Computer graphics as a whole is an area making very fast progress and it is not easy for anyone, including experts, to keep abreast of the frontiers of its various basic and application fields. By issuing over 100 thousand calls for papers through various journals and magazines as weil as by inviting reputed specialists, and by selecting high quality papers which present the state of the art in computer graphics out of many papers thus received, this book "Frontiers in Computer Graphics" has been compiled to present the substance of progress in this field. This volume serves also as the final version of the Proceedings of Computer Graphics Tokyo '84, Tokyo, Japan, April 24-27, 1984 which, as a whole, attracted 16 thousand participants from all over the world; about two thousand to the conference and the remaining 14 thousand to the exhibition. This book covers the following eight major frontiers of computer graphics in 29 papers: 1. geometry modelling, 2. graphie languages, 3. visualization techniques, 4. human factors, 5. interactive graphics design, 6. CAD/CAM, 7. graphie displays and peripherals, and 8. graphics standardization. Geometry modelling is most essential in displaying any objects in computer graphics. It determines the basic capabilities of computer graphics systems such as whether the surface and the inside of the object can be displayed and also how efficiently graphical processing can be done in terms of processing time and memory space.

The second half of this century will remain as the era of proliferation of electronic computers. They did exist before, but they were mechanical. During next century they may perform other mutations to become optical or molecular or even biological. Actually, all these aspects are only fancy dresses put on mathematical machines. This was always recognized to be true in the domain of software, where "machine" or "high level" languages are more or less rigourous, but immaterial, variations of the universaly accepted mathematical language aimed at specifying elementary operations, functions, algorithms and processes. But even a mathematical machine needs a physical support, and this is what hardware is all about. The invention of hardware description languages (HDL's) in the early 60's, was an attempt to stay longer at an abstract level in the design process and to push the stage of physical implementation up to the moment when no more technology independant decisions can be taken. It was also an answer to the continuous, exponential growth of complexity of systems to be designed. This problem is common to hardware and software and may explain why the syntax of hardware description languages has followed, with a reasonable delay of ten years, the evolution of the programming languages: at the end of the 60's they were" Algol like" , a decade later "Pascal like" and now they are "C or ADA-like". They have also integrated the new concepts of advanced software specification languages.

Spectral Techniques in VLSI CAD have become a subject of renewed interest in the design automation community due to the emergence of new and efficient methods for the computation of discrete function spectra. In the past, spectral computations for digital logic were too complex for practical implementation. The use of decision diagrams for spectral computations has greatly reduced this obstacle allowing for the development of new and useful spectral techniques for VLSI synthesis and verification. Several new algorithms for the computation of the Walsh, Reed-Muller, arithmetic and Haar spectra are described. The relation of these computational methods to traditional ones is also provided. Spectral Techniques in VLSI CAD provides a unified formalism of the representation of bit-level and word-level discrete functions in the spectral domain and as decision diagrams. An alternative and unifying interpretation of decision diagram representations is presented since it is shown that many of the different commonly used varieties of decision diagrams are merely graphical representations of various discrete function spectra. Viewing various decision diagrams as being described by specific sets of transformation functions not only illustrates the relationship between graphical and spectral representations of discrete functions, but also gives insight into how various decision diagram types are related. Spectral Techniques in VLSI CAD describes several new applications of spectral techniques in discrete function manipulation including decision diagram minimization, logic function synthesis, technology mapping and equivalence checking. The use of linear transformations in decision diagram size reduction is described and the relationship to the operation known as spectral translation is described. Several methods for synthesizing digital logic circuits based on a subset of spectral coefficients are described. An equivalence checking approach for functional verification is described based upon the use of matching pairs of Haar spectral coefficients.

Recent developments in computer graphics have largely involved the following: Integration of computer graphics and image analysis through computer data structure; integration of CAD/CAM as computer-integrated manufacturing (CIM) through the design and simulation of manufacturing processes using computer graphics; progress in basic research on the modeling of complex and mathematical graphic objects, such as computational geometry, graphic data bases, hierarchical windows, and texture; use of computer graphics as an improved human interface to present information visually and multidimensionally; and advancement of industrial technology and computer art based on developments in the areas listed above. These trends are strongly reflected in the contents of the present volume either as papers dealing with one particular aspect of research or as multifaceted studies involving several different areas. The proceedings comprise thirty selected, previously unpublished original papers presented in nine chapters.

