Showing papers in "Ibm Systems Journal in 1984"

Ease of use: a system design challenge

Abstract: While it is becoming increasingly obvious that the fundamental architecture of a system has a profound Influence on the quality of its human factors, the vast majority of human factors studies concern the surface of hardware (keyboards, screens) or the very surface of the software (command names, menu formats). In this paper, we discuss human factors and system architecture. We offer best-guess guidelines for what a system should be like and how it should be developed. In addition, we suggest ways in which advances in research and education could result in systems with better human factors. This paper is based on an address by L. M. Branscomb and a publication by the authors in the Proceedings of the IFIP 9th World Computer Congress, Paris, France, September 19-23, 1983.

Managing IBM database 2 buffers to maximize performance

Abstract: The relational data base system, IBM Database 2 (DB2), has a component that manages data buffering. This paper describes the design considerations of the Buffer Manager and the tradeoffs involved in managing the allocation of DB2 buffers to maximize performance.

Data recovery in IBM database 2

Abstract: This paper presents the various forms of data recovery provided by IBM Database 2 (DB2). It describes the DB2 recovery log, introduces the notion of a unit of recovery, and discusses the two-phase commit protocol used by DB2. Furthermore, it describes what type of information is logged, the DB2 checkpoint process, what a compensation log record is, and how DB2 handles undo/redo processing, media recovery, restart after abnormal system termination, and data unavailability.

A comparative study of system response time on program developer productivity

Abstract: Skilled programmer time and computer time and resources are valuable. Earlier studies had shown that added computer resources can decrease system response time and increase programmer productivity significantly. A controlled study has been made to determine whether that finding is true for the particular conditions in another program development organization. That study is reported here. Programmer productivity increased sixty-two percent with subsecond system response time. A new finding is that individual group project offices lead to greater efficiency than large open rooms.

Speech filing: an office system for principals

Abstract: Business people spend most of their time communicating, or attempting to communicate, with others. We briefly describe our ideas about these communication activities and their resulting problems, and then discuss an experimental tool we developed to help business people solve some of their communication problems. This tool, called the Speech Filing System, allows users to send messages to anybody in the world and receive messages from anybody in the world, The system offers powerful editing, filing, retrieval, and message distribution and control functions, using pushbutton telephones as the terminals.

Factors affecting programmer productivity during application development

Abstract: The effects of good computer services on programmer and project productivity during application program development are examined. Programmers' terminal activity and the nature of terminal work are analyzed. The discussion includes the effects of short response times, programmers' skills, and program complexity on productivity.

Performance issues in local-area networks

Abstract: This paper discusses several important performance problems in the design of local-area networks. The questions discussed relate to various aspects of architecture, design, and implementation: (1) the delaythroughput characteristics of the medium access protocols, (2) the performance of local-area networks on which a file server provides file storage and retrieval services to intelligent workstations, and (3) timing problems in local-area network adapters. Since the paper does not primarily addressth e performance analyst, it is descriptive in nature; analytic details are omitted in favor of a more intuitive explanation of the relevant effects.

IBM database 2 overview

Abstract: IBM Database 2 (DB2) is a data base management system that supports the relational model of data. This paper presents the major features of DB2 and discusses its architecture and the relationship of DB2 with the host operating system. These principles are illustrated by an example.

IBM database 2 performance: design, implementation, and tuning

Abstract: The larger and more complex a relation data base, the more efficient the data base management system must be to maintain an acceptable level of performance. The design and implementation of IBM Database 2 (DB2) have been aimed toward this objective. Techniques for achieving this key objective in DB2 are the subject of this paper. Presented are performance-related strategies in query processing and performance-related design tradeoffs. Data base and application design options and their resolution for optimum performance are also discussed. Also presented are techniques to maintain performance by application monitoring and tuning and DB2 system tuning.

Playback: a method for evaluating the usability of software and its documentation

Abstract: Human factors evaluations of software products and accompanying user publications must be conducted so that developers can be certain that the target user population can learn to use the product with a minimum of difficulty and be able to perform the intended tasks efficiently. A methodology is described for obtaining objective measures of product usability by collecting performance data on the user interface without affecting the user or the system being evaluated. The log of stored activity is later played back through the host system for analysis.

