[TUHS] V8, V9 and V10 now in the "Unix Tree"

[Norman Wilson]

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