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Originally Posted by DRC Yes! technically all processors can be over clocked if they are not operating at their obsolute maximum specifications. I stand corrected. However it is not the case in specific applications like ECU. For the reason that difference in clocking may mean a different software, especially when there are time dependant applications are run. So, I actually meant, over clocking is not a user option as in case of x86 systems. (Apple uses(d) PPC processors, but I am not sure if there was over clocking facility in their Macs) |
The firmware is usually designed that it does not rely on the PLL clock to measure event duration. So as long as relative clock frequency is same, the same firmware will work in *MOST* cases.
The reason is that in case of the clock generator PLLs the circuitry is analog and clock frequency changes slightly during operation. There is shift and jitter. To get an extremely accurate clock generator, costs will be prohibitive. So the firmware takes this into account, and event duration is usually measured in terms of external Stimuli.
Some companies make their processors such that the clock generator circuit cannot be tweaked at all to minimize failure etc., The limitation is more of a design rather an a functional limitation. |