Posted By
Caruso, Fabrizio
on 2019-10-31
08:50:36
|  Re: cpu speed ntsc double clock blank
What does the double clock bit do? Does it set double clock when on the borders? What switches the clock to double and when exactly? Is the kernal setting a raster interrupt that switches the double clock?
Is it used directly by the hardware or by the kernal?
If I do NOT use the kernal, will the double clock be used?
What I don't understand is what reads this bit. The hardware alone? Some portion of the kernal?
I do not use bit 5 of $FF07, instead I set bit 6 of $ff07 to set NTSC mode on PAL machines. This read that this can produce a 2,1mhz clock (see Ultimate Map 2.0).
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