A supercomputer is a computer that leads the world in terms of processing capacity, particularly speed of calculation, at the time of its introduction. The term Super Computing was first used by New York World newspaper in 1920 to refer to the large custom built tabulators IBM had made for Columbia University. Supercomputers introduced in the 1960s were designed primarily by Seymour Cray at Control Data Corporation (CDC), and led the market into the 1970s until Cray left to form his own company, Cray Research. He then took over the supercomputer market with his new designs, holding the top spot in supercomputing for 5 years (1985–1990). In the 1980s a large number of smaller competitors entered the market, in a parallel to the creation of the minicomputer market a decade earlier, but many of these disappeared in the mid-1990s "supercomputer market crash". Today, supercomputers are typically one-of-a-kind custom designs produced by "traditional" companies such as IBM and HP, who had purchased many of the 1980s companies to gain their experience, although Cray Inc. still specializes in building supercomputers.
The term supercomputer itself is rather fluid, and today's supercomputer tends to become tomorrow's also-ran. CDC's early machines were simply very fast single processors, some ten times the speed of the fastest machines offered by other companies. In the 1970s most supercomputers were dedicated to running a vector processor, and many of the newer players developed their own such processors at lower price points to enter the market. In the later 1980s and 1990s, attention turned from vector processors to massive parallel processing systems with thousands of simple CPUs; some being off the shelf units and others being custom designs. Today, parallel designs are based on "off the shelf" RISC microprocessors, such as the PowerPC or PA-RISC, and most modern supercomputers are now highly-tuned computer clusters using commodity processors combined with custom interconnects.
Software tools
Software tools for distributed processing include standard APIs such as
MPI and PVM and open source-based software solutions such as Beowulf and
openMosix which facilitate the creation of a sort of "virtual supercomputer"
from a collection of ordinary workstations or servers. Technology like
Rendezvous pave the way for the creation of ad hoc computer clusters.
An example of this is the distributed rendering function in Apple's Shake
compositing application. Computers running the Shake software merely need
to be in proximity to each other, in networking terms, to automatically
discover and use each other's resources. While no one has yet built an
ad hoc computer cluster that rivals even yesteryear's supercomputers,
the line between desktop, or even laptop, and supercomputer is beginning
to blur, and is likely to continue to blur as built-in support for parallelism
and distributed processing increases in mainstream desktop operating systems.
An easy programming language for supercomputers remains an open research
topic in Computer Science.
Uses
Supercomputers are used for highly calculation-intensive tasks such as
weather forecasting, climate research (including research into global
warming), molecular modeling (computing the structures and properties
of chemical compounds, biological macromolecules, polymers, and crystals),
physical simulations (such as simulation of airplanes in wind tunnels,
simulation of the detonation of nuclear weapons, and research into nuclear
fusion), cryptanalysis, and the like. Military and scientific agencies
are heavy users.
Design
Supercomputers traditionally gained their speed over conventional computers
through the use of innovative designs that allow them to perform many
tasks in parallel, as well as complex detail engineering. They tend to
be specialized for certain types of computation, usually numerical calculations,
and perform poorly at more general computing tasks. Their memory hierarchy
is very carefully designed to ensure the processor is kept fed with data
and instructions at all times—in fact, much of the performance difference
between slower computers and supercomputers is due to the memory hierarchy
design and componentry. Their I/O systems tend to be designed to support
high bandwidth, with latency less of an issue, because supercomputers
are not used for transaction processing.
As with all highly parallel systems, Amdahl's law applies, and supercomputer
designs devote great effort to eliminating software serialization, and
using hardware to accelerate the remaining bottlenecks.
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