[Coco] Instruction cycles per 60Hz frame.

Alex Evans varmfskii at gmail.com
Sun Nov 17 16:52:53 EST 2019


Is it worth taking into consideration that the 60Hz should actually be
59.94Hz assuming NTSC (30/1.001 full frames or 60/1.001 half frames).

On Sun, Nov 17, 2019 at 2:39 PM Ed Snider <zippster278 at gmail.com> wrote:
>
> Correct.  Round down to the nearest whole cycle of course.
>
> 894886 cycles per second at single speed.
> 1789772 cycles per second at double speed.
>
> - Ed
>
>
> > On Nov 17, 2019, at 12:41 PM, James Ross <jrosslist at outlook.com> wrote:
> >
> > continued:  actually the math can simplified to ...
> >
> > cycles_per_60hz_frame = (1d / 60d) * 1000000 * coco_clk;  // 0.8948... MHz
> > double_cycles_per_60hz_frame = (1d / 60d) * 1000000 * double_speed; // 1.789... MHz
> >
> > which gives the same results:
> > standard 60hz (vsync) frame = 14914.7727272727 cycles per frame
> > double speed 60hz (vsync) frame = 29829.5454545455 cycles per frame
> >
> > so, unless I am really confused (which is quite possible!), then the #'s above have to be correct ... ok moving on then :) :)
> >
> > james
> >
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>
>
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