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Hypermedia: A Tool for Teaching Complex Technologies
María D. Valdés, María J.Moure and Enrique Mandado
Abstract -Present technological solutions tend to become very complex, interrelated and difficult to characterize systems, thereby giving rise to what we name "complex technologies". Complex Technologies have a lot of related concepts comprising a large number of non-excluding or excluding subconcepts. Complex technologies education is usually based on the analysis of specific devices from different manufacturers, but this method is not suitable because it provides only one particular insight. This situation demands a new methodology summarizing all the characteristics of a particular technology and making the dynamic link between related concepts possible.
From this perspective our work describes an original method for the characterization of complex technologies and proposes the hypermedia technique as a suitable solution for its practical implementation. The method has been applied for teaching Field Programmable Gate Arrays (FPGAs) and Monolithic Digital Integrated Circuits (MDICs), which are complex technologies constituting two of the most dynamic areas of Microelectronics.
The origin and evolution of complex technologies is due to the confluence of technical and commercial factors, principally the progress of top technologies like Electronics and the interest of manufacturers in obtaining a dominant market position, promoting their trademarks through the development of their own products. Consequently a lot of new systems with the same functionality but differing in aspects like architecture, operation rates, portability, size or package are being continuously commercialized inducing a very rapid and chaotic development of complex technologies .
This situation motivates the interest in looking for adequate methods to analyze, characterize and teach these technologies. Educators recognize the need to radically revise traditional educational methods based on concept-oriented curricula and propose new models and pedagogical methods which give rise to concepts like: self-learning programs, engaged learning  , or inverted curricula  .
Although there is not a widespread consensus about the best educational method, "inverted curricula" has been successfully accepted and applied to the teaching of subjects in which it is possible for the learner to make use of increasing levels of knowledge. The "inverted curriculum" suggests using a "system-oriented" curriculum instead of a "concept-oriented" one. In this way students receive a user's view of the highest-level concepts and techniques that are really applied in the most advanced industrial environments, then, little by little, unveiling the underlying principles.
Despite the usefulness of this method to understand complex subjects in an intuitive way, "...an inverted curriculum does not teach technology -- technology is a moving target. Instead, the inverted curriculum coaches students about people, process and technology, providing a holistic view of systems development in the context of the application domain...". Inverted curriculum, as well as other new teaching methods, is focused to determine and structure the subjects that must be included in a system-oriented curriculum, but says nothing about how to teach the concepts concerning the different subjects. This is the responsibility of the educator.
Taking into account that disciplines like Electronics, Computing or Telecommunications are not single complex technologies but combine a lot of complex technologies, teaching all concepts associated to these disciplines constitutes a very difficult task even when methods like "inverted curriculum" are applied. As a consequence, complex technologies education is often based on the analysis of specific systems, like for example, in the case of Digital Electronics the study of hardware devices from several manufacturers or in the case of Computing, a specific programming language. In this way students acquire a restricted insight of the technology and in the majority of cases cannot easily analyze other systems of the same technology by themselves.
All the above motivated our interest in researching new strategies for the analysis and teaching of complex technologies. As a result we propose an original method oriented to the development of hypermedia tools for the analysis of this kind of technologies  . Our work is not intended to replace formal teaching methods (traditional or more sophisticated ones like "inverted curriculum") but to complement them.
Using our method the analysis of a complex technology seems similar to the idea of the "inverted curriculum" or the progressive opening of black boxes. The analysis begins with the highest-level concepts making it possible to understand essentials of a technology without understanding all of it. Then, the students can go into it in depth discovering the underlying principles.
The results of our work are presented in this article by means of the following topics:
Characterization of complex technologies
A new methodology for the analysis of complex technologies
The implementation of the proposed method using hypermedia tools
Two practical examples
Evaluating the approach
Complex technologies can be described through a set of basic related concepts comprising a large number of non-excluding or excluding subconcepts .
