A logistics management game was modified to provide an information/decision system that would serve as a framework for experimentally investigating the impact of the mode of information presentation. Subjects played the game by making a series of weekly decisions during each of two playing sessions. The experimental treatments were varied between sessions to permit the testing of a set of hypotheses pertaining to the impact that information and its mode of presentation might have upon performance and the rate of performance change. Data on player decisions and simulated results (performance) were collected automatically by the modified gaming system while data on player backgrounds were collected via questionnaires. The experimental data provide some support for hypotheses relating to the superiority of display terminals and the influence of user background on exhibited learning. The data does not, however, provide solid support for hypotheses relating to the impact of additional information or of graphical forms of information presentation. Analysis of the experimental data suggests the need to consider individual and user-group differences in systems design. User background differences may also considerably complicate the design of graphical output for information systems. Experimental research involving human interaction with information systems is a very difficult undertaking. The experiences gained from this project and reported in this paper should aid other researchers in designing effective experiments. The findings discussed also point toward several areas offering potential for further research. Many different variables influence the development and use of computer-based information systems. This paper presents the results of an experiment designed to examine the impact of the amount of information provided, the mode of presentation of that information, and the differences in personal backgrounds on the performance and rate of performance change for users of a computer-based system.information systems: management, man-machine systems, organizational studies: information

This paper investigates the performance of 35 dynamic memory allocation algorithms when used to service simulation programs as represented by 18 test cases. Algorithm performance was measured in terms of processing time, memory usage, and external memory fragmentation. Algorithms maintaining separate free space lists for each size of memory block used tended to perform quite well compared with other algorithms. Simple algorithms operating on memory ordered lists (without any free list) performed surprisingly well. Algorithms employing power-of-two block sizes had favorable processing requirements but generally unfavorable memory usage. Algorithms employing LIFO, FIFO, or memory ordered free lisfs generally performed poorly compared with others.

The development of new large scale time-sharing systems has raised a number of problems for computation center management. Not only is it necessary to develop an appropriate hardware configuration for these systems, but appropriate software adjustments must be made. Unfortunately, these systems often do not respond to changes in the manner that intuition would suggest, and there are few guides to assist in the analysis of performance characteristics. The development of a comprehensive simulation model to assist in the investigation of these questions is described in this paper. The resulting model has a general purpose design and can be used to study a variety of time-sharing systems. It can also be used to assist in the design and development of new time-sharing algorithms or techniques. For the sake of efficiency and greater applicability, the model was implemented in a limited FORTRAN subset that is compatible with most FORTRAN IV compilers. The use of the simulation is demonstrated by a study of the IBM 360/67 tlme-sharing system. I n t r o d u c t i o nThe brief history of automatic digital computing has been marked by a series of hardware developments followed by striking changes in computer usage. At the present time we are midway between one of these new developments and the resulting change. The success of the experimental time-sharing systems which have been developed at such places as the Massachusetts Institute of Technology (Project MAC) [1, 2], the RAND Corporation [10,11], and the System Development Corporation [7][8][9] have clearly demonstrated both the desirability and the feasibility of this technique for computer utilization. Now, new third generation computers employing solid logic or integrated circuit (IC) technology are becoming available. Not only are these machines able to eliminate many of the hardware-imposed limitations of earlier timesharing systems, but certain models within some manufacturers' lines are being marketed especially for general purpose time-sharing applications. The first deliveries of some of the new hardware have already taken place, and comprehensive software packages are currently under development for these systems. Consequently, it is expected that a sharp change will take place over the next few years in the manner in which man employs the computer.Such a sharp change has already taken place in the way in which management purchases (leases) computation equipment. Based upon surprisingly meager information, hundreds of millions of dollars have been conmfitted for the acquisition of new equipment for time-sharing applications. Yet no one has ever seen one of these time-sharing systems in operation, much less learned of its performance characteristics. Past experience is of little help in the evaluation of these systems, and neither manufacturer nor purchaser can realistically answer such simple questions as "How many terminals can a particular system configuration support?" As many managers are now coming to realize, the acquisition of one of these new time-sharin...

The widespread use of complex third generation computing systems has led to a much broader concern about the means by which the resources of these systems are allocated among the user community. One means that is suggested more and more frequently is a pricing procedure. In this paper the manner in which one would like to allocate computing resources is considered, and then the extent to which a pricing mechanism fits this mold is discussed. Inasmuch as pricing must serve as a rationing mechanism at times, consideration is given to the means by which prices can be adjusted flexibly in order to make a dynamic allocation of resources. Consideration is also given to the means by which users can be insulated from the harmful effects of frequent price fluctuations. Although the subject of pricing has been given a lot of attention recently, a number of misconceptions persist about its purpose and its operation. An attempt is made to clarify some of these misunderstandings and to highlight the advantages and disadvantages of pricing. Two illustrative pricing systems are also discussed in order to demonstrate the applicability of pricing in quite different environments.