Dr. Jay Liebowitz Orkand Endowed Chair in Management and Technology University of Maryland University College Graduate School of Management & Technology 3501 University Boulevard East Adelphi, Maryland 20783-8030 USA jliebowitz@umuc. edu When I first heard the general topic of this book, Marketing Intelligent Systems or what I'll refer to as Marketing Intelligence, it sounded quite intriguing. Certainly, the marketing field is laden with numeric and symbolic data, ripe for various types of mining-data, text, multimedia, and web mining. It's an open laboratory for applying numerous forms of intelligentsia-neural networks, data mining, expert systems, intelligent agents, genetic algorithms, support vector machines, hidden Markov models, fuzzy logic, hybrid intelligent systems, and other techniques. I always felt that the marketing and finance domains are wonderful application areas for intelligent systems, and this book demonstrates the synergy between marketing and intelligent systems, especially soft computing. Interactive advertising is a complementary field to marketing where intelligent systems can play a role. I had the pleasure of working on a summer faculty f- lowship with R/GA in New York City-they have been ranked as the top inter- tive advertising agency worldwide. I quickly learned that interactive advertising also takes advantage of data visualization and intelligent systems technologies to help inform the Chief Marketing Officer of various companies. Having improved ways to present information for strategic decision making through use of these technologies is a great benefit.

For the near future, the recent predictions and roadmaps of silicon semiconductor technology all agree that the number of transistors on a chip will keep growing exponentially according to Moore's Law, pushing technology towards the system-on-a-chip (SOC) era. However, we are increasingly experiencing a productivity gap where the chip complexity that can be handled by current design teams falls short of the possibilities offered by technological advances. Together with growing time-to-market pressures, this drives the need for innovative measures to increase design productivity by orders of magnitude. It is commonly agreed that the solutions for achieving such a leap in design productivity lie in a shift of the focus of the design process to higher levels of abstraction on the one hand and in the massive reuse of predesigned, complex system components (intellectual property, IP) on the other hand. In order to be successful, both concepts eventually require the adoption of new languages and methodologies for system design, backed-up by the availability of a corresponding set of system-level design automation tools. This book presents the SpecC system-level design language (SLDL) and the corresponding SpecC design methodology. The SpecC language is intended for specification and design of SOCs or embedded systems including software and hardware, whether using fixed platforms, integrating systems from different IPs, or synthesizing the system blocks from programming or hardware description languages. SpecC Specification Language and Methodology describes the SpecC methodology that leads designers from an executable specification to an RTL implementation through a well-defined sequence of steps. Each model is described and guidelines are given for generating these models from executable specifications. Finally, the SpecC methodology is demonstrated on an industrial-size example. The design community is now entering the system level of abstraction era and SpecC is the enabling element to achieve a paradigm shift in design culture needed for system/product design and manufacturing. SpecC Specification Language and Methodology will be of interest to researchers, designers, and managers dealing with system-level design, design flows and methodologies as well as students learning system specification, modeling and design.

1 Aims and Features of This Book The contents of t. his book were originally planned t. o be included in a book en titled Geometric lIIodeling and CAD/CAM to be written by M. Hosaka and F. Kimura, but since the draft. of my part of the book was finished much earlier than Kimura's, we decided to publish this part separately at first. In it, geometrically oriented basic methods and tools used for analysis and synthesis of curves and surfaces used in CAD/CAM, various expressions and manipulations of free-form surface patches and their connection, interference as well as their qualit. y eval uation are treated. They are important elements and procedures of geometric models. And construction and utilization of geometric models which include free-form surfaces are explained in the application examples, in which the meth ods and the techniques described in this book were used. In the succeeding book which Kimura is to write, advanced topics such as data structures of geometric models, non-manifold models, geometric inference as well as tolerance problems and product models, process planning and so on are to be included. Conse quently, the title of this book is changed to Modeling of Curves and Surfaces in CAD/CAM. Features of this book are the following. Though there are excellent text books in the same field such as G. Farin's Curves and Surfaces for CAD /CAM l] and C. M."

