computer science

HITAC

HITAC 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 rather than just read about it. In short: HITAC (HItachi Transistor Automatic Computer)[1] is the designation for the majority of Hitachi large and midrange computer models spanning several decades. The HITAC 301, released in May 1958, was Hitachi's first fully transistorized computer model.

Key takeaways

HITAC 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 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HITAC from memory before moving on to harder problems.

Reference excerpt

HITAC (HItachi Transistor Automatic Computer)[1] is the designation for the majority of Hitachi large and midrange computer models spanning several decades. The HITAC 301, released in May 1958, was Hitachi's first fully transistorized computer model. Earlier Hitachi computers made use of semiconductors known as parametrons.[2]

Beginnings Hitachi Ltd. (now referred to as Hitachi), first began research in analog computers in 1951 with digital Computers following in 1956. As a prototype for the parametron logic circuit, the HIPAC-MK-1 was developed. The main transmission lines designed by Tadami power development utilized these as tensiometers. It was then that as Parametron calculators, the HIPAC 101 and HIPAC 103 became commercialized products. Parallel research in transistor computers soon became commercialized as well.

HIPAC MK-1（1957） 38 bit-words. fixed-point number. 1024 words of Drum memory. HIPAC 101（1960） 42 bit-words. fixed-point number. 2048 words of Drum memory. In Paris, 1959, Automath was exhibited. HIPAC 103（1961） 48 bit-words. fixed/floating-point. 1024/4096 words of Magnetic-core memory. (8192 words of Drum memory). As a base, the ETL Mark IV transistorized computer model was introduced and was the first commercialized in 1959. The Japan Electronics and Information Technology Industries Association produced this model intended for business use. In the following year, the HITAC 501 was released and now supplies the Eastern Osaka Kansai Electric substation as a control system.　Additionally, the Electric Testing Lab still accepts orders for the ETL Mark V. Using this as a base, researchers at the University of Kyoto cooperated to improve the technology which resulted in the HITAC 102 (also referred to as the Kyoto-Daigaku Digital Computer 1). Researchers at Japan's Economic Planning Agency introduced an improved version (HITAC 102B) as a substitute to the punch card system. In 1961, the HITAC 201 was developed as a smaller computer for business use.

HITAC 301（1959） BCD12 fixed decimal point expression. 1960 words of Drum memory. (High speed access of 60 words is possible) HITAC 501（1960） First computer as a control system （Insufficient Details） HITAC 102（1960） ETL Mark V prototype HITAC 201 （1961） BCD11 fixed decimal point expression. 4000 words of Drum memory. Moreover, in 1958, The Railway Technical Research Institute of Japan dispatched MARS. Although the first version of MARS did not include the HITAC system, its successor MARS101 utilized the HITAC 3030. After that point, Hitachi consistently used it as its mainframe.

Worked examples

Example 1 — a first encounter with HITAC

Start with the simplest possible case. Write down what HITAC 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 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 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

In research: HITAC 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 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 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer hardware stubs, Hitachi products, so understanding it makes those chapters shorter.
In everyday life: Look for HITAC 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 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HITAC 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 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HITAC in simple terms?

Why does HITAC 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?

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.