Showing papers on "Iterative design published in 1981"

A structured design methodology and associated software tools

Abstract: The problems encountered designing very large scale integrated circuits (VLSI) are fundamentally different from the problems encountered in the design of small scale integrated circuits. The differences require a new methodology of design for the new large scale circuits, and the new design methodology requires a new set of tools. The computer-aided design work at Caltech has progressed from a recognition of the inherent differences and has produced a new design methodology and a set of tools which attack the new problems in integrated circuit design.

Measuring designer performance to verify design automation systems

Abstract: Design automation at the register transfer level of design is still in its infancy, and it is not yet completely understood what the appropriate measures used in direction the automated design process should be. To establish these measures, results of these design automation systems must be compared with some near optimal designs. A set of statistically based experiments is developed to estimate near optimal designs. A method is demonstrated for gathering data on designer performance, specifically at the different levels of systems design, and in general for calibration of other design automation systems where the intuitive designer still performs more capably than the present design algorithms. An analysis of variance is used to indicate the relative importance of various decisions in a system design. It is shown that the algorithm to be implemented and the hardware design style account for 90 percent of the variation in the results. Thus, selecting the design style (e.g., distributed, microprocessor, pipelined, etc.) is the most important parameter for a design automation system.

Prototyping: An approach to information and communication system design

Abstract: This paper describes prototyping, a state-of-the-art methodology to assist a design team in making a through definition and analysis of new requirements, feasibility, alternative selections, workload impact, system and/or application specification, implementation, and testing. Suggested prototype tools and techniques are presented, and guidance is included to aid a design team in obtaining accurate and timely results. This paper is not intended to be a complete text on design. It should be enhanced with a design team's expertise, consultation from sources with design experience, and reference to other design literature.Prototyping is a process (the act, study, or skill) of modeling an information-communication system architecture in one or more levels of detail, using descriptive models, abstract models, and working models of the system and its component parts (synonym: archetyping).This work was completed while the author was working with prior employers.

Iterative Design Of Pupil Functions For Bipolar Incoherent Spatial Filtering

Abstract: An iterative algorithm is described for the computer generation of complementary pupil functions to be used in hybrid incoherent optical systems for bipolar spatial filtering. Through repeated transformations between the Fourier and spatial domains, and the application of constraints in both, the pupil functions are constructed subject to the ultimate constraint that the difference of the associated PSFs result in a desired bipolar spatial impulse response. Minimization of component PSF bias is a major concern. The case of bandpass spatial filtering will be discussed in detail and preliminary results presented.© (1981) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Management of the Galileo attitude and articulation control flight software development

Abstract: Management concepts are presented for software development for a new technology area, i.e., real-time autonomous, computer-based spacecraft control. Flight computer selection and sizing are done initially to maximize performance within constraints of size, power, and cost. A higher order language is chosen to enhance productivity. Because the computer is embedded in the control systems hardware and is tied to the iterative design process of the spacecraft, the management and configuration control of the software is different from more typical applications. The development process must permit early coding but accept late changes. Margin management must be a continuing process in the development. Validation and verification is a special problem because it is not feasible to test the software in the actual operating environment prior to launch.

Top-Down Design

Abstract: In this chapter a large-scale programming problem, the production of a text-formatting program, is tackled from scratch, as a demonstration of how a program can be constructed from the top down.

The Impact of Testing on VLSI Design Methods

Abstract: The question ``why design for testability?'' will be answered by discussing some existing test philosophies. Exhaustive testing, functional testing and structural testing will be treated, also with regard to their usefulness for VLSI circuits. There is no general agreement on how to design for testability. Various approaches exist, and each has its specific applications. Some of these approaches will be discussed in detail, also regarding the influence of the complexity on necessary CAD tools for test pattern generation.

Optimum preliminary design of a non-terminal railroad station

Abstract: A deterministic model is constructed for preliminary design of non-terminal railroad stations. Monotonicity analysis is used to obtain a simple and rigorous procedure for optimizing the principal design characteristics of the station layout. The resulting design procedure has no iterative computations and can be automated for parametric studies. This provides a rational basis for design decisions when architectural and esthetic considerations are included.