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WEIZAC

WEIZAC 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 WEIZAC rather than just read about it. In short: WEIZAC (Weizmann Automatic Computer) was the first computer in Israel, and one of the first large-scale, stored-program, electronic computers in the world. It was built at the Weizmann Institute during 1954–1955, based on the Institute for Advanced Study (IAS) architecture developed by John von Neumann and was operational until the end of 1963.

WEIZAC — main illustration
WEIZAC — illustration

Key takeaways

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

Reference excerpt

WEIZAC (Weizmann Automatic Computer) was the first computer in Israel, and one of the first large-scale, stored-program, electronic computers in the world. It was built at the Weizmann Institute during 1954–1955, based on the Institute for Advanced Study (IAS) architecture developed by John von Neumann and was operational until the end of 1963. WEIZAC was widely used by Israeli scientists and researchers and helped with the advancement of science and technology in the young nation.

History

The WEIZAC project was initiated by Prof. Chaim L. Pekeris, who worked at the IAS at the time von Neumann's IAS machine was being designed. Chaim Weizmann, Israel's future first president, asked Pekeris to establish the Department of Applied Mathematics at the Weizmann Institute, and Pekeris wanted to have a similar computer available there. Pekeris wanted it as means to solve Laplace’s tidal equations for the Earth's oceans, and also for the benefit of the entire scientific community of Israel, including the Defense Ministry. In July 1947, an advisory committee for the Applied Mathematics Department discussed the plan to build the computer. Among the committee's members were Albert Einstein, who did not find the idea reasonable, and John von Neumann, who supported it. In one conversation, von Neumann was asked: "What will that tiny country do with an electric computer?" He responded: "Don’t worry about that problem. If nobody else uses the computer, Pekeris will use it full time!" In the end, a decision was made to proceed with the plan. Chaim Weizmann assigned US$50,000 for the project (equivalent to $720,939 in 2025), which was 20% of the Weizmann Institute total budget. In 1952, Gerald Estrin, a research engineer from the von Neumann project, was chosen to lead the project. He came to Israel along with his wife, Thelma, who was an electrical engineer and also involved in the project. They brought with them schematics, but no parts. Estrin later commented: "As I look back now, if we had systematically laid out a detailed plan of execution we would probably have aborted the project." After arriving, Estrin's impression was that besides Pekeris, other Israeli scientists thought it is ridiculous to build a computer in Israel. To recruit skilled staff for the project, a newspaper advertisement was posted. Most of the applicants had no records of prior education because those were lost in the Holocaust or during immigration, but in Israel's budding technical community everyone knew or knew about everybody else. The WEIZAC project also provided an opportunity for mathematicians and engineers to move to Israel without sacrificing their professional careers.

WEIZAC performed its first calculation in October 1955. Subsequently, it was used to study problems like worldwide changes in tide, earthquakes, atomic spectroscopy, X-ray crystallography, random walk methods, numerical analysis, and other problems. The computer found out that there was an amphidromic point in the South Atlantic at which the tide does not change. It also numerically calculated the eigenvalues of a two-electron atom quantum system based on programming by Yigal Accad who put Pekeris' development of the relevant equations into machine code. These results were later experimentally verified by the Brookhaven National Laboratory. WEIZAC was kept constantly busy, and users (especially from other institutions) became increasingly frustrated with not being able to get computing time, and demanded more computers to become available. WEIZAC's success led to the recognition of the demand for computers and digital technology in Israel, and ultimately, provided the foundation for Israel's computer and technology industries.

Specifications WEIZAC was an asynchronous computer operating on 40-bit words. Instructions consisted of twenty bits: an eight-bit instruction code and twelve bits for addressing. Punched paper tape was used for I/O, and later, in 1958, magnetic tape. The memory was initially a magnetic drum containing 1,024 words which was later replaced with a much faster 4,096 word magnetic-core memory module. In 1961, the memory was further expanded with two additional 4,096 word modules. As with almost all computers of its era, it was a one-of-a-kind machine that could not exchange programs with other computers (even other IAS machines).

After WEIZAC Until 1961, WEIZAC was the only computer in the State of Israel; it operated until 29 December 1963. The institute also bought a commercially built computer, a CDC 1604A. At the same time the institute's staff began working on Golem, based on the ILLIAC II architecture, but with several improvements.

Recognition On 5 December 2006, WEIZAC was recognized by the IEEE as a milestone in the history of electrical engineering and computing, and the team who built it was awarded the "WEIZAC Medal".

References

Bibliography The WEIZAC Years (1954-1963), Gerald Estrin, IEEE Annals of the History of Computing, vol. 13, no. 4, pp. 317–339, Oct-Dec 1991. ISSN 1058-6180. Corry, Leo, Raya Leviathan (2019). WEIZAC: An Israeli Pioneering Adventure in Electronic Computing (1945–1963). New York: Springer Verlag.{{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: publisher location (link) Corry, Leo, Raya Leviathan (2023). Chaim L. Pekeris and the Art of Applying Mathematics with WEIZAC (1955–1963). New York: Springer Verlag.{{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: publisher location (link)

External links

Weizmann Institute Computer Studies – With a historical overview including the WEIZAC. IEEE History Center: WEIZAC Computer, 1955 Remembering WEIZAC: the beginning of computing in Israel, in Google's official blog WEIZAC: Israel's first computer – Prof. Aviezri Fraenkel recounts WEIZAC's beginning (video)

Illustrations

WEIZAC: Section of WEIZAC on display at Weizmann Institute
Section of WEIZAC on display at Weizmann Institute
WEIZAC: WEIZAC construction
WEIZAC construction
WEIZAC: WEIZAC in use
WEIZAC in use
WEIZAC: Zvi Rizel with WEIZAC, 1957
Zvi Rizel with WEIZAC, 1957

Worked examples

Example 1 — a first encounter with WEIZAC

Start with the simplest possible case. Write down what WEIZAC 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 WEIZAC 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 WEIZAC 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 WEIZAC

In research
WEIZAC 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 WEIZAC 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
WEIZAC is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1950s computers, Computer-related introductions in 1955, IAS architecture computers, so understanding it makes those chapters shorter.
In everyday life
Look for WEIZAC 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 WEIZAC in 20 minutes

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

Frequently asked questions

What is WEIZAC in simple terms?

WEIZAC (Weizmann Automatic Computer) was the first computer in Israel, and one of the first large-scale, stored-program, electronic computers in the world. It was built at the Weizmann Institute during 1954–1955, based on the Institute for Advanced Study (IAS) architecture developed by John von Neu…

Why does WEIZAC 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 WEIZAC?

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 WEIZAC.

Tags

  • 1950s computers
  • Computer-related introductions in 1955
  • IAS architecture computers
  • Israeli inventions
  • Science and technology in Israel
  • Weizmann Institute of Science

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