An observation ... in reading the last few days emails, I fear there may be some confusion - there were two different tapes. The infamous 'patch tape' that Lou was discussing was patches to the *Sixth Edition* which I want to say '76 or 77 timeframe (should be able to be dated by when Chesson graduated from UofI and Ken was on his way to UCB for a sabbatical). I can date this because we had a copy of the patch tape at CMU at least by I think late '77/early '78 when I was hacking full-time for the EE Dept. CS had switched from the Fifth Edition on their systems, which was my introduction. I would eventually bring up 6th on an original 11/34 (not a 34A). The 11/34 did not 'just work' due to some small differences between the 11/40 and the 11/34 and remember having to do it from first principles borrowing a hacked CS system (11/40e), that had CSR/CRET stuff in their compiler, so I went back to just booting Ken's original tape, hacking until both 11/34 and the 11/40 boot and then having to reapplied the patches, because I wanted to make sure I did get polluted with the 11/40e stuff. The V7 addendum was obviously post Seventh Edition. The Seventh Edition was released in 1979 for general availability**; although it's direct predecessor (UNIX/TS) which was not officially released made its way to number of places such as MIT and CMU via OYOCs and summer students as Noel and I have pointed out in the past. Noel (MIT) and I (CMU) both had heavily hacked systems that were combo's of V6, PWB [1.0], UNIX/TS plus local additions. UNIX/TS had a newer kernel, updated FS and the compiler that was released with troff - a.k.a. 'Typesetter C' [Historical note - this was the system Ted with a small amount of help from me, used to create fsck]. If I recall the V7 'addendum' is in reference to the later (post 1980) V7 distribution tapes, that had one more file on it with some additions/corrections from Research as Doug mentioned. IIRC: The first V7 tapes that went out in '79 (such as the ones I recieved at CMU and then Tektronix) did not have that file and the copy said tape I have home is missing it (I just checked the label). Clem **V7 GA was in Feb '79 I think, I can not find my copy of Al Arm's letter to the licensees announcing it, I seem to have lost it - any other pack rat/old f*rt please check your files.