Subject: [stella] Prop Cycles From: kurt.woloch@xxxxxxxxx Date: Mon, 25 May 1998 09:47:46 +0200 |
Last night I hooked up my 2600 and tried to "prop up" the Pitfall II cart, as described here earlier. Guess what? It *worked*! Thank you guys. Still I wonder if there's a way to get it working again without needing to be propped. Anyway, I also tried to prop the Mangia cart, and this one didn't work. So I think it's really the bits got rotten here. But since this is not such a great game (and it's on a wanted list of someone who even is interested to give me something for it), this is less important. For propping, I used a Ms.Pac-Man cart. Of course, afterwards I wanted to know if this one still worked, and put it in, and came across something strange, which I think has nothing to do with the propping: Some of my carts seem to display a sort of interference in the black part of the picture (and also in other parts, but not so good visible). You can see it at least if you hook up the VCS to a VCR and on to an Amiga 1081 monitor, but maybe you also can see it on a TV. The pattern of the interference will be visible if you turn the brightness control up very high, so that the black appears as grey. There are some stripes appearing, which seem to be the processor cycles, since they're all 3 pixels wide. Still, they only appear at some carts, and not at the whole screen. Some examples: -Ms. Pac-Man: They appear below the displaying part of the screen. -Q*bert: They seem to be in the whole screen here. -Mario Bros.: On the title screen, they only appear at scanlines where something's displayed. At the other scanlines, they don't appear. -Moon Patrol, Smurf, Carnival... There are no interferences here. Now the question is how these interferences come together, and why they only appear at some carts. Does it have to do with bank-switching, or with a special way the kernal is written? Does the interference disappear why the processor waits for a WSYNC? Only interested in it... Has anyone else come across these interferences? With love (and about 60 visible vertical stripes per scanline) Kurt Woloch -- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/stella.html
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