Basic concepts represent the general characteristics that define the technology. These characteristics are common to all systems included in the technology and can be described by means of some others which are named subconcepts. The subconcepts are the particularities that distinguish different systems of a technology. A same subconcept can be presented in several systems but not in all. The set of subconcepts that describes each system is different in each case.
An accurate analysis of a technology brings about a large number of description levels. As basic concepts comprise a set of subconcepts, each subconcept can be described by others and so on until it reaches the maximum level of specification. The related concepts and subconcepts that describe a specific technology can be structured into the different description levels to obtain adescriptive model of the complex technology (figure 1).
Basic concepts are non-excluding characteristics because they are present in all the systems belonging to the same technology. The existence of any of them cannot exclude the others, on the contrary, to ensure that a system belongs to a certain technology it must present all the general characteristics (basic concepts) associated to such a technology. In the case of subconcepts, as they describe the particularities of the different systems, they can be excluded or not. The existence of a specific characteristic sometimes excludes other(s) of the same description level.
Fig. 1. A simplified descriptive model of a complex technology.
Due to the large number of concepts associated to a complex technology, in most cases it cannot be described using only one descriptive model, but several. For example, if we are analyzing microcontrollers we must study some aspects like architecture, interconnections, manufacturing technology, programming technology, applications, performance constraints, etc. Each one of these subjects must be associated to a different descriptive model. In any case the different models can be considered as part of a single and very complex one.
The greatest advantage of a descriptive model is that it provides all the characteristics of a complex technology (from general characteristics to more specific ones) as well as the possible interactions between them. In this way any system or device can be described from it. Nevertheless, as the characteristics associated to each system differ from one to another, it is necessary to go through the model in an appropriate way.
According to the previous analysis, in the descriptive model of a complex technology each individual system is associated with a particular route linking the concepts and subconcepts that characterize its properties and applications. For example, infigure 2 the red and the yellow arrows represent two different systems of a complex technology. Both systems have the same general characteristics (basic concepts 1, 2 and N) and some characteristics of the second and the third level of description (subconcept 1). Nevertheless they have some specific characteristics distinguishing one from the other, as for example, subconcept 2 in the integrated circuit 1 and subconcept X in the integrated circuit 2.
Fig. 2. A method for the analysis of complex technologies.
Taking into account the advantages of using descriptive models to characterize complex technologies we propose a method to obtain it. This method is represented in figure 3 and comprises four principal stages:
Firstly, many different representative systems or devices are chosen.
In the second stage the selected systems are analyzed in detail to define the concepts associated to the technology. This task is carried out in two different phases:
All the common characteristics are determined and classified to define the general characteristics or basic concepts of the complex technology (Level 1 in figure 2).
In the second phase the basic concepts are characterized (including functionality, implementation, architecture, etc., that can bring about different descriptive models) taking into account the specific characteristics of each particular system. As a result the subconcepts of the descriptive model are obtained as well as its dependence relations (Level 2 and 3 in figure 2). As has already been stated a same subconcept can be present in different systems but the set of subconcepts associated to each system is always different.
In the third stage all the basic concepts and subconcepts are structured to obtain the descriptive model(s).
Finally, the descriptive model must be tested to verify its ability for describing not only the systems chosen to obtain the model but all the commercial systems known.
Developing descriptive models is a tedious task that requires a lot of time and effort, nevertheless, once it is obtained the result is a very useful tool for the analysis of complex technologies as well as the particular systems included in them. Besides, if new systems are developed, updating the model with the inclusion of new characteristics is very easy.
Once the descriptive model has been obtained and tested, the question is how to present the information contained in the model.
The descriptive model of a complex technology cannot be analyzed sequentially, like a simple hierarchical model, because interactions must be take into account. To understand some concepts it is often necessary to come back to the previous concepts or link different ones. Printed books, databooks, or tables are linear documents that present the information in a sequential way so they are not suitable for the characterization of complex technologies with a multiroute structure (figure 2).
