Evolutionary Extension Research Articles

Macintosh Workstations

RENOVATING APPLE: THE MACINTOSH IIFX AS EVIDENCE. Last month Apple released a new high‐end Macintosh, dubbed the IIfx, aimed squarely at the technical workstation market. Utilizing a 68030 processor speeding along at 40 MHz, the IIfx is competitive with products such as Sun Microsystems' Sparcstation. Are there clues to Apple's future plans with the Macintosh product line imbedded in the novelty of the IIfx, or is it an evolutionary extension of IIci, IIcx, and IIx into the realm of veritable workstations? More important, does the IIfx represent a new direction for Apple, in light of its turbulent history over the past six months? Let's examine some of these events and place the IIfx in context.

System structure for parallel logic programming

A system structure supporting parallel processing in general and parallel logic programming and expert system applications in particular is described. It is not based on special hardware but has rather been designed as an evolutionary extension to most existing machine architectures. It is aimed at parallel processing support for e.g. PROLOG as well as for expert system (shells) implemented in a general purpose language. A layered structure consisting of an extended machine interface and a macro language is chosen to support a range of various applications.

The “New” Theories of Trade and UK's Comparative Advantage in Engineering Products

The Leontief Paradox (Leontief, 1953) generated two major responses. There was, on the one hand, the body of research which was directed at further empirical verification of the simple Heckscher‐Ohlin theory using other countries' data. On the other hand, there were the studies which attempted to explain the paradox by turning on the alleged invalidity of specific Heckscher‐Ohlin assumptions. It was from the latter category that the “new” theories of trade emerged as evolutionary extensions of the basic Heckscher‐Ohlin theory. These hypotheses are concerned with the separate influences of inter‐country differences in specific labour skills, technology, and scale economies on the pattern of trade flows in manufactures.

Aspects of a Dynamically Adaptive Operating System

-Real-time optimization of the overall performance of a large computer system or network such as an air-traffic control system or teleprocessing network inherently requires the introduction of adaptive control into selected control functions or sets of control functions. Such adaptive control is necessitated by the high variance of the available resource inventory and the workload resource demands within the system environment. Global management of the resulting multiloop control system becomes the responsibility of the operating system. Investigated aspects of this evolutionary extension of the operating system called the dynamically adaptive operating system (DAOS) include the general methodology and the real-time modeling and estimation of resource demands. The methodology specifies the general identification, decision, and modification processes required for an adaptive operating system. Support of such processes could be attractively provided by a peripheral or miniprocessor. The problem of estimating resource service times both with and without partial service times is explored and statistical models possessing utility for real-time modeling are developed. In particular, a dynamically partitioned second moment model (DPSMM) is described. The feasibility of such models is established with respect to a General Principle of Locality. Selected simulation results are presented to evaluate selected developments with respect to an adaptive central processing unit (CPU) scheduling discipline.