Specification writing is a specific design technique, that can be used where suitable if the consequences are acceptable. These matters are considered briefly. Design specifications are distinguished fron tendering sp...
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Specification writing is a specific design technique, that can be used where suitable if the consequences are acceptable. These matters are considered briefly. Design specifications are distinguished fron tendering specifications, of which they may be expansions, and from product specifications. Reasons are put forward for writing a specification in natural language, as are reasons for specifying program suites by data tables. programming is treated as an engineering discipline, though one in which the artifact cannot be represented by scale drawings.
In this paper the approach adopted for providing the software of a large real time system is described. The software project organization which resulted is then given. The project planning and progressing are describe...
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In this paper the approach adopted for providing the software of a large real time system is described. The software project organization which resulted is then given. The project planning and progressing are described. Finally observations on the software production, its rate, and the success of the storage and run time estimates are given.
Virtual computersystems can improve software reliability by localizing and controlling the impact of operating system errors and by permitting large systems to be constructed from a set of independent and less comple...
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Virtual computersystems can improve software reliability by localizing and controlling the impact of operating system errors and by permitting large systems to be constructed from a set of independent and less complex modules. In this discussion, the authors used availability as an indicator of reliability; characterized the overall value of a system in terms of a utility function defined on the possible degrees of availability; demonstrated a number of conditions under which virtual computersystems would be superior to comparable multiprogrammingsystems organized in the conventional manner.
A simulation model is presented for a hypothetical geographically distributed network computer. The approach is to design a general n node network simulator and then to particularize the input parameters to describe I...
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A simulation model is presented for a hypothetical geographically distributed network computer. The approach is to design a general n node network simulator and then to particularize the input parameters to describe ILLINET (the computer communications network at the University of Illinois.
Evaluation of a computer system is an art which relies upon an analysis of pertinent data. A methodology is described which allows data relating to the behavior of a system to be collected by software without introduc...
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Evaluation of a computer system is an art which relies upon an analysis of pertinent data. A methodology is described which allows data relating to the behavior of a system to be collected by software without introducing perturbation. Simulation techniques which allow the system to be represented by a real operating system in a simulated environment, permit performance estimates of simulated hardware configurations under the influence of bench mark programs.
The authors have proposed an analytical model for the behavior of processes in a non-CPU-bound virtual-memory system, and for the performance of the paging drum. The model is unusual in that it takes into account the ...
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The authors have proposed an analytical model for the behavior of processes in a non-CPU-bound virtual-memory system, and for the performance of the paging drum. The model is unusual in that it takes into account the tradeoff between two scarce resources of the system: main memory page frames and paging channel capacity. Combining the definition for ″value″ with the model, the authors have developed methods of measuring the value of a given page-frame allocation, and of finding the optimal allocation of a given number of pages among a given set of processes. The methods were tested on simple systems and the results found to be reasonable. Also proposed by the authors is a pair of simple, low overhead heuristics for page management. These were evaluated by means of the model. Under the conditions of the experiments, the heuristics provide an inexpensive means for dynamically tuning a system for near-optimal throughput.
For problems which are to be solved by digital computer simulation, an optimum solution is, in general, not obtained by analytic techniques, but rather by a search of the relevant parameter space. This search tends to...
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For problems which are to be solved by digital computer simulation, an optimum solution is, in general, not obtained by analytic techniques, but rather by a search of the relevant parameter space. This search tends to be overwhelming, especially in those cases where more than three of four parameters are involved. Because of this, an OPTIMIZER computer program has been developed to provide efficient semi-automatic procedures of searching for an optimum computer simulation solution. The development of the OPTIMIZER is described in this paper.
Allocation of paged memory in a multiprogramming environment is considered. Based on uniprogramming studies, such as statistical observations of actual programs as well as primitive program models, a memory space shar...
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Allocation of paged memory in a multiprogramming environment is considered. Based on uniprogramming studies, such as statistical observations of actual programs as well as primitive program models, a memory space sharing algorithm is constructed which selects a program to lose a page when a new page is demanded.
A design Automation System for the RT level of design is described. The System explores the design space by finding alternative implementations for a user given behavioral specification. The alternative solutions are ...
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A design Automation System for the RT level of design is described. The System explores the design space by finding alternative implementations for a user given behavioral specification. The alternative solutions are obtained by transformations on a graph model. These transformations effect trade-offs between the cost of the hardware and the speed of the algorithm. Heuristic routines are used to reduce the design space by exploring only those alternatives whose characteristics approach a user given set of goals.
This article suggests ways to effectively use a third generation operating system. Most of the examples used are from the most generalized and complicated of them all - IBM OS/360. Examination of operating systems beg...
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This article suggests ways to effectively use a third generation operating system. Most of the examples used are from the most generalized and complicated of them all - IBM OS/360. Examination of operating systems begins with the typical hardware resources of a computing plant and the OS response to those resources. A brief overview of the user tools supplied by the operating system is then presented, followed by discussions on bugs and debugging and other problems of performance.
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