Analysis of free-storage algorithms: revisited

Abstract: Most research in free-storage management has centered around strategies that search a linked list and strategies that partition storage into predetermined sizes Such algorithms are analyzed in terms of CPU efficiency and storage efficiency The subject of this study is the free-storage management in the Virtual Machine/System Product (VM/SP) system control program As a part of this study, simulations were done of established, and proposed, dynamic storage algorithms for the VM/SP operating system Empirical evidence is given that simplifying statistical assumptions about the distribution of interarrival times and holding times has high predictive ability Algorithms such as first-fit, modified first-fit, and best-fit are found to be CPU-inefficient Buddy systems are found to be very fast but suffer from a high degree of internal fragmentation A form of extended subpooling is shown to be as fast as buddy systems with improved storage efficiency This algorithm was implemented for VM/SP, and then measured Results for this algorithm are given for several production VM/SP systems

Directions in cooperative processing between workstations and hosts

Abstract: Advancements in technology have provided us with the availability of high-peformance processors from the high end of computing to the personal computer. In addition, technology growth has enabled us to envision sixteen megabytes of real storage for a personal computer. As a result, we have witnessed not only a tremendous growth at the high end of the computing spectrum, but also the development of sophisticated personal computers (e.g., the IBM PC XT/370) with real storage capacities approaching those of high-end computers of a decade ago. This growth at both ends of the computing spectrum has given us a choice. We can either allow a clean separation to grow between personal computer and host or provide a means by which they cooperate in providing quality service to the user without the complexity normally associated with high-end systems. This paper explores what such a cooperation could mean.

The design of the REXX language

Abstract: One way of classifying computer languages is by two classes: languages needing skilled programmers, and personal languages used by an expanding population of general users. REstructured eXtended eXecutor (REXX) is a flexible personal language designed with particular attention to feedback from its users. It has proved to be effective and easy to use, yet it is sufficiently general and powerful to fulfil the needs of many demanding professional applications. REXX is system and hardware independent, so that it has been possible to integrate it experimentally into several operating systems. Here REXX is used for such purposes as command and macro programming, prototyping, education, and personal programming. This paper introduces REXX and describes the basic design principles that were followed in developinigt.

An overview of computer security

Abstract: Presented is an overview of computer security, including concepts, techniques, and measures relating to the protection of computing systems and the information they maintain against deliberate or accidental threats. Motivations for security measures are discussed. Security strategies are considered. Actions and events that threaten security are described, along with technical problems that can prevent the computer from adequately dealing with threats. Security models are surveyed. Specific technical and administrative measures for promoting security are described. Among the technical measures discussed are design of secure systems, hardware and operating systems, identification of users, encryption, and access control packages. Administrative measures include personnel, physical security of the computing system, and auditing. Also presented is the establishment of a security program. Reviewed are special problems and their solutions, including communications and networks, data base management systems, and statistical data bases. This paper is based on a paper by the author published in The Handbook of Computers and Computing, edited by Arthur H. Seidman and Ivan Flores, Van Nostrand Reinhold Company, Inc., New York (1984).

Architecture prototyping in the software engineering environment

Abstract: This technical essay presents a perspective on the evolution and problems of the software development craft and how software engineering techniques show promise to solve these problems. It introduces architecture prototyping as a program development technique for improving software quality. Experience with large software systems shows that over half of the defects found after product release are traceable to errors in early product design. Furthermore, more than half the software life-cycle costs involve detecting and correcting design flaws. In this paper, we explore a disciplined approach to software development based on the use of formal specification techniques to express software requirements and system design. As a consequence, we can use techniques like rapid prototyping, static design analysis, design simulation, and dynamic behavior analysis to validate system design concepts prior to element design and implementation. We explore how these techniques might be organized in a software architecture prototyping facility that would be similar to the Computer-Aided Design and Manufacturing (CADAM) tools used in other engineering disciplines. We also examine the process by which software engineers might use these facilities to create more reliable systems.

Security considerations for personal computers

Abstract: The wide use of personal computers and general access to telecommunications links have intensified the need for computer security, Security practices as discussed in this paper relate to protecting an organization's personal computers as physical propedy, protecting the organization's data and applications, and protecting the organization itself. These matters are discussed from the point of view of protection from the improper use of personal computers.

The query management facility

Abstract: Data from a relational data base can be displayed in reports, changed, and otherwise controlled using a program called Query Management Facility (QMF). An overview of this program is presented and is followed by a discussion comparing equivalent forms of various queries expressed in two distinctly different languages. Both languages are designed for use with relational data and are supported by QMF.

