[TUHS] A New History of Modern Computing - my thoughts

Ken Thompson kenbob at gmail.com
Mon Nov 29 07:31:52 AEST 2021

The PDP-11 had very little the syntax of B expressions.
All of that was in place in B long before the PDP-11.
To be honest, the byte addressing of the 11 was a
significant hindrance. It was the genius of Dennis
that was able to conquer the 11 as he installed types
into the language.

So, my opinion, the PDP-11 had no design on the
type system of C and moreover it was not even helpful.

On Sun, Nov 28, 2021 at 1:17 PM Jon Steinhart <jon at fourwinds.com> wrote:

> Rob Pike writes:
> > Is there a symbiosis between C and the PDP-11 instruction set? The
> > machine was vital to C and Unix's success, but primarily due to the
> > availability of a department-sized machine. Was the instruction set a
> > significant component? Most Unix programmers wrote little to no
> > assembly, although perhaps more read what came out of the compiler.
> > But did it matter? Auto-increment and -decrement are often cited in
> > this story, but they are not that important, really, and were around
> > well before the PDP-11 made its appearance.
> >
> > I'm curious to hear arguments on either side.
> >
> > -rob
> Well, might just be my personal experience, but most of the machines
> that I had used before the 11 were classic accumulator architectures.
> I feel that the 11's pointer architecture combined with autoincrement
> and autodecrement was an amazing fit for C.  If I remember correctly,
> it was very cool to have *p++ = *q++ be a single instruction.
> BTW, one thing that I forgot in my earlier post is that I think that
> the book also omitted any mention of Creative Commons.  The book did
> talk about the business of the web and such, and it's my opinion that
> CC was an an essential third prong.  The machines were one, the software
> was another, the third was content and CC was a big enabler.
> Jon
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