Fujitsu VP2000
Encyclopedia
The VP2000 were the second series of vector
Vector processor
A vector processor, or array processor, is a central processing unit that implements an instruction set containing instructions that operate on one-dimensional arrays of data called vectors. This is in contrast to a scalar processor, whose instructions operate on single data items...

 supercomputer
Supercomputer
A supercomputer is a computer at the frontline of current processing capacity, particularly speed of calculation.Supercomputers are used for highly calculation-intensive tasks such as problems including quantum physics, weather forecasting, climate research, molecular modeling A supercomputer is a...

s from Fujitsu
Fujitsu
is a Japanese multinational information technology equipment and services company headquartered in Tokyo, Japan. It is the world's third-largest IT services provider measured by revenues....

. Announced in December 1988, they replaced Fujitsu's earlier FACOM VP Model E Series
Fujitsu VP
The FACOM VP is a series of vector supercomputers designed, manufactured, and marketed by Fujitsu. Announced in July 1982, the FACOM VP were the first of the three initial Japanese commercial supercomputers, followed by the Hitachi HITAC S-810 in August 1982 and the NEC SX-2 in April 1983. The...

. The VP2000 was succeeded in 1995 by the VPP300, a massively parallel
Massively parallel
Massively parallel is a description which appears in computer science, life sciences, medical diagnostics, and other fields.A massively parallel computer is a distributed memory computer system which consists of many individual nodes, each of which is essentially an independent computer in itself,...

 supercomputer with up to 256 vector processors.

The VP2000 was similar in many ways to their earlier designs, and in turn to the Cray-1
Cray-1
The Cray-1 was a supercomputer designed, manufactured, and marketed by Cray Research. The first Cray-1 system was installed at Los Alamos National Laboratory in 1976, and it went on to become one of the best known and most successful supercomputers in history...

, using a register
Processor register
In computer architecture, a processor register is a small amount of storage available as part of a CPU or other digital processor. Such registers are addressed by mechanisms other than main memory and can be accessed more quickly...

-based vector processor for performance. For additional performance the vector units supported a special multiply-and-add instruction that could retire two results per clock cycle. This instruction "chain" is particularly common in many supercomputer applications.

Another difference is that the main scalar units of the processor ran at half the speed of the vector unit. According to Amdahl's Law
Amdahl's law
Amdahl's law, also known as Amdahl's argument, is named after computer architect Gene Amdahl, and is used to find the maximum expected improvement to an overall system when only part of the system is improved...

 computers tend to run at the speed of their slowest unit, and in this case unless the program spent most of its time in the vector units, the slower scalar performance would make it 1/2 the performance of a Cray-1 at the same speed. The reason for this seemingly odd "feature" is unclear.

One of the major complaints about the earlier VP series was their limited memory bandwidth -- while the machines themselves had excellent performance in the processors, they were often starved for data. For the VP2000 series this was addressed by adding a second load/store unit to the scalar units, doubling memory bandwidth.

Several versions of the machines were sold at different price points. The low-end VP2100 ran at an 8 ns cycle time and delivered only 0.5 GFLOPS (about 4-8 times the performance of a Cray), while the VP2200 and VP2400 decreased the cycle time to 4 ns and delivered between 1.25 and 2.5 GFLOPS peak. The high-end VP2600 ran at 3.2 ns and delivered 5 GFLOPS. All of the models came in the /10 versions with a single scalar processor, or the /20 with a second, while the 2200 and 2400 also came in a /40 configuration with four. Due to the additional load/store units, adding additional scalar units improved performance by increasing memory bandwidth, as well as allowing several programs to run at the same time and thereby increase the chance there was something to process on the vector unit. Each unit is said to increase performance 1.5 times, allowing the VP2400/40 to match the performance of the earlier VP2600/20.

The machines were supplied with either the Unix
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...

-compatible UXP/M or the MVS
MVS
Multiple Virtual Storage, more commonly called MVS, was the most commonly used operating system on the System/370 and System/390 IBM mainframe computers...

-compatible VSP/S operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

s, both supplied by Amdahl
Amdahl Corporation
Amdahl Corporation is an information technology company which specializes in IBM mainframe-compatible computer products. Founded in 1970 by Dr. Gene Amdahl, a former IBM employee, it has been a wholly owned subsidiary of Fujitsu since 1997...

. The later was used for Fortran
Fortran
Fortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...

 programs while the former was typically used for C
C (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....

, and vectorizing compilers were supplied for both languages.

Like most companies, Fujitsu turned to massive parallelism for future machines, and the VP2000 family were not on the market for very long. Nevertheless over 100 were sold, and in July 1993, there were 180 installed.
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