+  RHDN Forum Archive
|-+  Romhacking
| |-+  ROM Hacking Discussion
| | |-+  Graphics editing bug (Genesis)
Pages: [1]
Author Topic: Graphics editing bug (Genesis)  (Read 304 times)
Aeris130
Guest
« on: February 09, 2007, 01:25:17 pm »
I've come across a little issue for the second time now, when editing Genesis graphics. This time, it concerns the font below, which (as far as I can see) displays just fine in 1BPP.



The problem is, that if you add/remove as much as a pixel, the game (Soleil, in .bin format in case it matters) displays a bright red screen on startup, and refuses to go further than that. But if you use savestates to get pass the initial loading of the rom, the edited font displays just fine in dialogues and such.

Last time this type of error occurred, I was also working on a Genesis rom (some hockey game, me thinks). Does anyone know the cause of this, and is there any workaround available?
Nightcrawler
Guest
« Reply #1 on: February 09, 2007, 02:02:01 pm »
Hmm.. What you've described sounds a lot like some sort of modification protection code in the beginning of the game. If you really are only changing one byte in a font letter and that triggers this, I'd imagine the game is running it's own checksum calculations at startup or something to that effect.

Try changing one byte somewhere else. I'd suspect changing a byte ANYWHERE will cause the same result if what I said is happening.

If that's the case, you'll need to disable that routine.
Aeris130
Guest
« Reply #2 on: February 09, 2007, 02:08:46 pm »
Thanks, that seemed to be the problem.
RedComet
Guest
« Reply #3 on: February 09, 2007, 02:43:45 pm »
That's how Genesis games are. I don't remember the specifics offhand, but the game has to verify its checksum otherwise the Genny'll lock up. You can break the game so it doesn't check the checksum. I can look it up if you you want.

Either way, grab Fix CheckSum from the site. It's a must have tool for Genesis work.
Aeris130
Guest
« Reply #4 on: February 09, 2007, 03:13:21 pm »
It appeared that another copy of the game (with its protection removed) was already on the net, so I just patched the original.
Pages: [1]  


Powered by SMF 1.1.4 | SMF © 2006-2007, Simple Machines LLC