From this perspective, an alternative solution for navigating through the information in different ways must be established. This constraint turns hypertext into a very useful tool to present a descriptive model for the analysis of complex technologies   .
Fig. 3. Characterizing different systems of the same technology.
Many authors have defined "hypertext"   . Shneiderman , refers to it as a database with active cross-references allowing the "jump" from one part to other parts of the database. This definition points out the main characteristic that makes hypertext suitable for the analysis of complex technologies: its non-sequential nature.
The information in a hypertext application is structured in nodes containing different concepts. Links can be established between related nodes (related information) providing users with different paths to analyze and understand a concept. In this way, there is not a pre-defined sequential order to access the information. Each user looks up the application in an intuitive way, pathing through those nodes that allow him/her to extend the information or introduce himself/herself in a new concept.
Hypertext features avoid the drawbacks of sequential documentation methods: the impossibility of connecting related concepts at any time and the time required for looking up any information in the document.
From this perspective a hyperdocument results in a suitable tool for the analysis of complex technologies. Using hypertext, links between different description levels of a descriptive model are possible as well as the combination of related concepts for describing real systems. A hyperdocument oriented to the study of a complex technology allows the global analysis of the technology, including all the concepts contained in its descriptive model, as well as the analysis of a single system, navigating only through the concepts associated to it. In the same way, concepts can be presented by means of several levels of complexity (corresponding to different information levels of the descriptive model).
On the other hand, using a hypermedia application it is possible to associate related information dynamically. Two different but related concepts can be presented in the same screen allowing the associative (parallel) analysis of those concepts. This is the greatest advantage offered by hypermedia aimed at the study of complex technologies (by nature they involve a great number of related, and in many cases dependent, concepts). It can be said that the hypertext presentation of information corresponds more closely to the way in which a student thinks and needs information (semantic network of associated concepts). Hypertext, therefore, favors analytical thought and parallel acquisition of knowledge (more than one concept can be analyzed at the same time). It would be impossible to achieve a similar effect using hard-copy sequential text or a lecture.
Among the multiple advantages of hyperdocuments we can point out the following:
The facility to select, share and access the information.
The different options to navigate through related information.
The possibility to include powerful audio-visual resources like texts, images, animations, videos, etc. : Audio-visual resources are especially useful to present many concepts which are very difficult to explain by means of words. In the case of complex technologies their great complexity demands the use of a lot of graphic information for the better understanding of their architectures and behaviors.
The updating facilities: When new systems with different characteristics are commercialized the hyperdocument can be easily updated by the addition of the corresponding data.
There are several opinions on how to create a hypermedia application aimed at teaching. In this article we neither intend to analyze the strategies to develop a hypermedia application nor the problematic of this technique, but rather we want to point out some interesting aspects.
There appears to be a certain degree of consensus over a set of criteria which we have taken into account when developing our applications:
A single working environment which eases familiarity with the application in the shortest time possible: Maintaining the screen format with regard to text and graphics layout, toolbars, navigation buttons, icons, hotword, etc.
Brief and concise texts: Using only strictly necessary texts and reinforcing their contents through audio-visual resources. Avoiding text scroll bars as far as possible.
Not abusing colors and sounds so that these do not distract the student's attention.
Including resources that permit safe navigation: As the potentiality of hypermedia for the analysis of complex technologies lies on the possibility of navigating through the information, enough links must be provided. However, more links than necessary should never be included to avoid the user disorientation. Navigation must be comfortable and secure and there are different methods and resources to secure navigation: a thematic index (this could be present on all screens or appear at the touch of a button or other navigation device), a way of getting back to the last page visited, or a record of screens visited.
The approach we use for creating a hypermedia application from a descriptive model is made up of the following three basic stages:
Page format design:
Definition of screen size and resolution and colors (palette).
Implementation of frame and background.
Definition of text, graphics and animation areas.
Definition of text formats including colors and sizes.
Definition and implementation of the toolbar (resources for navigation, notes, help, sounds, etc.)
