I've noticed that the smaller 18F parts are rated at 40 MHz, but the
larger ones are not. My guess is that the larger ones have more
peripherals hanging on the internal bus, making it hard to move the bus
that fast.  Does my guess sound reasonable? When I first started with one
of the big 18F chips, the datasheet said 40 MHz. My prototype worked, but
production didn't. A piclist member pointed out an erratta dropping the
clock speed to something like 25MHz.

Harold

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