WEIZAC

The Birth of a Computer in a Nation Being Born

WEIZAC, the Weizmann Automatic Computer, was the first computer in Israel and one of the first large-scale stored-program electronic computers in the world.¹² It was built at the Weizmann Institute of Science¹⁶ in Rehovot during 1954 and 1955, at a moment when the country was still fighting for the basics of statehood: housing, roads, food production, immigrant absorption, industry, and scientific institutions.

The decision was not practical in the narrow sense. Israel had no computer industry, no pool of trained digital engineers, no established programming profession, and no easy way to buy the parts for a machine of this class. That is exactly why WEIZAC matters. It was not only a machine for calculations. It was a deliberate attempt to create national scientific capacity before the infrastructure for that capacity existed.³

For eight years, from late 1955 until December 29, 1963, WEIZAC served physicists, mathematicians, geophysicists, chemists, crystallographers, defense researchers, and young programmers. Until 1961 it was the only computer in Israel.¹

Princeton, 1945: Where It All Started

The technical roots of WEIZAC ran through Princeton. In the mid-1940s, the Institute for Advanced Study¹⁷ brought together figures such as Albert Einstein, John von Neumann, Herman Goldstine, Julian Bigelow, and a younger generation of engineers. Von Neumann's group was building the IAS computer, a binary stored-program machine that used 40-bit words, two 20-bit instructions per word, and a shared memory for data and instructions.¹⁴

Working in that environment was Chaim L. Pekeris, a Lithuanian-born Jewish physicist and applied mathematician. Pekeris understood earlier than most scientists that electronic computing could change the scale of scientific work. His specialty was turning difficult physical problems into numerical methods that a machine could actually execute.

In 1945, the Weizmann Institute asked Pekeris to establish a Department of Applied Mathematics in Rehovot. He accepted on one condition: the Institute must build a computer similar to the IAS machine. His immediate target was Laplace's tidal equations for the Earth's oceans, a problem with too many coupled numerical steps to be handled realistically by hand calculation.¹⁴

From ENIAC to WEIZAC: The First Electronic Computers

WEIZAC belonged to the first generation of electronic digital computers. The list below gives the machines that formed the path from ENIAC to WEIZAC, with a one-line view of where each was built, what it could do, and why it is remembered.¹⁴

The Advisory Committee: Einstein Says No, Von Neumann Says Yes

In July 1947, an advisory committee for the Weizmann Institute's Applied Mathematics Department discussed Pekeris' proposal. Its members included Albert Einstein and John von Neumann. Einstein was skeptical. Electronic computers were experimental, expensive, and far from proven. For a young country short of material resources, the plan sounded almost unreasonable.³

Von Neumann took the opposite view. When someone asked, "What will that tiny country do with an electric computer?", he replied:

"Don't worry about that problem. If nobody else uses the computer, Pekeris will use it full time!" John von Neumann, 1947⁴

Einstein was eventually persuaded. Chaim Weizmann, head of the Institute and Israel's first president, assigned US$50,000 to the project, about one fifth of the Institute's budget.⁵ It was an astonishing bet: a fifth of a scientific institute's resources for a machine that almost nobody in the country yet knew how to build, program, repair, or even fully imagine using.

Gerald and Thelma Estrin: Schematics But No Parts

In 1952, Gerald Estrin¹⁸, a research engineer from the IAS computer project, was chosen to lead construction in Israel. He came with his wife, Thelma Estrin¹⁹, an electrical engineer who also worked on the project. They arrived by ship, carrying the design knowledge of Princeton but not the parts needed to turn that knowledge into hardware.

The Estrins brought schematics. The rest had to be found, fabricated, adapted, or invented locally. Gerald later captured the strange confidence required by the project:

"As I look back now, if we had systematically laid out a detailed plan of execution we would probably have aborted the project." Gerald Estrin¹

Estrin discovered that many Israeli scientists, except Pekeris, thought the plan was ridiculous. He was placed in three rooms in the basement of the Ziskind Building and told, in effect, to turn drawings into a national computing laboratory.³

Building It: Improvisation and Determination

WEIZAC was built in conditions very different from Princeton, Cambridge, Manchester, or IBM. The team had to create both the computer and the local craft needed to make a computer possible. The vacuum tubes, chassis, memory, power systems, testing tools, punched tape equipment, wiring, and documentation all demanded a mix of formal engineering and practical improvisation.