Screen creation. There will be as many screens as there are concepts and subconcepts contained in the descriptive model.
Screen contents design:
To develop the contents of the hyperdocument a script is required. Selecting, organizing and connecting the information that should be contained in the application requires a lot of time and maybe is the most important stage in its development process. In our case all this work has already been done because the descriptive model constitutes the script for the application. It contains the concepts that must be explained as well as the possible links between them. Therefore, designing a hyperdocument from a descriptive model is a "relatively simple" task.
Each concept and subconcept (figure 1) is associated with a different screen of the application. These will be main or additional screens, depending on the importance of the concept.
Main screens contain concepts that must by obligation be understood in order to understand the technology. Navigation through them is therefore compulsory. The "additional" screens can be seen within the application, in such a way that they can be accessed by sequential navigation; or can be hidden screens, in which case they are only accessible from more important screens. Normally the additional hidden screens correspond to subconcepts from the last descriptive levels of the model.
The combination of main screens with additional ones (concepts and subconcepts) is the key which provides associative analysis and parallel acquisition of knowledge, and which is the great advantage that defines hypertext as an ideal tool for teaching complex technologies   . However, the application's success would not be such if it did not make perfectly organized information available which related concepts to each other, and this is what the descriptive model provides.
On the other hand, the description levels of the descriptive model establish the structure of the document. This situation is shown infigure 4 where the information of the hyperdocument is organized into subjects, topics and subtopics, corresponding to the basic concepts, the first level of subconcepts and the second level of subconcepts of the descriptive model, respectively.
Screen contents design is not limited to defining the topic of each screen and the text but also all the audio-visual resources to which special attention must be paid.
From a functional point of view: Verification of contents, spelling, links, etc.
From the point of view of effectiveness: Evaluation by students whose opinions are taken into account in order to change screens, improve links etc.
Developing a hypermedia application is not a trivial task in any case, audio-visual resources design, programming tasks and testing require a lot of time and patience, nevertheless, to start from a descriptive model is a significant help.
Figure 4. Associating the structure of a hyperdocument to a descriptive model.
The proposed methodology has been applied to develop two hypermedia applications with educational purposes. The hyperdocuments are oriented to the analysis of Monolithic Digital Integrated Circuits (MDICs) and Field Programmable Gate Arrays (FPGAs), complex technologies which are two of the most dynamic areas of Microelectronics.
In both cases, following the methodology described before(A methodology for the analysis of complex technologies), a lot of different commercial devices were analyzed to obtain the respective descriptive models. This information was portable to hypermedia applications that combine a lot of audio-visual resources to support the presentation of some concepts.
There are different tools oriented to the development of hypermedia applications: author's tools (AuthorWear, Director, ToolBook), programming languages (HTML, Java), etc. To select a suitable one some aspects must be considered like for example, if the application will be a multiplatform or an oriented-platform system, if it will be executed from a CD or in the network, the nature and the magnitude of the audio-visual resources to be used, and others. In our case hyperdocuments run over a Windows platform (Windows95 and 98) and have been developed using ToolBook, an Asymetrix author system.
MDICs has been developed to support a printed book entitled "Sistemas Electrónicos Digitales" by Enrique Mandado. This book is the main text book used in teaching Digital Electronic Circuits in the third year of the Telecommunications Engineering degree. The aim of this application is to expand some of the topics included in the book and ease understanding of concepts that are difficult to explain in words but are easily understood when audio-visual resources are used. Furthermore, this application includes a self-evaluation section in which the student can answer a set of questions related to the book's topics and which will help the learner to know how well they have taken on board the concepts being imparted. The self-evaluation section includes further information, bibliographical pointers and references to the various sections of the book.