This volume contains papers representing a comprehensive record of the contributions to the fifth workshop at EG '90 in Lausanne. The Eurographics hardware workshops have now become an established forum for the exchange of information about the latest developments in this field of growing importance. The first workshop took place during EG '86 in Lisbon. All participants considered this to be a very rewarding event to be repeated at future EG conferences. This view was reinforced at the EG '87 Hardware Workshop in Amsterdam and firmly established the need for such a colloquium in this specialist area within the annual EG conference. The third EG Hardware Workshop took place in Nice in 1988 and the fourth in Hamburg at EG '89. The first part of the book is devoted to rendering machines. The papers in this part address techniques for accelerating the rendering of images and efficient ways of improv ing their quality. The second part on ray tracing describes algorithms and architectures for producing photorealistic images, with emphasis on ways of reducing the time for this computationally intensive task. The third part on visualization systems covers a num ber of topics, including voxel-based systems, radiosity, animation and special rendering techniques. The contributions show that there is flourishing activity in the development of new algorithmic and architectural ideas and, in particular, in absorbing the impact of VLSI technology. The increasing diversity of applications encourage new solutions, and graphics hardware has become a research area of high activity and importance.

This book is based on lectures presented at an international workshop on geometric modeling held at Hewlett Packard GmbH in Boblingen, FRG, in June 1990. International experts from academia and industry were selected to speak on the most interesting topics in geometric modeling. The resulting papers, published in this volume, give a state-of-the-art survey of the relevant problems and issues. The following topics are discussed: - Methods for constructing surfaces on surfaces: four different solutions to the multidimen sional problem of constructing an interpolant from surface data are provided. - Surfaces in solid modeling: current results on the implementation of free-fonn solids in three well established solid models are reviewed. - Box splines and applications: an introduction to box spline methods for the representation of surfaces is given. Basic properties of box splines are derived, and refinement and evaluation methods for box splines are presented in detail. Shape preserving properties, the construction of non-rectangular box spline surfaces, applications to surface modeling, and imbedding problems, are discussed. - Advanced computer graphics techniques for volume visualization: the steps to be executed in the visualization process of volume data are described and tools are discussed that assist in handling this data. - Rational B-splines: an introduction to the representation of curves and surfaces using rational B-splines is given, together with a critical evaluation of their potential for industrial application."

Over the past decade there has been a dramatic change in the role played by design automation for electronic systems. Ten years ago, integrated circuit (IC) designers were content to use the computer for circuit, logic, and limited amounts of high-level simulation, as well as for capturing the digitized mask layouts used for IC manufacture. The tools were only aids to design-the designer could always find a way to implement the chip or board manually if the tools failed or if they did not give acceptable results. Today, however, design technology plays an indispensable role in the design ofelectronic systems and is critical to achieving time-to-market, cost, and performance targets. In less than ten years, designers have come to rely on automatic or semi automatic CAD systems for the physical design ofcomplex ICs containing over a million transistors. In the past three years, practical logic synthesis systems that take into account both cost and performance have become a commercial reality and many designers have already relinquished control ofthe logic netlist level of design to automatic computer aids. To date, only in certain well-defined areas, especially digital signal process ing and telecommunications. have higher-level design methods and tools found significant success. However, the forces of time-to-market and growing system complexity will demand the broad-based adoption of high-level, automated methods and tools over the next few years.

Integrated circuit densities and operating speeds continue to rise at an exponential rate. Chips, however, cannot get larger and faster without a sharp decrease in power consumption beyond the current levels. Minimization of power consumption in VLSI chips has thus become an important design objective. In fact, with the explosive growth in demand for portable electronics and the usual push toward more complex functionality and higher performance, power consumption has in many cases become the limiting factor in satisfying the market demand. A new generation of power-conscious CAD tools are coming onto the market to help designers estimate, optimize and verify power consumption levels at most stages of the IC design process. These tools are especially prevalent at the register-transfer level and below. There is a great need for similar tools and capabilities at the behavioral and system levels of the design process. Many researchers and CAD tool developers are working on high-level power modeling and estimation, as well as power-constrained high-level synthesis and optimization. Techniques and tools alone are, however, insufficient to optimize VLSI circuit power dissipation - a consistent and convergent design methodology is also required. Power Optimization and Synthesis at Behavioral and System Levels Using Formal Methods was written to address some of the key problems in power analysis and optimization early in the design process. In particular, this book focuses on power macro-modeling based on regression analysis and power minimization through behavioral transformations, scheduling, resource assignment and hardware/software partitioning and mapping. What differentiates this book from other published work on the subject is the mathematical basis and formalism behind the algorithms and the optimality of these algorithms subject to the stated assumptions. From the Foreword: `This book makes an important contribution to the field of system design technologies by presenting a set of algorithms with guaranteed optimality properties, that can be readily applied to system-level design. This contribution is timely, because it fills the need of new methods for a new design tool generation, which supports the design of electronic systems with even more demanding requirements'. Giovanni De Micheli, Professor, Stanford University

