UX400S: a decent machine

[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.

If someone in the know wishes to correct me (I've never actually seen a
UX400S, I'm just guessing based on what I presume are the design
constraints), I'd like to hear how it does it.  What kind of processor is
the Ifep, anyway, and how much memory does it have?  How small can an
X/TCP/IP implementation be?  The cold load stream is supposed to be usable
when the scheduler has been disabled, so how does it use X and TCP/IP
without the scheduler?  I know it's possible to write X and TCP/IP for
single-tasking systems, but I find it difficult to believe that Symbolics
is maintaining three implementations of all of these (FEP, cold load, and
full Genera).

				    BTW: if the UX was already booted, when
   you invoke the Unix "Genera" command, both the FEP cold load and Genera
   X windows will come up with the last state (i.e., you don't have to boot
   every time you start a session).  Note also that although the Sun and
   Symbolics share the port, they have distinct addresses with no
   interference.

The same is true of MacIvory.  You can reboot the Mac without losing your
Genera state, except that you end up warm booting (this is presumably
necessary so that Genera will notice if the screen has changed).