History of BulgariaHistory of Bulgaria
Cut-out detail; background removed. Reconstructed add-subtract module from the Atanasoff–Berry Computer.
ABC reconstruction

John Vincent Atanasoff · 20th century

Atanasoff and the computer dispute

What do Atanasoff and Berry create?

9 scenes · 4 min · Sources · 22

StartListen

John Atanasoff and Clifford Berry build a machine for difficult calculations in Iowa. Decades later, their ideas become part of a dispute over another computer's patent.

Reconstruction of the Atanasoff–Berry Computer in the Durham Center.
John Vincent Atanasoff, portrait. The photographic date is not established.

Part 1 · 20th century

A machine against long calculations

In Ames, Iowa, John Atanasoff wants to save hours of calculation. A mechanical calculator helps, but long problems still demand much work. Between 1939 and 1942, Atanasoff and Clifford Berry build the machine in Ames.

This is the Atanasoff–Berry Computer, or ABC. A working test model exists by December 1939. The full machine is designed for up to 29 equations in 29 unknowns. These are linked equalities with shared missing numbers. Imagine several calculations with unknown prices that must all be true together.

Listen to scene · 1

Synthetic voice · 0:37
Sources · 4
  1. JVA Initiative Committee; Iowa State University Atanasoff-Berry Computer: Operation/Purpose John Vincent Atanasoff Discovery Center
  2. Earl R. Larson; United States District Court, District of Minnesota Honeywell Inc. v. Sperry Rand Corporation and Illinois Scientific Developments, Inc.: Findings of Fact, Conclusions of Law, and Order for Judgment (excerpts) PDF Iowa State University Library, John Vincent Atanasoff Collection · 1973 · 47–49; final unnumbered order
  3. User:Manop File:Atanasoff-Berry Computer.jpg Wikimedia Commons
  4. Eye Steel Film from Canada File:ATANASOFF Pic^1 - Flickr - Eye Steel Film.jpg Wikimedia Commons
John Vincent Atanasoff, second portrait. The photographic date is not established.
Geographic context, without historical bordersGeographic context, without historical borders123
Geographic context, without historical borders

Part 2 · 20th century

His father's village across the ocean

The Bulgarian connection begins with John Atanasoff's father. Ivan Atanasov came from Boyadzhik in the Yambol region. He emigrated to the United States in 1889. His son John works in America; the machine is built in Iowa.

In 1970 John Atanasoff comes to Bulgaria. In his memoir, he describes a lecture in Sofia and meetings with relatives in Boyadzhik. This happens before the court ruling later associated with his name.

Listen to scene · 2

Synthetic voice · 0:27
Sources · 7
  1. JVA Initiative Committee; Iowa State University Global Connections John Vincent Atanasoff Discovery Center
  2. University of Florida, Department of Electrical and Computer Engineering John Vincent Atanasoff Department history
  3. Благовест Сендов; quoted memoir excerpt by John V. Atanasoff Джон Атанасов: Пионерът на информационната ера PDF Природа (БАН) · 2013 · 44–51
  4. Wikimedia geographical database contributors Boyadzhik: geographical record
  5. Wikimedia geographical database contributors Iowa State University, Ames: geographical record
  6. Wikimedia geographical database contributors Sofia: geographical record
  7. Eye Steel Film (provider); Lomita / Wikimedia Commons (processing); original photographer unknown File:ATANASOFF Pic^2 - Flickr - Eye Steel Film.jpg
Reconstructed Atanasoff–Berry Computer: drum, control panel and tubes.
Reproduction memory drum and electronic circuit in a display case.
Reproduction memory drum; not the surviving original.
Reproduction memory drum and electronic parts, wider view.

Part 3 · 20th century

How a drum remembers numbers

Look at the cylinder at upper left. It is a memory drum. The photograph shows a reconstruction, rather than the surviving wartime machine. Inside the ABC, numbers are represented by zeros and ones. This is called the binary system.

Capacitors, small devices that hold electrical charge, store these signs. The charge fades and needs regular refreshing. This keeps numbers in memory between operations. A person selects what to calculate. The machine stores no program: a series of instructions for automatic execution.

