Magma PCI Expansion System User Manual

The PCI Local Bus Specification defines the PCI bus as a hierarchical 
bus, where PCI to PCI Bridges (PPBs) may be used to add "levels" to 
the PCI bus hierarchy. Because hierarchies are organized systems 
arranged into different levels, you can take advantage of this automatic 
organizing and layering to expand the number of available PCI slots 
beyond the number available in your computer’s motherboard.  

You can easily add two or more Magma expansion systems to your 
current system in either a "fan-out" or "daisy-chain" configuration. Each 
of these configurations has advantages and uses. To determine which 
type of configuration you wish to use, you should first understand a few 
basic facts:  

1.  In a desktop computer, the bios enumerates automatically 

behind PCI bridges. In the Magma configuration, the bios finds 
the Magma host card in a PCI Express slot. The bios 
configures it, and then looks beyond it to find any PCI cards 
installed in the expansion chassis. The bios then configures 
the cards and allocates resources. Empty PCI slots are ignored 
during configuration.  

 

In theory, your computer “should” be able to travel across up to 
255 PCI buses to identify and configure all installed PCI cards. 
Unfortunately, not all computers are created equal. The 255 
PCI bus limit is actually a theoretical maximum. The practical 
limit is somewhat lower, but should still be a fairly large number. 

 

 

In a desktop computer the bus numbers tend to be lower (0, 1, 
2, etc.).  Once the bios is finished configuring everything and 
assigning resources, the Operating System starts loading and 
activates the PCI cards found. 

 

 

When adding more Expansion Systems to an existing system, 
be sure to connect and test them “one-at-a-time.” This will allow 
you to quickly resolve any connectivity, or other, issues right at 
the start. DO NOT INSTALL any 3

system until ALL attached systems are working correctly.