[rescue] Rescued VAX 4500 question

[Dave McGuire]

On June 12, Scott Newell wrote:
> >  I don't *need* to say it, Josh.  There are hundreds of them in
> >everyday use even today, some of which haven't gone down or been
> >rebooted in years.
> 
> Impressive.  The -8s I've had (limited) dealings with are not all that
> reliable--core corruption and paper tape readers seem to be some of the
> weak spots, along with the power supply.  Granted, these machines were in a
> harsh environment (metal forming industry).

  Most of the pdp8 systems that are still in use are of the pdp8/a
variety, most of which use semiconductor memory.  The core is
generally pretty reliable in the 8/e systems if you keep the
temperature under control, though.

> I've also had run-ins with LSI-11 boxes running those little Bridgeport CNC
> milling machines.  Again, I can't say that I was impressed with the
> reliability--lots of downtime in the summer when it gets hot.  On those, I
> used to have to look for the main cpu board and memory cards.

  Having done pdp11 field maintenance for hire for a few years in a
previous life, I can tell you that this isn't a representative case.
The only big problems I ran into were heat...if you keep the air
intakes clean and don't let metal chips get into the backplanes, those
machines are about as close to indestructible as I've ever seen.  You
specifically stated heat problems though, which does correlate with
the most common issuss that I dealt with.

> You know, I could probably score enough LSI-11 bits & pieces to build up a
> working system...but what would you use such a thing for?

  Pretty much anything you'd use any other computer for, except for
perhaps web browsing or playing mp3s.

  I've been doing a lot of embedded systems work lately, using
8051-derived processors.  The C compiler I'm using (a relatively
recent, free, and very good microcontroller cross compiler) is shipped
with a 3rd party cross assembler that supports a few different
processors.  Upon studying the documentation, I read with some
amusement that it was originally written for RT11. :-)

> Are there still assemblers and compilers floating around?

  Of course.  It's an architecture that's still in volume production
and sold commercially.

  I find it interesting that the pdp11, as a commercial product, has
outlived its first successor, the VAX, and will likely outlive its
second...the Alpha.

       -Dave

-- 
Dave McGuire                       "*BURRRP!*  Mmm...tastes like cannoli,
St. Petersburg, FL                    smells like garlic!" -Sridhar