Roadmap History Synchronized vs. Asynchronous overview How it works Benefits of clockless chips Limitations of clockless chips Potential for the future
How fast is your computer? Speed of clock Billionth of a second long All operations governed by speed of clock Many operations take different speeds Must be coordinated
History Asynchronous design considered in 1946 by Alan M. Turing David A. Huffman and David E. Muller ILLIAC II (1962) Was not reliable with technology of the time Vacuum tubes and relay circuits Moore's law
Disadvantages of clock Process of diminishing returns Slowest process governs speed Clock runs during idle time Increased power consumption Speed of light
Asynchronous Processor Event driven System of local handshaking No global clock Needs way govern processes Signals indicate completion Employes Rendezvous and Arbiter gates
Asynchronous Processor (cont.) State of circuit changes instantly with signal Varying speed patterns results in varying electromagnetic waves Design must account for speed patterns
Asynchronous Processor (cont.) Without clock, must know when operation is done Dual-rail circuits Yes, no, or no answer yet
Delay-Intensive Model Makes no assumptions All transistors must be acknowledged
Principle of their advantages Variable length processes division
Do they exist? ARM Holdings and Handshake Solutions Philips ARM996HS Proposed for use in automotive/medical equipment Philips Pagers Intel, IBM, Sun
Benefits of Clockless chips Executing of individual functions does not wait for next clock pulse Up to 3 times faster Less power consumption Idle time Lower electromagnetic pulse
Limitations Lack of automated designing/testing tools Strict attention to physical design Lengths of wires, logical gates Predicting complex sequences and coordinating
Inhibitors of Development Pace of market competition Education Synchronous easier to test
Conclusion Many advantages over synchronous Handshakes and coordination circuits Implementation lengthy, lack of resources Physical limitations of clock
References http://iqmagazineonline.com/IQ/IQ17/LowRes. pdfs/Pgs20-24_IQ17.pdf http://www.technologyreview.com/featured- story/401226/its-time-for-clockless-chips/2/ http://www-classes.usc.edu/engr/ee- s/552/coursematerials/ee552-H5.pdf http://www.youtube.com/watch?v=xXL8oYmkt qM&feature=related http://www.eetimes.com/electronics- products/processors/4082174/ARM-offers- first-clockless-processor-core http://www.scribd.com/doc/19613420/Cockless -Chip