How the first programmable robot works

The first programmable robot was completed in 1772 by Pierre Jacquet-Droz, a talented watchmaker. The robot is 100% mechanical and can be programmed to write 40 character texts.

This automaton is the first programmable robot, but also the first programmable computer – and the first printer.

The robot was built for marketing purposes and contributed to Jacquet Droz worldwide popularity in the 18th century. Marketing was the only purpose, but we can imagine, today, how this technology could be implemented to automate multiple tasks.

Physical aspect

The automaton writes a text using the left hand to move the pen, and the right hand to move the paper. The eyes follow the hand when writing, and the head moves.

The automaton was created with the following materials:

  • Body in linden
  • Moving parts in brass and steel
  • Pen in goose feather


Moving parts:

  • Two eyes, in synchronisation with the movement of the right hand
  • Left hand, moving to write and fill the pen with ink
  • Right end, to move the piece of paper
  • The head (up and down)
Automoton eyes moving

Cam technology

The cams stores the information, the order of the cams set the order of the operations. Thia robot implements programmable direct access cams, so the order of the sequence can be set to change the message, using a rudimentary user interface.


The computing unit contains 120 cams to store the information related to 40 characters. The information required to write a character is transferred mechanically from the cam to the hands.

The operator installs the characters on a disk. The shape of the characters determines the location of the information required to draw the character, and the related cam are accessed directly.

Special characters has special functions. One of them is a command to re-fill the pen: when the character is found, the hand move to re-ink.

The robot can write 10 characters per line. The visible characters (excluding the one to re-fill the ink) are counted and when 10 is reached, the right hand will move the paper and the left hamd will start writing the next character on the next line.

It is impressive to see all the logic implemented when the technics and the logic was not yet associated into the technology:

  • Direct access memory
  • Embedded command to re-ink
  • Auto-end of line. The robot will go to a new line and not try to “write” multiple white spaces at the end of a line

Technical specifications

The automaton has two sources of energy: two keys the user must turn for 5 minutes of operations.

Name: The Writer

Creator: Pierre Jacquet-Droz

First operation: 1772

Current status: Active

Location: Neuchâtel, Switzerland

Parts: More than 4000

Technology: Direct Access Cam

Programmable Memory: 40 characters

Direct Access Memory: 120 cams

Autonomy: 5 minutes

Power type: Mechanical

More about “The Writer”

The Writer was restored recently and a video was released while the automaton was completely opened. This is a great opportunity to see all the parts and to better understand how it works. (sorry, audio not in english).


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