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Re: Apple Graphics Tablet
Hey Alex,
On Mon, 18 Jun 2012, Alex Freed wrote:
On 6/18/2012 11:10 PM, Vladimir Ivanov wrote:
Q3 is more like strobe than clock - both composite and non-50% duty
cycle. The creative abuse in Disk II interface won't work for all
scenarios.
Actually a 50% duty is not often needed for a clock - the circuits like
flip-flops and counters only care about one edge.
True. I was merely pointing out that there is no regular 2 MHz clock in
the Apple II.
I don't know the MockingBoard, Phasor and the likes, but if they feed
re-generated 2 MHz to the internal sound oscillators (i.e. don't have
on-board master clock) that explains why Q3 wasn't suitable.
BTW using a tuned LC circuit for frequency multiplication is not very
"creative" as it is a standard practice in radio transmitters since the
dawn of radio. For low integer factors beats the fancy PLLs in terms of
jitter not to mention the cost.
The "creative" I put for Disk II, where Q3 edge only was enough.
BTW, have you done any test with those NTSC tables? Just curious.