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Showing papers in "Ibm Systems Journal in 1971"


Journal ArticleDOI
TL;DR: Experimental techniques that can significantly reduce paging exceptions in existing, frequently executed programs and computer displays of memory usage facilitate further optimization of program structure are described.
Abstract: Program reference patterns can have a more profound effect on paging performance in a virtual memory system than page replacement algorithms. This paper describes experimental techniques that can significantly reduce paging exceptions in existing, frequently executed programs. Automated procedures reorder relocatable program sectors, and computer displays of memory usage facilitate further optimization of program structure.

170 citations


Journal ArticleDOI
TL;DR: The performance of a complex time-sharing system was monitored under actual operating conditions during a period in which changes in system configuration took place.
Abstract: The performance of a complex time-sharing system was monitored under actual operating conditions during a period in which changes in system configuration (both hardware and software) took place. Various techniques for assessing the impact of those changes on performance are discussed.

44 citations


Journal ArticleDOI
TL;DR: Central to successful operation of a computer system based heavily on reentrant (or pure) procedures is reliable and efficient dynamic management of free storage, which is crucial for any list-processing system.
Abstract: Central to successful operation of a computer system based heavily on reentrant (or pure) procedures is reliable and efficient dynamic management of free storage. Such systems must allocate, use, and release one or more blocks of free storage for each task or system operation, e.g., each I/O task or each request for supervisor services. For any list-processing system, such as AED or LISP, efficient management of free storage is a fundamental problem. The consequence of errors in allocation and release is usually total collapse of the system; that of mismanagement is usually processor inefficiency or under-utilization of the free-storage pool. The processor inefficiency resulting from a poor or ill-chosen management algorithm is usually tolerated, even though it is high relative to that of other system functions; under-utilization of free storage is less tolerable, as “lock-up” can be encountered. This circumstance must be averted by task deferral or “garbage collection” procedures, both of which are costly to system performance.

38 citations


Journal ArticleDOI
TL;DR: Through a nationwide network of interactive terminals in a teleprocessing configuration, users perform over twenty major business functions by sharing a single large and varied data base.
Abstract: Through a nationwide network of interactive terminals in a teleprocessing configuration, users perform over twenty major business functions by sharing a single large and varied data base. Emphasized are system design principles of the central complex whereby terminal message processing and data-base management are independently yet cooperatively performed. Also discussed is system security, which includes user authorization and data-base reconstruction and auditing.

30 citations


Journal ArticleDOI
E. J. Neuhold1
TL;DR: The formal description methods introduced in this paper were related to the simple language SPL for explanation purposes and an extension to the execution control of the abstract interpreter was used in the formal description of PL/1.
Abstract: The formal description methods introduced in this paper were related to our simple language SPL for explanation purposes. Actually, the methods (i.e., abstract trees, predicates, state components, control trees, etc.) apply to all programming languages. However, some programming languages contain facilities that cannot be expressed using the methods described in this paper alone. For example, additional definitions are required to represent the multitasking facilities of PL/1. To solve this particular problem, an extension to the execution control of the abstract interpreter was used in the formal description of PL/1.

27 citations


Journal ArticleDOI
TL;DR: The asymptotic properties of the machine interference model were described and it was shown that the size dependencies of these properties were of order 1/n in regions of the most interest, that is, w < 1.
Abstract: The asymptotic properties of the machine interference model were described in this paper. When the properties of the system were appropriately normalized and represented in terms of the variable w (=nu/v), the size dependencies of these properties were of order 1/n in regions of the most interest, that is, w < 1. Furthermore, the model displayed a functionally different behavior in the region w ≥ 1. The region around w = 1 was described as an unstable region in which an equivalent simulation model could be expected to stabilize slowly and probably give results different from the mathematical model. The asymptotic formulas are simple in form and quite accurate, and they allow the performance of queuing analysis with very little effort. In the last section of the paper, the solution and the properties of the generalized machine interference model were given.

22 citations


Journal ArticleDOI
TL;DR: A probability-based, theoretical model of a multiprogrammed computing system is suggested for planning future computing center requirements and applications to short-range and long-range planning are attempted.
Abstract: A probability-based, theoretical model of a multiprogrammed computing system is suggested for planning future computing center requirements. Validation of the planning model is attempted with respect to the theoretical model and applications to short-range and long-range planning.

