SegaCD bios background


Staff member
does anyone know if there's a good way to extract the bios background image in the model 1 bioses, modify it, and re-insert it?

any info would be appreciated.
Do you mean the background with the planets? You could try using a program like Tile Layer Pro (in Genesis format) to maybe track down potential background tiles and dump them to a bitmap for editing. You can also reinsert them. There are probably problems with this, because I remember hearing somewhere that lots of the SegaCD's bios data is compressed, and decompressed into memory while it's in use. Also you would likely need to modify the palette to accomodate any new colors you would introduce... please, someone smarter than me, help out! :)
I managed to find the copyright message in the top right in the model 1 US bios (but not in the model 1 jap bios), and some parts of the segacd logo, but the rest seems to be compressed :/
Well if you _really_ want to modify it, you could try tracing the code somehow to find out how it decompresses it... and figure out some way to recompress it. You'd probably have to write a custom util for that. I don't think there is a way to trace 68k code in an emu or anything though.
have you tried lhz and those? Maybe that helps out... there are algorithms around there, and you could try them on different offsets...

just a "brute force" idea...
Just remembered: Didn't Eidolon's Inn have a decompressed bios image on their site? It probably wouldn't be too useful but you might be able to figure out if the tiles you want are indeed compressed.
I checked that one out already, there's in fact absolutely nothing useful visible in a tile editor, even less than with the normal BIOS.

as for the other suggestions.. I can't program worth a ####, so I myself can't do much in that direction.. if anyone wants to help out, it'd be appreciated, tho.
this week I have no time, unfortunately...

But maybe during the weekend or next week, I can give it a try...(I haven't even advanced in my project...*sniff*)

(Edited by Artemio Urbina at 9:46 pm on Oct. 4, 2001)
yeah, it is, Radsil. I'd like to add in a different logo, change the background (different images) and add credits for the people who helped out, as well as links to SX and eidolon's inn.