Computer Graphics Tokyo, now in its fourth year, has established a world-wide reputation as an international technical conference, presenting work of high quality in the field of computer graphics. Each conference has been attended by a couple of thousand partiCipants from all over the world and tens of thousands have visited the exhibition. After strict peer review, 34 papers were accepted this year, of which about 40% were from the USA, 30% from Japan, 20% from Europe, and 10% from Canada. A good balance of papers on advanced research results, industrial/marketing surveys, and computer art technology has made Computer Graphics Tokyo an indispensable forum for researchers, engineers, and administrators working in this field. Computer graphics is a rapidly developing and expanding area and it is not easy to keep abreast of all the progress that has been made. This volume contains the proceedings of Computer Graphics Tokyo '86 and provides the reader with a comprehensive survey of the state of the art in computer graphics. Computational geometry (Chapter 1) is one of the fastest growing areas in computer graphics. This is well recognized as the basis of shape modeling. After shapes are modeled, they are displayed for visual observation. Chapter 2 on rendering presents various novel methods and technological innovations for visualizing shapes. To make display systems more acces sible to users, rich visual interfaces and languages are being designed, as shown in Chapter 3. Visual data bases for sharing graphics-and image-data are handled in Chapter 4."

Intelligent robotics has become the focus of extensive research activity. This effort has been motivated by the wide variety of applications that can benefit from the developments. These applications often involve mobile robots, multiple robots working and interacting in the same work area, and operations in hazardous environments like nuclear power plants. Applications in the consumer and service sectors are also attracting interest. These applications have highlighted the importance of performance, safety, reliability, and fault tolerance. This volume is a selection of papers from a NATO Advanced Study Institute held in July 1989 with a focus on active perception and robot vision. The papers deal with such issues as motion understanding, 3-D data analysis, error minimization, object and environment modeling, object detection and recognition, parallel and real-time vision, and data fusion. The paradigm underlying the papers is that robotic systems require repeated and hierarchical application of the perception-planning-action cycle. The primary focus of the papers is the perception part of the cycle. Issues related to complete implementations are also discussed.

This book is a collection of the best papers originally presented as state-of-the-art reports or tutorials at the EUROGRAPHICS'91 conference in Vienna. A choice has been made giving priority to information of lasting value. Another goal was to cover all aspects of computer graphics -except hardware -as completely as possible from modelling to advanced visualization and communication. The editors consider that the ten contributions by internationally renowned experts fulfil this goal perfectly. Some important problem areas are treated from different viewpoints thus enhancing and deepening the reader's perspective. Sabine Coquillart Wolfgang Strafier Peter Stucki Table of Contents l. Through the Cracks of the Solid Modeling Milestone 1 J arek R. Rossignac 2. Kinematics and Dynamics for Computer Animation 76 H. Ruder, T. Ertl, K. Gruber, M. Gunther, F. Hospach, M. Ruder, J. Subke, K. Widmayer 3. Dynamic Animation of Deformable Bodies 118 Marie-Paul Gascuel, Claude Puech 4. Stochastic Methods and Non-Fractal Applications 140 Huw Jones 5. State of the Art in Volume Visualization 166 Arie Kaufman 6. On the Theorey and Application of Stereolithographics in Scientific Visualization 178 Eric Hibbard, Michael Bauer, Margaret Bradshaw, Glenn Deardorff, Ken Hu, David Whitney 7. User Interface Management Systems: Present and Future 197 Michel Beaudouin-Lafon 8. Trends in Edge Detection Techniques 224 Eduard Antoniu 9.

"Image Synthesis: Theory and Practice" is the first book completely dedicated to the numerous techniques of image synthesis. Both theoretical and practical aspects are treated in detail. Numerous impressive computer-generated images are used to explain the most advanced techniques in image synthesis. The book contains a detailed description of the most fundamental algorithms; other less important algorithms are summarized or simply listed. This volume is also a unique handbook of mathematical formulae for image synthesis. The four first chapters of the book survey the basic techniques of computer graphics which play an important role in the design of an image: geometric models, image and viewing transformations, curves and surfaces and solid modeling techniques. In the next chapters, each major topic in image synthesis is presented. The first important problem is the detection and processing of visible surfaces, then two chapters are dedicated to the central problem of light and illumination. As aliasing is a major problem in image rendering, the fundamental antialiasing and motion blur techniques are explained. The most common shadow algorithms are then presented as well as techniques for producing soft shadows and penumbrae. In the last few years, image rendering has been strongly influenced by ray tracing techniques. For this reason, two chapters are dedicated to this important approach. Then a chapter is completely dedicated to fractals from the formal Mandelbrot theory to the recursive subdivision approaches. Natural phenomena present a particularly difficult challenge in image synthesis. For this reason, a large portion of the book is devoted to latest methods to simulate these phenomena: particle systems, scalar fields, volume density scattering models. Various techniques are also described for representing terrains, mountains, water, waves, sky, clouds, fog, fire, trees, and grass. Several techniques for combining images are also explained: adaptive rendering, montage and composite methods. The last chapter presents in detail the MIRALab image synthesis software.

