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Re: Max Nr of IC in 66 MHz PCI ?

Hi Silvano,

66MHz PCI supports 5 loads, where you can consider any device on the
motherboard as one load and any PCI socket as two loads.
So, if you just wire 4 devices on a mainboard it's not a big deal. There are
some general layout guielines to follow and your schematic/board design has
to support low skew clock distribution.
If you wanted to have 4 motherboard devices plus one PCI socket it would sum
up to 6 loads which violates the general rules of PCI. This does not mean
that this configuration wouldn't work, but you had to simulate this
environment on your own. In this case I would recommend using PCI-X for the
66MHz environment which is more relaxed in terms of loading and timing
issues. Probably this would mean less efforts than doing a simulation.


Peter Marek
General Director
MarekMicro GmbH
tel.: 049-9621-9732-110
fax: 049-9621-9732-199

----- Original Message -----
From: "Silvano Bettinzana" <bettinzana@diadix.it>
To: <pci-sig@znyx.com>
Sent: Monday, August 05, 2002 2:38 PM
Subject: Max Nr of IC in 66 MHz PCI ?

> Hi all,
> I have to design a system with 4 PowerPC processor (MPC7450).
> I need to use Marvell (Galileo Technology) GT64260 PowerPC-PCI bridge.
> In your opinion, is it possible to connect 4 GT64260 with a shared 64/66
> bus in daisy-chain ?
> Many says that at 66 MHz you can have only 1 IC and 1 connector on one
> What about 4 IC on a 66 MHz PCI ?
> Thanks,
> Silvano