A recovery block scheme for a VAX11/750 running unix

In this paper we describe an implementation of a scheme that is widely used in software fault tolerance, the recovery block scheme. This scheme is usually implemented using special purpose hardware and software. Our implementation runs on a VAX11/750 which has not been modified in any way. This machine uses a very slightly altered version of Berkeley's 4.2 Unix

1 Unix is a trademark of AT&T Bell Laboratories in the USA and other countries.

.     

A crash resistant UNIX file system

The UNIX

1 UNIX is a trademark of AT&T Bell Laboratories.

operating system has been extended to support a crash resistant file system. This paper describes the modifications which were made to the UNIX kernel to support such a file system and the associated recovery facilities for maintaining the internal consistency of files despite the failure of the host processor, transient hardware failures and decay of the storage medium.     

The program animation system PASTIS

The software animation system PASTIS (Program Animation System with Interactive Solutions) for program animation with emphasis on the visualization of the dynamic behaviour of algorithms and data structures is presented. Its main properties are unmodified source code of the visualized program, concurrent multiple views on algorithms and data structures, and interactive alterations of views during run time. PASTIS is distinguished by high modularity and strict separation of its components. This makes it particularly suitable for distributed computing environments. The interface between program and animation is a relational data model. Animations are directed by a single tuple, or sets of tuples, called relations, or sets of relations, called networks. Animations can be nested hierarchically. A prototype of PASTIS was implemented under Unix

1 Unix is a trademark of AT&T.

using the GNU source level debugger gdb and the X-window system.     

The pulse distributed file system

A network of powerful personal computers, linked by a high-speed local area network, is being seen increasingly as an alternative to a traditional centralized time-sharing operating system. The PULSE project is investigating how such a system may be constructed to give the benefits of a self-sufficient personal computer to each user without losing the facilities for communication and sharing of data inherent in centralized systems. In particular, a distributed file system has been built which provides a single global UNIX

1 UNIX is a trademark of Bell Laboratories.

-like hierarchy, with a consistent appearance when accessed from any machine. Replicated copies of files are maintained to improve reliability, increase performance, and enable each machine to run stand-alone, albeit with reduced facilities.     

The EMMA2 multiprocessor operating system

The EMMA2

1 EMMA is a registered trademark of Elsag—Elettronica San Giorgio.

parallel architecture is a network of nodes, named 'Regions': each region is based on two shared-memory hierarchical bus levels, on which a large series of monocpu, multicpu and specialized I/O boards can be inserted, grouped in 'Families'. Its typical applications are Image processing, pattern recognition and artificial intelligence, characterized by intensive computation requirements, real-time constraints and good price-performance ratio for building large industrial systems. This paper presents the main characteristics of the EMMA2 parallel operating system, highlighting the internal organization and mechanisms offering the parallel co-operation model for user programs. Section 1 briefly introduces the overall hardware architecture. It allows application partitioning into parallel independent subsystems, on two levels of computation: the lower level (family) is dedicated to massive number crunching, while the upper (region) permits the interaction of these lower machines. Section 2 deals with the system software environment, based on a host-target configuration: the host is mainly devoted to machine control, system monitoring, program development and debugging in a multi-user environment. Sections 3, 4 and 5 describe respectively the fundamental concepts of the operating system internal organization and the basic mechanisms with respect to the machine architecture; the basic functions that constitute the internal layers and services; the resulting parallel programming and co-operation model and the typical mapping rules of algorithms to this architecture, completed with some examples of their functionalities. The most important aspect of the EMMA2 operating system is the fact that it offers a uniform interface to user tasks, independently of their allocation on the target machine. Objects managed by system services can be referred to via logical names. Code for system services is distributed among processors and resides on a private read-only memory. The operating system's data reside in shared memory only for system functions that need to be distributed, while private functions are based on different copies of data in private memories. Section 6 gives more details on the most relevant EMMA2 industrial applications, also showing their mapping to the parallel architecture and some performance-related information. Section 7 contains a brief outline of the novel architecture currently in development and of the subsequent OS Improvements. In conclusion, we report some considerations about the present status of the EMMA2 system, compared with some other well-known architectures, and about research efforts for its future evolution.     

