Genesis/Megadrive graphics glitches

[PanzerDrake]

I've installed a 50/60hz switch on two PAL Megadrives, and both cause the same graphics glitch in both 50 and 60hz mode.

In both mods the cutting of the jumper trace failed at first, causing a short circuit (and switching off of the console) after flicking the switch. a deeper cut of the trace fixed this.

Afterwards though, there were slight graphics glitches to be seen in all sonic games and, for example, rocket knight adventures. These glitches appear only on the water effects found in those games. Where the 'air' meets the 'water surface' in levels like the labyrinth zone in sonic 1 or the horizontal flying level in Rocket Knight, there's a line of weird flickering pixels to be seen exactly on the line that separates the water from the air. It seems, therefore, to have something to do with transparent water effects and the like. On the reflecting lava level in Rocket Knight there's the same glitch.


Does anyone know if this could have something to do with the shortcircuiting of the 50 and 60 hz jumpers? And why did it have the exact same effect on both megadrives, and only on certain graphical effects in different games?

 

[Mask of Destiny]

Are you sure that wasn't there before you did the mod? I'm pretty sure that's just a side effect of the way those games change the pallette around in the middle of the screen for the underwater effect.

 

[PanzerDrake]

Hey, thanks for the reply!


I'm pretty sure it wasn't there before. I have to admit I'm not 100% sure though. I checked some screenshots as well as an emulator (which I hate, but I just had to check...), and those didn't seem to show it...


On the reflecting lava level in rocket knight adv. for example, I'm pretty sure the lava surface used to be really straight and sharp. Now it is a bit flickery and has those pixels that seem to be out of place. Maybe someone has the game and could check?


thanks again!

 

[fonzievoltonov]

Any raster effect to fake lava or water transparency will produce dots (of the background color) on the line the effect is done. It is not emulated of couse since its more a hardware problem than a real feature 😉

I have those dots too... sorry :/

Maybe your dots are more visible than normaly due to your short circuit, but héhé, that would be strange and very interesting.

 

[PanzerDrake]

Well, I don't mean the rasters that fake tranparency, but when real pallette changes are used to create an underwater effect, like the one seen in the labyrinth zone in sonic 1. There's no raster effect used there, but exactly on the water surface (where the 'waves' are) there are flickering pixels to be seen, which also continue to flicker when the game is paused by the way. Do you see this on your sonic as well? It looks glitchy to me...


thanks!

 

[PanzerDrake]

Mask of Destiny, you may be right. I just tested it on another megadrive and unless I somehow managed to screw up a couple of carts, getting the same glitch in all of them, it definitely looks like it's a side effect of the pallette change. It's also there on the other megadrive...


Apologies for my lack of faith, my master... I shall not doubt thee again ;-)