[TUHS] PDP-11 legacy, C, and modern architectures

[Clem Cole]

On Thu, Jun 28, 2018 at 10:40 AM, Larry McVoy <lm at mcvoy.com> wrote:

> Yep.  Lots of cpus are nice when doing a parallel make but there is
> always some task that just uses one cpu.  And then you want the fastest
> one you can get.  Lots of wimpy cpus is just, um, wimpy.
>

​Larry Stewart would be better to reply as SiCortec's CTO - but that was
the basic logic behind their system -- lots of cheap MIPS chips. Truth is
they made a pretty neat system and it scaled pretty well.   My observation
is that they, like most of the attempts I have been a part, *in the end
architecture does not matter nearly as much as economics*.

In my career I have build 4 or 5 specially architecture systems.  You can
basically live through one or two generations using some technology
argument and 'win'.   But in the end, people buy computers to do a job and
the really don't give a s*t about how the job gets done, as long as it get
done cheaply.​   Whoever wins the economic war has the 'winning'
architecture.   Look x66/Intel*64 would never win awards as a 'Computer
Science Architecture'  or in SW side; Fortran *vs*. Algol *etc*...; Windows
beat UNIX Workstations for the same reasons... as well know.

Hey, I used to race sailboats ...  there is a term called a 'sea lawyer' -
where you are screaming you have been fouled but you drowning as your
boating is sinking.   I keep thinking about it here.   You can scream all
you want about goodness or badness of architecture or language, but in the
end, users really don't care.   They buy computers to do a job.   You
really can not forget that is the purpose.

As Larry says: Lots of wimpy cpus is just wimpy.    Hey, Intel, nVidia and
AMD's job is sell expensive hot rocks.   They are going to do what they can
to make those rocks useful for people.  They want to help people get there
jobs done -- period. That is what they do.   Amtel and RPi folks take the
'jelly bean' approach - which is one of selling enough it make it worth it
for the chip manufacture and if the simple machine can do the customer job,
very cool.  In those cases simple is good (hey the PDP-11 is pretty complex
compared to say the 6502).

So, I think the author of the paper trashing as too high level C misses the
point, and arguing about architecture is silly.  In the end it is about
what it costs to get the job done.   People will use what it is the most
economically for them.

Clem
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