Subject: Re: [stella] asymmetrical playfields From: "Roger Williams" <mer02@xxxxxxxxxxxxx> Date: Thu, 20 Sep 2001 18:03:59 -0700 |
> It doesn't look like you can do any meaningful processing at the head of > any scanline and guarantee any sort of accurate cycle count which I would > need when rewriting PF2, which makes using the added cycles of my desired > kernel hard to exploit. > > Any advice? When loading the second set of playfield registers you still want to load PF0 first, since it disappears first, but reverse the order of PF1 and PF2. You will have a real problem getting the timing exactly right since you transition instantly from PF2A to PF2B; if you don't bang it on the exact cycle you will get an artifact. Other than this it should not take any longer than the duplicate version; you should be able to get the new playfield regs set up by shortly after the middle of the screen, after which you will have 30 or 40 cycles until you have to WSYNC. Since you have to do it every line there is basically very little time left for anything else, though you could probably run a software UART or other quick table lookup for sound or something. --Roger Williams - Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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