Integration of diskless workstations in unix united

This document evaluates the feasibility of diskless UNIX systems connected to a disk-providing machine via a local area network. The diskless UNIX systems are to be used as workstations in a UNIX United

1 UNIX is a trademark of A. T. & T. Bell Laboratories.

environment. Several solutions are presented and estimated to enable booting, file system access and swapping. Implementation techniques, compatible with the UNIX United philosophy, are proposed. Specific topics covered are file servers, swap servers, disk servers, indirect drivers, system call service access from kernel coroutines of UNIX processes, and communication subsystems. It is shown that the modifications to the UNIX system can be limited to one new device driver in the diskless workstation and one in the system providing the secondary storage facility.     

A communication system supporting large datagrams on a local area network

This paper describes an implementation of a software interface designed for use from within UNIX

1 UNIX is a trademark of A T & T Bell Laboratories.

application programs for network communications. This interface provides the abstraction of possibly very large datagrams, supports ‘scatter-gather’ facilities, and maintains standard network addresses consisting of (host number; port number) pairs. This interface has been provided on different data communication facilities, allowing uniform program access to those facilities. The particular implementation developed for a local area network is described, and performance results obtained are examined and compared with those obtained from a conventional datagram interface to that network. The results obtained confirm that the abstraction of very large datagrams enables the construction of an efficient mechanism for process-to-process communications over the network that is not only more convenient, but also has significant performance advantages over the use of conventional (small) datagrams.     

The UNIX™ programming environment

The UNIX

1 UNIX is a trademark of Bell Laboratories.

operating system provides an especially congenial programming environment, in which it is not only possible, but actually natural, to write programs quickly and well. Several characteristics of the UNIX system contribute to this desirable state of affairs. Files have no type or internal structure, so data produced by one program can be used by another without impediment. The basic system interface for input and output provides homogeneous treatment of files, I/O devices and programs, so programs need not care where their data comes from or goes to. The command interpreter makes it convenient to connect programs, by arranging for all data communication. Complex procedures are created not by writing large programs from scratch, but by interconnecting relatively small components. These programs are small and concentrate on single functions, and therefore are easy to build, understand, describe, and maintain. They form a high level toolkit whose existence causes programmers to view their work as the use and creation of tools, a viewpoint that encourages growth in place of reinvention. Tools interact in a limited number of ways, but can be used in many different combinations. Thus, an addition to the toolkit tends to improve the programming power of the user faster than it increases the complexity of interconnection and maintenance. Finally, tools are connected at a very high level by a powerful command language interpreter. The error-prone and expensive process of program writing can often be avoided in favor of program-using. In this paper we will present a variety of examples to illustrate this methodology, focusing on those aspects of the system and supporting software which make it possible.     

Description of a menu creation and interpretation system

The Menu Creation and Interpretation System (MCIS) is a menu system development tool that can provide the high-level control structure and the user interface for any application program or software system. MCIS simplifies the task of building menu-driven systems while presenting a user interface that is easily learned and easy to use. Human factors considerations have been stressed in the system design. A user is able to jump from one menu to another, obtain help whenever it is needed, and easily recover from errors. Menu systems created with MCIS are extensible and easily modified, enabling them to meet changing user needs. In addition, through the specification of user profiles, menu systems can be customized to meet the needs of individual users. MCIS is written in the C programming language under the UNIX

1 Unix is a trademark of Bell Laboratories.

operating system. It can be used in any environment that includes a C compiler and the UNIX standard I/O library.     

The Cambridge ring and Unix

In March 1980, a VAX 11/780

1 VAX is a trademark of Digital Equipment Corp.

was installed at the Computing Laboratory of the University of Kent. The VAX runs UNIX as a user service. This paper discusses what has been learnt from the integration of an existing operating system (UNIX) into a local area network based on the Cambridge ring. The approach which has been evolved attempts to make the network connections invisible to the operating system so that the utilities running on the system can access the network as if they were talking to standard peripherals. The paper gives an overview of the ring and the protocols in use at Kent; and points to alternative approaches to the implementation which could be used in a different environment.     

