Most of the DEC core planes use a fair number of special-purpose transistor arrays (often specially matched) for drivers as well as pulse transformers and delay lines. If you look back at alt.sys.pdp8 archives (or its mailing-list twin, PDP8-LOVERS) you'll find some suggestions for part substitutions and/or rebuild directions. I believe that at least one of the electronics rags in the Lasnerian mid-70's (Radio Electronics? Popular Electronics?) published an article on using surplus core arrays that were readily available at the time, but the article was remarkably detail-free when it came to the actual details of driving and sensing. There were at least a few implementations of S-100 core memory in the mid-70's, and one of them was a S-100 to Unibus translator of sorts. (Not to be confused with the IMSAI S-100/Unibus shared memory module, which is in several of my IMSAI price lists from 1977/1978 but which I believe to be vaporware.) -- 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