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Re: UX400S: a decent machine

    Date: Sat, 20 Jan 90 09:47:15 EST
    From: tk@research.att.com

      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 thattalks

I'm sorry if I confused.  The "genera" program is a Unix program running
on the Sun with the display (not on the Sun hosting the board).

	 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 still maintain this last statement (see my last paragraph).
      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).

Just to confirm understanding: the Unix box containing the UX board is
not responsible for any of this window stuff.  The Unix box hosting the
display is responsible for running the genera program (and thus
generating the FEP window).  This distinction is important to people
thinking about putting a UX in a fileserver that they do not want to
spend any CPU cycles hosting the board but want the client Unix box with
the display to shoulder all the burden.