WDR paper computer (pen and matchsticks)

The WDR paper computer or Know-how Computer is an educational model of a computer consisting only of a pen, a sheet of paper, and individual matches in the most simple case. This allows anyone interested to learn how to program without having an

electronic computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as programs. These program ...

at their disposal. The paper computer was created in the early 1980s when computer access was not yet widespread in Germany, to allow people to familiarize themselves with basic computer operation and

assembly Assembly may refer to: Organisations and meetings * Deliberative assembly, a gathering of members who use parliamentary procedure for making decisions * General assembly, an official meeting of the members of an organization or of their representa ...

-like programming languages. It was distributed in over copies and at its time belonged to the computers with the widest circulation. The Know-how Computer was developed by and Ulrich Rohde and was first presented in the television program

WDR Computerclub WDR may refer to: * Waddell & Reed (stock ticker: WDR), an American asset management and financial planning company * Walt Disney Records Walt Disney Records is an American record label of the Disney Music Group. The label releases soundtrack a ...

in 1983. It was also published in German computer magazines mc and . The original printed version of the paper computer has up to 21 lines of code on the left and eight registers on the right, which are represented as boxes that contain as many

match A match is a tool for starting a fire. Typically, matches are made of small wooden sticks or stiff paper. One end is coated with a material that can be ignited by friction generated by striking the match against a suitable surface. Wooden matc ...

es as the value in the corresponding register. A pen is used to indicate the line of code which is about to be executed. The user steps through the program, adding and subtracting matches from the appropriate registers and following program flow until the stop instruction is encountered. The instruction set of five commands is small but

Turing complete Alan Mathison Turing (; 23 June 1912 – 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher, and theoretical biologist. Turing was highly influential in the development of theoretical co ...

and therefore enough to represent all mathematical functions: incrementing ("inc") or decrementing ("dec") a register, unconditional jump ("jmp"), conditional jump ("isz", skips next instruction if a register is zero), and stopping program execution ("stp"). An emulator for

Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ...

is available on Wolfgang Back's website, but a JavaScript emulator also exists. Emulators place fewer restrictions on line count or the number of registers, allowing longer and more complex programs. The paper computer's method of operation is nominally based on a

register machine In mathematical logic and theoretical computer science a register machine is a generic class of abstract machines used in a manner similar to a Turing machine. All the models are Turing equivalent. Overview The register machine gets its name from ...

by Elmar Cohors-Fresenborg, but follows more the approach of

John Cedric Shepherdson John is a common English name and surname: * John (given name) * John (surname) John may also refer to: New Testament Works * Gospel of John, a title often shortened to John * First Epistle of John, often shortened to 1 John * Seco ...

and Howard E. Sturgis in their

Shepherdson–Sturgis register machine In mathematical logic and theoretical computer science a register machine is a generic class of abstract machines used in a manner similar to a Turing machine. All the models are Turing equivalent. Overview The register machine gets its name ...

model. A derived version of the paper computer is used as a "Know-How Computer" in

Namibia Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and e ...

n school education.

See also

References

Further reading