The classic reference would be Don Lancaster's _TTL Cookbook_, which is still being published in pretty much its original early-1970's version. For a slightly broader view of electronics - and a very solid introduction to both digital and analog techniques - you'll also want Horowitz and Hill's _The Art of Electronics_. Mr. Transistor Man, here you come! -- Tim Shoppa Email: shoppa(a)trailing-edge.com Trailing Edge Technology Voice: 301-767-5917 7328 Bradley Blvd Fax: 301-767-5927 Bethesda, MD, USA 20817