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{\bf
Sequent Symmetry S27 and Symmetry S81
}


\noindent
{\bf
Parallel Bus Architecture
}

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\noindent
{\bf Architecture:}
Two products, Symmetry S27 and Symmetry S81, employing same
system components and differentiated only by capacity.

\noindent
The S81 has from 2 to 30 32-bit INTEL 80386 microprocessors (2
to 10 on the S27), each with  an INTEL floating-point coprocessor,
64 Kbyte two-way associative cache, memory management unit,
sharing a global memory via a 64-bit wide pipelined packet bus
supporting multiple, overlapped memory and I/O transactions with a
sustained data transfer rate of up to 53.3 Mbyte/sec (Peak rate is
80 Mbyte/sec).  Optionally, each processor can be fitted with a
floating-point accelerator based on the Weitek 1167 chip.  The
cache uses a copy back control scheme implemented in custom
designed VLSI.  Each CPU board contains 2 Intel 80386 and 80387
microprocessors per board running at 16 MHz with plans to increase
rate to 20 MHz.

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\noindent
It is possible to upgrade from the earlier Sequent machines
simply by swapping boards. A buy-back scheme for the old boards is
currently in operation.

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\noindent
Each memory controller has either 8 or 16 Mbytes of
memory, while expansion boards contain 24 Mbytes each. 1 Mbyte
DRAM devices are used and the maximum physical memory is 240
Mbytes.  Each process has a maximum virtual address space of 256
Mbytes.  Processor and memory boards can go in any slot on the
bus.

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\noindent
A Sequent-designed IC chip (SLIC, System Link, and Interrupt
Controller) resides on each board to manage interprocessor
communication, synchronization, interrupts, diagnostics, and
configuration control. There is an extensive diagnostic subsystem.

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\noindent
{\bf Configuration:}
Industry-standard I/O, interfaces:

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\noindent
MULTIBUS - has terminal multiplexor and other controllers
and provides a link for up to four IEEE 796 standard MULTIBUS systems. 
Also MULTIBUS-based controllers for connecting RS-232
terminals, 1/2" 1600 and 6250/1600 bpi tape drives and parallel
line printer controllers.


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\noindent
Ethernet - at 10 Mbits/sec. Connection to PC as virtual disk
through Ethernet.


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\noindent
SCSI - at 2.5 Mbyte/sec. Offers 5-1/4 in. disk drives (72 and 150
Mbytes formatted) and streamer tape drives with adaptor boards
for the SCSI bus.

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\noindent
DCC - a very high performance SMD and SMD-E disk controller
supporting up to 8 disks allowing two simultaneous data transfers
at up to 3 Mbyte/sec and overlapped seeks on all drives.
Performance enhanced by rotational position sensing and slip sector
bad block handling.

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\noindent
NFS - a version of SUN Microsystem's Network File System.
TCP/IP - a standard network protocol.
X-Windows,
X.25,
Colored book software available by 2Q 1988.

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\noindent
Peripherals include 1/2" 1600 and 6250 bpi
tape drives and 396, 264, and 540 Mbyte disk drives.

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\noindent
\begin {tabbing}
aaa\=bbb\=ccc\=  \kill
Other features:\\
\&gt;    Dimensions  30.5"h x 23.3"w x 26.8"d (S27)\\
\&gt;\&gt;              67.0"h x 38.0"w x 27.5"d (S81)\\
\&gt;  S27 16 amps max at 60Hz 115VAC.\\
\&gt;\&gt;       8 amps max at 50Hz 220VAC.\\
\&gt;\&gt;       Maximum configuration dissipates 1500 Watts\\
\&gt;  S81 15 amps max at 50Hz 415 VAC three phase.\\
\end{tabbing}

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\noindent
{\bf Software:}
The operating system, called DYNIX 3, is a version of
UNIX supporting a dual universe for System V.2 and BSD 4.2 UNIX
applications, enhanced for application-transparent multiprocessing
and user-controlled parallel processing.  Among the enhancements
are a completely reentrant kernel, tunable virtual memory,
user-level shared memory, and synchronization services.  All
processors run a shared copy of the operating system.  The
configuration is symmetric, and load balancing is automatic and
dynamic.

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\noindent
{\bf Languages:}
C, Fortran, and Pascal are fully supported and have support for
parallel programming.  A parallel programming library is callable
from any language.  There are extensions to Fortran, C, and Pascal
to allow shared common blocks.  There is a preprocessor for
Fortran to parallelize DO-loops.  Pdbx, a version of the dbx
source level debugger that has been enhanced to support the
debugging of parallel programs, is available.

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\noindent
{\bf Performance:}
From 8 to 108 mips.
The S27 runs at 5 Mflops (single precision) on the LINPACK benchmark
(with a one-line compiler directive), and the S81 at
13 Mflops (single precision)
when configured with the Weitek floating-point accelerator.
 

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\noindent
{\bf Status:}
Symmetry machines being delivered since December 1987.
By January 1988, over 50 Sequent Symmetry machines had been delivered.

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\noindent
Cost:  Cheapest system is \$60,000, and smallest increment
is an 8 mips board at \$21,000.

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\noindent
{\bf Contact:}
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\begin{flushleft}
Sequent Computer Systems, Inc.\\
15450 SW Koll Parkway\\
Beaverton, Oregon 97006-5903\\
503-626-5700    800-854-0428     Telex 296559\\

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Casey Powell and Scott Gibson, co-founders.\\
Technical: David Rodgers and Gary Fielland\\

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Sequent Europe Limited\\
1 Martindale Road\\
Hounslow\\
Middlesex TW4 7EW\\
England\\
01-570-2066   Fax 01-577-5834  Telex 946114 SQNTUK\\

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European General Manager : Stuart Bagshaw\\
UK Research and Academic : Ian Blagg\\
UK Sales Director:         Peter Winder\\
UK Technical Support:      Steve Wanless\\

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Sales offices throughout Europe\\
\end{flushleft}
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