1 · Memory drum
The cylinder at upper left is a memory drum. In the machine, capacitors hold charges representing numbers. This is a reconstruction.
2 · Operator controls
Buttons and switches let a person select operations. The machine does not read a program stored in memory.
3 · Vacuum tubes
These glass parts control electrical signals. They are called vacuum tubes. The whole machine has about three hundred.

Listen to scene · 3

Synthetic voice · 0:34
Sources · 8
  1. JVA Initiative Committee; Iowa State University Atanasoff-Berry Computer: Operation/Purpose John Vincent Atanasoff Discovery Center
  2. John Gustafson Reconstruction of the Atanasoff-Berry Computer PDF The First Computers—History and Architectures, ed. Raúl Rojas and Ulf Hashagen; MIT Press · 2000 · 91–106
  3. Computer History Museum Atanasoff-Berry Computer Revolution: The First 2000 Years of Computing
  4. Ik T from Kanagawa, Japan File:Atanasoff-Berry Computer ー Computer History Museum (30781535612).jpg Wikimedia Commons
  5. WilliamSnail File:ABC memory circuit display, Durham Center, Iowa State University.jpg Wikimedia Commons
  6. WilliamSnail File:ABC memory drum reproduction, Durham Center, Iowa State University.jpg Wikimedia Commons
  7. WilliamSnail File:ABC memory drum reproduction 2, Durham Center, Iowa State University.jpg Wikimedia Commons
  8. Iowa State University; photographs Bob Elbert Taking the replica cross-country PDF Inside Iowa State · 2010

Part 4 · 20th century

Activity: the machine's purpose

What do Atanasoff and Berry build the ABC to do?

  1. Translate letters automatically
  2. Solve linked equations
  3. Run different games from memory
Why is that?

The machine is designed for linked equations with shared unknown numbers.

Correct · Solve linked equations

  1. Earl R. Larson; United States District Court, District of Minnesota Honeywell Inc. v. Sperry Rand Corporation and Illinois Scientific Developments, Inc.: Findings of Fact, Conclusions of Law, and Order for Judgment (excerpts) PDF Iowa State University Library, John Vincent Atanasoff Collection · 1973 · 47–49; final unnumbered order
  2. John Gustafson Reconstruction of the Atanasoff-Berry Computer PDF The First Computers—History and Architectures, ed. Raúl Rojas and Ulf Hashagen; MIT Press · 2000 · 91–106

Listen to scene · 4

Synthetic voice · 0:04
Sources · 2
  1. Earl R. Larson; United States District Court, District of Minnesota Honeywell Inc. v. Sperry Rand Corporation and Illinois Scientific Developments, Inc.: Findings of Fact, Conclusions of Law, and Order for Judgment (excerpts) PDF Iowa State University Library, John Vincent Atanasoff Collection · 1973 · 47–49; final unnumbered order
  2. John Gustafson Reconstruction of the Atanasoff-Berry Computer PDF The First Computers—History and Architectures, ed. Raúl Rojas and Ulf Hashagen; MIT Press · 2000 · 91–106

Part 5 · 20th century

The court invalidates the patent

In 1973 Judge Earl Larson invalidates the patent for ENIAC, another electronic computer. A patent protects rights to an invention. The patent holder demands payments from a competitor. The holder argues that ENIAC's creators worked independently. The competitor objects: they used Atanasoff's ideas. The court finds that the claimed invention derives from Atanasoff. The ruling removes rights under this patent. It does not name a sole creator of all computers.

Listen to scene · 5

Synthetic voice · 0:30
Sources · 3
  1. Earl R. Larson; United States District Court, District of Minnesota Honeywell Inc. v. Sperry Rand Corporation and Illinois Scientific Developments, Inc.: Findings of Fact, Conclusions of Law, and Order for Judgment (excerpts) PDF Iowa State University Library, John Vincent Atanasoff Collection · 1973 · 47–49; final unnumbered order
  2. University of Pennsylvania, University Archives and Records Center ENIAC Trial Exhibits Master Collection, UPD 8.12 University Archives finding aids
  3. Computer History Museum Atanasoff-Berry Computer Revolution: The First 2000 Years of Computing
Reconstructed computer during exhibition preparation; part of it is covered.

