Konrad Zuse. Biography. Contributions. Zuse-Companies. Z3r. Tour-Zuse-Computer. Z23 Crosses Altlantic. Early Computers. Neumann vs Konrad Zuse. Impressum and Contact. Professor Dr.-Ing. habil.
Horst Zuse


Today considered the Z1 is the first freely programmable computer of the world using Boolean logic and binary floating point numbers. It was completed in 1938 and financed completely from private funds. Konrad Zuse's first computer, built between 1936 and 1938, was December 1943 destroyed in the bombardment of Berlin in WW II, together with all construction plans. In 1986, Konrad Zuse decided to reconstruct the Z1.

The Z1 contained almost all parts of a modern computer, e. g. control unit, memory, micro sequences, floating point logic (Only the logical unit was not realized).

Konrad Zuse constructed the Z1 in the apartment of his parents, in fact, he was allowed to use the living room for his construction. In 1936 Zuse quitted his job in airplane construction to build the Z1. His parents were not enthusiastic, but they did support him anyway they could.

It was a privately financed machine. Konrad Zuse got money by his parents, his sister Lieselotte, some students of the Akademischer Verein Motiv and Kurt Pannk, an entrepreneur in Berlin.

The Z1 was in many ways a remarkable machine. Konrad Zuse used thin metal sheets in order to construct this machine. There were no relays in it. The only one electrical unit was an electrical engine in order to give the clock frequency of one Hertz to the machine. The Z1 was freely programmable via a punch tape and a punch tape reader. There was a clear separation of the punch tape reader, the control unit for supervising the whole machine and the execution of the instructions, the arithmetic unit, and the input and output devices.

In 1986 Konrad Zuse decided to rebuilt the Z1. The reason was that the Z1 contained almost all the important features of a modern computer. In 1986 he constructed thousands of elements of the Z1 again, because the original Z1 was destroyed by allied airraids in 1943. In 1989 the rebuilt Z1 was finished and can be visited in the Deutsche Technik Museum Berlin-Kreuzberg.

Architecture of the Z1. There are separate units: Control unit, memory, aritmetic unit with the four basic operations for floating point numbers, the input- and output devices and the programming unit with the punch tape reader. Not realized was the logical unit for comparing bits and the arithmetic exception handling.

The Z1 had two registers, each with 22 bits, for the arithmetic operations.


Z1 (German)

Zuse-Computer (German)

How can the Z1 calculate with metal sheets?

Name of Machine
Z1 (1936-1938)
Metal sheets
1 Hertz
Arithmetic Unit
Four basic operations +, -, *, / for binary floating point numbers. Word length 22 bits.
Average calculation Speed
Addition 5 sec. Multiplication 10 se.
Decimal floating point numbers.
Decimal floating point numbers.
Word Length
22 bits.
Ca. 30.000 metal sheets.
64 words with a length of 22 bits.
Power Consumption
Electical engine of a vacuum cleaner.
1000 KG
Area of Application
Privately financed.
Zuse-Computer (English)
Zuse-Computer (German)
Konrad Zuses Work on a DVD
First programmable computer with Boolean logic and binary floating point numbers.

Goto the Z2 ...

Top Image: Z1 in the living room of Konrad Zuse's parents in 1936. Middle: The rebuilt Z1 in the Deutsche Technik Museum Berlin in 1989. Konrad Zuse at the Z1 (1989).
A testversion of metal sheets.
The memory of the Z1 in 1937.