A while ago I found 5 out of 8 eproms of Sonic Spinball (build 1910).

The eproms are labelled 'Spinball 19/10' and each has a number signifying which eprom it is (from 1 to 8).

I have dumped the chips and I've confirmed that this is an unreleased ROM of Spinball (it has header checksum $xxDD). The 19/10 date means it's either a 10 month early build, or a 1 month late build (which could mean a bugfix or a rerelease). Probably the former.

I have chips 2, 3, 6, 8 and an unknown one (of 1 through 8). Unfortunately, since Megadrive ROMs are 16-bit, and EPROMs used were 8-bit, they are interleaved. Meaning that odd bytes are on chips 1, 3, 5, 7 and even bytes are on chips 2, 4, 6, 8, making the ROM completely unplayable. However, it might be possible to salvage some art/music data from it. It might be even possible to reconstruct the code based on the final code (though that would be a lot of work)

There is some hope that I will find any more Spinball chips. Most likely they were recycled, but I might find the others yet.

Here are the EPROM dumps, dig in.

Thanks to Stonerboy for help with this release.