14 citations


Journal ArticleDOI
TL;DR: A FORTRAN subprogram library developed primarily to support extended-precision floating-point arithmetic, which makes limited use of guard digits is developed to achieve high accuracy with reasonable execution time and storage space.
Abstract: This paper discusses a FORTRAN subprogram library developed primarily to support extended-precision floating-point arithmetic. The general strategy, which makes limited use of guard digits, is developed to achieve high accuracy with reasonable execution time and storage space. In addition to describing some previously unpublished algorithms, the authors present subprograms for simulating extended-precision arithmetic and for input and output conversion.

10 citations


Journal ArticleDOI
TL;DR: Used worldwide by the National Aeronautics and Space Administration to schedule its manned and unmanned space flight missions up to one year in advance, the system operates in either batch or interactive modes to produce, modify, and observe actual and simulated schedules.
Abstract: Discussed are design principles, file structures, and programming techniques of a scheduling system that approximates the overall magnitude and complexity of an airline scheduling system. Used worldwide by the National Aeronautics and Space Administration to schedule its manned and unmanned space flight missions up to one year in advance, the system operates in either batch or interactive modes to produce, modify, and observe actual and simulated schedules.

8 citations


Journal ArticleDOI
C. D. Allen1
TL;DR: The use of first-order predicate calculus in proving correctness and other properties of programs is shown to be possible in practical situations.
Abstract: The use of first-order predicate calculus in proving correctness and other properties of programs is shown to be possible in practical situations. The necessary concepts and theory are explained, and some practical examples worked through.

7 citations


Journal ArticleDOI
TL;DR: An experimental on-line network design system is proposed that consists of a small computer with graphic display equipment connected to a time-sharing computer and includes the necessary programming support for the equipment.
Abstract: An experimental on-line network design system is proposed. Called DESIGNPAD, it consists of a small computer with graphic display equipment connected to a time-sharing computer and includes the necessary programming support for the equipment. The system is designed to accept problems covering a broad spectrum of applications in the form of labeled block diagrams. The input/output medium, the man-machine interface, and the supporting data structures, particularly the cellular structure, are discussed.

Journal ArticleDOI
TL;DR: This bibliography attempts to help the reader select from the rich body of sorting literatrue that which is in accord with his interests, needs, and prior training.
Abstract: This bibliography attempts to help the reader select from the rich body of sorting literatrue that which is in accord with his interests, needs, and prior training. Historical trends within the field are briefly outlined, and subspecialties are identified. Critical comments and classification of the cited works are intended to help the reader to avoid wasted effort.

Journal ArticleDOI
TL;DR: Estimates of the response variables in the simulation are reported for a variety of conditions of system overhead, queuing delays, and transient response, and sensitivity of these factors to the assumptions of the model are discussed.
Abstract: Explored by simulation is the performance of a probabilistic model of a multiprogrammed single-processor computing system operating under demand paging. Results of experiments on statistical methods for improving the efficiency of the simulation are presented. Estimates of the response variables in the simulation are reported for a variety of conditions of system overhead, queuing delays, and transient response. Sensitivity of these factors to the assumptions of the model are discussed.

Journal ArticleDOI
TL;DR: An optimal programming model for lot-size, inventory, and work-force planning over a finite planning horizon for assembly-type production having precedences with nonlinear (set-up) costs using essentially linear programming computations is discussed.
Abstract: Discussed is an optimal programming model for lot-size, inventory, and work-force planning over a finite planning horizon for assembly-type production. The object is to prepare a minimum cost lot-size and work-force plan that meets the deterministic demands within the resource constraints. Planning for end-items, components, and overtime is included. The main feature of the model is the ability to plan for assembly production having precedences with nonlinear (set-up) costs using essentially linear programming computations.

Journal ArticleDOI
TL;DR: Algorithms were developed for recognizing the length patterns of vehicles passing over detectors and using these for precisely computing traffic density in several sections of the Lincoln Tunnel.
Abstract: Discussed are methods underlying the real-time monitoring and controlling system of a critical traffic link. Algorithms were developed for recognizing the length patterns of vehicles passing over detectors and using these for precisely computing traffic density in several sections of the Lincoln Tunnel. Vehicle control was adjusted by the system to optimize tunnel throughput.