Evolvable hardware (EHW) has attracted increasing attention since early 1990's with the advent of easily reconfigurable hardware such as field programmable gate arrays (FPGAs). It promises to provide an entirely new approach to complex electronic circuit design and new adaptive hardware. EHW has been demonstrated to be able to perform a wide range of tasks from pattern recognition to adaptive control. However, there are still many fundamental issues in EHW which remain open. This paper reviews the current status of EHW, discusses the promises and possible advantages of EHW, and indicates the challenges we must meet in order to develop practical and large-scale EHW. 1 Introduction Evolvable hardware (EHW) refers to hardware that can change its architecture and behaviour dynamically and autonomously by interacting with its environment. At present, almost all EHW uses an evolutionary algorithm (EA) as their main adaptive mechanism. One of the key motivations behind EHW is to learn from N...

Inspired by biological development where from a single cell, a complex organism can evolve, we are interested in nding ways in which arti cial development may be introduced to genetic algorithms so as to solve our genotype challenge. This challenge may be expressed in terms of shrinking the genotype. We need to move away from a oneto -one genotype-phenotype mapping so as to enable evolution to evolve large complex electronic circuits. We present a rst case study where we have considered the mathematical formalism L-systems and applied their principles to the development of digital circuits. Initial results, based on extrinsic evolution, indicate that our representation based on L-systems provides an interesting methodology for further investigation. We also present our implementation platform for intrinsic evolution with development, enabling on-chip evaluation of grown solutions.

Biological organisms are among the most intricate structures known to man, exhibiting highly complex behavior through the massively parallel cooperation of numerous relatively simple elements, the cells. As the development of computing systems approaches levels of complexity such that their synthesis begins to push the limits of human intelligence, engineers are starting to seek inspiration in nature for the design of computing systems, both at the software and at the hardware levels. This paper will present one such endeavor, notably an attempt to draw inspiration from biology in the design of a novel digital circuit: a field-programmable gate array (FPGA). This reconfigurable logic circuit will be endowed with two features motivated and guided by the behavior of biological systems: self-replication and self-repair. 1

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of the work presented in this thesis has been previously published as listed below. Although some of these papers have co-authors, the work appearing in this thesis is entirely my own, with the exception of parts of chapter 3, which presents work jointly carried out by myself and Adrian Thompson. The respective contributions to this work will be explicitly stated at the beginning of the chapter. List of Previous Publications Kuntz, P., Layzell, P., & Snyers, D. (1997). A Colony of Ant-like Agents for Partitioning

Abstract. Evolvable Hardware (EHW) is a scheme- inspired by natural evolution, for automatic design of hardware systems. By exploring a large design search space, EHW may find solutions for a task, unsolvable, or more optimal than those found using traditional design methods. During evolution it is necessary to evaluate a large number of different circuits which is normally most efficiently undertaken in reconfigurable hardware. For digital design, FPGAs (Field Programmable Gate Arrays) are very applicable. Thus, this technology is applied in much of the work with evolvable hardware. The paper introduces EHW and outlines how it can be applied for hardware design of real-world applications. It continues by discussing the main problems and possible solutions. This includes improving the scalability of evolved systems. Promising features of EHW will be addressed as well, including run-time adaptable systems. 1

This paper describes an image compression system based on Evolvable HardWare (EHW) for High Precision Printers (HPP). These printers are especially flexible for book publishing, but require large disk space for images, in particular those of higher resolution. To increase the printing speed and reduce the disk space, the images should be compressed. The system for this compression must be 1) adaptive, so that it changes depending on image characteristics and 2) on-line, which means implemented in hardware. The standard compression methods have a simple template change strategy which is not efficient for the images of HPP. We used an EHW system for compressing HPP images in real time. The EHW is a type of adaptive hardware which allows evolutionary algorithms to change the hardware configuration in real time. It works as fast as other compression systems (like JBIG standard), but changes the image modeling to reflect the changes in the image characteristics. Simulation results show more than a 50 % increase in compression ratio compared to JBIG for the printer system. 1.

life into dead silicon