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Stella inaccuracies?


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#1 atari2600land OFFLINE  

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Posted Thu Nov 29, 2012 5:40 PM

Ever since I got my Harmony cart, I've wondered why in Stella the first row of pfblocks is at the very top, while on an actual TV, it's a lot lower (about where row 1 is supposed to be, and by row 1, I mean the second row, since there's a row 0.) I was working on a game and hadn't even noticed my bug I had until I got it onto my Harmony cart. For example, the first row of the word Explosive should be lower in the screenshot to emulate a TV more correctly.

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#2 FujiSkunk OFFLINE  

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Posted Thu Nov 29, 2012 6:18 PM

TV's are hardly standardized on where they put scanlines anyway, and if you have a decent TV or monitor with geometry controls, you can orient the screen pretty much any which way you want.

I'm not much on the inner workings of Stella, but since any game program is technically supposed to have a set number of vertical-blank scan lines at the top of each frame, perhaps Stella just skips that set number and begins drawing what should be the first active scanline. If so, it may be easier just to keep in mind how Stella's window compares to your TV, and note that what you see on your TV may not be what someone else sees on a different TV.

Edited by FujiSkunk, Thu Nov 29, 2012 6:19 PM.


#3 Random Terrain OFFLINE  

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Posted Thu Nov 29, 2012 8:28 PM

Stella's default YStart number is 34. I adjusted YStart until it looked like what I was seeing using my real Atari 2600 and it appears that the correct number to use is 28. To change YStart, load a game into Stella, press the Tab key, click on Game Properties, then click the Display Tab. After you change YStart, click OK, then click the Exit Menu button. Now hold down the Ctrl key and press R.

#4 atari2600land OFFLINE  

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Posted Thu Nov 29, 2012 8:56 PM

OK, cool. Thanks for the info.

#5 stephena OFFLINE  

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Posted Thu Nov 29, 2012 9:49 PM

This has been reported before. At some point I hope to make 'YStart' dynamic, and depend on the ROM itself (vs. hardcoding it to 34, which although is acceptable for most ROMs, fails on some others).

#6 SpiceWare OFFLINE  

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Posted Fri Nov 30, 2012 3:14 PM

If you want to be anal about it, it should really look like this:
2600.png

:ponder:

#7 FujiSkunk OFFLINE  

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Posted Fri Nov 30, 2012 6:18 PM

Poor choice of words there, SpiceWare. :)




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