Date/time battery and "rebooting" the camera

Well, everyone knows that if your camera is behaving strangely you should remove the main battery and the small date/time battery and let the camera sit for a while, right?

I've been skeptical for some time. Didn't work that way on my 300D, as I recall. Turns out it doesn't work that way on my 30D either.

I just removed both batteries and let the camera sit (with power switch on) for 35 minutes.

I had to reset date and time. Nothing else. All my CFs remained the same. Which means, I assume, that they're stored in NVRAM.

Are there Canon cameras that lose their CF settings when the small battery is removed? Or do we all "know" a fact that's not true?

-js

But it's likely that it forces the CPU to reset, as the CPU will need power all the time to run. So if the firmware has some obscure bug, which under some special circumstances causes some kind of malfunction, that may very well be cured anyway, even if the user's settings like custom functions are stored in some flash memory.

Pulling the batteries isn't necessarily so much that it'll reset CFs as that it'll let corrupted working (dynamic) memory "zero out". I do know that my D60 also reset the frame counter when I pulled both batteries on it.

Personally I've always been reasonably convinced that the small battery for date/time backup is just that - backup for the date/time facility and actually has nothing to do with the cameras operating system per se. From what N6 is saying it would seem that custom functions are held in a non volatile flash type memory and as such will remain intact ad infinitum. I can see however that removing the main battery for any length of time will, as Anders says, reset the CPU and remove any 'bugs' or erroneous operation that may have occurred.

If they have a separate clock chip, or a separate part of the CPU acts as the clock chip, then, yes.
But if the CPU administrates the clock from interrupts from the timer, then the CPU needs to be powered, at least in part, all the time. As the clock do run when you take the main battery out, that would mean that the small battery does run the CPU as well. At least to some extent.

But I have far too little insight in the architecture of the control circuitry of Canon's modern cameras to have any idea about how they've solved this problem. In some designs, even taking the backup battery out will not make it loose the time, as the clock may run for a while from a supercap anyway.