Likewise, FPGAs is used as complementary material for Configurable Devices, which is also taught in the third year of Telecommunications Engineering. This application contains all the characteristics of the FPGAs organized and related so as to ease understanding of the technology in its setting. Furthermore, the objective of the application is not limited to explain the characteristics of the technology but to characterize commercial FPGAs too . To accomplish this the application is divided into two different parts. The first one contains all the concepts and subconcepts of the descriptive model and the second one constitutes a database for consulting the specific characteristics of commercial devices. This database links with the topics contained in the first part of the application giving additional information. Thus, using this application the student is provided not only with a vision of an abstract technology but is also introduced to the design of real systems as a natural and parallel achievement following from the understanding of technology. The student does not perceive the analysis of technology and its use as unlinked themes but rather as dependent subjects.
The main difference between both applications lies in the way of accessing the information. In the case of MDICs an index screen containing the descriptive model of the technology is available (figure 5) and from this screen the student can navigate through all the application. An example of the hyperdocument pointing out the information access from the index screen is presented in movie 1. In the case of the FPGAs the students can navigate through the entire application to analyze all the characteristics of the technology or through the links that combine the characteristics of a specific commercial device. An example of the hypermedia application called FPGAs is shown in movie2.
Fig. 5 The descriptive model of the complex technology MDICs.
In order to evaluate the methodology proposed in this article, we must do so from three different points of view: the student's, the teacher's and the application designer's.
Although MDICs and FPGAs are not the only applications that have been designed following this methodology, our analysis will be based on the results obtained from these applications as they are the ones we have worked with directly (designing and using) and have been able to track.
It must be remembered that the methodology we propose does not intend to replace current teaching methods but is instead aimed at developing applications to be used as complementary and backup material for these methods. Both MDICs and FPGAs are offered to students as alternative study tools and their use is never compulsory.
Concerning student reaction to the use of hypermedia applications:
It has been noted that students willingly accept computers as study tools and need little time to get to grips with a hypermedia application.
It has been demonstrated that learners use the applications and are involved in their improvement, suggesting new topics be included or animation and other multimedia resources be added in order to explain a concept that still remains complicated for them.
When asked what benefits they perceive by using the applications they refer to two basic aspects:
The way information is organised1 and the possibility of associating related concepts immediately2 (by presenting further information or jumping to other screens in the application) give them, to a great extent, an analysis of the technology.
1This is a direct consequence of previously obtaining the descriptive models and their use as a script when designing the hypermedia applications.
2Associative (parallel) analysis of related concepts is the greatest advantage offered by hypermedia aimed at the study of complex technologies   .
Use of audio-visual resources makes certain concepts much easier to understand.
It has been noted that several students have gone ahead of the study program for the subject and analyzed topics on their own before they are covered in class. This shows an increased motivation in the subject.
Regarding FPGAs, some students, under their own initiative, look for new commercial devices to add to the application in order to keep the database up to date.
No student has admitted to finding navigation through the application difficult or to having gotten lost.
From the subject teacher's point of view:
Greater motivation has been observed for the subject. The fact that students discover certain knowledge intuitively for themselves encourages them and makes them feel more motivated and confident.
It must be remembered that the applications are made up of pages associated with the concepts included in the descriptive model. In order to navigate through the application an order of preference has been established (occasionally obligatory) which leads the learner to an extent. However, there are a great number of links leading to related pages which give freedom when analyzing the different topics. The students navigate through pages related according to their preferences and way of reasoning.
Greater participation by students has been noted in the lecture room.
It should be pointed out that in the field of electronics, which is the one we are directly concerned with, the bibliography available for the study of a complex technology such as FPGAs, consists of a set of books in which each author analyses the technology from the point of view of a particular manufacturer and adopts the terminology used by them. As a result, a great number of books and manufacturers' manuals, perhaps using ten different names for the same concepts, need to be consulted in order to analyze a topic in depth. The multimedia application (the descriptive model as such) constitutes the compendium for an exhaustive bibliographical search with its corresponding task of unifying terminology. Having this type of material available is of great help to learners who do not have to be told to study ten different books in order to understand a single topic.
