Author's blurb Thunderbird will demand your undivided attention and all of the memory the unexpanded VIC-20 has to offer. User summary Thunderbird was written by Dave Sanders and published as type-in source code on Compute! Issue 32, January 1983. The game is a modified type of "breakout" with added complications. Much of the article is devoted to memory conservation techniques to enable the fairly complicated game to "fit" in the memory available on a standard VIC-20. Atari and TRS-80 versions also were provided.