> what I want to know is how did they do those electronic signs in the > 50's or 60's, with lightbulbs. was it some kind of punched card > triggering a mechanical switch? I believe they did, and recall a post from a very very long time ago that mentioned mercury-wetted contacts. You'd expect improvements in both bulbs and driving to give much better "pixel" lifetime -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist