Showing papers on "Personal computer published in 1979"

Educational uses of a dynabook

Abstract: The Dynabook personal computing concept, as introduced by the Xerox Learning Research Group (LRG) in the early 1970's, is a new communications tool based on the retrieval of dynamic information. Implementing the Dynabook concept is requiring several stages of computer hardware and software development. At each stage of developing an experimental (or ‘interim Dynabook’) system, we are studying its use for educational purposes by conducting computer programming classes for children ranging in age from 6 to 15 years and by implementing a number of laboratory situations for particular subject areas. Preliminary results of our studies have demonstrated the ease with which we can teach programming when it involves the combination of existing instructions in order to cause some computer-based effect. But more than the ability to combine existing instructions is needed in order to invent and construct a generally useful tool such as a graphical layout system or a text editor. These involve skills we typically associate with expert designers. Many of these skills are teachable, especially with the instructional assistance of a personal computer. Supported by several examples of laboratory situations that we have implemented, we propose a design curriculum based on three conceptual areas: process, symbolic representation, and methods of interpretation, especially with respect to the use of information retrieval as an aid in decision making. In the examples we have chosen to describe, the design skills exercised are: simple and conditional sequencing, rule or constraint specification, hypothesis testing and modelling. The particular situations cited are: programming in Smalltalk, computer-based animation, GameX (a game that involves programming by rule specification). ThingLab (a laboratory for describing physical or geometric objects) and a ‘kit’ for assembling event-driven simulations.

Modern analysis and control of unsteady flow in pipelines

Abstract: This book is intended for the practising engineer who desires detailed instruction in the solution of water hammer problems of simple fluids in pipelines using a digital computer. The work is not a comprehensive treatise on unsteady flow, but concentrates primarily on water hammer problems and uses the method of characteristics exclusively to arrive at numerical solutions. The book takes the reader step by step through a series of examples of increasing complexity and provides a number of computer program listings. The material is presented in an organized fashion and at a level of sophistication normally reached with the Bachelor's degree. In the first chapter a very brief history of water hammer analysis is provided and the difference between rigid water column theory and elastic theory is explained. In the second chapter the phenomenon of surging is illustrated with examples and the unsteady flow equations are derived for flow of a simple fluid in a rigid circular pipe. This is followed in Chapt. 3 by examples of unsteady flow caused by valve closure (or opening) with the valve located at the end of a pipeline. This concludes the simple rigid water column theory. In Chapt. 4 the concept of water hammer is introduced in which an elastic fluid flows in an elastic pipe, resulting in two partial differential equations, the continuity and the Euler (including friction) equations. In Chapt. 5 the method of characteristics is introduced to solve the equations of Chapt. 4 numerically subject to various boundary conditions. A FORTRAN source program listing representing the behaviour of a pipeline connected to a reservoir and a valve (and a comparison of the program's predicted results with experimental data) completes this chapter. In Chapt. 6 the Hardy Cross, the linear theory, and the Newton-Raphson methods for solving steady state pipe network flow problems are introduced as a basis for the pipe network water hammer analysis which follows. The chapter considers series pipes, three pipe junctions, four pipe junctions, valves, pressure-reducing valves, and timevarying boundary conditions. The effects of column separation are not considered and the author cautions the reader for wave speed errors resulting from local pressures below the vapour pressure. Several FORTRAN program listings are given in this chapter. In Chapt. 7 the theory of pumps is reviewed and applied to pump-pipeline systems. The specific cases of pump power failure, with reverse flow and windmilling, and pump start-up are treated. Chapter 8 lists potential problems and refers the reader to specific literature for assistance. Finally, Chapt. 9 introduces control devices such as valves with controller movement, surge relief valves, surge tanks, and air chambers as a means of reducing maximum pressures. Throughout the book the author presents the subject matter to the reader in a clear manner. The reviewer converted several of the listed programs in the book from FORTRAN into BASIC and tested them on a personal computer with good results. The output is generally in tabular form. With few additional statements in the source programs, the output can be stored in arrays for plotting o n a plotter or for graphical output on a printer, which adds significantly to the understanding of the pressure and flow regimes.

Experience with processes and monitors in Mesa (Summary)

Abstract: In early 1977 we began to design the concurrent programming facilities of Pilot, a new operating system for a personal computer [5]. Pilot is a fairly large program itself (25,000 lines of Mesa code). In addition, it supports some large applications, ranging from data base management to internetwork message transmission, which are heavy users of concurrency (our experience with some of these applications is discussed in the paper). We intended the new facilities to be used at least for the following purposes:Local concurrent programming: An individual application can be implemented as a tightly coupled group of synchronized processes to express the concurrency inherent in the application.Global resource sharing: Independent applications can run together on the same machine, cooperatively sharing the resources; in particular, their processes can share the processor.Replacing interrupts: A request for software attention to a device can be handled directly by waking up an appropriate process, without going through a separate interrupt mechanism (e.g., a forced branch, etc.).

