Hello, I wanted to share this evening a scan I just finished. It is linked to in this thread where I will continue adding ESS-related materials (for those interested in that sort of thing): http://www.classicrotaryphones.com/forum/index.php?topic=28001.0 The document therein is the Guide to Stored Program Control Switching, a Bell System document concerning #1 and #2 ESS telephone exchanges and varieties of networking connections. It's interesting in that the guide is three separate little flip decks of cards, some of which can represent steps in a network. Flip to the components you need and the traces at the edges meet to create a diagram of that particular configuration. I quite like the concept, seems like a great way to visualize variable networks. Anywho, as mentioned I'm going to be putting some more ESS stuff up there, mostly related to 5ESS and 3B20 computers. That seems to now squarely be my main documentation focus since I'm starting to bleed the Bell System UNIX well a bit dry of stuff I can randomly find on eBay. 5ESS and 3B20 are still adjacent enough that I'm sure UNIX-y things will be scattered throughout this material. Finally, a long shot but is anyone aware of preserved copies (or in possession of) the March 1980 issue of the Bell Laboratories Record? An index on archive.org indicates that issue has a focus piece on the 3B20 which I am quite interested in getting eyes on. I've come across several other copies around this time frame, some of which I've purchased to scan, but not this one yet. As always happy to answer any questions about what I'm working on or consider scanning jobs for other documentation folks have leads on, happy new year everyone! - Matt G.