 EST
  From: barmar@Think.COM
     Date: Fri, 19 Jan 90 13:34 CST
     From: dmitchell@backus.trc.amoco.com (Donald H. Mitchell)
     A user on any Sun that has a graphics terminal
     with X merely types in the Unix command:
     Genera UXboard-name
     where UXboard-name is the Symbolic's host name (not the Sun that it is
     embedded in, the board itself).  I don't know the technical details but
     somehow the Genera program causes a new X window to appear that talks
     directly to the Symbolics's FEP.  The user then types, "hello" and
     "boot" and up comes another X window containing the genera interface.
     Note, the Sun that contains the board does nothing during any of this
     except share its Ethernet port.  
  I find this difficult to believe.  I doubt very much that the FEP and cold
  load stream actually include TCP/IP and X Windows.  It seems more likely
  that there's a simple terminal protocol being used between the hosting Sun
  and the Ivory processor.  The control software on the Unix side then brings
  up an X window in which the dialogue with the FEP is displayed.

This is correct, though I don't see how the latter interpretation
contradicts the former (except perhaps for the part about the host
Sun doing "nothing"). The genera program that runs on the unix side is
responsible for creating the X window that corresponds to the cold load
stream, and manages FEP I/O with a simple protocol. Communication
between the host Sun and the Ivory is through a driver in the unix
kernel, so no TCP/IP or X protocol support is involved when only the
FEP is active. The Genera console window isn't opened until the world
has booted (when TCP/IP and X are of course available). The genera
program, like any other X client, can open the cold load window on 
on a X server on any host the Sun knows; the console window can
be opened only on hosts in the ivory's namespace (if it were the 
FEP itself negotiating the TCP/IP and X connections, it would 
need access to the namespace as well).