[Info-vax] Y3K for PDP-11 Operating Systems

[John Wallace]

On May 10, 2:31 pm, koeh... at eisner.nospam.encompasserve.org (Bob
Koehler) wrote:
> In article <iqa6a7$gu... at dont-email.me>, glen herrmannsfeldt <g... at ugcs.caltech.edu> writes:
>
> > I remember stories from near the beginning of the 11/780 about
> > the polynomial expansion and bounds check instructions being
> > slower than doing either without those instructions.
>
>    On the 11/780, the speed of several of those instructions depended on
>    whether or not you had a floating point accelerator.  The FPA actually
>    did a lot of integer and address arithmatic, in addition to floating
>    point.

I remember one of my 1980s customers whose hardware service was done
by a 3rd party. Their 2*78x cluster had a problem in that one node
wouldn't mount one of the shared disks. They'd been waiting for their
fixit folks to sort this for months, no progress. Then one day the
other 78x failed, leaving them unable to produce vehicles (cars, and
an IT company in this picture which is now part of HP, work it out).
As a favour, DEC Field Circus came in, ran the usual diagnostics, and
within minutes it emerged that an FPU fault had been preventing the
disk being mounted on the original dodgy 785. It was a bit of a
surprise to me to see an FPU involved in mounting a disk, but
apparently it shouldn't have been a surprise.