HP stuff (was HP's not cool)

From: Eric Smith <eric_at_brouhaha.com>
Date: Mon Nov 22 20:06:37 1999

"Jay West" <west_at_tseinc.com> wrote:
> HP 21MX's a DEC me-too copy? That's just ridiculous. I have yet to see a DEC
> that split the backplane the way HP did on the MX line. Without that
> fundamental change you would be stuck in the "gee I've got to remove some
> memory cards to fit in my extra I/O cards" scenario.

You certainly didn't have to remove memory cards from a PDP-8 to add I/O
cards. Or, for that matter, from the PDP-4, PDP-5, PDP-7, and PDP-9, which
I also claim to be the intellectual forebears of the HP 21xx. Where on earth
did you get that idea?

> But don't say the old HP line is just a PDP-8 wannabe/knockoff.

In terms of the instruction-set architecture, it clearly was derived
from the DEC 18-bit and 12-bit architectures.

Whether the machine was microprogrammed, had writable control store, or
had variable-length cycle times, have nothing to do with whether the
instruction set architecture is a clone of the DEC architecture. None
of these ideas were original with either DEC or HP. All of those ideas
were used in various DEC machines, although none of the 12-bitters were
microcoded.

I didn't say that there was anything WRONG with cloning DEC
architecture, or that HP didn't innovate around the edges of it. Why
invent something completely new and different, when you can copy and
tweak existing successful designs? There's nothing wrong or sinister
about that. When you buy this year's automobile, it is full of features
and designs copied from hundreds of past models of automobiles from many
different manufacturers.

The 2100A/S added more bells and whistles to the original 2116 design,
and the 21MX machines add yet more. But that doesn't in any way make
the 21xx instruction set architecture any less of a decendent of the DEC
machines. And it's not surprising, since HP used a lot of PDP-8s before
they decided to get into the computer business themselves.

As is usual around here, (e.g., the flame war over the word "obsolete"),
people seem to associate way to much emotional baggage with simple terms
and phrases.
Received on Mon Nov 22 1999 - 20:06:37 GMT