Subject: Re: Time travel..
From: Matt Christian (mattc@visi.com)
Date: Thu Sep 20 2001 - 14:40:20 MDT
Hi,
"Timothy A. Seufert" <tas@mindspring.com> writes:
> At 1:48 PM -0500 9/20/01, Matt Christian wrote:
>
> >I know this was addressed for Adam but I have been having a similar
> >problem. I have a Power Computing PowerCenter Pro (originally 210 MHz
> >604e) upgraded to a 390 MHz G3 via an XLR8 accelerator card.
>
> What is the card's bus frequency and PLL multiplier setting? At 390 MHz
> in a PowerCenter Pro, it seems likely that it's 60 MHz * 6.5. (This is
> important -- see below.)
Yes, I probably should have given that information out...
I do know that the bus is running at 60 MHz, which is the maximum stable
bus speed on a PowerCenter Pro and I chose a cpu speed of 390 MHz
because of that fact. Logic dictates that 390 / 60 = 6.5 so that's the
correct multiplier.
> >> What does the "Dec frequency" line in the mol-log say?
> >
> >Mine states:
> >DEC frequency: 14 MHz, 140:10 mticks/usec
>
> PowerPCs have a high precision built-in timer called the "decrementer",
> which decrements at 1/4 the bus frequency on most PPCs (including the G3
> and the 604e). If MOL and the MacOS running inside of MOL think the
> decrementer runs at 14 MHz, and it is actually running at 60/4 = 15 MHz,
> you've definitely got a source of clock drift.
That makes sense. The XLR8 Mac OS extension must be fixing up something
(the clock?) to compensate for the decrementer speed change because I
don't see much of a time drift (according to NTP) in "normal" Mac OS as
I would with Mac OS running under MOL. I can't run the XLR8 Mac OS
extension in MOL because it freezes up the emulation but that's a
different problem...
- Matt
-- Matt Christian - mattc@visi.com http://www.visi.com/~mattc/ ftp://ftp.visi.com/users/mattc/ Learn to love and love to learn.
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