In this paper, we show a compiler that generates high speed pipeline circuits for loop and recursive programs written in C programming language, which are the most time exhaustive parts in many application problems. The compiler has following features. First, all operations (except for memory accesses) are divided into cascades of 8-bit width (at maximum) operations in order to achieve high speed clock cycle. Second, in order to fulfil the pipeline, variables that have data feedback dependencies between loop cycles are specially scheduled based on several kinds of optimizing techniques. Furthermore, computations of each loop cycle are speculatively started in every clock cycle even if an array on the same memory bank may be accessed more than once in a loop cycle and there may be data feedback dependencies caused by the array accesses. When the array is accessed more than once, the pipeline is stalled while the array access operations are executed sequentially, and when the feedback dependencies are detected, the speculative computations are cancelled, and restarted after the updates of array are finished. Experiments on simple combinatorial programs showed that the pipeline circuits generated by the compiler run about 39-47 MHz on ALTERA EPF10KA serious (which is as fast as hand optimized circuits), and the speed up by the speculative execution is more than two.

Group foraging and colonial formation in avian species are examined with an artificial life (alife) model using genetic algorithms (GA) and neural networks. Horn's classical model predicts that colonial birds are more successful than territorial ones in a patchy resource environment, and the reverse is true when resources are evenly distributed. The weak point of the model is confusion between colony formation and flock foraging and implicit assumption of perfect knowledge of resource distribution by foraging birds. The authors made an alife model that realized both flock foraging and colonial formation simultaneously during evolution in a patchy environment. The reference organisms were egrets, which make colonial nests in the breeding season and colonial roosts in the nonbreeding season. In the computer model, artificial egrets used the presence of other egrets as an indicator to locate resource-rich patches in a resource-clumped environment. On the contrary, egrets were less reliant on other individuals as a source of foraging information in evenly distributed resource conditions. Colonial nesting was also induced only in a patchy environment where the foraging efficiency was always higher than the evenly distributed condition. Local enhancement played an important role in achieving colonial and flock foraging.

PACS-32 is a prototype supercomputer used for a broad range of scientific calculations.It has a synchronizable MIMD processor array, and on the basis of this facility, it provides efficient nearest neighbor communication.Processors are combined into a rectangular array with endaround connections, and can synchronize at user-specified points with little overhead.The hardware has been constructed with 32 processors, and the operating software includes a highlevel language.The PACS-32 system has performed in a number of applications, such as Poisson equation solving, nuclear reactor calculation, aerodynamics, Monte Carlo simulation of plasma particles, and molecular dynamics modeling in solid state physics.The processor efficiency measure ranges from 78 percent through 99 percent in these applications.