[Coco] Coco game engine demo

[Frank Swygert]

Date: Sun, 03 Feb 2013 08:42:23 -0800
From: Richard Goedeken<Richard at fascinationsoftware.com>

Art,

That is a very astute observation, and actually illustrates why my number is
correct.  The field rate for NTSC video is not exactly 60 fields/sec, but
59.94, or more precisely, 60000/1001.

This brings up a separate question.  Does anyone know if the PAL and NTSC
versions of the Coco use different clock frequencies?  I know that they did
for the Commodore Plus/4, and the PAL version was run at a speed that was a
few percent higher than the NTSC machine.
====================================

Hmmmm.... IIRC the PAL machine (at least the CoCo1) had a separate video generation board with a separate crystal. It read the NTSC video signal then converted to PAL. I believe the later CoCo2s (if not all) had a different motherboard for NTSC and PAL versions. The 6809e and main circuitry all used the same clock.

-- 
Frank Swygert
Editor - American Motors Cars Magazine
www.amc-mag.com