Business card realization (2013 version) of a universal Turing machine by Alvy Ray Smith is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at alvyray.com/CreativeCommons, which is the .pdf version of this image.

Required attribution is: "By Alvy Ray Smith, 2013." The work is to be used in its entirety only.

Business card realization (2014 version) of a universal Turing machine by Alvy Ray Smith (on a suggestion of Dan Garcia) is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at alvyray.com/CreativeCommons, which is the .pdf version of this image.

Required attribution is: "By Alvy Ray Smith, 2014." The work is to be used in its entirety only.

Details:

The 2013 design of the business card machine is by Alvy Ray Smith, based on a suggestion from Tom Griffiths at the University of California at Berkeley, but the underlying rules and the proof of universality are Rogozhin’s [Rogozhin (1996), 231–233]. He called it UTM(4, 6), a universal Turing machine with 4 states and 6 symbols. This machine is strongly universal, meaning that only a finite non-blank configuration may exist on the tape initially. This was the original meaning of universal.

The 2014 design is based on an improvement noted by Dan Garcia at the University of California at Berkeley that always leaves the business card in landscape mode.

download an explanation (using the 2013 design)

download an explanation (using the 2014 design)

Reference:

Rogozhin, Yurii. Small universal Turing machines. Theoretical Computer Science 168(1996):215–240.