Konrad Zuse developed the world's first mechanical and electromechanical computers called the Z1, Z2, and Z3. Written by Konrad's eldest son, Horst, this article features many hitherto unpublished photographs from Horst's private collection. In this installment Horst presents a foreword and introduction.

Overview (By Clive "Max" Maxfield)

Many encyclopedias and other reference works state that the first large-scale automatic digital computer was the Harvard Mark 1, which was developed by Howard H. Aiken (and team) in America between 1939 and 1944. However, in the aftermath of World War II it was discovered that a program controlled computer called the Z3 had been completed in Germany in 1941, which means that the Z3 pre-dated the Harvard Mark I.

The Z3's architect was a German engineer called Konrad Zuse, who developed his first machine, the Z1, in his parents' living room in Berlin in 1938.

Figure 1-1. Konrad Zuse's Z1 mechanical computer
(In the foreground is the manual crank for generating the clock by hand)

The Z1 was followed by the Z2 and Z3. Although based on relays, the Z3 was extremely sophisticated for that era; for example, it utilized the binary number system and could perform floating-point arithmetic.

Zuse was an amazing man who was years ahead of his time. To fully appreciate his achievements, it is necessary to understand that his background was in construction and civil engineering (not electronics). Also, Zuse was completely unaware of any computer-related developments in Germany or in other countries until a very late stage, so he independently conceived and implemented the principles of modern digital computers in isolation.

Today, the Z3 is widely acknowledged as being the first fully functional automatic digital computer, and Konrad Zuse is acclaimed by computer scientists as being a highly respected computer pioneer. However, much of the previously published material on Zuse comes from the same limited pool of source material. Also, this material tends to concentrate on Zuse the engineer and neglects Zuse the man.

TechBites is therefore honored to present the following article on the life and work of Konrad Zuse. This article was written by Konrad's eldest son, Horst, and features many hitherto unpublished photographs and images from Horst's private collection.

Foreword (By Prof. Horst Zuse)
The development of the computer is a fascinating story. Many brilliant scientists contributed to the development of the modern computer, including my father, Konrad Zuse (Figure 1-2).

Figure 1-2. Konrad Zuse working on a Z1 Computer.

My first recollection of my father's computers is from 1949, when he took a photograph of me looking at the memory unit of a Z4 computer in Hopferau (Allgäu, Bavaria) as shown in Figure 1-3. Following this I observed the development of his machines, I listened to the discussions of my father and visitors, and I used relays and stepwise relays in order to program and control my Märklin model railway.

Figure 1-3. Horst Zuse looking at a Z4's memory (1949).

I was very curious and had the opportunity to visit several times the company of my father (Zuse KG). There was an order to the head of the stock of the Zuse KG by my father. He said "My son Horst can get everything that is not needed for the development and production of the computers."

Today, I am working as a scientist in the area of computer science. I am, among others, interested in the history of computing. After the death of my father I read almost everything about the history of computing very carefully. Especially, I looked at my father's papers from 1936 to 1949.

The evolution of computers is a fascinating story and I am very happy to have been an eyewitness of this development from 1949 in Germany.

Introduction (By Prof. Horst Zuse)
Today, throughout the world, Konrad Zuse is almost unanimously accepted as the inventor and creator of the first freely-programmable¹  computer² with a binary floating point and switching/circuit system, which really worked. This machine – called the Z3 – was completed in his small workshop in Berlin-Kreuzberg in 1941.

¹Freely programmable means that the machine is able to interpret a sequence of meaningful instructions on a data carrier. These could be punched tapes, punched cards or the memory of the machine itself.

²We use the term "computer" although we know that this term changed over the years. Ceruzzi gives the following definition of a computer: Before 1945 a person who did calculations. After 1945 a machine capable of the four operations of arithmetic, automatic storage and retrieval of intermediate results, and automatic input and output, all directed by a control unit. The modern definition is a machine which can manipulate symbolic information in any combination or way one desires, and which contains an internally stored program, which the machine may also manipulate if desired. Following this definition, Konrad Zuse's machines were computers at the time of their construction. We can say, therefore, that Konrad Zuse's computers were the prototype of modern computers.

Konrad Zuse first started to consider the logical and technical principles of computers as far back as 1934 when he still was a student. He also created the world's first programming language (1942-1945/46), which he called the Plankalkül.

In the past, scientists and engineers had many discussions about the components of a computer and who can be accepted as the true inventor of the computer. At the International Conference on History of Computing (August 14-18, 1998), there was a panel session in which scientists discussed the question: Who is the inventor of the computer? After a discussion lasting one and a half hours, the great majority denoted Konrad Zuse as the most admired computer pioneer.

This article will give an extended view on Konrad Zuse's work building computers. Although hundreds of articles have been written about Konrad Zuse and his computers, the contents of these articles do not differ very much. For this reason, we will give a new insight in his computers and will show unknown facts and pictures of his computer developments and the architecture of his machines.

The article is structured as follows: In Part 2 we consider some aspects of Konrad Zuse before 1934, in Part 3 the first ideas on computing of Konrad Zuse are discussed. In Part 4 we discuss the architecture of his Z1 machine in detail, while the Z2 and Z3 computers are discussed in Part 5. In Part 6 we describe the development of the Z4 from 1942 to 1945 in Berlin and the slightly modified architecture of the Z4 for the ETH-Zürich (1950). In Part 7 Konrad Zuse's Plankalkül is described, and in Part 8 the very innovative Zuse KG is presented, which produced from 1949-1969 more than 250 computers of a value of 100 Million DM. In Part 9 we introduce Konrad Zuse's paintings and his last project, the Helix-Tower. In Part 10 we discuss other early computers in USA and UK, in Part 11 we compare the John von Neumann computer with the computers Z1-Z4 of Konrad Zuse. We close In Part 12 with some conclusions, followed by references to other literature in the Bibliography.

Now we continue to Part 2, in which we consider some aspects of Konrad Zuse before 1934 (see also the Main Index for a quick and easy way to navigate the entire article).