29 Nov
2021
29 Nov
'21
3:40 a.m.
It's been a long time but my memory is that PDP-11 instructions were way
cleaner than any other system I've seen. My TA for my PDP-11 assembly
class could read octal like it was C, I was never that good. He told
me it was actually pretty easy once you memorized the instruction set,
which he claimed was not hard because it was so uniform. I never learned
it well enough to know, just did a handful of programs in assembler,
but his description has stuck with me. I've had to learn enough SPARC,
MIPS, and (shudder) x86, to do kernel debugging and I've never gotten
the sense that they were are clean as PDP-11 was.
On Mon, Nov 29, 2021 at 08:07:57AM +1100, Rob Pike wrote:
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
On Mon, Nov 29, 2021 at 7:29 AM Jon Steinhart <jon(a)fourwinds.com> wrote:
>
> Eugene Miya visited by last week and accidentally left his copy of the
> book here so I decided to read it before he came back to pick it up.
>
> My overall impression is that while it contained a lot of information,
> it wasn't presented in a manner that I found interesting. I don't know
> the intended target audience, but it's not me.
>
> A good part of it is that my interest is in the evolution of technology.
> I think that a more accurate title for the book would be "A New History
> of the Business of Modern Computing". The book was thorough in covering
> the number of each type of machine sold and how much money was made, but
> that's only of passing interest to me. Were it me I would have just
> summarized all that in a table and used the space to tell some engaging
> anecdotes.
>
> There were a number of things that I felt the book glossed over or missed
> completely.
>
> One is that I didn't think that they gave sufficient credit to the symbiosis
> between C and the PDP-11 instruction set and the degree to which the PDP-11
> was enormously influential.
>
> Another is that I felt that the book didn't give computer graphics adequate
> treatment. I realize that it was primarily in the workstation market segment
> which was not as large as some of the other segments, but in my opinion the
> development of the technology was hugely important as it eventually became
> commodified and highly profitable.
>
> Probably due to my personal involvement I felt that the book missed some
> important steps along the path toward open source. In particular, it used
> the IPO of Red Hat as the seminal moment while not even mentioning the role
> of Cygnus. My opinion is that Cygnus was a huge icebreaker in the adoption
> of open source by the business world, and that the Red Hat IPO was just the
> culmination.
>
> I also didn't feel that there was any message or takeaways for readers. I
> didn't get any "based on all this I should go and do that" sort of
feeling.
>
> If the purpose of the book was to present a dry history then it pretty much
> did it's job. Obviously the authors had to pick and choose what to write
> about and I would have made some different choices. But, not my book.
>
> Jon
--
---
Larry McVoy lm at mcvoy.com http://www.mcvoy.com/lm