Say you want to print the character 'W'. You put the letter 'W' into the accumulator, and tell it to output to the serial port. For a truly portable interface, you use a mix of carriage returns, line feeds, and spaces/tabs to put the cursor where you want. If you know you'll have a VT52 or VT100 or ADM3A or (insert generic type of terminal here) you can send a specific character sequence. If you're going to be eventually turning this machine into a CP/M platform, I heavily recommend that you read the copy of your "CP/M Customization Guide" that shipped with your CP/M distribution. You'll find the terminal output/input routines explicitly coded as an example in that book. Just about anything. The Z80 certainly is a popular and easy-to-interface to choice. -- 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