Re: [stella] Timing blues...

Subject: Re: [stella] Timing blues...
From: Chris Wilkson <ecwilkso@xxxxxxx>
Date: Tue, 31 Jul 2001 00:44:49 -0400 (EDT)
The NTSC VCS runs at 3.58MHz (3.57, 3.56, 3.6...).  This clock feeds directly
into the TIA where it is divided by three to form a 1.19MHz 2-phase clock for
the 6507.

In NTSC *everything* runs off that same 3.58 clock.  Scanlines are 227.5
clocks each.  Fields are 262.5 scanlines each.  Frames are 2 fields each.
Etc.  The color burst is defined by the clock, both frequency and cycle
count.  The timing for all the blanks, porches, sync pulses, everything.

Regarding KoolAid Man glitches, it could be anything.  It could be different
pcb routing, but more likely it's something in the chip (TIA) that just
doesn't happen fast enough.  Or said another way, something else is happening
too soon.


On Mon, 30 Jul 2001, Eckhard Stolberg wrote:

> OK, I looked up television in the encyclopedia. It seems that the
> 4.433618 clock corresponds with the carrier frequency for the
> colour encoding on PAL systems. The 3.546894 clock corresponds
> with the PAL colour burst signal. The colour burst signal on NTSC
> seems to be a little higher at about 3.57 MHz, so I'm assuming
> that the NTSC VCS is running at that speed? So it seems that the
> PAL VCS is a little slower than the NTSC VCS.  How this can cause
> effects like in Kool Aide Man I don't know either.
> Ciao, Eckhard Stolberg
> -
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