RE: PLL in PCI mode.

[Neal Palmer <neal@dinigroup.com>]

Austin,

  I have not seen a system that actually stopped the clock completely.  
But I have gone through the "spread-spectrum" hassles.  The host chipset 
manufacturers (Intel based motherboard) implemented spread spectrum 
clocking which screwed up most of the PLLs that were available at the 
time.  So anybody who had a PLL in their chip more than about 4 years ago 
probably would have had to re-spin their chip with a new PLL to make it 
even function properly in those "newer" motherboards.

  Also, how long do you think it is going to be before people realize that 
computers take a lot of power, and since they are allowed to stop the 
clocks in the system, why not do it to save power?

-- Neal


On Sun, 28 Jul 2002, Austin Franklin wrote:

> Neal,
> 
> Do you actually know of any commercial systems that allow the clock to be
> stopped on the PCI bus?
> 
> Some of the early PCI bus systems were able to change the PCI bus speed
> between 25 and 33 MHz...but I haven't seen one able to do that for a
> while...and I certainly have never seen one that stops the PCI clock...at
> least when the power switch is on, and it's working right ;-)
> 
> Regards,
> 
> Austin
> 
> 
> > Kanti,
> >
> >   If you are running in 66Mhz PCI mode, then you are allowed to
> > use a PLL.
> > But if you are running in 33Mhz PCI mode, then you are most
> > definitely not
> > allowed to use a PLL (the clock can stop).
> >
> > -- Neal
> >
> > On Sun, 28 Jul 2002, Kanti Ohri wrote:
> >
> > > Hello,
> > >
> > > Is it Ok to use the PLL, in the PCI mode of operation, in PCI-X
> > rev 1.0 to
> > > meet the PCI timings?
> > >
> > > Cheers,
> > > KKO
> > >
> >
> > --
> > -- Neal Palmer
> >
> > The Dini Group
> > 1010 Pearl St #6
> > La Jolla, CA 92037
> > (858) 454-3419 x16
> > (858) 454-1728 (Fax)
> >
> 

-- 
-- Neal Palmer

The Dini Group
1010 Pearl St #6
La Jolla, CA 92037
(858) 454-3419 x16
(858) 454-1728 (Fax)