The Role of Personal Computer Systems in Education

Abstract: This paper reviews the role of computers, particularly the personal computer, in the learning process. Many ways of using the computer to assist learners are discussed. The advantages of personal computers over time-sharing computers are considered.

Pilot: An operating system for a personal computer (Summary)

Abstract: The Pilot operating system is designed for the personal computing environment. It provides a basic set of services within which higher-level programs can more easily serve the user and/or communicate with other programs on other machines. Pilot omits certain functions sometimes associated with “complete” operating systems, such as character-string naming or user-command interpretation; higher-level software provides such facilities as needed. On the other hand, Pilot provides a higher level of service than that normally associated with the “kernel” or “nucleus” of an operating system. Pilot is closely coupled to the Mesa programming language and runs on a rather powerful personal computer, which would have been thought sufficient to support a substantial timesharing system of a few years ago. The primary user interface is a high resolution bit-map display, with a keyboard and a pointing device. Secondary storage generally takes the form of a sizable local disk. A local packet network provides a high bandwidth connection to other personal computers, and to server systems offering such remote services as printing and shared file storage.Much of the design of Pilot stems from an initial set of assumptions and goals rather different from those underlying most timesharing systems. Pilot is a single-language, single-user system, with only limited features for protection and resource allocation. Pilot's protection mechanisms are defensive, rather than absolute, since in a single user system, errors are a more serious problem than maliciousness. Similarly, Pilot's resource allocation features are not oriented toward enforcing fair distribution of scarce resources among contending parties.

Impact of Personal Computing on Education.

Abstract: This discussion of microcomputers presents a brief explanation of microcomputer operation. Five generalizations about technologies in the past are developed to explore the impact of the personal computer on education. The attraction for the microcomputer to education is the large capability relative to cost of the new small machines. The limiting factors include the ability to generate large capital investment and a propensity for man to leave the future to new generations.

A Personal Computer Based on a High-Level Language

Abstract: Considerations of economy have in the past led to the so-called timesharing of large computers. The premise of such systems is to project to each user the image of the entire computer being at his own exclusive disposal. This requires str ingent measures of protection on programs and data of the individual part icipants against misbehaviour of programs and malfunctions of hardware. These measures, called overhead, are not only extensive, but also expensive.

How Do I Choose A Personal Computer

Abstract: The problem educators face in deciding which personal computer system to purchase from among a bewildering array of possibilities is described. An approach to making such a decision is proposed. The approach involves defining a vector of computer characteristics including cost, portability, and a variety of performance measures. The elements of this vector are modified by importance factors (assigned by the decision-maker) and by assessments of the extent to which each computer realizes each of the characteristics. The combination of these modified vector elements yields a single number which may be regarded as a figure of merit for that computer. On the basis of this figure of merit, the decision-maker may base the choice on a somewhat more objective criterion than is possible by talking to salespeople.

Uses of computers in the office of the future

Abstract: This chapter discusses the use of computers in the office of the future. Society is entering the “information age.” Computer communication is one essential ingredient in accessing information. The communication link may stretch halfway around the world, but it is equally important that it may only stretch to computers in adjacent offices, with very high communication bandwidths available. The ability to get widely distributed information is economically feasible and an important element of the office of the future. Most of the work that is conducted in business offices involves narrative information, rather than the kind of highly structured digital information stored in computers today. The office of the future will have interactive computer tools capable of helping knowledge workers in the office and handling the large volumes of narrative information in which they deal on a daily basis. The personal computer will put computer tools into the hands of knowledge workers, in the offices where they work, to aid them in doing their jobs. Because the commodity they deal in is information, these computers need to be highly interactive, and they need to function as friendly extensions to individual brain power. A major process in any office is planning. Some other major processes include resource allocation, monitoring execution of plans, and decision making.

Personal computers demand new perspectives

Abstract: The arrival of the inexpensive personal microcomputer system now makes it necessary to change traditional views of the computer - programmer - user relationship and to approach software design in concert with this new relationship. The new consumer market for the personal computer system must also be considered as an opportunity to provide a medium for creative expression for the individual and in light of its potential for long-range educational benefits for society as a whole.

3000 Arcs for 3000 Bucks: How to Justify a Personal Computer for Your Own OR/MS Department

Abstract: An essay about purchasing an Apple II computer configuration solely for the purpose of obtaining a quick solution of an important warehouse simulation problem while the company's mainframe was being repaired.

The role of information retrieval in the second computer revolution

Abstract: Information retrieval is conceptually fundamental in human communication as well as in man-computer communication. Computing and Information Retrieval professionals have the opportunity to apply information retrieval techniques within the second computer revolution to foster a new potential revolution in education, brought about by the advent of the personal computer.