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PCI-ISA


PCI-ISA Passive Backplane Standard

Introduction

The PCI-ISA Passive Backplane Standard was developed by PICMG member companies to adapt desktop PCI standards for industrial applications.

 

Dual Pentium SBC
Dual Pentium PCI-ISA Passive
Backplane Single Board Computer

Desktop computers generally have most of their circuitry on a single large "motherboard" that mounts to the bottom of the computer's chassis. While this is the least expensive packaging method, it leaves a lot to be desired when used in industrial applications. The motherboard, usually constructed from 0.062" material, is thin enough and large enough to flex when inserting plug-in boards. This flexure can, and often does, break small traces and solder joints on fine pitch surface mount devices. Replacing a motherboard necessitates complete disassembly, removing all cards and cables from the system. Downtime ranges from 30 minutes to several hours. This is unacceptable for many critical industrial or telephony applications. Since motherboard technology changes literally monthly, is is usually impossible to find an exact replacement. Using another motherboard often causes software problems due to BIOS changes, changing device drivers, and different timing. These can take days or weeks to completely solve.

The PCI-ISA passive backplane standard moves all of the components normally located on the motherboard to a single plug-in card. Looking much like a standard ISA or PCI card, a PCI-ISA CPU card has two edge connectors on it - one for the PCI bus and one for the ISA bus. The "motherboard" is replaced with a simple "passive backplane" that has only connectors soldered to it. This backplane is simple and robust, with a very low likelihood of failure.

Passive backplane systems have several advantages. First, they are more maintainable than a motherboard system and have a much lower mean time to repair (MTTR). Second, it is easy to upgrade to a newer and faster processor if desired. Third, passive backplane CPU's are generally manufacturerd by industrial suppliers who provide configuration control and longer product lifetimes than those typical of the desktop world.

Single board computers conforming to the current standard (Revision 2.0) have been in production for over two years by over 30 manufacturers worldwide.

PCI-ISA Passive Backplane Specification

A more detailed description of the PCI-ISA Passive Backplane specification is available in Adobe Acrobat PDF format. If you currently do not have Acrobat Reader software, please download the free software and installation instructions from Adobe.

   
Download a more detailed description of the PCI-ISA Passive Backplane
Specification in PDF Format
(16K)

 

The Complete PCI-ISA Passive Backplane Specification

The complete specification can be obtained from the PCI Industrial Computer Manufacturers Group (PICMG) by using our Non Member Specification Order Form, or by calling PICMG at 1-781-246-9318.


PCI-PCI Bridge Standard

The PCI-PCI Bridge Standard provides for a standardized way to extend the number of PCI slots available in a passive backplane system.

The complete specification can be obtained from the PCI Industrial Computer Manufacturers Group (PICMG) by using our Non Member Specification Order Form, or by calling PICMG at 1-781-246-9318.