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Print - P-21 (band structure)

P-21 (band structure)

  • Object:


  • Place of origin:

    Paris (made)

  • Date:

    1970 (made)

  • Artist/Maker:

    Mohr, Manfred, born 1938 (artist)

  • Materials and Techniques:

    Photogravure on paper

  • Credit Line:

    Given by the Computer Arts Society, supported by System Simulation Ltd, London

  • Museum number:


  • Gallery location:

    Prints & Drawings Study Room, level C, case 3H, shelf 24

This photogravure, by Manfred Mohr (born 1938, Germany), is from a plotter drawing produced using a computer program written by the artist. A plotter is a mechanical device that holds a pen or brush and is linked to a computer that controls its movements. Pen plotter drawings can be very time consuming to produce. The artist transferred the image from the plotter drawing into a photogravure as this allowed him to produce multiple copies of the image, and was much quicker and more economical.

The artist created the photogravure by copying an image of the original plotter drawing onto unexposed film, which, through a photochemical process, created a 1:1 negative. This negative was then copied onto light sensitive paper by feeding it into a special copy machine.

The computer program was based on a series of decision making processes that were used to structure the image. The artist deliberately wrote random variables into the process to allow the computer to make certain choices from a given number of options. Mohr would not be able to fully predict the appearance of an image until the plotter finished drawing. 'P-21' refers to the name of the program.

Physical description

Black and white photogravure on paper, from a plotter drawing. Mounted on board.

Place of Origin

Paris (made)


1970 (made)


Mohr, Manfred, born 1938 (artist)

Materials and Techniques

Photogravure on paper

Marks and inscriptions

PROG. 21 IRA = 23
In pencil, in lower left side. May be IR1?

Artist's signature and date, in pencil, in lower right side.

Black sticker with the number 23 on. Attached to lower right side. Possibly an exhibition reference number.


Height: 52.9 cm, Width: 53.3 cm

Descriptive line

Photogravure from a plotter drawing, 'P-21 (band structure)', 1970, by Manfred Mohr.

Bibliographic References (Citation, Note/Abstract, NAL no)

Herzogenrath, Wulf and Nierhoff-Wielk, Barbara, eds. Ex-Machina - Frühe Computergrafik bis 1979. Munich: Deutscher Kunstverlag, 2007. ISBN 978-3-422-06689-2. p. 419, ill.


Paper (fiber product); Ink


Photogravure; Plotter drawing


Prints; Computer Art


Prints, Drawings & Paintings Collection

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