Re: [stella] slightly offtopic: Apple II mouse pointer in vblank?

Subject: Re: [stella] slightly offtopic: Apple II mouse pointer in vblank?
From: KirkIsrael@xxxxxxxxxxxxx
Date: 28 Jan 2004 03:06:43 -0000
> On Tue, 28 Jan 2004 KirkIsrael@xxxxxxxxxxxxx wrote:
> > Just a thought...could they mean "draw the cursor" to video memory
> > or something like that, as opposed to the literal video signal? That
> > occured to me after I sent this...
> Yep. The Apple II has a framebuffer (video RAM), so you could draw into
> RAM which the graphics hardware will display when it gets around to
> drawing the frame.

Heh...I guess 2600 has slightly muddled my old thinking 
about framebuffers :-)

So, is there essentially TWO video buffers in play?  It seems that 
if there was only one, the mouse pointer would "corrupt it", and 
it would need to be always refreshed by the program running?  
I guess there could be some clever XOR trickery to get an inverse
pointer, but then if the graphics "underneath" the pointer changed,
you'd get bad interactions?

"God or somebody save us from any society founded on Darwinian principles."
   --Richard Dawkins 

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