The termination issues are different. In general, with single-box Q-bus configurations there aren't any worries about termination, as the box designers took care of this for you. Once you get out of the realm of "toy" machines and into serious Q-bus configurations with multiple chained backplanes, termination issues do become very important. You want to look at Micronote #29, _Q-bus Expansion Concepts_. The Micronotes are available from: http://sunsite.unc.edu/pub/academic/computer-science/history/pdp-11/hardwar… A question for the net-savvy (of which I am certainly not one; I've tried http://www.slashdot.com/ without any success - all I get is "404 Not Found" errors!): I've submitted the above index to the Micronotes to many search engines - most notably Altavista - but none of them have indexed any of the text files, containing the actual information, referenced in the index. Can anyone figure out why? -- 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