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Re: tiBook CPU speed

Go to the main penguinppc.org page. Apparent BenH has gotten the 800Mhz TiBook's to run at native speed. I have a hunch though, that maybe the 667Mhz and 800Mhz TiBook's are exactly the same hardware, and it is only a software hack to get them to go to 800Mhz (this is why the speed throttling on the 800Mhz only goes down to 667Mhz). Wouldn't it be interesting if there was a hack so that all of a sudden the 667Mhz is equal to the 800? Since the rest of the machine is exactly the same except for addon components like RAM and Airport, it certainly would entice many people to get a low-end TiBook. Who knows, hopefully BenH will say something about it.

Bobby MacGregor

On Monday, August 5, 2002, at 05:01  PM, Toby Sargeant wrote:

I noticed this issue mentioned previously on this list, but there didn't
seem to be any resolution.

The 800MHz tiBook boots linux in 667MHz mode:


0000000: 27c1 9cc0                                '...
0000000: 2faf 0800                                /...
0000000: 27c1 9cc0                                '...
0000000: 0000 0001                                ....

I don't know if that last entry is a bitmask, or a state. I imagine that
if it's a state, I can just go and reset it in Open Firmware, and
everything will be OK, but for laptop users, being able to throttle the
CPU speed is really useful.

A cursory poke around the PPC 7455 docs on the motorola website seems to
indicate that the speed throttling isn't done with an MSR on the CPU. I
don't know where to look for good documentation about Open Firmware and
Apple hardware (any pointers?).


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Bobby MacGregor
Austin, TX, USA

"Beer is proof that god loves us and wants us to be happy"
-- Ben Franklin

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