Re: [stella] Supercharger screens...

Subject: Re: [stella] Supercharger screens...
From: "John Saeger" <john@xxxxxxxxxxx>
Date: Tue, 12 Jan 1999 11:29:53 -0800
-----Original Message-----
From: Eckhard Stolberg <Eckhard_Stolberg@xxxxxxxxxxxxxxxxxxxxx>
To: stella@xxxxxxxxxxx <stella@xxxxxxxxxxx>
Date: Tuesday, January 12, 1999 6:12 AM
Subject: Re: [stella] Supercharger screens...

>At 09:32 11.01.99 -0800, you wrote:
>>Hmmm, as I recall the window of opportunity to get a complete display of
>>second set of sprites is only one pixel wide, but I forget the exact
>>The demo earlyb.bin rings a bell though...  But I think more
>>is necessary.  I haven't tested all possible positions of the second RESPx
>>so there may be other places that the second RESPx could produce a
>>set of sprites.  But I'm just guessing.  But until all possible
>>have been tested, one really can't be sure.
>I have experimented with different NUSIZx values and I'm pretty sure
>about the five pixel window. The reason why you might think it is only
>one pixel could be that one can not position the second hit to RESPx
>pixelwise but has to do it cyclewise. One cycle means three pixel more
>or less and that can be just outside the window.

Yeah, you're right ;-)  It takes me a while to warm up my engines.
>But look at your trick18 and my extra18. In your program the second hit
>happens 12 cycles or 36 pixels after the first hit. That is one pixel
>before the third copy of the sprite would be displayed. In my program
>the second hit happens 11 cycles or 33 pixels after the first. That
>is four pixel before the third sprite. And the grid demo does the
>second hit six cycles or 18 pixels after the first hit. That is three
>pixels before the second sprite. All three programs produce three
>copies for the second set of sprites.

O.K. I'm not sure about the counting.  But here are results of some
experimenting that I did.  I tested all cases from a 3 cycle delay to a 12
cycle delay.

Hit3  9, 25 , 41  -- 18 , 34*, 50*  (d-7)   (i.e. 18-25=-7)
Hit4  9, 25 , 41  -- 21 , 37*, 53*  (d-4)   (     21-25=-4)
Hit5  9, 25 , 41  -- 24*, 40*, 56*  (d-1)*  (     etc.)
Hit6  9, 25 , 41  -- 27*, 43*, 59*  (d+2)*
Hit7  9, 25*, 41  -- 30 , 46*, 52*  (d+5)
Hit8  9, 25*, 41  -- 33 , 49*, 65*  (d+8)
Hit9  9, 25*, 41  -- 36 , 52*, 68*  (d-5)
Hit10 9, 25*, 41  -- 39 , 55*, 71*  (d-3)
Hit11 9, 25*, 41  -- 42*, 58*, 74*  (d+1)*
Hit12 9, 25*, 41* -- 45 , 61*, 77*  (d+4)

The numbers are the nominal display positions of the sprites if all of them
were displayed, the ones marked with an asterisk are the ones that I see.
The final column shows how the first sprite of the second group is
positioned with respect to the closest sprite in the first group.  From that
column, the ones marked with an asterisk are the ones that display 3

I see a window of (d-1) to (d+2) that will give 3 sprites.  Does this make
sense to you?


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