[stella] perfect timing

Subject: [stella] perfect timing
From: Glenn Saunders <cybpunks2@xxxxxxxxxxxxx>
Date: Sat, 10 Nov 2001 21:41:35 -0800
Okay, I think I managed to get a 2 line kernel working completely without the use of WSYNCs at all!

Boy was it a lot of work. I think my cycle counting notation is correct also.

Thomas, I integrated your new Tombstone indexer routines which seem to work but the first row of tombstones only shows 7 lines instead of 8. Do you what that might be?

I took out all the sprite code for now, and I pushed the playfield load-stores together, so once the playfield code is working 100% we'll get a good idea of how much space is left.

So right now we've got 26 cycles of processing time before I blank out the playfield for the 2nd line of the linepair (the blankout code can move around some of course) and then a whopping 64 cycles in a row.

So that's a total of 90 cycles free for the line-pair.

It takes 30 cycles a piece, by my calculations, to do the missiles. So that's 60 cycles right there. That would consume the majority of the sprite line, leaving barely enough to generate one car.

It looks to me like there is enough time to do 3 of the 4 objects, but not all 4.

If I turn this into a 4-line kernel and interleave the pedestrians (in other words, keep them even/odd startline) ala Super Challenge Football then I think it will work and will look okay. If I keep the pedestrians bouncing like the dragons in Adventure then it might not seem so deliberate. They are going to be animating a run cycle anyway. It's more important to keep the movements of the cars smooth because they are under user-control. You don't want to quantize the car movements to even or odd scanlines because that would become apparent rather quickly, espcially if you pointed your car up and started to slowly accelerate. It would be jerky (but then again, the Intellivision and the Astrocade didn't suffer much from not having 200-line movement accuracy).

What does everyone think?

Glenn Saunders - Producer - Cyberpunks Entertainment Personal homepage: http://www.geocities.com/Hollywood/1698 Cyberpunks Entertainment: http://cyberpunks.uni.cc

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