John Vincent Atanasoff: Inventor of the Digital Computer October 3, 2006 History of Computer Science (2R930) Department of Mathematics & Computer Science Technische Universiteit Eindhoven Bas Kloet 0461462 [email protected] Paul van Tilburg 0459098 [email protected] Abstract This essay is about John Vincent Atanasoff’s greatest invention, the Atana- soff Berry Computer or ABC. We look into the design and construction of this computer, and also determine the effect the ABC has had on the world. While discussing this machine we cannot avoid the dispute and trial surrounding the ENIAC patents. We will try to put the ENIAC in the right context with respect to the ABC. Copyright c 2006 Bas Kloet and Paul van Tilburg The contents of this and the following documents and the LATEX source code that is used to generate them is licensed under the Creative Commons Attribution-ShareAlike 2.5 license. Photos and images are excluded from this copyright. 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CONTENTS CONTENTS Contents 1 Introduction 3 1.1 Outline . 3 2 Atanasoff before the ABC 3 3 The Atanasoff Berry Computer 4 3.1 Key principles . 4 3.2 Design . 6 3.3 Construction . 8 3.4 Comparisons . 9 4 The ENIAC and EDVAC 10 4.1 History . 10 4.2 Meetings and letters . 11 4.3 Derived concepts . 12 4.4 Innovations . 13 4.5 Conclusion . 13 5 Proof, court & patents 13 5.1 The IBM settlement . 13 5.2 The court case . 14 6 Why nobody knows the ABC 14 6.1 Reasons . 15 6.2 Honour restored . 15 7 Conclusion 16 References 17 2 2 ATANASOFF BEFORE THE ABC 1 Introduction In 1937 a professor of mathematics and physics went for a long drive to Illinois. Forgetting his daily troubles, he conceived several ideas that in the 21st century still change the world. These ideas led Professor John Vincent Atanasoff to- gether with his PhD assistant Clifford Edward Berry1 to inventing and building the Atanasoff Berry Computer (ABC), the first digital electronic computer of the world. This essay looks into the four ideas conceived by Atanasoff and the effect the ABC had on the world. We also examine the machine built by John W. Mauchly and J. Presper Eckert, the ENIAC, and some of its principal ideas since we cannot avoid the dispute and trial surrounding the ENIAC patents. However, we will try to put the ENIAC in the right context with respect to the ABC and hereby not disregard its tremendous contributions. 1.1 Outline In the next section we will give some background information about John Vin- cent Atanasoff, the main character of this essay. His invention, the ABC, is discussed in section 3. In section 4 we will explain what the ENIAC and EDVAC have to do with this story. The patent lawsuit that revolved around the ABC and ENIAC is briefly discussed in section 5. This lawsuit made the ABC more known and visible to the public, but still most people cannot give you the answer to the question “Do you know who invented the first computer?”. Possible reasons why this is the case will be discussed in section 6. We’ll finish this essay with section 7, the conclusion. Here is a list of useful acronyms of computing machines of the years 1935–1955 used throughout this essay: ABC Atanasoff Berry Computer ENIAC Electronic Numerical Integrator And Computer EDVAC Electronic Discrete Variable Automatic Computer UNIVAC UNIVersal Automatic Computer 2 Atanasoff before the ABC To give more insight into the knowledge and qualifications that gave John Atana- soff the basis needed to invent the first digital computer, his education and achievements before his work on the ABC are described in this section. We got the information in this section mostly from [BB88] and [Mol88]. 1John Vincent Atanasoff, Clifford Edward Berry and John William Mauchly will often be referred to by us with Atanasoff, Berry and Mauchly respectively for abbreviation purposes. With these abbreviations we intend no disrespect. 3 3 THE ATANASOFF BERRY COMPUTER John Vincent Atanasoff was born on October 4, 1903 in Hamilton, New York. We begin the account of Atanasoff’s scientific life with his high school education. Atanasoff started high school in 1919 and finished 2 years later with excellence in both Science and Mathematics, after which he went on to study at the University of Florida (1921). His Bachelors degree in Electrical Engineering, which he got in 1925, gave him the knowledge of electronics that would later aid him in creating his electronic computer. After finishing his Bachelor, Atanasoff got his Masters degree in Mathematics from Iowa State College in 1926, where he subsequently got a job teaching physics and mathematics. While he was teaching, he also got his Doctoral degree in Theoretical Physics from University of Wisconsin in 1930. In his doctoral thesis, “The Dielectric Constant of Helium”, Atanasoff was re- quired to do many complicated and time consuming computations on the Mon- roe mechanical calculator. This, amongst others, is what sparked his interest in developing a better and faster computing machine. In 1930 Atanasoff returned to the staff of Iowa State College and began the work that would eventually lead to the invention of the ABC. 3 The Atanasoff Berry Computer The computing machine that is central to this essay was conceived in 1937 by Atanasoff. The purpose of this machine was to solve up to 29 simultaneous linear equations with up to 29 variables. He built the machine with the help of Clifford Berry and therefor it was later named the Atanasoff Berry Computer. The core of the machine was finished in 1939, but it would take until 1942 to built the complete computer (see [RRH00, Wika]). This section first discusses the key principles of the ABC, followed by a descrip- tion of the design and workings of the computer. After this the construction of the design is treated, both of the prototype and the final implementation. We end this section with a comparison of the ABC to other computing machines of that era. 3.1 Key principles The ABC is based on four key principles that discern it from other computing machines of that time. These principles are the separation of memory and computational units, the use of electronic switching (by means of vacuum tubes), calculations based on binary numbers and the use of a regenerative memory. We will look into each of these concepts in more detail. For a truly detailed description, see [BB88] and [Mac88]. 1. Separation of computation and memory: When Atanasoff first started designing the ABC he intended to use scale- of-two electronic counters that were available at that time. However, after 4 3.1 Key principles 3 THE ATANASOFF BERRY COMPUTER months of experimenting, he discarded them due to “the inherent insta- bility of the circuits” [BB88, chapter 2]. Discarding them however, meant that he had to replace them with a dif- ferent implementation. His solution was based on an observation of the workings of the electronic counter, specifically that the counter incorpo- rated two distinct functions: the addition of the numbers and storage of the results. By implementing these functions separately, he could greatly simplify his design and avoid using counters. He was able to do this be- cause he had already developed a separate memory unit. 2. Regenerative memory: The memory of the ABC consisted of rotating drums, in which capacitors were mounted. There were two large memory drums for the main number storage, named the keyboard and counter drums, as well as a smaller drum used to store carry or borrow bits. These drums can be seen on the rear of the ABC as depicted in figure 1 (page 7). Each of the two main drums had 1600 capacitors, each of which had one contact that was connected to the ground and another that was connected to a stud penetrating surface of the the drum. A simplified version of this can be seen in the memory disk of the prototype in figure 2. The studs were arranged in 32 bands of 50 studs, of which 30 bands were used to store numbers of 50 binary places and 2 bands were used as spares. The capacitors were used in a binary mode, where a high capacitor voltage indicates a zero and a low capacitor voltage indicates a one. The studs in a band were placed at 6 degree intervals, occupying 300 degrees of the drums circumference. The remaining 60 degrees were left empty, to allow for time to do control actions. Each rotation of the drum took one second, meaning that of each second about 835 ms were used for calculation and 165 ms for control purposes. The main problem with using capacitors as a memory unit is that they lose their charge.