Multis: a new class of multiprocessor computers.

Multis are a new class of computers based on multiple microprocessors. The small size, low cost, and high performance of microprocessors allow the design and construction of computer structures that offer significant advantages in manufacture, price-performance ratio, and reliability over traditional computer families. Currently, commercial multis consist of 4 to 28 modules, which include microprocessors, common memories, and input-output devices, all of which communicate through a single set of wires called a bus. Adding microprocessors together increases the performance of multis in direct proportion to their price and allows multis to offer a performance range that spans that of small minicomputers to mainframe computers. Multis are commercially available for applications ranging from real-time industrial control to transaction processing. Traditional batch, time-sharing, and transaction systems process a number of independent jobs that can be distributed among the microprocessors of a multi with a resulting increased throughput (number of jobs completed per unit of time). Many scientific applications (such as the solving of partial differential equations) and engineering applications (such as the checking of integrated circuit designs) are speeded up by this parallel computation; thus, multis produce results at supercomputer speed but at a fraction of the cost. Multis are likely to be the basis for the next, the fifth, generation of computers-a generation based on parallel processing.