Part 6 · 20th century

Sparks burn holes in paper

The machine can hold numbers but still make mistakes during calculation. The ABC records intermediate results on paper. Electrical sparks burn tiny holes that the machine later reads. A result from one step can then be used in the next.

According to a study of the reconstruction, recording on paper causes errors. These prevent reliable solutions to the largest systems of equations. The number 29 shows how many unknowns the machine is designed for. It does not prove that it solves such problems without errors.

Listen to scene · 6

Synthetic voice · 0:32
Sources · 2
  1. John Gustafson Reconstruction of the Atanasoff-Berry Computer PDF The First Computers—History and Architectures, ed. Raúl Rojas and Ulf Hashagen; MIT Press · 2000 · 91–106
  2. Steve Jurvetson from Menlo Park, USA File:The First Digital Electronic Computer (5111068123).jpg Wikimedia Commons

Part 7 · 20th century

Activity: three moments

Put the events in order, earliest first.

  1. A working test model
  2. Atanasoff visits Bulgaria
  3. Patent invalidated
Why is that?

The work in Iowa precedes the visit; the visit precedes the judgment.

Correct order

  1. A working test model
  2. Atanasoff visits Bulgaria
  3. Patent invalidated
  1. Earl R. Larson; United States District Court, District of Minnesota Honeywell Inc. v. Sperry Rand Corporation and Illinois Scientific Developments, Inc.: Findings of Fact, Conclusions of Law, and Order for Judgment (excerpts) PDF Iowa State University Library, John Vincent Atanasoff Collection · 1973 · 47–49; final unnumbered order
  2. Благовест Сендов; quoted memoir excerpt by John V. Atanasoff Джон Атанасов: Пионерът на информационната ера PDF Природа (БАН) · 2013 · 44–51

Listen to scene · 7

Synthetic voice · 0:03
Sources · 2
  1. Earl R. Larson; United States District Court, District of Minnesota Honeywell Inc. v. Sperry Rand Corporation and Illinois Scientific Developments, Inc.: Findings of Fact, Conclusions of Law, and Order for Judgment (excerpts) PDF Iowa State University Library, John Vincent Atanasoff Collection · 1973 · 47–49; final unnumbered order
  2. Благовест Сендов; quoted memoir excerpt by John V. Atanasoff Джон Атанасов: Пионерът на информационната ера PDF Природа (БАН) · 2013 · 44–51
Reconstructed add-subtract module from the Atanasoff–Berry Computer.

Part 8 · 20th century

Tubes on a metal plate

The original ABC is dismantled in the late forties and almost entirely discarded. In 1997 a team demonstrates a working reconstruction. This photograph shows a reconstructed part. The little metal plate with glass tubes is an add-subtract module, rather than the whole computer.

A reconstruction helps test a design. Our interpretation is that ‘who came first’ depends on the question. First in electronic calculation, programming or reliable operation? A ruling about one patent does not make computer history one person's work.

1 · Arithmetic module
This is a reconstructed add-subtract module, not an entire machine from the nineteen forties.
2 · Tube on the plate
One of the glass vacuum tubes on the metal plate. The photograph shows a reconstructed object.

Listen to scene · 8

Synthetic voice · 0:35
Sources · 4
  1. Iowa State University; photographs Bob Elbert Taking the replica cross-country PDF Inside Iowa State · 2010
  2. John Gustafson Reconstruction of the Atanasoff-Berry Computer PDF The First Computers—History and Architectures, ed. Raúl Rojas and Ulf Hashagen; MIT Press · 2000 · 91–106
  3. Computer History Museum Atanasoff-Berry Computer Revolution: The First 2000 Years of Computing
  4. ArnoldReinhold File:Atanasoff-Berry add-subtract module.agr.jpg Wikimedia Commons

Part 9 · 20th century

Activity: people and parts

Match each person or object to its role in this story.

  1. Clifford Berry · Works with Atanasoff on the ABC
  2. Capacitor · Holds electrical charge
  3. Earl Larson · The judge in the patent case
Why is that?

Berry helps build the machine, a capacitor is part of its memory, and Larson issues the judgment.

