Skip to main content

Agents: a distributed client/server system for leaf cell generation

Moreira, Dilvan de Abreu (1995) Agents: a distributed client/server system for leaf cell generation. Doctor of Philosophy (PhD) thesis, University of Kent. (doi:10.22024/UniKent/01.02.94541) (KAR id:94541)

PDF (Optical Character Recognition (OCR) of this thesis enables read aloud functionality of the text.)
Language: English

Click to download this file (63MB) Preview
[thumbnail of Optical Character Recognition (OCR) of this thesis enables read aloud functionality of the text.]
This file may not be suitable for users of assistive technology.
Request an accessible format
Official URL:


The Agents system generates the mask level layout of full custom CMOS, BICMOS, bipolar and mixed digital/analogue leaf cells. Leaf cells are subcircuits of a complexity comparable with SSI (Small Scale Integration) components such as small adders, counters or multiplexers. The system is formed by four server programs: the Placer, Router, Database and Broker. The Placer places components in a cell, the Router wires the circuits sent to it, the Database keeps all the information that is dependent upon the fabrication process, such as the design rules, and the Broker makes the services of the other servers available. These servers communicate over a computer network using the TCP/IP Internet Proto­col. The Placer server receives from its client the description and netlist of the circuit to be generated using EDIF (Electronic Design Interchange Format). The output to its client is the layout of the circuit (no virtual grid is used), again codified in EDIF. The concept of agents as software components which have the ability to communicate and cooperate with each other is at the heart of the Agents system. This concept is not only used at the higher level, for the four servers Placer, Router, Broker and Database, but as well at a lower level, inside the Router and Placer servers, where small rela­tively simple agents work together to accomplish complex tasks. These small agents are responsible for all the reasoning carried out by the two servers as they hold the basic inference routines and the knowledge needed by the servers. The key concept is that competence emerges out of the collective behaviour of a large number of rela­tively simple agents. In addition and integrated with these small agents, the system uses a genetic algorithm to improve components’ placement before routing.

Item Type: Thesis (Doctor of Philosophy (PhD))
Thesis advisor: Walczowski, Les T.
DOI/Identification number: 10.22024/UniKent/01.02.94541
Additional information: This thesis has been digitised by EThOS, the British Library digitisation service, for purposes of preservation and dissemination. It was uploaded to KAR on 25 April 2022 in order to hold its content and record within University of Kent systems. It is available Open Access using a Creative Commons Attribution, Non-commercial, No Derivatives ( licence so that the thesis and its author, can benefit from opportunities for increased readership and citation. This was done in line with University of Kent policies ( If you feel that your rights are compromised by open access to this thesis, or if you would like more information about its availability, please contact us at and we will seriously consider your claim under the terms of our Take-Down Policy (
Uncontrolled keywords: Knowledge based systems
Subjects: Q Science > QA Mathematics (inc Computing science) > QA 76 Software, computer programming,
Divisions: Divisions > Division of Computing, Engineering and Mathematical Sciences > School of Engineering and Digital Arts
SWORD Depositor: SWORD Copy
Depositing User: SWORD Copy
Date Deposited: 21 Jun 2022 13:57 UTC
Last Modified: 17 Jul 2023 09:14 UTC
Resource URI: (The current URI for this page, for reference purposes)
  • Depositors only (login required):

Total unique views for this document in KAR since July 2020. For more details click on the image.