How Wirth's Law Works

Beyond Moore's Law
Wirth's Law states that software is getting slower more rapidly than hardware becomes faster.
Wirth's Law states that software is getting slower more rapidly than hardware becomes faster.
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Moore's Law makes things useful. By increasing the number of transistors on integrated circuits to several billions and reducing their size to mere nanometers, engineers can produce ever-faster microprocessors that are the same size, or even smaller, than the ones in today's computers. At the same time, Moore's Law increases efficiency and reduces costs of production. This consistent improvement in processing speed and memory capacity has paved the way for numerous improvements -- without it, we wouldn't be able to have technological advances such as more pixels on high-definition televisions and digital cameras. Intel's Web site lists off some of the more impressive things electronics might achieve in the future with the help of Moore's Law, including facial recognition software and real-time language translation [source: Intel].

While some expect Moore's Law to continue for at least another decade and others -- especially Intel -- think it will hold true for much longer, some have questioned if the statement will continue to matter. Piling transistors onto computer chips, according to critics, doesn't really matter in the end. One of the most prominent critics of Moore's Law is Niklaus Wirth, a prominent Swiss computer scientist who introduced his own "law" as a sort of counterproposal.

Wirth, born in 1934, is an expert in software engineering, and is known for developing the programming language for Pascal and other notable computer languages during the 1960s and 1970s. His is an important voice in computer engineering topics, and in1995 he published a paper titled "A Plea for Leaner Software." In it, Wirth called attention to two statements, with tongue slightly in cheek. This is what he said:

  • Software expands to fill the available memory.
  • Software is getting slower more rapidly than hardware becomes faster.

Both statements are important in Wirth's thinking, but it's the second statement that we associate with Wirth's Law. In the paper, Wirth actually attributes the sentence to Martin Reiser, so the popular statement we know as Wirth's Law is really a paraphrasing of something Reiser supposedly said at one point. Ironically, Reiser felt he had nothing to do with the idea whatsoever, saying: "It is not the first time I am accused of having said something that I cannot remember having said -- and most likely never have said" [source: IEEE].

So what do these two statements, and especially the second one, have to say about computer engineering?

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