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Introduction

Summary (salesman)

EL => Entry Level: a departmental supercomputer or minisupercomputer.

Air- cooled, < 6kW of power per cabinet - can be installed in an air conditioned office.

Supports a full implementation of UNICOS - Cray's flavour of UNIX.

Supports all/most of Cray's software development tools.

System Specifications

CPU

• CMOS Technology

• 30ns clock period

• 64 bit architecture

• Maximum of 4 single processors or 8 dual processors

• 133 Mflops peak per CPU

• Shared registers for inter-processor communication and synchronization

Memory

• Shared central memory

• 4 ports per CPU

• 70 ns CMOS DRAM

• 256 - 1024 Mbytes memory (32 - 128 Mwords)

• 1.05 Gb/sec memory bandwidth per CPU, approximately 130 Mwords/sec

• 4.2 Gb/sec total bandwidth

• 64 memory banks (regardless of memory size)

I/O

• VME based - 40 Mb/sec per VME

• 1 - 4 per CPU

• 1 - 4 in-cabinet (40 Gb max disk capacity)

• Up to 3 expansion cabinets with a max of 16 VME sub-systems (200 Gb max disk capacity)

• 1.05 Gb/sec total system I/O

• 640 Mb/sec total VME bandwidth

• 100 Mb/sec HIPPI

• 264 Mb/sec per CPU

Physical Characteristics

• 635 Kg

• 1 square metre footprint

• 127 cm x 381 cm

• 6 kw power consumption

• Air cooled

• Operating temperature 10xb0 - 30xb0 - any air-conditioned office is suitable no need for an expensive controlled environment.

CPU Schematic

• Primary registers accessible directly by the functional units:
  • V(ector) - 8 registers each containing 64 elements of 64 bits.

  • S(calar) - 8 registers (64 bits each).

  • A(ddress) - 8 registers.

• Intermediate registers B and T support (caching) for primary registers.

• VM - 64 bit vector mask. Each bit refers to an element in a vector register. The mask is used to select elements from a vector.

• VL vector length - range 1 to 64 specifying the length of the vector.

• RTC - run time clock

Functional Units

• Vector: Add, Shift, Logical, 2nd Logical, Population/Parity

• Floating point: Add, Multiply and Reciprocal Approximation - operands may be a pair of vector or scalar registers.

• Scalar: Add, Shift, Logical and Population/Parity/Leading zero.

• Address: Add and multiply.

• Segmented ie operations broken down into steps can complete in 1 clock cycle. Pipelining - a result every clock cycle.

• Independent - Add & Multiply may occur in parallel.

• Chaining - a result becomes the input.

QUB configuration

• 4 CPUs (single processor per board)

• 1 Gb of memory

• 15 Gb disk

• Ethernet connection

• Possible upgrade to FDDI connection

• 1 I/O sub system

SOFTWARE

• Introduction to Unicos for Application Programmers (iuap) - a computer based training package for new users of the Cray

• Compilers for Fortran 77, C and Pascal

• Cray Tools - a suite of tools for measuring and improving the performance of programs run

• Application packages - PVM/Hence, Nag Libraries, Unichem, TurboKiva, MPGS.

On-line information

• Manual pages

• Document viewer - docview

• Computer based training -iuap

• explain & whatis

Running programs

• Cray(QUB) primarily intended for use as a batch environment

• submit all compute intensive operations to the batch queues - includes compilation of large programs

• submit a job to a queue using a script file which is submitted to the queue system using the `qsub' command - validates all Network Queuing System request options

• Versions of the NAG routines which have been optimized for the Cray are available.

• Reducing compilation time - makefiles

• File compression utility - pack