Micha Kedem, an Israeli electrical engineer, joined Pekeris in roaming the streets of Tel Aviv searching for parts to build a tube tester. When precision machinery was needed, the team turned to a shop that normally made fans and bicycle parts, owned by recent immigrants from Bulgaria.³

Zvi Riesel, who had run the IDF radar workshop, joined after seeing a newspaper advertisement looking for people to build an electronic computer. Many applicants had lost education records during the Holocaust or immigration. In Israel's small technical community, reputation and demonstrated skill often mattered more than paperwork.³

Ephraim Frei brought physics and electronics expertise. Phillip Rabinowitz, a Whirlwind veteran from MIT, taught programming courses at Weizmann. Hans Jarosch, a new immigrant and aeronautical engineer, wrote application programs. Together with Kedem, Riesel, Thelma Estrin, and others, they turned WEIZAC into a working institution, not merely a finished device.³¹⁰

First Calculation: October 1955

Construction began in earnest in 1954 and continued through 1955. As the machine neared completion, Gerald and Thelma Estrin returned to the United States. Shortly afterward, in October 1955, WEIZAC performed its first calculation.⁷ By early 1958 it was in full operation, with a growing user community and a backlog of scientific work waiting for time on the machine.³

Technical Specifications

WEIZAC followed the IAS style but, like almost every first-generation computer, it was a one-of-a-kind machine. Even other IAS-family computers could not simply exchange programs with it.¹

Scientific Breakthroughs

WEIZAC justified Pekeris' insistence almost immediately. Its value was not that it made arithmetic faster in the abstract. It made certain scientific questions newly reachable.

• Ocean tides: WEIZAC was used to solve Laplace's tidal equations on a global scale. The calculations helped identify an amphidromic point in the South Atlantic, a point around which tides rotate and at which the tide level does not change.¹
• Quantum mechanics: Yigal Accad translated Pekeris' equations for a two-electron atom into machine code. WEIZAC calculated eigenvalues for the system, and the results were later checked against experimental work at Brookhaven National Laboratory.⁸
• Geophysics and seismology: The machine supported earthquake and earth science calculations that required repeated numerical solution of physical models.¹
• Chemistry and materials: WEIZAC was used in atomic spectroscopy and X-ray crystallography, fields where mathematical models had to be matched to experimental data.¹
• Numerical analysis: It supported random walk methods, approximation work, and the training of Israeli scientists in machine-based computation.¹

Israel's Only Computer

Until 1961, WEIZAC was the only computer in the State of Israel. That fact turned it into a national resource. Users from other institutions competed for computing time, and frustration over the waiting list became one of the clearest proofs that Israel needed more computers, more programmers, and more digital engineers.¹⁶

End of an Era

WEIZAC operated until December 29, 1963. It was replaced by a commercially built CDC 1604A²⁰, while the Institute's staff began work on a locally designed successor called GOLEM. The transition marked the end of the heroic one-machine era and the beginning of a broader Israeli computing ecosystem.¹

Legacy

"Remarkable changes in Israel were evident. New roads, new buildings, new people, new problems. Before the start of the WEIZAC project there were no digital electronic computers in Israel. No electronic digital engineers. No programmers and no support personnel. The WEIZAC people succeeded in creating the technological know-how necessary for Israel to play a strong role in the information revolution." Gerald Estrin, 1963³

In 2006, IEEE recognized WEIZAC as a Milestone in the history of electrical engineering and computing. The honor was not simply for building a machine. It recognized a cultural and technical leap: a group of scientists and engineers built a first-generation computer in a young country, used it for serious science, and created the skills that later fed Israel's computing and technology industries.⁶⁹

WEIZAC Timeline

The People Who Built WEIZAC

References

1. Wikipedia: WEIZAC
2. Weizmann Institute: Computer Studies
3. Weizmann Institute: The WEIZAC (from Interface, Spring/Summer 1998)
4. Corry, Leo; Leviathan, Raya (2023). Chaim L. Pekeris and the Art of Applying Mathematics with WEIZAC, 1955-1963. Springer Nature. ISBN 978-3-031-27125-0
5. Weizmann Institute: WEIZAC IEEE Milestone Invitation
6. IEEE Milestone: WEIZAC Computer, 1955
7. Weizmann Institute Scientific Activities (1962), p. 19
8. Koutschan, Christoph; Zeilberger, Doron (2011). "The 1958 Pekeris-Accad-WEIZAC Ground-Breaking Collaboration." The Mathematical Intelligencer 33(2): 52-57. arXiv:1006.0200
9. Bogdanowicz, Anna (2006). Middle East's First Computer Named History Milestone. IEEE.
10. Estrin, Gerald (1991). "The WEIZAC Years (1954-1963)." IEEE Annals of the History of Computing 13(4): 317-339.
11. Corry, Leo; Leviathan, Raya (2019). WEIZAC: An Israeli Pioneering Adventure in Electronic Computing (1945-1963). Springer Verlag.
12. Google Blog: Remembering WEIZAC
13. YouTube: Prof. Aviezri Fraenkel recounts WEIZAC
14. Wikipedia: History of computing hardware
15. Wikipedia: IAS machine
16. Wikipedia: Weizmann Institute of Science
17. Wikipedia: Institute for Advanced Study
18. Wikipedia: Gerald Estrin
19. Wikipedia: Thelma Estrin
20. Wikipedia: CDC 1604