Mike Willegal <mike@willegal-nospamplease.net> writes:
>   The color burst signal should be 3.579.  With the PAL crystal, the 
>resulting color burst of 3.56 MHZ must be too far off to work.

This is correct.

>   Both PAL and NTSC have color burst information in the horizontal sync 
>signal, however it doesn't appear that the Apple II natively supported 
>color PAL, but I'm not sure about this.   Perhaps that was the reason 
>for the additional PAL encoder card that was available in PAL markets.

Also correct. PAL uses a 4.43MHz color burst and alternates the phase on
each line (hence the name). The color encoder board takes the video bit stream,
looks at 4 pixels at a time (in a sliding window), uses a simple resistor
network to generate an appropriate pair of color signals and feeds this
into a color decoder chip working as an encoder.

>   One final observation, it appears that the CPU on PAL configured 
>Apples runs slightly slower than NTSC Apples.   1.017 MHZ vrs 1.023 MHZ

Also correct. It is however close enough that disk reads still work (the
drives themselves have much larger variations in speed).
-- 
David Wilson  School of IT & CS, Uni of Wollongong, Australia