Sonic and Sega Retro Message Board: Early MD VDP bug - Sonic and Sega Retro Message Board

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Early MD VDP bug Sprite limit and such

#16 User is offline Sik 

Posted 26 March 2010 - 09:47 PM

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There are more warnings in the addenums. Also the last page of the main docs show how the board should be set up to prevent the VDP from going insane. The issues are worse with the 32x (those docs have more warnings involving development boards).

#17 User is offline Chilly Willy 

Posted 26 March 2010 - 10:31 PM

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QUOTE (Sik @ Mar 26 2010, 08:47 PM)
There are more warnings in the addenums. Also the last page of the main docs show how the board should be set up to prevent the VDP from going insane. The issues are worse with the 32x (those docs have more warnings involving development boards).


In my experience working on Wolf32X and talking with Steve Snake, you can just ignore all the 32X warnings when working on 32X homebrew. Which is good - it means we can do things like use the free-running timers. smile.png

#18 User is offline Sik 

Posted 27 March 2010 - 01:18 AM

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Except that the hardware we use currently has nothing to do with the development boards Sega used back in the day. Current hardware is designed to gimmick ROM characteristics to the MD, while development boards used crappy DRAM and other components in a pretty hackish way.

#19 User is offline TmEE 

Posted 27 March 2010 - 06:23 AM

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Dev HW was generally only slightly modified retail units ala CPU replaced with emulator terminals for low level debugging... and stuff was run on EPROMs or PSRAM(aka DRAM) boards... nothing hackish about the DRAM stuff, just 32X does not pass the refresh signal through untouched and that will cause some timing related problems which result in peculiar random crashes etc.... which 32X love to do when the ribbons are not tight...

#20 User is offline Pinkerton 

Posted 30 May 2010 - 08:13 AM

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I'm not sure if this is even relevant at all since I'm no MD tech wizard or anything, but it sounds kinda like what's going on. I've got a Genesis Model 1/TMSS and whenever I clear virtually any second act in Sonic 2, the flickies leaving the egg container cause the parts of the container they're parallel with to disappear. It looks like there's more or less an eraser moving up and down it, revealing what's behind. IIRC my friend's Genesis 2 doesn't do this, but it's been forever so I'd have to check.

#21 User is offline ICEknight 

Posted 30 May 2010 - 08:34 AM

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The container is a sprite, so that's normal.

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