[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: A few technical q's from an apple newbie



Mark McDougall replied:

<snip>

>> The high bit of $C019 goes low during the VBL period, which starts
>> at line 192 and continues to line 261.  (Each line is approximately
>> 64 cycles.)
>
>Since all the video timing on the prototype is linked to the VGA output, 
>I've generated a 'fake' 60Hz vsync/vblank (nominally 1460us since that's 
>what Centipede uses). But looks like it's not required for ][+...

I'm sure you intended something other than 1460us, since the
correct period is closer to 16700us...  ;-)

-michael

Check out parallel computing for 8-bit Apples on my
Home page:  http://members.aol.com/MJMahon/