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UX400S product backgrounder

    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.

    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

I think this should be able to work.

	      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.