  1. JVA Initiative Committee; Iowa State University Atanasoff-Berry Computer: Operation/Purpose John Vincent Atanasoff Discovery Center
  2. John Gustafson Reconstruction of the Atanasoff-Berry Computer PDF The First Computers—History and Architectures, ed. Raúl Rojas and Ulf Hashagen; MIT Press · 2000 · 91–106
  3. Earl R. Larson; United States District Court, District of Minnesota Honeywell Inc. v. Sperry Rand Corporation and Illinois Scientific Developments, Inc.: Findings of Fact, Conclusions of Law, and Order for Judgment (excerpts) PDF Iowa State University Library, John Vincent Atanasoff Collection · 1973 · 47–49; final unnumbered order

Listen to scene · 9

Synthetic voice · 0:04
Sources · 3
  1. JVA Initiative Committee; Iowa State University Atanasoff-Berry Computer: Operation/Purpose John Vincent Atanasoff Discovery Center
  2. John Gustafson Reconstruction of the Atanasoff-Berry Computer PDF The First Computers—History and Architectures, ed. Raúl Rojas and Ulf Hashagen; MIT Press · 2000 · 91–106
  3. Earl R. Larson; United States District Court, District of Minnesota Honeywell Inc. v. Sperry Rand Corporation and Illinois Scientific Developments, Inc.: Findings of Fact, Conclusions of Law, and Order for Judgment (excerpts) PDF Iowa State University Library, John Vincent Atanasoff Collection · 1973 · 47–49; final unnumbered order

A new find for your collection

A decision about one patent does not assign all the credit for inventing computers.

Ruse–VarnaFrom the Danube to the seaSee how people lived and worked in another period.Georgi Ivanov · BaikonurInto orbit, without dockingGabrovo school of 1835 · GabrovoHow a school changed a town

People in this story

Ivan AtanasovEarl LarsonJohn Vincent AtanasoffClifford Berry

Sources

  1. Computer History Museum Atanasoff-Berry Computer Revolution: The First 2000 Years of Computing
  2. Wikimedia geographical database contributors Boyadzhik: geographical record
  3. Wikimedia geographical database contributors Iowa State University, Ames: geographical record
  4. Wikimedia geographical database contributors Sofia: geographical record
  5. Earl R. Larson; United States District Court, District of Minnesota Honeywell Inc. v. Sperry Rand Corporation and Illinois Scientific Developments, Inc.: Findings of Fact, Conclusions of Law, and Order for Judgment (excerpts) PDF Iowa State University Library, John Vincent Atanasoff Collection · 1973 · 47–49; final unnumbered order
  6. JVA Initiative Committee; Iowa State University Global Connections John Vincent Atanasoff Discovery Center
  7. John Gustafson Reconstruction of the Atanasoff-Berry Computer PDF The First Computers—History and Architectures, ed. Raúl Rojas and Ulf Hashagen; MIT Press · 2000 · 91–106
  8. Iowa State University; photographs Bob Elbert Taking the replica cross-country PDF Inside Iowa State · 2010
  9. JVA Initiative Committee; Iowa State University Atanasoff-Berry Computer: Operation/Purpose John Vincent Atanasoff Discovery Center
  10. University of Pennsylvania, University Archives and Records Center ENIAC Trial Exhibits Master Collection, UPD 8.12 University Archives finding aids
  11. Ik T from Kanagawa, Japan File:Atanasoff-Berry Computer ー Computer History Museum (30781535612).jpg Wikimedia Commons
  12. User:Manop File:Atanasoff-Berry Computer.jpg Wikimedia Commons
  13. Steve Jurvetson from Menlo Park, USA File:The First Digital Electronic Computer (5111068123).jpg Wikimedia Commons
  14. ArnoldReinhold File:Atanasoff-Berry add-subtract module.agr.jpg Wikimedia Commons
  15. WilliamSnail File:ABC memory drum reproduction, Durham Center, Iowa State University.jpg Wikimedia Commons
  16. WilliamSnail File:ABC memory drum reproduction 2, Durham Center, Iowa State University.jpg Wikimedia Commons
  17. WilliamSnail File:ABC memory circuit display, Durham Center, Iowa State University.jpg Wikimedia Commons
  18. Eye Steel Film from Canada File:ATANASOFF Pic^1 - Flickr - Eye Steel Film.jpg Wikimedia Commons
  19. Eye Steel Film (provider); Lomita / Wikimedia Commons (processing); original photographer unknown File:ATANASOFF Pic^2 - Flickr - Eye Steel Film.jpg
  20. Благовест Сендов; quoted memoir excerpt by John V. Atanasoff Джон Атанасов: Пионерът на информационната ера PDF Природа (БАН) · 2013 · 44–51
  21. University of Florida, Department of Electrical and Computer Engineering John Vincent Atanasoff Department history
  22. Iowa State University News Service Biographies of the inventors of the first electronic digital computer News releases · 1997

