Re: Running PCI cards at slow clock speeds

[johnp@iia.com]

> From:          "Witalka, Jerome J           RV" <jjw1@PO9.RV.unisys.com>
> Cc:            "Steege, Richard H           RV" <rhs1@PO9.RV.unisys.com>
> Subject:       Running PCI cards at slow clock speeds
> Date:          Thu, 22 Aug 96 10:11:00 CDT
> To:            Mailing List Recipients <pci-sig-request@znyx.com>

> 
> We are building a PCI Bus Host bridge chip and are looking at a test tool   
> that will allow us to simulate our VHDL design and run a real PCI Bus at   
> approximately 1/1000 the normal clock speed.  We would like to run the   
> tester with a real SCSI PCI card with SCSI hard disks attached.
> The PCI Bus spec requires that the cards run at any clock speed between   
> zero Mhz and the maximum speced speed (33/66 Mhz).  Has anyone tried   
> running disks attached to a PCI card with a significantly slowed down PCI   
> clock?  Is this really feasible?
> 
> Jerry Witalka  M.S. 4873                 EMail:jjw1@po9.rv.unisys.com
> Unisys Corporation                          Voice:  612-635-7958
> P.O. Box 64942
>  St. Paul, MN 55164-094   
> 
> 

I've never dealt directly with a systme doing this, but I know of several 
companies that have run the PCI VERY slowly in order to use h/w emulators to 
develop PCI bus interfaces.

My question is -

Does anyone know of a PCI-PCI bridge that allows different clock rates on 
each of the PCI busses?  For this emulation/test scheme, it would be great to 
run the main PCI bus at 33MHz and have a bridge to a secondary bus that runs 
at 1MHz or less.  This allows the processor and major peripherals to run at 
high speed while the device being emulated runs at slow speed.


Any ideas?

Thanks!

John Providenza  (johnp@iia.com)
503-968-1270 (voice)
503-968-1773 (FAX)
t