"Chuck Guzis" <cclist at sydex.com> wrote: If you buy TTL parts from either of the above sources, they are also likely to date from the mid-70's, somewhat matching your machine :-). I won't talk about the house number parts and unlabeled parts that sometimes show up too! Amazing quantities of chips from the 70's show up regularly on E-bay. You know, quantity 100000 of 7407's etc. It's hardly the same as buying a few spares, though! Tim.