The use of Petri Nets for Occam programming for transputers

There is undoubtedly a need for software-design tools for parallel programming. A main problem with design tools for parallel programming is their inability to check for liveness (no deadlock) and safeness. In this paper, the use of Ordinary Petri net as a software design tool for Occam Petri Net and Occam constructs are discussed. The similarities between Ordinary Petri Net and Occam constructs are highlighted, and an Occam Petri Net model is proposed as a design tool to aid in writing Occam codes. The Occam Petri Net model is graphical. It is capable of modelling deterministic concurrent and choice systems. As a top-down design, the net is similar to Occam ‘folds’, and, in its use in bottom-up implementation, it is similar to unfolding. This unfolding using the Occam Petri Net model makes writing Occam source codes easier. The availability of Petri Net CASE tools will make it more attractive for designing Occam programs.     

Transputer-based robot control system for six-joint robot manipulators

A transputer-based robot control system was designed and built to control an industrial robot PUMA 560. The goal was to develop a research tool for the investigation of practical and theoretical aspects of various advanced control strategies in the robot system. A transputer network consisting of thirteen transputers is employed for the application, where the parallelization of the algorithms is utilized for speeding up the computation. The kinematics, path planning and a collision avoidance module associated with a vision system are implemented on the network. Six joint controller modules were designed and constructed to handle input/output signals from the joint motors of the robot manipulator. The advanced multitransputer structure is capable of integrating the extern sensor information in a simple way and implementing control algorithms in parallel processes. For Software development, the parallel programming language Occam is used. The code development is performed on an IBM-PC-based toolset system.     

Combining Graphics and Windowing Standards in the XGKS System

In the past few years we have seen the acceptance of standards for both two and three dimensional computer graphics. Also during this time, the workstation community has converged on a common windowing system. This paper discusses the problems encountered in implementing graphics standards such as GKS and PHIGS PLUS within the X Window System environment.     

A Method of Displaying Transformed Picture Rectangles Using GKS Raster Functions

The GKS raster functions Fill Area and Cell Array allow area primitives in Computer Graphics to be used in a GKS environment.
In implementing these functions, the computing time and memory required are important factors in deciding their usability especially for interactive work. The trend in the implementation of algorithms for such primitives is to use specialized hardware.
In this paper, algorithms are introduced which are suitable for computers of low and middle efficiency and provide a sufficient image quality and an acceptable response time for dialogues.     

Transputer在高速雷达视频回波采集系统中的应用

介绍以ＴｒａｎｓｐｕｔｅｒＴ４２５单片高速并行计算机为中心控制环境，与高速Ａ／Ｄ（３５ＭＨｚ，８ｂｉｔ相结合构成的实时高速雷达回波采集系统。该系统的特点是：采集速度高，存贮量大；利用标准的Ｔｒａｎｓｐｕｔｅｒ链路实时完成处理器间的数据传输和通讯；系统采用并行Ｏｃｃａｍ语言编程。这样既充分发挥处理器的并行功能，又使数据采集和数据处理同步进行，这在实时信号采集与处理系统中具有特别重要的意义。     

A parallel logic system on a multicomputer architecture

This paper describes the implementation of a logic programming language on a massively parallel architecture. This implementation is based on the AND/OR Process Model which allows the exploitation of both AND and OR parallelism in logic programs. A distributed memory model is used, and a decentralized control mechanism has been designed. The multicomputer, which the system has been implemented on, consists of a network of Inmos Transputers. The AND/OR processes are implemented as Occam processes mapped onto the Transputer nodes. After the presentation of the system architecture and a deep discussion of the distributed memory management, some preliminary performance results are discussed.     

Functional conformance testing of graphics software using a configurable reference system

This paper introduces a scheme for conformance checking of GKS implementations with the given GKS standard specification[1] based on functional black box testing. Specific testing problems caused by the nature of graphics systems and a solution are presented. Thereby emphasis is laid on a software generation technique which allows to configure reference implementations from a suitable specification of GKS. The reference implementation is used to produce correct reference data the contents and formats of which are adjusted for the particular candidate implementation.     

两维时间域上的实时程序语义

超稠密计算模型是实时系统的一种重要抽象模型．该文首先简要介绍一种两维的超稠密时间域及在该域上定义的一种区间逻辑,然后用一个并行模型语言（类Ｏｃｃａｍ 语言）讨论用这种逻辑定义并行语言（在超稠密模型中）的时间语义的问题,最后讨论了在这种语义框架中实时系统性质的描述     

A Multi-Microprocessor GKS Workstation

Implementers of graphical application sytems hesitate to interface their applications to the GKS standard not only because GKS functionality seems to be less suffcient for a particular application but also because the use of GKS-as it is offered in portable software implementions-uaually means a loss of system performance. This article describes an installation of GKS on a multi-microprocessor that is based on functional distribution principles as well as on the object-oriented distribution of a graphics system. The main concepts and advantages of a GKS workstation using more than one processing unit with at least one output pipeline are described. The flexibility of this approach opens a perspective view to a GKS workststion that is configurable to application requirements.     

