The Turtle System

The Turtle System is a free educational program developed at the University of Oxford, designed to support the new Computer Science component of the National Curriculum. It is based on Turtle Graphics, an idea invented by Seymour Papert, in which an imaginary turtle moves around the computer screen drawing as it goes, all under the control of instructions given by a computer program. This sort of programming, and the results it produces, are easy to understand because they are so immediately visual. But the Turtle System provided here shows that Papert‘s idea can go well beyond simple graphics, to provide a basis for fascinating and powerful programs that introduce fundamental concepts of software engineering and artificial intelligence.


We are actively developing two versions of the Turtle System: the Delphi Turtle System (or Turtle System D), written in Delphi Pascal, and the Electron Turtle System (or Turtle System E), written in JavaScript and Electron. The former is faster and has more features, but is currently only available for Windows. The latter is available on Windows and Mac, and can also be run in a web browser (see

Turtle System DTurtle System E
Windows WindowsApple Windows
Turtle BASICYesYesYes
Turtle PascalYesYesYes
Turtle PythonYesNoYes
Arrays SupportOne-dimensionalMulti-dimensionalNo support
File HandlingYesNoNo

The Turtle System requires no installation. Once you have downloaded your preferred file from the links above, simply click or double-click the file to run it. The first time you run the program, your operating system may warn you that it is of unknown origin, and therefore potentially unsafe. On Windows, click ‘More Information’ and then ‘Run Anyway’. On MacOS, control-click the file, select ‘Open’ from the menu, and then click ‘Open’.

Versions 12 and 13 of the Turtle System D have been superseded by version 14, which will soon integrate support for Turtle Python, making version 11 obsolete as well. As version 14 is still quite new, however, and not as thoroughly tested, versions 12 and 13 will continue to be available for a short time from the following links:

Further Information

Please see the Documentation page for detailed information about the Turtle System and how to use it. For a discussion of the principles behind the System, see the About page, or Peter Millican’s articles in Computing at School’s SwitchedOn magazine (reproduced on the Articles page).

As part of a joint project between Oxford University and Queen Mary, University of London, and with funding from the Department for Education, a book entitled “Computer Science Across the Curriculum” has been written, to illustrate the value of Computer Science in various different aspects of the national curriculum. For details, and links to the example programs, see the CSAC page. These examples are also available directly from the 'File' tab of the Online Turtle System.

For any additional information, or to make suggestions for future developments, please contact us — details on the Contact page.


This project is funded by the Department for Education, with matched funding from various sources within the University of Oxford (the Department of Computer Science, the Van Houten Fund, and a private donor at Hertford College). It is housed in the University of Oxford’s Faculty of Philosophy.