Computer perspectives: the bandwidth famine

A number of years ago I visited a young and successful computer company and was given a tour of the facilities by one of the directors. We passed offices in which people were working at computer terminals; I was told they constituted the accounts department. A little further on we came to the software department; here people were also using terminals. “Now,” said my host, “I will show you the hardware department.” To my surprise, instead of the oscilloscopes and waveform analyzers that I had expected to find, I saw more computer terminals. This was a sign of the times.Today, the designer of printed circuit boards such as those intended to be plugged into PCs, has a great variety of software tools from which to choose: programs for layout and routing; programs for checking that the design rules have been followed correctly; logic simulators for checking that the design is functionally correct; and more elaborate simulators for checking the timing. These tools make it possible to produce a working prototype without performing any experimental work on a laboratory bench.In the dark ages of electronics, the debugging of circuits was carried out using experimental versions made by screwing the components down on a piece of wood and connecting them. The behavior of the circuit was checked using an oscilloscope. These experimental versions were known as breadboards, because someone had compared them to those boards on which bread was sliced. The wooden board has been obsolete for years, but the term has survived. A modern version of the breadboard (still used occasionally) is the wire-wrapped prototype. It is, however, costly in time and money and the effort spent on it does not advance the physical design of the final product. Moreover, in certain respects, particularly as regards electrical interference and cross talk, the wire-wrapped version may give misleading information.

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