PCI-SCI Protocol Translations: Applying Microprogramming 
                Concepts to FPGAs.

   Georg Acher, Wolfgang Karl, Markus Leberecht

     Lehr- und Forschungseinheit Informatik X
  Rechnertechnik und Rechnerorganisation (LRR-TUM)
          Institut für Informatik der 
        Technischen Universität München
     Arcisstr. 21, D-80290 München, Germany
        karlw@informatik.tu-muenchen.de

                      Abstract

The SMiLE project at LRR-TUM adopts and implements the Scalable
Coherent Interface (SCI) interconnection technology to couple
Pentium-II based PCs into a compute cluster with distributed shared
memory. A custom PCI-SCI adapter has been developed for bridging the
PC's PCI local bus with the SCI network. Such a PCI-SCI adapter
intended for connecting PCI-based PCs via  SCI involves complex
protocol processing. In the paper we describe the rationale and
implementation issues of our custom PCI-SCI adapter design. In
particular, we demonstrate how traditional microprogramming techniques
can be applied for a structured and simplified FPGA design.