Multithreading is an operating system concept, not a microprocessor concept. Multithreading allows to create a process with more than one concurrent execution path and multiple concurrent subsystems (cpu, network, and memory) to be utilized simultaneously. This gives the impression, the reality, of being able to do more than one thing at a time.This is advantageous on uniprocessor systems as well, since the processor is utilized while the memory system services misses.its similar in concept to preemptive multitasking but is implemented at the thread level of execution in modern superscalar processors


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http://faqspatents/app/20100115244
http://en.wikipediawiki/Simultaneous_multithreading
http://portal.acmcitation.cfm?id=894572