Thanks, you've been a great help. I'd ended up having a silver in my collection but because I couldn't get any info on it I was a bit suss about the whole concept :P thanks again for clearing it up.

Also, I was still wondering about the incomplete Sonic Spinball eprom that you have in your collection. Granted I can understand that you must get a great deal of requests from unknowns that aren't really worth answering, but I'd be genuinely interested in knowing a price tag.