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Communications of the ACM


The Tyranny of the Clock

The Tyranny of the Clock, photo illustration

Credit: Erik Velldal

Promoting a clock-free paradigm that fits everything learned about programming since Turing.

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See also the greenarrays chips by Chuck Moore, also known as the inventor of the FORTH programming language.

CACM Administrator

The following letter was published in the Letters to the Editor in the January 2013 CACM (
--CACM Administrator

As an undergrad at MIT in 1972, I took a course in asynchronous design from Prof. Jonathan Allen. Having some background at the time in digital circuitry, it was exciting to see this latest work as presented by Allen, and it was easy to imagine that in a few years most computers and other digital systems would operate this way. The reasoning was much like what Ivan Sutherland advocated in his Viewpoint "The Tyranny of the Clock" (Oct. 2012). Following graduation I started out in the working world designing digital hardware. Industry opens a student's eyes to the real world, and it was clear rather quickly that the synchronous world would not in fact budge for a long time. Though my work today involves mostly software, I still see the appeal of asynchronous logic and hope the vision of asynchronous computing finally takes hold. We could use more calls-to-arms like Sutherland's: "The clock-free design paradigm must eventually prevail." I look forward to that day, just as I look forward to another paradigm that should eventually prevailparallel processing.

Larry Stabile
Cambridge, MA

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