Examines the benefits of the early resolution of branch instructions and the impact of unresolved branches on history-based branch prediction schemes by using two new metrics that are more revealing than branch prediction accuracy alone. The authors first briefly review a number of branch prediction schemes and introduce two new branch prediction scheme performance metrics. They then utilize these metrics to gauge the improvement in branch prediction scheme performance when only the outcomes of unresolved branches are predicted. Finally, they examine two approaches for handling multiple unresolved branches in history-based branch prediction schemes, and determine that prediction accuracy remains quite stable when older branch histories are used.>

This paper applies a form of instruction stream interleaving to the problem of high performance real-time systems.Such systems are characterized by high bandwidth, stochastically occurring interrupts as well as high throughput requirements,The DISC computer is based on dynamic interleaving where the next instruction to be executed is dynamically selected from several possible simultaneously active streams.Each stream context is stored internally making possible active task switching in a single instruction cycle.For several RTS applications the DISC concept promises higher computation throughput at lower cost than is possible on contemporary RISC processors.Implementation and register organization details are presented as well as simulation results.

Software engineering project management (SEPM) has been the focus of much recent attention because of the enormous penalties incurred during software development and maintenance resulting from poor management. To date there has been no comprehensive study performed to determine the most significant problems of SEPM, their relative importance, or the research directions necessary to solve them. We conducted a major survey of individuals from all areas of the computer field to determine the general consensus on SEPM problems. Twenty hypothesized problems were submitted to several hundred individuals for their opinions. The 294 respondents validated most of these propositions. None of the propositions was rejected by the respondents as unimportant. A number of research directions were indicated by the respondents which, if followed, the respondents believed would lead to solutions for these problems.

The problem of minimizing mean-square quantization error is considered and simple closed form approximations based on the work of Max and Roe are derived for the quantization error and entropy of signals quantized by the optimum fixed-Nquantizer. These approximations are then used to show that, whenNis moderately large, it is better to use equl-interval quantizing than the optimum fixed-Nquantizer if the signal is to be subsetiuently buffered and transmitted at a fixed bit rate. Finally, the problem of optimum quantizing in the presence of buffering is examined, and the numerical results presented for Gaussian signals indicate that equllevel quantizing yields nearly optimum results.

The concept of time-shared computer operations is briefly described and a model of a time-sharing system is proposed, based on the assumption that both interarrival and service times possess an exponential distribution. Although the process described by this model is non-Markovian, an imbedded Markov chain is analyzed by exploiting the fact that the instants of completion of a “quantum” of service are regeneration points. It is shown that user congestion possesses a limiting distribution, and the method of generating functions is used to derive this distribution. The concept of cycle time is discussed and two measures of cycle time developed for a scheduling discipline employing a single queue. Finally, a number of numerical examples are presented to illustrate the effect of the system parameters upon user congestion, system response time and computer efficiency.

An investigation of methods for solving the transportation problem within the framework of a cyclic real-time digital computer program system is reported.Two techniques for obtaining a basic feasible solution, the Northwest Corner Rule and a modification of Vogel's Approximation Method, are considered.The solution is then iterated using the Dual Theorem.A statistical analysis is made of the solution times of each method for different matrix dimensions.Consideration is given to methods for truncating the process, and recommendations are made.The use of Vogel's Approximation Method is shown to yield significantly faster solution times.