[TUHS] Why did PDPs become so popular?

Larry McVoy lm at mcvoy.com
Sat Dec 30 09:58:31 AEST 2017

On Fri, Dec 29, 2017 at 03:35:27PM -0800, Jon Forrest wrote:
> >Alpha generally maintained integer/ALU and clockspeed leadership for
> >most of the '90s
> >http://www.cs.columbia.edu/~sedwards/classes/2012/3827-spring/advanced-arch-2011.pdf
> As nice as the Alphas were, I don't recall any compelling reason we
> would have used them if we had to pay for them. In fact, at the same
> time Mike Stonebraker and I wrote a grant proposal to Sun to get a
> couple of SparcStation 10s to use to port Postgres to Solaris. The
> SparcStations were just as nice to use as the Alphas.

Yeah, that's my memory as well.  Alpha was fine but it wasn't the bat
it out of the park that DEC thought it would be.

I've worked at Sun and SGI and had some influence on some of their 
processor work (Andy B redesigned the memory interconnect on one of
the SparcStation SMP boxes because I showed him data that proved that
we were about to suck; got a processor at SGI cancelled because it 
was just beyond hopeless, it was a floating point machine called
Beast and it was being developed as the focus was shifting heavily
from floating point to integer.  The stupid thing had pins on all
6 sides - top, bottom, and the edges.  The socket, just the socket,
was predicted to cost SGI $1400/each at volume.  No CPU, just the
socket.  And it had miserable integer performance.  Bzzt.)

What I've seen over and over is teams compete against their previous
design rather than the competition.  Many, many times I've seen 
designers who had barely a passing knowledge of what the other guys
could do.  Blew my mind.  It was part of the reason I wrote LMbench,
at least that gives you an idea of what the other guys can do.


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