Quote:
Originally Posted by Toni Wilen
All Amiga models have same CIA timer clock rates, ~709KHz if PAL model and ~715KHz if NTSC model.
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Not necessarily all Amigas use standard PAL or NTSC modes. I use a customized DblPal driver on my A1200 that's 50.04 hertz according to MonSpecsMui, and 49 hertz according to my monitor's OSD (now what is the true frequency?) . In the past I've even used a custom 96 hertz interlaced mode.
How can you get accurate timing if these vertical rates can vary so much?
Quote:
Originally Posted by thomas
VBLANK has a resolution of 50Hz or 60Hz. This is by far enough to wait for the next second. There is no need to waste a CIA for timing.
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On systems with an RTC you simply count VBlanks and read the clock once per second. Accurate and fast.