Architecture implications in the design of microprocessors

Abstract: This paper examines how architecture, the definition of the instruction set and other facilities that are available to the user, can influence the implementation of a very large scale integration (VLSI) microsystem. The instruction set affects the system implementation in a number of direct ways. The instruction formats determine the complexity of instruction decoding. The addressing modes available determine not only the hardware needed (multiported register files or three-operand adders), but also the complexity of the overall machine pipeline as greater variability is introduced in the time it takes to obtain an operand. Naturally, the actual operations specified by the instructions determine the hardware needed by the execution unit. In a less direct way, the architecture also determines the memory bandwidth required. A few key parameters are introduced that characterize the architecture and can be simply obtained from a typical workload. These parameters are used to analyze the memory bandwidth required and indicate whether the system is CPU- or memory-limited at a given design point. The implications of caches and virtual memories are also briefly considered.

VM/370, attached processor, and multiprocessor performance study

Abstract: This paper discusses performance studies of Attached Processors, multiprocessors, and VM/370. A methodology for evaluating performance is discussed. Performance improvements are explained and evaluated. These studies played a role in a new option to the VM/ System Product control program that is called the High Performance Option (HPO).

An overview of three relational data base products

Abstract: This issue of the IBM Systems Journal focuses on aspects of three recently announced ISM relational data base products. They are IBM Database 2, Query Management Facility, and Data Extract. This essay illustrates the requirements that these products were designed to address and gives a brief overview of their content and history. Its objective is to provide an introduction to the more specific and detailed papers that follow.

An application analyzer

Abstract: An interactive tool, aimed at supporting the application user/analyst in specifying and analyzing a business area, is presented. The features of the tool, named the Application Analyzer/Experimental, are described both in their theoretical foundations and their actual implementation. A brief description of the architecture of the tool and its internal Structure is given. A review of the main concepts of the application development area is also included. The follow-on of the prototype described here is the program offering known as System A.

Use of images in commercial and office systems

Abstract: This paper examines some of the simpler processing techniques that may usefully be performed on bi-level (two-tone) images by a competent commercial applications programmer if a few basic (albeit complex internally) tools are provided. Such processes include storage, indexing, changing resolution, rotating, trimming, and then display and printing. These processes can provide the facilities for an enterprise to incorporate images and image data into its office systems and into its main line-of-business data processing applications.

A tight coupling of workstations

Abstract: This paper addresses the problem of situations in which people at physically distant locations must have access to essentially the same computing environment at the same time. That is, each user must be able to provide input to whatever application or system is active, and must be provided with all relevant output. Common examples of this situation are demonstrations, presentations, education, and troubleshooting. A prototype system has been developed to study ways of solving this problem in the microcomputer workstation environment. The prototype allows users at two IBM Personal Computers to share access to the computing environment through the keyboard and the display screen by tightly coupling the computers.

System/370 capability in a desktop computer

Abstract: A desktop computer with System/370 capability was produced by enhancing the IBM Personal Computer XT with additional hardware and developing software that provides a compatible interface. The computer, the IBM Personal Computer XT/370, and this software allow users to run most System/370 Conversational Monitor System application programs unaltered in a desktop environment. The evolution of the development and details of the function of the hardware and software are described.

TSO attach: a multipurpose communication channel to IBM database 2

Abstract: TSO Attach provides IBM Database 2 capabilities in a productive work environment that appears as a natural extension of the Time Sharing Option (TSO) and the Interactive System Productivity Facility (ISPF). It was designed and built with careful consideration for the varied and complex user group for which it was intended. Ease of use and ease of development and maintenance were among the significant factors in the design. These factors and others are addressed in this paper, which discusses the basic design decisions made in building the TSO Attachment Facility.

IBM database 2 in an information management system environment

Abstract: Over the years, the IBM Information Management System (IMS/VS) has been developed to meet expanding user needs. During that time, a parallel development has taken place. The relational data model grew from Codd's original theory to a practical data base prototype. Now a new data base management system, IBM Database 2 (DB2), has been built on the relational model. This paper discusses the implementation and design considerations for the integration of IMS and DB2 from the user's viewpoint. It also presents the attachment facilities from a design perspective.