Institute for New Generation Computer Technology (ICOT) Japan

Machine:	PIM, Multi-PSI
Environment:	SIMPOS
Language:	KL1
Source Code:	5.5 MB
Documents:	Japanese manuals,
	Introductory manual in English

Overview
The operating system used commonly on all models of PIM.

Characteristics
With large-scale parallel computer systems, the centralized manage- ment policy conventionally taken will make management the bottle- neck of the whole sy[s]tem. PIMOS employs a hierarchical and distributed management policy to avoid the bottleneck. Actually, even on PIMs with their largest configuration currently available (with 256 processors), management does not at all makes a bottle- neck. PIMOS is thoroughly written in KL1, a concurrent logic lang- uage, and its superior portability has been proved on its porting to different models of PIM.

Function
For coherency with fine-grain parallel programs in KL1, the user in- terface is based on data-flow synchronization, which is one of the basic features of KL1.

PIMOS, of course, features I/O resource management functions that virtualize and multiplex physical I/O devices. PIMOS, in addition, virtualizes resources required for software development, such as executable program codes, in a coherent manner. All the virtualized resources are managed under the server-client model, keeping the kernel of the operating system smaller and allowing easier extens- ion of the system by simply adding servers.

In addition to its conventional "telnet" remote login feature, a speci- alized remote access feature from PSI sequential inference work- stations is provided, allowing effectively combining features PSI with those of the parallel inference machines.

Software development support tools (compiler with powerful macro and preprocessing functions, low overhead debugging tracer for compiled codes, graphical visualizer of execution profile such as load distribution, etc) provide a comfortable software development environment for KL1. For still easier software development, basic software building blocks are provided such as utilities for data storage, search and update, or libraries for semi-automatic dynamic load distribution.