For four decades and over six computer generations, there has been a countable demand, much of it arising from defense needs, for a few score to a few hundred supercomputers, machines built to be as fast as the state of the art would allow. These machines have cost from $5 million to $25 million each (in current dollars). The small market size has always meant that a large part of the per-machine cost has been development cost, tens to hundreds of millions of dollars. Such products are peculiarly susceptible to cost-rise, market-drop spirals.
As supercomputers have become faster, they have become ever more difficult and costly to design, build, and maintain. Conventional supercomputers use exotic electronic components, many of which have few other uses. Because of the limited supercomputer market, these components are manufactured in small quantities at correspondingly high cost. Increasingly, this cost is capital cost for the special manufacturing processes required, and development cost for pushing the state of the component and circuit art.
Moreover, supercomputers' large central memories require high bandwidth and fast circuits. The speed and complexity of the processors and memories demand special wiring. Supercomputers require expensive cooling systems and consume large amounts of electrical power. Thoughtful prediction shows that supercomputers face nonlinear cost increases for designing and developing entirely new circuits, chip processes, capital equipment, specialized software, and the machines themselves.
At the same time, the end of the Cold War has eliminated much of the historical market for speed at any cost. Many observers believe we are at, or within one machine generation of, the end of the specialized-technology supercomputer line.
Meanwhile the opposite cost-volume spiral is occurring in microcomputers. Mass-production of integrated circuits yields single-chip microprocessors of surprising power, particularly in comparison to their cost. The economics of the industry mean that it is less expensive to build more transistors than to build faster transistors. The per-transistor price of each of the millions of transistors in mass-produced microprocessor chips is extremely low, even though their switching speeds are now quite respectable in comparison to those of the very fastest transistors, and a single chip will now hold a quite complex computer.
While microprocessors do not have the memory bandwidth of supercomputers, the 300-megaflop performance of single-chip processors such as the MIPS 8000 is about one-third the 1-gigaflop performance of each processor in the Cray C-90, a very fast supercomputer. Microprocessor development projects costing hundreds of millions of dollars now produce computing chips with millions of transistors each, and these chips can be sold for a few hundred dollars apiece.
Moreover, because of their greater numbers, software development for small machines proves much more profitable than for large machines. Thus an enormous body of software is available for microprocessor-based computers, whereas only limited software is available for supercomputers.