Apple II timing vs. NTSC (was Re: Good Composite->VGA converters for classic computers (& video games...)

[Eric Smith]

Eric Smith wrote:
> The Apple II horizontal rate is 228.0 times the color subcarrier
> frequency, so that the color phase is the same on every line.

Jim wrote:
> Was there a reason for this design decision?

It was done so that the same bit pattern that produces green on one scan
line also produces green on the next scan line, rather than purple.  This
is especially important for the low-res graphics mode, but not doing it
would also have made the high-res mode harder to use.

Eric