Images

ArnoldReinhold · CC BY-SA 4.0 · Wikimedia Commons

Open source

Full attribution

Photo: ArnoldReinhold / Wikimedia Commons, CC BY-SA 4.0. Reconstructed add-subtract module from the Atanasoff–Berry Computer. Cut-out detail; background removed.

User:Manop · CC BY-SA 3.0 · Wikimedia Commons

Open source

Full attribution

Photo: User:Manop / Wikimedia Commons, CC BY-SA 3.0. Reconstruction of the Atanasoff–Berry Computer in the Durham Center. Processed image.

Eye Steel Film from Canada · CC BY 2.0 · Wikimedia Commons

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Full attribution

Photo: Eye Steel Film from Canada / Wikimedia Commons, CC BY 2.0. John Vincent Atanasoff, portrait. The photographic date is not established. Processed image.

Original photographer unknown · CC BY 2.0 · Wikimedia Commons

Open source

Full attribution

Portrait of John Atanasoff. Provider: Eye Steel Film; processing: Lomita / Wikimedia Commons, CC BY 2.0. The original photographer and date are Unknown. Processed image.

Ik T from Kanagawa, Japan · CC BY 2.0 · Wikimedia Commons

Open source

Full attribution

Photo: Ik T from Kanagawa, Japan / Wikimedia Commons, CC BY 2.0. Reconstructed Atanasoff–Berry Computer: drum, control panel and tubes. Processed image.

Photo

WilliamSnail · CC BY-SA 4.0 · Wikimedia Commons

Sources disagree about the origin of the tubes in the display case. Which are original has not been established.

Open source

Full attribution

Photo: WilliamSnail / Wikimedia Commons, CC BY-SA 4.0. Reproduction memory drum and electronic circuit in a display case. Sources disagree about the origin of the tubes in the display case. Which are original has not been established. Processed image. Museum display: reproduction drum

WilliamSnail · CC BY-SA 4.0 · Wikimedia Commons

Open source

Full attribution

Photo: WilliamSnail / Wikimedia Commons, CC BY-SA 4.0. Reproduction memory drum; not the surviving original. Processed image.

Photo

WilliamSnail · CC BY-SA 4.0 · Wikimedia Commons

Sources disagree about the origin of the tubes in the display case. Which are original has not been established.

Open source

Full attribution

Photo: WilliamSnail / Wikimedia Commons, CC BY-SA 4.0. Reproduction memory drum and electronic parts, wider view. Sources disagree about the origin of the tubes in the display case. Which are original has not been established. Processed image. Museum display: reproduction drum

Steve Jurvetson from Menlo Park, USA · CC BY 2.0 · Wikimedia Commons

Open source

Full attribution

Photo: Steve Jurvetson from Menlo Park, USA / Wikimedia Commons, CC BY 2.0. Reconstructed computer during exhibition preparation; part of it is covered. Processed image.

ArnoldReinhold · CC BY-SA 4.0 · Wikimedia Commons

Open source

Full attribution

Photo: ArnoldReinhold / Wikimedia Commons, CC BY-SA 4.0. Reconstructed add-subtract module from the Atanasoff–Berry Computer. Processed image.

Geographic context, without historical borders

Tom Patterson · Nathaniel Vaughn Kelso · Public domain · Natural Earth

Open source

Full attribution

Tom Patterson · Nathaniel Vaughn Kelso