My _guess_ is perhaps not; the disks were really small (the UNIX people started with an RF11, which the first DEC machine I used - a RSTS system - also had; that was _really small - 512KB :-). Probably it did whatever V1 did. I was not up for going to look, since I wasn't familiar with the V1 code - but then I decided to break down and look at it, and also create a minimal index to say what's in each module. (Here: https://gunkies.org/wiki/UNIX_First_Edition#Source_index if anyone is interested. Made easier because the code is very well commented; it's very easy to read.) The code to take core dumps is in u1, at 'badsys:'. It dumps the user's entire possible memory space (i.e. not just up to the 'break'), and then (separately) the 'user' area. The system is not included. I doubt V2/V3 are different. Interesting. How did you work that out, BTW? Also, V1 seems to mandate use of a KE11-A (use is made of it throughout the kernel). Interesting; how did you work that out? V3's core (V): http://squoze.net/UNIX/v3man/man5/core doesn't give the format, just says "The actual format of the information is complicated because it depends on what hardware is present (EAE, floating-point option)". Do you have C3's db(I) source? Oh, wait, TUHS has what claims to be V2's db source: https://minnie.tuhs.org/cgi-bin/utree.pl?file=V2/cmd/db1.s but it actually seems to be later; it's conditionalized for having the FPP. So it must be for a machine running the -11/45 - which we seem to have decided is V3? The header for TUHS' V2 says: "The files in cmd/ are recreated from the text fragments found on the file s1-bits.gz." Which agrees with your take: That's all for the moment... Noel