computer science

HITAC S-820

HITAC S-820 is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand HITAC S-820 rather than just read about it. In short: The HITAC S-820 is a family of vector supercomputers developed, manufactured and marketed by Hitachi. Announced in July 1987, it was Hitachi's second supercomputer, succeeding the HITAC S-810.

Key takeaways

HITAC S-820 belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect HITAC S-820 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HITAC S-820 from memory before moving on to harder problems.

Reference excerpt

The HITAC S-820 is a family of vector supercomputers developed, manufactured and marketed by Hitachi. Announced in July 1987, it was Hitachi's second supercomputer, succeeding the HITAC S-810. The S-820 is categorized as a second generation Japanese supercomputer. The S-820 system has both a scalar and vector processor, similar to the architecture of the S-810. The scalar processor is based on the Hitachi M-series mainframe processor, so is compatible with its operating system. The S-820 was reported to have a theoretical peak performance of 2 GFLOPS, and a theoretical maximum computational performance of 3 GFLOPS. Initially the S-820 was available in two variations: the S-820 model 80 and the S-820 model 60 (hereafter S-820/80 and S-820/60). The S-820/80 had double the vector computational capability, as well as more storage capability, compared to the S-820/60. The peak performance of the S-820/80 was 3 GFLOPS, and that of the S-820/60 as 1.5 GFLOPS. There were five models. The first two, the mid-range S-820/60 with a peak performance of 1.5 GFLOPS and the top-end S-820/80 with a peak performance of 3.0 GFLOPS, were announced in July 1987. These two models differ in the number of vector pipelines installed. In May 1988, the S-820/20 and S-820/40 were announced, followed by the S-820/15 in November 1989. A team from the Institute for Supercomputing Research (Tokyo) and the Los Alamos National Laboratory benchmarked the S-820/80 against the similar generation NEC SX-2 and Cray X-MP/416, as well as the S-810, during early 1988. They concluded that the S-820 was "a great deal faster in vector mode than any other supercomputer we have measured".

See also HITAC S-810 HITAC S-3000 Supercomputing in Japan

References

Worked examples

Example 1 — a first encounter with HITAC S-820

Start with the simplest possible case. Write down what HITAC S-820 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to HITAC S-820 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about HITAC S-820 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of HITAC S-820

In research: HITAC S-820 appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses HITAC S-820 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: HITAC S-820 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer hardware stubs, Hitachi supercomputers, Vector supercomputers, so understanding it makes those chapters shorter.
In everyday life: Look for HITAC S-820 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study HITAC S-820 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HITAC S-820 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain HITAC S-820 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HITAC S-820 in simple terms?

The HITAC S-820 is a family of vector supercomputers developed, manufactured and marketed by Hitachi. Announced in July 1987, it was Hitachi's second supercomputer, succeeding the HITAC S-810.

Why does HITAC S-820 matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study HITAC S-820?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on HITAC S-820.