[Coco] Software testing for FDC emulator

[gene heskett]

On Tuesday, April 26, 2011 12:21:46 PM Frank Pittel did opine:

> Gene,
> 
> Between you, me, the floor and anyone else reading this I don't this is
> a fixable problem either. I was just giving Mark a little grief. :-) In
> my never humble opinion the only way to make the "gun" work is to have
> the coco communicate with the "gun" hardware.
> 
> The Other Frank

Chuckle, but it does communicate with the gun hardware, by checking for the 
pulse from the photo-transistor in the gun as the electron beam goes flying 
by the spot on the screen that is focused on the photo-transistor.  When 
that is detected, take the current h & v scan value in pixels, subtract 2 
or 3 from the h value for the delay in the gun circuit & the IRQ service 
time, and you then have the pixel the gun is aimed at in a 3 byte value.

To do the same thing on an lcd screen, one would have to blink one pixel 2 
or 3 times, then if the gun doesn't detect that, go on and blink the next 
pixel until you finally get a response from the gun.  One could I suppose 
accelerate the search by blinking 1/4th of the screen at a time to detect 
which quadrant, then sub divide the block detected into quarters, wash, 
rinse, repeat till you have the exact pixel,  but I don't see how that 
could be done in Steve's quoted 10 milliseconds since one 60 frame cycle is 
16.something milliseconds.

Not to mention all that pixel flashing would have to be distracting.

-- 
Cheers, Gene
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