Unix and the Am29000 microprocessor

Features that make the AM29000 a good Unix host are examined. The discussion covers the C calling sequence, context switching, system calls, interrupt handling, memory access protection, cache support, multiprocessor Unix, floating-point support, and system costs     

基于知识库的Unix主机配置安全审计软件的设计与实现

配置安全审计是保证Unix主机安全的重要措施,并进一步为Unix操作系统所承载的业务应用提供了安全保障。本文首先分析Unix操作系统的配置安全和传统的配置安全审计方法,并针对传统方法的不足,提出一种基于可灵活配置的知识库实现Unix操作系统配置安全审计软件的设计方案,最后给出这种方案的具体实现。     

UCSD Pascal on the VAX,portability and performance

Between 1976 and 1980 the Pascal Project at UCSD produced a ‘nearly portable’ operating system based on Pascal. Under the auspices of a graduate student project at UCSD, the UCSD Pascal system was ported to run in the 32-bit address environment of the VAX 11/780 under VMS and UNIX

1 UNIX is a trademark of Bell Laboratories. VAX and VMS are trademarks of Digital Equipment Corporation. UCSD Pascal is a trademark of the Regents of the University of California.

. This paper describes the implementation decisions and the portability and efficiency considerations that motivated the decisions. Improvements to portability and efficiency are discussed.     

Software development tool for target systems and EPROM programmers within a Unix environment

A computer running under a Unix operating system is an excellent host on which to develop software for target systems which have the same type of microprocessor as the host computer. Unfortunately, facilities for preparing executable modules able to be sent to an EPROM programmer or to be loaded onto a RAM portion of target memory space are lacking in standard Unix. These facilities can be improved in any version of Unix without the need for expensive software using the set of commands presented in this paper.     

A parallel-programming process model

A process model is presented for constructing and executing parallel programs on a shared-memory multiprocessor running under Unix. The model involves some simple extensions to the standard Unix process model, a set of language extensions, runtime library support, and additional operating-system support. The model is easy to use, and it supports several higher-level parallel programming constructs in several languages, including microtasking in C and Fortran and multitasking in Ada and C++. It frees programmers to concentrate on parallel algorithms instead of low-level implementation details, and it yields good performance     

基于大型光电设备网络数据录取系统的设计和实现

介绍了光电设备网络数据录取系统的开发方法.系统包括主机VC开发和目标机VxWorks开发,两者建立在网络通信(客户/服务器)模式上.主机包括Socket套接字网络接收、多线程建立、文件的存储及读取.目标机包括Socket网络发送、多任务环境的建立.     

An experiment with the newcastle connection protocol

An experiment is described in which a set of Unix systems linked together into a Unix United system by means of the Newcastle Connection Protocol¹ is also linked to a system with a dissimilar structure. It demonstrates that the Newcastle Connection technique can be used to connect together operating systems with differing structures and philosophies. The non-Unix system, known as Nimrod, offers a set of services which can be mapped onto requests for service from standard user processes running on a remote Unix system. The services offered by Nimrod are restricted to those required for providing remote input and output to a terminal, but the results of the experiment suggest that increasing the range of services offered would be possible, despite the substantial differences in structure between Nimrod and Unix. Some of the problems associated with greater levels of inter-system connection are also discussed.     

基于Unix网络信息安全加密机的设计

本文通过综合运用防火墙、加密解密、身份认证、审计及网络管理等多种网络安全方面的技术手段,设计了一种基于Unix操作系统的网络信息安全加密机,有效地解决了网络信息传输过程中安全性和保密性的问题。     

系统级体系结构仿真器的研究与实现

系统级体系结构仿真器是可以作为一个虚拟目标机器运行的软件系统,它可以实现对单（多）处理器、内存系统、Cache和外部设备等于系统的功能模拟。在体系结构设计和操作系统开发等工程,体系结构仿真器有着广泛的应用。本文介绍了一个基于MISC CPU和SPARC体系结构的系统级仿真器FMCS。     

Experiences with the UNIX time-sharing system

The UNIX

1 UNIX is a trademark of Bell Laboratories.

Time-sharing System has been in use at the University of New South Wales since 1975, and favourable experience has led to its widespread adoption on campus for both teaching and research. It has proved very adaptable to the university's needs, and very usable in a situation where staffing levels are critically low. One important application area, the teaching of Computer Science, is now firmly based upon the use of the UNIX system.