[Coco] Update on new Coco 3 game engine

[Nick Marentes]

Or you could simply have a prompt at the start of the game asking for 
which GIME chip you have along with whether you are running PAL/NTSC. 
(If one doesn't work, try the other)

In some of my earlier games, I also ask if you wish 50/60Hz operation 
for those users in countries using a PAL video system (Some PAL monitors 
lose sync at 60Hz, such as the CM-8)

It's all working for me now with an '87 GIME CoCo3. I'll setup an '86 
GIME CoCo3 on the weekend and test my code.

Good to see you back John.

Nick



Original message:
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There are two things you can do:
A) In the 60hz IRQ, set up and enable the timer to trigger FIRQs. In
the FIRQ, advance a counter. In the next 60hz IRQ, disable the
timer/FIRQ again and check how many times the counter advanced. The
count will be different from both '86 and '87 GIME ('87 will give a
higher count value than '86)

B) Use the 279.365 nsec source clock for the timer instead of the
63.695 usec source clock. The timer frequency will still be off by
one count depending on GIME, but since you have to set the countdown
to a high value to set your sample rate, the audible difference
between the two will be imperceptible.