Author Topic: PowerMac 5400/5500/6400/6500 Cuda Button?  (Read 699 times)

Online OminousSilence

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PowerMac 5400/5500/6400/6500 Cuda Button?
« on: November 07, 2019, 04:58:04 PM »
Hey so I have a bit of a worry that has wriggled its way back into my head as I prepare clean the dust bunnies out of my 5500 in the next couple of days (we own a cat so this is essential maintenance).

There is a Cuda reset button on the motherboard that erases and resets certain things. I will be honest and I have no idea what these certain things are, nor have I ever encountered the desire to touch the button.

Mainly my fear is if I ever accidentally touch the button, it will reset all the monitor settings and I do not have the fabled Monitor Adjustment Cable (part 922-1513) to readjust the display. In fact, I would really really like to own one of these cables because the PAL video display mode was never adjusted, and the right pincushion needs tweaking because it was very obvious that the last person who adjusted the monitor was sat to the left of it. Anyway, I digress.

My questions are: will accidentally pressing the Cuda button reset all the display modes, rendering the 5500 totally useless? What settings are held on the Cuda management chip anyway? Why does Apple have to make adjusting a monitor so bloody hard? And finally, does anyone know why MacTracker brings down the system if I have virtual memory turned off? There's 128MiB RAM in there, MacTracker can't possibly need more than 16MiB to run in, right?
IF $MachineID = 512
THEN $Normal = FALSE : $Reason = just because, lol
ENDIF

Offline IIO

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Re: PowerMac 5400/5500/6400/6500 Cuda Button?
« Reply #1 on: November 08, 2019, 01:52:38 AM »
the cuda/pmu button disconnects the buffer battery. this does not only reset the PRAM but also the NVRAM.

if that affects your custom flashed GPU“s monitor settings or if those prefs are stored in a file? no idea.

p.s. PRAM content can theoretically be saved and restored (using techtool among others)
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Online OminousSilence

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Re: PowerMac 5400/5500/6400/6500 Cuda Button?
« Reply #2 on: November 08, 2019, 12:44:01 PM »
but also the NVRAM.

Not gonna lie, having seen the amount of faff it takes to get a Sun booted when its NVRAM chip is dead (who on Earth thought putting the NVRAM battery inside the memory die itself was a good idea?), this fills me with moderate feelings of doom.

I shall treat it with utmost caution then. I think I have some plastic caps I can put over for safety. Thanks!  ;D
IF $MachineID = 512
THEN $Normal = FALSE : $Reason = just because, lol
ENDIF