Sounds like you have the updated 20th Anniversary ROM by Chad H.
DESW as released in 1992 was a game with great toys, sound and art package hampered by unbalanced rules that made it a one-shot game. Chad released a version that balanced the scoring and put more of an emphasis on tri-ball jackpots for the big points. There's also a lot of other cool additions such as a ball save and other tweaks.
Explanation of changes at Chad's site:
http://www.pinballcode.com/sw104
There are a number of threads discussing the new code, and the general consensus is that it improved the game immensely.
Mt Zion, IL
