Minor corrections to the material in Paul's text. This is meant to be a laundry-list of facts, not a suggested set of words; I'm feeling too prolix this morning to produce the latter, and figure those on the list may be interested in the petty details anyway. The initial user-mode environment was a mix of 32V, subsequent work within 1127, and imports from 4.1BSD. I don't know the exact heritage: whether it was 1127's work with 4.1BSD stuff added or vice-versa. The kernel was a clean break, however: 4.1xBSD for some value of x (probably 4.1a but I don't remember which) with Research changes. By the time of V8, that means: -- All trace of BSD's original network interfaces removed, except that select(2) remained in a slightly-different form. -- Stream I/O system added; all communication-device drivers (serial ports, Ethernet, Datakit) changed to work with streams. Pipes were streams. -- File system switch added, supporting Killian's /proc and Weinberger's first-generation (neta) network file system. -- Berkeley FFS replaced by Weinberger's bitmapped file system: essentially the V7 file system except the free list was a bitmap and the blocksize was 4KiB. Hacky implementation, depending on a flag bit in the minor device number; didn't use the file system switch. Old 512-byte-block file systems had to be supported partly to ease the changeover, partly because the first version had a limited bitmap size so file systems larger than about 120MiB wouldn't work. This limit was removed later. (In retrospect I'm surprised I didn't then insist on converting any remaining old-format file systems in our domain and then removing the old-format code from the kernel, since user-mode tools--including a user-mode file server!--could be used to access any old disks discovered later.) For the purposes of Paul's note it probably suffices just to say that there was a restart with a 4.1-series kernel with changes as he describes, except also the new file system format. Norman Wilson Toronto ON