For the benefit of Old Farts around here, I'd like to share the good word that an ITS 138 listing from 1967 has been discovered. A group of volunteers is busy transcribing the photographed pages to text. Information and link to the data: https://gunkies.org/wiki/ITS_138 This version is basically what ITS first looked like when it went into operation at the MIT AI lab. It's deliciously arcane and primitive. Mass storage is on four DECtape drives, no disk here. Users stations consist of five teletypes and four GE Datanet 760 CRT consoles (46 colums, 26 lines). The number of system calls is a tiny subset of what would be available later. There are more listings from 1967-1969 for DDT, TECO, LISP, etc. Since they are fan-fold listings, scanning is a bit tricky, so a more labor- intensive photographing method is used.