> As my current timing routines are geared to 4MHz, it was my
> objective to use the RC oscillator at 4MHz. The RC oscillator
> wave form at 4MHz is a clean square wave with rounded upper
> corners. The amplitude, turn on and turn off times of the wave

4MHz isn't really pushing it for an F84A. 6MHz would be I think.
Main thing is that you've got something cheap, predictable,
repeatable etc etc

I mentioned the comparison between F84/F84A and F628 to
illustrate how the RC high end is being extended with each
new release. I'm sure 4MHz RC on an F84A / F628 would more
than likely be superior to that of the older F84. I'm still waiting
for a 17C44 to upgrade my PSP so I can use F628s. AFAIK
Microchip has still not quantitised the single R mode for the
F628 and that was going to be one of my first little jobs. As you
know this thread started because there was apparently no (I
have to say easily produced) graph from Microchip for selecting
RC values for the F84A

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