Reminds me of the person on Wikipedia who tried to argue with me about the 'History of the Internet' article... :-) It was probably a fixed-head disk (RS11 or RS04); can't exactly stick a different pack in! :-) Probably the DEC OS's only used it for swapping or something, since they were both relatively small - 512KB. (Speaking of RS11's: the first PDP-11 I used - an 11/20 running RSTS - had a grand total disk storage of _one_ RS11!) And speaking of putting file systems on them: I recently wrote this command for V6 called 'si' which allowed me (among many other interesting things) to watch the contents of the disk buffer(s). It turns out that even with other packs mounted, the buffer is almost always completely full of blocks from the root device; it makes plain the value of having the root on a _really_ fast disk. I don't know if that usage pattern is because /bin is there, or because pipes get created on the root, or what. When I get up the energy I'll move /bin to another drive (yeah, yeah, I know - good way to lose and create a systen that won't boot, so I'll actually make a _copy_ of /bin and mount it _over_ the original /bin - probably a host of interesting errors there, e.g. if a process has the old /bin as its current dir), and see what the cache contents look like then. Noel