UX400S product backgrounder

[Bharat Charan <Charan%alderaan.scrc.symbolics.com@RELAY.CS.NET>]

    Date: Thu, 10 Aug 89 19:05 EDT
    From: Barry Margolin <barmar@Think.COM>

	Date: Thu, 10 Aug 89 15:08 CDT
	From: dmitchell@backus.trc.amoco.com (Donald H. Mitchell)

	In particular, my deskside 4/110s (three of them) each have an extra 9U
	VME bus slot.   I can buy SCSI disks and tapes for these if necessary;
	however, I would love to avoid it and have the Symbolics page over
	Ethernet (I know about speed problems).  Symbolics, however, does not
	have 4/110's in its shop; so, they are reluctant to sell boards for
	them.  My questions to the net are how many others would be interested
	in 4/110 support? Does anyone see a compelling reason for a local drive
	and tape?  Should there be a technical reason the 4/110 won't work?

    I'm just guessing, but I suspect that the UX400S will require TWO 9U VME
    slots -- one for the processor board and the other for the memory board.

There is memory on the UX400s board itself (2MW or 4MW).  It does not require
a second slot.  A second slot is needed for the EXPANSION memory board. This 
slot needs to be adjacent to the UX400s.  (The Ivory processor board and the
expansion board are connected by their own private bus).

	I also have a SparcServer 390 on order for which I will not have a
	workstation terminal (just a RS232 dumb terminal and lots of file
	service clients running X).  This fine beast has 2 GigaBytes of disk and
	a tape drive; so, it passes those requirements.  However, because it
	does not have an X terminal directly attached, I'm not certain it will
	work for an embed board.  The Symbolics board would have to have
	something in its FEP telling it that its X device was whatever server I
	choose (statically or dynamically).  Does anyone see a reason this use
	of a remote X server wouldn't work (since X by definition supports
	remote)?  

    I think this should be able to work.

There is no requirement that the X-server be the host Sun machine.  It can be any
X-server on the network.

		  Does anyone see why you couldn't put more than one Symbolics
	board into this type of machine (it has somewhere between 9 and 13 9U
	VME bus slots available)?

    There was some discussion along these lines recently about doing this
    with the XL400; since the UX400S uses basically the same board as the
    XL400 (the board is called "Merlin", I believe), the answer should be
    the same.  I believe the problem was that all Merlin boards are
    configured with the same VME bus address.  There IS a way to change the
    address (they needed it so they could use one Merlin to test another),
    but I don't remember whether it is as simple as DIP switches or whether
    it requires replacing a chip.

    An issue specific to the UX400S is the communication between the host
    processor and the coprocessors.  The host software may not be designed
    to deal with multiple coprocessors on the bus.  (Not having actually
    seen a UX400S, I'm going to be making some assumptions about how the
    host communicates with the coprocessor -- specifically, that it uses a
    device driver.)  The standard VME address might be hard-coded into the
    device driver, for instance.  To allow for multiple coprocessors they'd
    need to arrange for the minor device number to be usable to select
    different VME addresses.  Then you could start up multiple copies of the
    host software, telling each one to use a different device.

Multiple UX400S's  are not supported in a single Sun host.  If you do have
such a requirement please communicate that to your sales rep.