ALan - thanks - reading that made me go looking for my copy of "Faster than Thought" (1954) which contains a copy of Ada's paper. When I didn't find it I recalled that I'd lent it to a friend 'some while ago'. I'll send him this link and inquire re the book :-). Russell --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .