RE: How can I extend the number of loads/slots ?

["Ingraham, Andrew" <Andrew.Ingraham@compaq.com>]

> How is the max number of loads calculated ? 
> Can I extend the number of loads/slots if I change capacitance
 
This is a "signal integrity" and timing problem.  The only good way to
determine it, is by simulation.

Keeping the number of EFFECTIVE loads to 10 or less (four connectors and two
motherboard ICs, or two connectors and six motherboard ICs), usually works
OK at 33MHz without having to simulate it, as long as the traces are kept
short.  Two, maybe three total devices is about the practical limit for
66MHz.

Reducing capacitance may help for motherboard devices where the routing is
daisy-chain with no stubs.  But on a PCI plug-in card, the connector and the
trace to the IC remain as significant components, even if you could reduce
the IC input capacitance to zero, so it might not help much.

Again, the best advice is to simulate it.

>  or add
> repeaters ?
 
You can add PCI-PCI bridges to break a long bus up into shorter ones, but at
some consequence in performance.

I don't think it is possible to extend a PCI bus using ordinary buffers
(transceivers), unless it is very slow and you add enough intelligence to
the buffers to control their direction.

Andy