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General discussion

What is PRAM?

Jan 1, 2006 1:35PM PST

I keep seeing references to this PRAM thing. What is it? What does it accomplish?
Thanks

Discussion is locked

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PRAM
Jan 1, 2006 9:41PM PST

is Parameter RAM which a non-volitile RAM chip that keeps various bits of information about the System Parameters(settings) stored between power downs.
Information like date, time, port settings, screen resolution, network settings and a bunch of other things. It is all kept running by the little 3.6 volt lithium battery that sits on the logic board. Usually the first noticeable indication that this battery is failing is that the date and time revert to a certain date. It used to be 1904, then 1956 and now it is some other date. Replacing the battery, resetting any of the settings that reverted to default, puts you back on track.
Occasionally the PRAM becomes corrupt and can prevent the machine from booting up. It's at this point that you ZAP the PRAM. All this does is erase certain parts of the information that is stored there, which forces the system to reload the PRAM with new, and uncorrupt, information and, hopefully, the machine will boot. Apple+Option+P+R will accomplish this. It is not a routine maintenance thing.

Does that help?

P

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Totally
Jan 2, 2006 3:11AM PST

Thanks, that was a perfect reply.
Except...so, you hold down the keys and then restart? How many times do you want to hear the "Tone of the Blessed Mac"?

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Three is the minimum
Jan 2, 2006 4:09AM PST

but four is OK too.

Press the power button, hold down the four keys and wait for four start up chimes and you should be good to go

P

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Got It!
Jan 5, 2006 5:00AM PST

Thanks for your thorough and clear explanation! Aloha!

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PRAM Revisited
Jan 11, 2006 1:19PM PST

Pete, Remember when on another post I thought my IT guy had reset the battery?
Was next to the battery and was a reset for the PRAM, after all. Asked one of the IT guys today to show me the reset switch and received the answer as you described exactly.

Also was taught something new today from him, hands-on and showed me the PRAM switch to reset after ten minutes with the computer off. Who knew!
Live and learn something new each day.

Thanks for your help to all of us,

-Kevin

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NOT the PRAM switch
Jan 11, 2006 8:41PM PST

Kevin,
That switch that your IT guy showed you was NOT the PRAM switch. It is called the CUDA switch and it discharges some power from the motherboard and, coincidentally, destroys some of the PRAM settings. PRAM is reset using Apple + Option + P + R at start up. Holding down those keys until at least the third chime, preferably four, will reset the PRAM.
Turning the computer off for 10 minutes and then pressing the button does nothing that just pressing the button with the computer on will not do. You already know how to reset the logic board, I have posted that to you a couple of times.
BTW, how many times does your IT guy advocate pressing this button?

P