Tuesday, April 22, 2008

Cache Memory

A CPU cache is a cache used by the central processing unit of a computer to decrease the average time to access memory. The cache is a smaller, faster memory which stores copies of the data from the most often used main memory locations. As long as most memory accesses are to cached memory locations, the average latency of memory accesses will be closer to the cache latency than to the latency of main memory.

When the processor needs to read or write a location in main memory, it first checks whether that memory location is in the cache. This is accomplished by comparing the address of the memory location to all tags in the cache that may contain that address. If the processor finds that the memory location is in the cache, we say that a cache hit has occurred; otherwise we talk of a cache miss. In the case of a cache hit, the processor immediately reads or writes the information in the cache line. The proportion of accesses that result in a cache hit is known as the hit rate, and is a measure of the effectiveness of the cache.

In the case of a cache miss, most caches assign a new entry, which comprises the tag just missed and a copy of the data from memory. The reference can then be applied to the new entry just as in the case of a hit. Misses are relatively slow because they require the data to be transferred from main memory. This transfer incurs a delay since main memory is much slower than cache memory, and also incurs the overhead for recording the new data in the cache before it is delivered to the processor.

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Thursday, April 17, 2008


Biological technology is technology based on biology, particularly when used in agriculture, food science, and medicine. Biotechnology means any technological application that uses biological systems, living organisms, or derivatives thereof, to construct or change products or processes for specific use.

Biotechnology combines disciplines like genetics, molecular biology, biochemistry, embryology and cell biology, which are in turn allied to practical disciplines like chemical engineering, information technology, and robotics.Biotechnology can also be defined as the exploitation of organisms to do practical things and to provide useful products.

One characteristic of biotechnology is the directed use of organisms for the manufacture of organic products (examples include beer and milk products). For another example, naturally present bacteria are utilized by the mining industry in bioleaching. Biotechnology is also used to recycle, treat waste, clean up sites infected by industrial activities (bioremediation)
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, and produce biological weapons.

Thursday, April 03, 2008

Abstract art

Abstract art is now usually understood to mean art that does not depict objects in the natural world, but instead uses colour and form in a nonfigurative way.In the very early 20th century, the term was more often used to describe art, such as Cubist and Futurist art, that depicts real forms in a easy or rather reduced way—keeping only an allusion of the original natural subject. Such paintings were often claimed to capture amazing of the depicted objects' absolute intrinsic qualities rather than its external appearance. The more precise terms, "non-figurative art," "non-objective art," and "non-representational art" keep away from any possible ambiguity.

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