02/12/2002
QMCS 425
In 1946, microchip designers made the choice to develop processors based around synchronous logic, coordinated by a revolutionary “clock” as opposed to asynchronous logic. At the time, it was the right choice. The design was simpler and more reliable, and the concept has always been easier for consumers to understand. Processors can be marked with a specific speed directly derived from its clock speed, for example a 1-gigahertz processor has a clock that ticks one billion times per second. The processor wars between Intel, AMD, etc. have always been based around the marketing principle that the faster the clock, the faster the computer. This is simply not true. The technological community is once again looking toward asynchronous logic for a number of reasons.
The design of a synchronous processor is quite simple. For each clock cycle, one instruction can be executed. The processor must wait until that clock cycle finishes before the next instruction can be executed. Asynchronous processors operate in a much different, much more abstract manner. These processors can execute multiple instructions at one time and at varying speeds, and the processors coordinate these instructions and data returns in such a manner that related instructions finish at the same time.
· Diminishing Returns: As clock speed increases, the clock demands an increasing amount computing power, in modern processors up to one third of the total computing power.
· Increasing Complexity: As clock speed increases, the number of transistors necessary increases exponentially.
· Component Dependency: A processor can only perform as fast as its slowest component. Indeed, a 700-megahertz chip may process more quickly than a 1-gigahertz chip depending on the speed of their slowest components.
· Moore’s Law vs. the laws of Physics: Electronic pulses can only move so quickly and are already being pushed close to their limits at current processor speeds. At some time the point will be reached where the oscillating crystals (clocks) simply cannot be designed any faster due to the laws of Physics.
· Power: Asynchronous chips use between 10% and 50% less power by drawing power only when a task requires it.
· Battery Life: Electrical efficiency leads to longer battery life.
· Encryption: There are no regularly timed signals for hackers to track and take advantage of.
· Less Component Dependency: An asynchronous processor performs at the average speed of all its components as opposed to the speed of its slowest component.
· Noise Level: Very little electromagnetic noise is generated by an asynchronous processor, which all but eliminates digital interference between devices, making these chips ideal for many large-market products (mobile phones, computer networks, embedded medical devices, etc.).
· Industry Evolution: The processor industry has evolved in the complete opposite direction, which makes market penetration not only expensive but also difficult in that there are very few people trained to design such processors in the first place.
· “Real Estate”: The chip itself requires more physical space, which adds an additional cost.
Asynchronous process design is not a brand-new concept, but is still revolutionary since it has not been significantly implemented. Despite companies such as Intel and Sun Microsystems having fully functional asynchronous prototypes that run three times as fast as their synchronous counterparts and on half the power, the costs associated with moving from synchronous to asynchronous design outweigh the benefits. The Intel Pentium IV does implement some asynchronous logic, but it is still a clock-dependent processor. Phillips Electronics has developed a pager using asynchronous design that runs twice as long as any other on the market.
The benefits that asynchronous design can bring to the technological world are quite promising, but many barriers must be broken before such processors can take over the market. Experts believe a transitional phase is much more likely, with more processors implementing both synchronic and asynchronic logic in a hybrid chip. Whether or not asynchronic processors will take over the market in their pure form remains to be seen.
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