This book contains papers presented at the NATO Advanced Research Workshop on "Real-time Object and Environment Measurement and Classification" held in Maratea, Italy, August 31 - September 3, 1987. This workshop was organized within the activities of the NATO Special Programme on Sensory Systems for Robotic Control. Four major themes were discussed at this workshop: Real-time Requirements, Feature Measurement, Object Representation and Recognition, and Architecture for Measurement and Classification. A total of twenty-five technical presentations, contained in this book, cover a wide spectrum of topics including hardware implementation of specific vision algorithms, a complete vision system for object tracking and inspection, using three cameras (trinocular stereo) for feature measurement, neural network for object recognition, integration of CAD (Computer Aided Design) and vision systems, and the use of pyramid architectures for solving various computer vision problems. These papers are written by some of the very well-known researchers in the computer vision and pattern recognition community, and represent both industrial and academic viewpoints. The authors come from thirteen different countries from Europe and North America. Therefore, readers will get a first hand and current information about the status of computer vision research in various western countries. Further, this book will also be useful in understanding the current research issues in computer vision and the difficulties in designing real-time vision systems.

A Practical Guide to Analog Behavioral Modeling for IC System Design presents a methodology for abstracting an IC system so that the designer can gain a macroscopic view of how sub-systems interact, as well as verify system functionality in various applications before committing to a design. This will prevent problems that may be caused late in the design-cycle by incompatibilities between the individual blocks that comprise the overall system. This book will focus on the techniques of modelling IC systems through analog behavioral modeling and simulation. It will investigate a practical approach by which designers can put together these systems to analyze topological and architectural issues to optimize IC system performance.Highlights: * Discussions on modeling and simulation from SPICE to behavioral simulators * Comparison of various hardware description languages and a discussion on the effects of language standardization * Explanation on how to reduce time-to-market by decreasing design-cycle time through modeling and simulation * Contains more than 25 building block examples that can be used to construct mixed-signal IC system models * Analysis of 4 different IC systems using various levels of model detail This book is intended for the practicing engineer who would like to gain practical knowledge in applications of analog behavioral modelling for IC system design.

Control networks span a wide range of application areas. These networks are put into action in the `Digital Home', industrial applications, commercial buildings, transportation systems, gas stations, security systems, and they are found in most instances where smart sensors and smart actuators are used to exchange information. The authors of this volume provide an overview of various control network protocols and discuss LonTalk (R) protocol, Neuron (R) chip, programming model, network structures, network management, interoperability between nodes, application profiles, development and maintenance tools, performance analysis, and standardization activities. Open Control Networks: LonWorks/EIA 709 Technology will be an important resource for advanced students of control systems and embedded systems, engineers designing distributed networks, systems designers and architects, and others developing smart buildings and intelligent transportation systems.

Perhaps nothing characterizes the inherent heterogeneity in embedded sys tems than the ability to choose between hardware and software implementations of a given system function. Indeed, most embedded systems at their core repre sent a careful division and design of hardware and software parts of the system To do this task effectively, models and methods are necessary functionality. to capture application behavior, needs and system implementation constraints. Formal modeling can be valuable in addressing these tasks. As with most engineering domains, co-design practice defines the state of the it seeks to add new capabilities in system conceptualization, mod art, though eling, optimization and implementation. These advances -particularly those related to synthesis and verification tasks -direct1y depend upon formal under standing of system behavior and performance measures. Current practice in system modeling relies upon exploiting high-level programming frameworks, such as SystemC, EstereI, to capture design at increasingly higher levels of ab straction and attempts to reduce the system implementation task. While raising the abstraction levels for design and verification tasks, to be really useful, these approaches must also provide for reuse, adaptation of the existing intellectual property (IP) blocks."

