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


Nowadays every large Organisation wishing to maintain its key position an the market has electronic installations for data processing as standard equipment. In order to allow the working of such installations in small and medium size organisations, ZUSE KG have developed the ZUSE Z 31 computer. This reasonably priced machine is program-controlled and has a very high degree of efficiency. Transistor technology is used for its construction. lt is made up of a carefully chosen assembly of units which enables numerous special applications to be carried out at low cost.

The ZUSE Z 31 can adapt itself to the type and importance of any kind of activity and its possibilities of further extension avoid any fear of under sizing or over sizing. The simplicity of servicing and the ease of maintenance give this computer an altogether special value. The internal use of the decimal System allowing very high input and Output speeds, enables this all purpose machine to handle a wide range of problems. One of the great advantages for the user of the ZUSE Z 31 is that it is possible to utilize existing punch tape devices irrespective of the code used by these devices.

For large organisations, the moderate cost of this computer permits a decentralization of the fields of activity which simplifies considerably the Organisation and transfer of data.

Installations for commercial data process­ing are characterised by the fact that in general their programs contain relatively few instructions. Indeed even if these instructions require a large volume of data the latter is processed in blocks, following the same method and therefore the machine will only be asked to store relatively small programs. However most of the time it is necessary to have a store with a very arge capacity (e. g. storage of the different articles of a arge shop, accounts of a bank etc.)

The greatest flexibility is required from the input and Output devices which are parts of primary importance in computers for commercial work. The System of layout units used in the construction offers the ideal solution that can satisfy the most exacting requirements. As it is a decimal Computer the installation is especially de­signed for the processing of a large volume of input and output data and is conse­quently suitable for the solution of commercial problems. The store capacity can be extended at will by connecting additional stores and the input and output speeds can be increased to 1.000 charac­ters/s by the addition of corresponding devices. A simple instruction Code facilitates operation. A comparison device offers great advantages for research processes or translation programs.

Equipped with two accumulators it can for example process simultaneously arithmetical and logical operations in the arithmetic unit. With one instruction the contents of the accu­mulators can be added in each cell of the fast store. Each instruction can be con­ditional depending an the contents of the special condition stores or those of the accumulators. During programming, in­structions and stores can be economised by address substitution and adress modifica­tion. Reconversion programs allow the use of a practical external code as required.

Principal technical data

Control unit

Execution of the instruction in the stored sequence until a jump order occurs. At the time of a jump for sub-routine, automatic recording of the sequence address in the return adress store.

Arithmetic unit

Two independant counting registers with shifting devices and units for addition, intersection and complement belonging to them. Index registers for address modification. A fast multiplication unit is available as an addition.

Store unit

The ferrite core working store has a capacity ranging from 200 to 9.000 store cells including 10 index registers for address modification. Each store cell comprises 10 + 1 decimal digits. According to requirements store extension is possible by adding auxiliary stores (magnetic drum of 6.750 words each, magnetic discs store with a capacity of 1 to 4.000.000 words, magnetic tape units with a store capacity of 750.000 words per tape), program store (fixed wiring ferrite core store) for storing basic programs as well as programs and constants frequently used, 2 individual and interchangeable units of 1.300 words each can be placed simultaneously in the machine. Two counting registers and 6 condition stores as programmable indicators.

Control desk

Address keyboard for selection of the store cells and the registers. Stored information can be displayed an a decimal display panel. lt can be modified by means of a keyboard with decades. The program can be easily and quickly controlled by an address stop device, 6 condition switches and 18 control indicators.

Input and output possibilities

Punched tape Possibilities of input and output with buffers for character, word and block. Several tape readers and tape punchers can be connected. Input speed up to 1.000 characters/s, output speed up to 150 characters/s.

Punched card

Input and output with complete storage of a card in the buffer store. Several punched card readers and card punchers can be connected.

Input speed

Up to 48.000 cards/h. Ouput speed: up to 15.000 cards/h.


Several typewriters can be connected. Output speed: 10 characters/s.

Line printer

Output with buffer store for one line. Printing speed up to 60.000 alphanumeric lines/h.

Analogue devices

A !arge number of analogue input and output devices can be used for the automatic collecting and processing of measurement values.

Punched tapes

Keyboard perforators and tape punching adding machines or typewriters, tape controlled

Off-line equipment

Typewriters, or fast printer for punched tape processing. Furthermore, the programming System allows the production, control, copying, modification, and transcription of the tapes. The tape or card-controlled ZUSE Z64 GRAPHOMAT is particularly well suited for the graphic reproduction of digital values.

Control unit Arithmetic unit

Areas of application:

Banks, insurance companies, research, industry, trade, public service. Compilers for German formula code and ALGOL 60 are available for the Z31.


Zuse-Computer (German)

Z1 (German)

Zuse-Computer with EPEMAG.COM (English)

Zuse-Computer (German)


Goto the Z64... Z64

Name of Machine
Z31 (from 1963)
See above
Arithmetic Unit
Average calculation Speed
Word Length
Power Consumption
Area of Application
1 machine for the ship technical experimental station in hamburg. The other 6 machines were used in the Kassenärtlichen Vereinigungen in Germany (Health insurance institutions).
Zuse-Computer (English)
Zuse-Computer (German)
Konrad Zuses Work on a DVD
The Z31 was a failure. Only 7 machines were sold.
Maintenance at the Z31 in Bad Seegeberg (Ca. 1965).