Any of the CP/M archives will be filled with more Z-80 and 8080 assembly source than you'll know what to do with. For starters, try http://oak.oakland.edu/pub/cpm/ If I remember correctly, Rodney Zaks had a book titled "Programming the Z-80" in his lineup. -- Tim Shoppa Email: shoppa(a)trailing-edge.com Trailing Edge Technology WWW: http://www.trailing-edge.com/ 7328 Bradley Blvd Voice: 301-767-5917 Bethesda, MD, USA 20817 Fax: 301-767-5927