Kazuo Taki

The design and implementation of a personal sequential inference machine: PSI

A Personal Sequential Inference Machine, called PSI, is a personal computer designed as a software development tool for the Fifth Generation Computer Systems (FGCS) project. PSI has a logic based, highlevel machine instruction set, called Kernel Language Version 0 (KL0). The machine architecture of PSI is specialized for direct execution of KL0. “Unification” and “backtracking” are the principal operations in Logic Programming, and they are efficiently performed by PSI hardware/ firmware. Its estimated execution speed is 20K to 30K LIPS. The machine is also equipped with a large main memory with a maximum of 40 bits×16M words. This paper presents the key points of its design and the features of its machine architecture.

A load balancing mechanism for large scale multiprocessor systems and its implementation

In large scale multiprocessor systems, the distance between processors should be taken into account by software to reduce the network traffic and the communication overhead. A load balancing method based on P3 (Processing Power Plane) model is proposed to enable programmers to specify distributing computational load, keeping the locality of the computation. In this method, a process is allocated to a rectangle on a hypothetical processing power plane. The size of the rectangle represents the processing power given to the process, and the distance between rectangles represents the communication cost between them. This plane is divided to processors, and the region of the processor may be dynamically reshaped to alleviate imbalance on P3. Mechanism for realization of the method has been implemented on the Multi-PSI/version, 2, which is a parallel processing system with 64 processing elements connected to form a 2-dimensional mesh network. A packet transmission mechanism of the Multi-PSI/version 2 is described, which realizes the process distribution along with the balancing method.

Outline of the Personal Sequential Inference machine: PSI

PSI is a personal computer system being developed as a tool for providing researchers with an efficient programming environment. It directly supports logic programming language, KL0 (Fifth Generation Kernel Language, Version 0), with firmware and hardware.Its interpreter is implemented in the firmware and several hardware mechanisms are provided to attain almost the same level of performance as the DEC-10 Prolog on DEC2060. It also provides the user with a large memory space, 40 bits × 2 to 16 MW, which is essential for developing actual application programs like an expert system.To make efficient man-machine interaction possible, such input and output devices as bit-map display, pointing device and key-board are provided. A local area network is also being developed to build a distributed system.