Subject: Re: Strange date problem
From: Chris Boot (bootc@worldnet.fr)
Date: Sun Jan 27 2002 - 09:51:42 MST
>> I haven't messed with the PRAM or the cuda switch. What is the cuda
>> switch exactly? Like a super-hard reset?
>>
>
> CUDA is the powermanagement unit, all recent macs have them, or something
> similar. This is what makes your mac go nighty-bye-bye after some defined
> amount of time of inactivity. Reseting this makes all your power setting
> go away, resets the PRAM and does some other things which I forget.
> Under the standard Apple Problem Diagnosis Workflow this is normally
> listed right before "Replace CPU, Replace Logic Board." (eg: it's pretty
> much the last thing you can do to solve problems with your mac unless you
> have spare CPU's and logic boards hanging about)
Not exactly. The way I see it is that every Mac is either CUDA based
(OldWorld: beige & black Macs) or PMU based (NewWorld: colorful Macs). The
CUDA switch is like a hardware PRAM reset, much like Command-Option-P-R, but
it resets things better. I don't know if PMU based Macs have such a switch
(haven't gutted my iMac yet), but the PRAM and OpenFirmware / PMU variables
can be reset from within the OpenFirmware prompt (reset-nvram, set-defaults,
etc...).
CUDA and the PMU are two different versions of the power management
facilities of the Mac. That's what starts your Mac up when you press the
power button on your keyboard / computer, what wakes it up from sleep, what
puts it to sleep, what helps the thing shut down, and what keeps the time.
It's like a mini computer all of its own that can only do what it's told to
do in the factory (or in the firmware).
That's how I understand it, anyway. Feel free to correct me, though.
--
.-. Chris Boot
/v\ bootc@mac.com
// \\
/( )\ L I N U X
^^-^^ >Phear the Penguin<
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