\noindent {\bf Sequent Symmetry S27 and Symmetry S81 } \noindent {\bf Parallel Bus Architecture } \vspace{.1in} \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. \vspace{.1in} \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. \vspace{.1in} \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. \vspace{.1in} \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. \vspace{.1in} \noindent {\bf Configuration:} Industry-standard I/O, interfaces: \vspace{.1in} \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. \vspace{.1in} \noindent Ethernet - at 10 Mbits/sec. Connection to PC as virtual disk through Ethernet. \vspace{.1in} \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. \vspace{.1in} \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. \vspace{.1in} \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. \vspace{.1in} \noindent Peripherals include 1/2" 1600 and 6250 bpi tape drives and 396, 264, and 540 Mbyte disk drives. \vspace{.1in} \noindent \begin {tabbing} aaa\=bbb\=ccc\= \kill Other features:\\ \> Dimensions 30.5"h x 23.3"w x 26.8"d (S27)\\ \>\> 67.0"h x 38.0"w x 27.5"d (S81)\\ \> S27 16 amps max at 60Hz 115VAC.\\ \>\> 8 amps max at 50Hz 220VAC.\\ \>\> Maximum configuration dissipates 1500 Watts\\ \> S81 15 amps max at 50Hz 415 VAC three phase.\\ \end{tabbing} \vspace{.1in} \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. \vspace{.1in} \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. \vspace{.1in} \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. \vspace{.1in} \noindent {\bf Status:} Symmetry machines being delivered since December 1987. By January 1988, over 50 Sequent Symmetry machines had been delivered. \vspace{.1in} \noindent Cost: Cheapest system is \$60,000, and smallest increment is an 8 mips board at \$21,000. \vspace{.1in} \noindent {\bf Contact:} \vspace{.1in} \begin{flushleft} Sequent Computer Systems, Inc.\\ 15450 SW Koll Parkway\\ Beaverton, Oregon 97006-5903\\ 503-626-5700 800-854-0428 Telex 296559\\ \vspace{.1in} Casey Powell and Scott Gibson, co-founders.\\ Technical: David Rodgers and Gary Fielland\\ \vspace{.1in} Sequent Europe Limited\\ 1 Martindale Road\\ Hounslow\\ Middlesex TW4 7EW\\ England\\ 01-570-2066 Fax 01-577-5834 Telex 946114 SQNTUK\\ \vspace{.1in} European General Manager : Stuart Bagshaw\\ UK Research and Academic : Ian Blagg\\ UK Sales Director: Peter Winder\\ UK Technical Support: Steve Wanless\\ \vspace{.1in} Sales offices throughout Europe\\ \end{flushleft}