Other teachers have become interested in this methodology and have used it to develop applications aimed at teaching microelectronics design. Thus a tool has been created for learning CADENCE (microelectronics design in a CAD environment) and another for teaching VHDL (digital systems description language). Both tools have been designed using the ToolBook author system.
Despite the advantages shown so far, it should be pointed out that there are still some teachers that are reluctant to introduce new technologies in teaching. Some accept the usefulness of hypermedia but consider making the applications to be extra work requiring so much time and dedication as not to be worth it.
From the application designer's point of view:
Developing the descriptive model requires an exhaustive bibliographical search which means a great effort and a lot of time in "extra" work. In both cases the descriptive models were developed by teams of teachers.
The applications have been developed by students and involved several months of work. In both cases they agree on the usefulness of the descriptive models as guides that indicate both the contents of each page and the links between them. This simplified their work considerably, allowing them to concentrate exclusively on the design of the application environment and the audio-visual resources.
The ToolBook author system proved to be a useful tool which, along with other programs dedicated to handling images and sound, allowed high quality hypermedia applications to be developed.
During the application verification period, incorrect links were detected and corrected and at the same time it was decided to add additional navigation resources in order to guarantee robustness.
This article introduces an innovative method for complex technologies analysis and education based on hypermedia. The result of combining the developed method to obtain the descriptive model of a complex technology with hypermedia techniques, generates a valuable tool for research and education. In the first case the designer is provided with detailed information about the different systems available in a technology, helping him/her to choose the suitable device to develop an application. From the education point of view the student is provided with an interactive document including all the characteristics of the technology that is being studied. They can "navigate" through the information from general to more specific concepts according to their interest and their level of knowledge. In this way a progressive opening of black boxes takes place leading to an intuitive comprehension.
As we said before, our proposal is not intended to replace formal teaching methods but to complement them. The hyperdocument will reinforce material covered earlier in the classroom, while material covered earlier in the hyperdocument means the student is better prepared when that topic is introduced in class.
The authors would wish to thank María A. Valdés Peña and José A. Tarrío Valcarcel for their assistance with the development of MDICs and FPGAs.
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María D. Valdés
Departamento de Tecnología Electrónica
Institute for Applied Electronics "Pedro Barrié de la Maza"
Universidad de Vigo
María J. Moure
Departamento de Tecnología Electrónica
Institute for Applied Electronics "Pedro Barrié de la Maza"
Universidad de Vigo
Departamento de Tecnología Electrónica
Institute for Applied Electronics "Pedro Barrié de la Maza"
Universidad de Vigo
María Dolores Valdésreceived the BS degree in Electrical Engineering (1990) from the Central University of Las Villas and the Ph.D. in Telecommunication Engineering (1997) from the University of Vigo (Spain). Nowadays she is a visiting professor in the Department of Electronics Technology of the University of Vigo. Her current research interest is in the area of field programmable gate arrays and programmable logic devices, comprising the development of new architectures oriented to coprocessing functions.
María José Mourereceived the BS degree in Telecommunication Engineering (1992) from the University of Vigo (Spain). Currently she is doing a Ph.D. in the Department of Electronics Technology of the University of Vigo where she is a professor in Digital Electronics since 1993. Her current research interest is in the area of reconfigurable logic and instrumentation systems. Since 1996 she is a member of the IEEE and the Computer Society.
Enrique Mandadoreceived the BS degree in Electronic Engineering (1969) from the Polithecnic University of Madrid, and the Ph.D. by the Polithecnic University of Barcelona (1976). From 1969 to 1978 he was an electronic application engineer working for Miniwatt (Philips). In 1979 he incorporated to the University of Vigo where nowadays he is full professor of Electronics and director of the Institute for Applied Electronics, developing electronic systems for control and measurement. He has published ten books about electronics including "Sistemas Electrónicos Digtales" with eight editions (Marcombo) and "Programmable Logic Controllers and Logic Devices" (Prentice-Hall).
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