并行数据库系统中并行I／O的研究与实现

并行Ｉ／Ｏ是基于无共享结构的并行数据库系统提高性能的有效途径之一。它通过并行磁盘服务和网络传输并行化提供了高带宽Ｉ／Ｏ。文章设计实现了基于无共享结构的并行数据库系统的并行Ｉ／Ｏ,探讨了设计并行Ｉ／Ｏ时的几个关键问题及实现技术。     

Overcoming rule-based rigidity and connectionist limitations through massively-parallel case-based reasoning

Symbol manipulation as used in traditional Artificial Intelligence has been criticized by neural net researchers for being excessively inflexible and sequential. On the other hand, the application of neural net techniques to the types of high-level cognitive processing studied in traditional artificial intelligence presents major problems as well. We claim that a promising way out of this impasse is to build neural net models that accomplish massively parallel case-based reasoning. Case-based reasoning, which has received much attention recently, is essentially the same as analogy-based reasoning, and avoids many of the problems leveled at traditional artificial intelligence. Further problems are avoided by doing many strands of case-based reasoning in parallel, and by implementing the whole system as a neural net. In addition, such a system provides an approach to some aspects of the problems of noise, uncertainty and novelty in reasoning systems. We are accordingly modifying our current neural net system (Conposit), which performs standard rule-based reasoning, into a massively parallel case-based reasoning version.     

BD-GKS3D图形软件的设计与实现

BD-GKS3D是按图形国际标准GKS-3D(ISO 8805)开发的三维图形支持软件。本文讨论了该软件的设计原则:符合国际标准及尽可能高效率。还讨论了实现的策略,包括二维GKS与三维兼容问题,裁剪与变换,实现环境,图段的数据结构及三维输入等内容。最后对开发BD-GKS3D的工作量、与PHIGS,CGI的关系等作了说明。     

Guidelines for Determining When to Use GKS and When to Use PHIGS

GKS, GKS-3D, and PHIGS are all approved ISO standards for the application programmer interface. How does a system analyst or programmer decide which standard to use for his application? This paper discusses the range of application requirements likely to be encountered, explores the suitability of GKS and PHIGS for satisfying these requirements, and offers guidelines to aid in the decision process.     

The evolution of standards for computer graphics

Although work towards international standards for computer graphics was started in 1976, it is in the last 2 years that real agreement and progress have been achieved. The first target, the functional specification of a graphics system, is satisfied by the graphical kernel system (GKS), which is now being processed as an International Organization for Standardization (ISO) draft international standard. GKS provides a reference model for two-dimensional graphics and an agreed vocabulary of terms covering the field. Many implementations of GKS as a package are now being produced. In addition to such a functional specification, two forms of communication are appropriate for graphics: a metafile and a virtual device interface. ISO is now reviewing a proposal for a metafile standard developed by the American National Standards Institute and closely related to GKS. Standards for a graphics virtual device interface and for three-dimensional graphics systems are also being actively developed. All these efforts and their interrelationships are described and examined.     

数据不规则问题全相关Block递归方程组多维流水线并行技术研究

主要讨论数据不规则问题全相关Block递归方程组多维流水线并行的实现.首先给出全相关Block递归方程组的模型方程,并从图论的角度给出了流水关系有向图的定义以及流水线并行条件的判别准则,分析了影响流水线并行效率的主要因素.在此基础上,提出一种基于流水关系有向图的流水线并行实现算法并应用于数据不规则问题.实验结果表明该方法在复杂区域情况下也可以取得较高的效率.     

GKS Programming in a PHIGS Environment

GKS is an international standard for the functional interface to 2D graphics, whilst PHIGS is currently an ISO work item for 2D and 3D graphics. In addition, PHIGS allows improved control over structuring graphics data in the system. With a new work item, the upwards compatability from GKS to PHIGS is being called into question. This paper is an attempt to give direction to these discussions by listing the implications of introducing a software layer between a GKS application program and a PHIGS environment on which this application is to be run. It is intended to highlight differences between the systems and to answer questions such as, “How compatible?”, “Is it possible?”, “How much does the software layer have to do?”, etc.     

The Formal Specification of Level la of GKS

In this paper the formal specification of a part of level la of GKS is given in the algebraic specification language OBJ. It shows that it is possible to produce a formal specification of a substantial part of GKS which is of manageable size and complexity specifying the appropriate level of abstraction of the system and using a suitable formal technique.     

A New Parallel Skeleton for General Accumulative Computations

Skeletal parallel programming enables programmers to build a parallel program from ready-made components (parallel primitives) for which efficient implementations are known to exist, making both the parallel program development and the parallelization process easier. Constructing efficient parallel programs is often difficult, however, due to difficulties in selecting a proper combination of parallel primitives and in implementing this combination without having unnecessary creations and exchanges of data among parallel primitives and processors. To overcome these difficulties, we propose a powerful and general parallel skeleton, accumulate, which can be used to naturally code efficient solutions to problems as well as be efficiently implemented in parallel using Message Passing Interface (MPI).