Those D connectors carry synchronous data to and from IBM SNA boxes. I've seen these set up in medium-sized businesses that had both IBM networked mainframes/minis and DEC minis that need to talk to each other. There's a beefier version called the "DEC Channelserver" which, I've always inferred from the name, hooks to the IBM Channel architecture. -- 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