I am working on a project with my Plus. The analog board is dead and while I do plan to fix it, I want to play around with a microcontroller. Anyway, One thing I'll need the microcontroller to do is read the video signal and convert the data to a VGA signal. I'm going to be using the Parallax Propeller microcontroller and it can generate a VGA signal natively. However, while doing research, I found that the video signal is 15.6672 MHz (the frequency of the oscillator). While the propeller runs at 80 MHz, sampling an odd frequency will be difficult, if not impossible. I can change the oscillator to 16 MHz rather easily, but I'm curious why Apple chose such an odd frequency in the first place. I know I've read the reason in the past, but I don't remember where and I don't remember why. If I were to swap out the oscillator, would it potentially damage the Mac? I doubt the .1664 MHz jump would hurt anything, but I want to make sure first.

While on the subject, I can get a 10MHz 68000. It might be interesting to upgrade the processor and the oscillator to 10 MHz...