Asynchronous Processors: Clockless Logic
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1. The document discusses asynchronous processors, which are processors without a central clock. Asynchronous processors have no clock to coordinate data flow through the pipeline. 2. Some advantages of asynchronous processors are better power efficiency, higher performance as components can run at different speeds, and reduced electromagnetic interference. Asynchronous processors can also be easier to design. 3. The document provides a brief history of asynchronous processors and concludes that asynchronous design is competitive with synchronous design in power efficiency and performance.
Asynchronous Processors: Clockless Logic
- 1. Asynchronous Processors: The Clock less Future By: Syeda Urooj Fatima Roll# 31
- 2. Clockless Logic or How do I make hardware fast, power- efficient, less noisy, and easy-to- design?
- 3. Introduction What is asynchronous design? Why do we want to study it? How is data represented in an asynchronous system?
- 4. “Designers are realizing that distributing a clock across even more complicated systems is becoming more and more difficult, and that sooner or later it won’t work.” Alain Martin Professor Computer Science Caltech built first clockless microprocessor in 1989.
- 5. What are Aynchronous Processors? • An asynchronous circuit, or self timed circuit is a sequential digital logic circuit is not governed by a clock circuit or global clock signal. • Unlike conventional processor, a clockless processor (asynchronous CPU) has no central clock to co ordinate the progress of data through pipeline.
- 6. It may actually be even easier to implement high performance devices in asynchronous as opposed to clocked, because: • Components can run at different speeds on asynchronous CPU. All major components of a clocked CPU must remain synchronized with central clock. • A traditional CPU cannot “GO FASTER” than the expected worst case performance of slowest stage/instruction. When an asynchronous CPU completes an operation more quickly than anticipated, the next stage can immediately begin processing the results, rather than waiting for synchronization with a entral clock.
- 7. Why Asynchronous Design? Better Power Efficiency Only activating functional units consume power. Inactivated parts remain in “stand-by state” No wasteful power dissipation. Higher Performance No global clock. Proceed data at appropriate rate of environment. Do not propogate local delay globally. Smaller chip size. Less high frequency EMI components due to small amplitude and wide current peaks.
- 8. Advantages Works at increased speed 2.8 times. Low power consumption Twice life time. Less heat generated. Good to mobile devices. Less EMI Less Noise More Applications.
- 9. Disadvantages: • Fewer people are trained in this style as compared to synchronization design. • Performance (speed) of asynchronous circuits must be reduced in architecture that require input- completness (More complex data path • Incompatible with commercial EDA tools.
- 10. Brief History of Asynchronous Processors ILLIAC I and ILLIAC II(first asynchronous designs, Uni of Illinous) The PDP6 (Programmed Data Processor-6) 1960 was an asynchronous computer model. In 2004, Epson manufactured world’s first bendable microprocessor called ACT11, an 8-bit asynchronous chip.
- 11. Conclusion: It is entirely practical to design a processor without a clock. Quality of such processors have improved with time. Some are commercially available. Clock less and self timed processors open up horizons for radical departure in main stream architectures to new and exciting areas. Asynchronous design is competitive with best synchronous design in power efficiency and is close in performance to them.
- 12. References