Change is one of the most significant parameters in our society. Designers are amongst the primary change agents for any society. As a consequence design is an important research topic in engineering and architecture and related disciplines, since design is not only a means of change but is also one of the keystones to economic competitiveness and the fundamental precursor to manufacturing. The development of computational models founded on the artificial intelligence paradigm has provided an impetus for much of current design research -both computational and cognitive. These forms of design research have only been carried out in the last decade or so and in the temporal sense they are still immature. Notwithstanding this immaturity, noticeable advances have been made both in extending our understanding of design and in developing tools based on that understanding. Whilst many researchers in the field of artificial intelligence in design utilise ideas about how humans design as one source of concepts there is normally no attempt to model human designers. Rather the results of the research presented in this volume demonstrate approaches to increasing our understanding of design as a process.

The series Advances in Industrial Control aims to report and encourage technology transfer in control engineering. The rapid development of control technology impacts all areas of the control discipline. New theory, new controllers, actuators, sensors, new industrial processes, computer methods, new applications, new philosophies, .... , new challenges. Much of this development work resides in industrial reports, feasibility study papers and the reports of advanced collaborative projects. The series offers an opportunity for researchers to present an extended exposition of such new work in all aspects of industrial control for wider and rapid dissemination. Within the control community there has been much discussion of and interest in the new Emerging Technologies and Methods. Neural networks along with Fuzzy Logic and Expert Systems is an emerging methodology which has the potential to contribute to the development of intelligent control technologies. This volume of some thirteen chapters edited by Kenneth Hunt, George Irwin and Kevin Warwick makes a useful contribution to the literature of neural network methods and applications. The chapters are arranged systematically progressing from theoretical foundations, through the training aspects of neural nets and concluding with four chapters of applications. The applications include problems as diverse as oven tempera ture control, and energy/load forecasting routines. We hope this interesting but balanced mix of material appeals to a wide range of readers from the theoretician to the industrial applications engineer.

Computer Integrated Manufacturing (CIM) is the computerized handling of integrated business processes among all different functions in an enterprise. The consistent application of information technology, along with modern manufacturing techniques and new organizational procedures, opens up great potential for speeding up processes. This book discusses the current state of applications and new demands arising from the integration principle. It mainly emphasizes on strategies for realization and implementation based on the author's concrete experience. The "Y-CIM information management" model is presented as a procedural method for implementing CIM. The third edition has been supplemented by up-to-date specified examples of applied CIM solutions and transfer strategies.

Designing is one of the foundations for change in our society. It is a fundamental precursor to manufacturing, fabrication and construction. Design research aims to develop an understanding of designing and to produce models of designing that can be used to aid designing. The papers in this volume are from the Sixth International Conference on Artificial Intelligence in Design (AID'00) held in June 2000, in Worcester, Massachusetts, USA. They represent the state of the art and the cutting edge of research and development in this field, and demonstrate both the depth and breadth of the artificial intelligence paradigm in design. They point the way for the development of advanced computer-based tools to aid designers, and describe advances in both theory and application. This volume will be of particular interest to researchers, developers, and users of advanced computer systems in design.

There is much excitement in the design and verification community about assertion-based design. The question is, who should study assertion-based design? The emphatic answer is, both design and verification engineers. What may be unintuitive to many design engineers is that adding assertions to RTL code will actually reduce design time, while better documenting design intent. Every design engineer should read this book! Design engineers that add assertions to their design will not only reduce the time needed to complete a design, they will also reduce the number of interruptions from verification engineers to answer questions about design intent and to address verification suite mistakes. With design assertions in place, the majority of the interruptions from verification engineers will be related to actual design problems and the error feedback provided will be more useful to help identify design flaws. A design engineer who does not add assertions to the RTL code will spend more time with verification engineers explaining the design functionality and intended interface requirements, knowledge that is needed by the verification engineer to complete the job of testing the design.

The success of VHDL since it has been balloted in 1987 as an IEEE standard may look incomprehensible to the large population of hardware designers, who had never heared of Hardware Description Languages before (for at least 90% of them), as well as to the few hundreds of specialists who had been working on these languages for a long time (25 years for some of them). Until 1988, only a very small subset of designers, in a few large companies, were used to describe their designs using a proprietary HDL, or sometimes a HDL inherited from a University when some software environment happened to be developped around it, allowing usability by third parties. A number of benefits were definitely recognized to this practice, such as functional verification of a specification through simulation, first performance evaluation of a tentative design, and sometimes automatic microprogram generation or even automatic high level synthesis. As there was apparently no market for HDL's, the ECAD vendors did not care about them, start-up companies were seldom able to survive in this area, and large users of proprietary tools were spending more and more people and money just to maintain their internal system.