[TUHS] DG UNIX History

Clem Cole clemc at ccc.com
Sun Nov 13 05:36:05 AEST 2022

To be honest, I've forgotten many (most) of the details.  But that sounds
about right.  As I remember it, it was like SunOS.  The key point was that
the kernel only had one view of the memory system period, no FS
buffer cache etc...which was a departure from many of the traditional UNIX
implementations.    IIRC they did not support BSD's mmap -- but check the
SVR3 docs to be sure -- they had the SVR3 user interfaces but none of the
BSD ones.  They did support the System V shared memory, however.  I do seem
to remember there was something funny in the driver interfaces, it was just
like UNIX only different, and that causes some heartache - but it was
fairly straightforward to move a DMA driver like getting a VME Xylogics
tape controller to work, but it took a little tweaking.  I've forgotten
exactly why that was --  it's been a long time ago.


On Sat, Nov 12, 2022 at 1:36 PM Larry McVoy <lm at mcvoy.com> wrote:

> On Sat, Nov 12, 2022 at 01:04:30PM -0500, Clem Cole wrote:
> > On Sat, Nov 12, 2022 at 11:52 AM <arnold at skeeve.com> wrote:
> > > DG-UX was a pretty generic SVR3
> > >
> > User space was generic.   But the SVR3/88K kernel was a heavy rewrite.
> >  LCC did a lot of work with DG adding stuff too it -- it was very well
> done
> > by the DG team in NC.   The memory and FS was well integrated.
> So read()/write()/mmap() all shared the same cache like SunOS?  In SunOS
> the
> only things not in the page cache were directories and inodes.  All data
> pages had one, and only one, place to be (ZFS broke this in Solaris,
> which has always blown my mind).
> --
> ---
> Larry McVoy           Retired to fishing
> http://www.mcvoy.com/lm/boat
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