Original TB-303 fills it's memory with random patterns when the batteries are taken out of it and put back. Some old acid house tracks have born this way.
You can simulate this by making an empty pattern in any of the fine 303 style gens and randomizing the note column and the accent columnand the slide column with ctrl+r. It's not the same as a real TB-303 (the note range is too wide) but you can get some really wicked sounds like that. - Elektroj?nis