28 Nov
2021
28 Nov
'21
9:26 p.m.
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
28 Nov
28 Nov
10:07 p.m.
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
10:15 p.m.
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
10:31 p.m.
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(a)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
10:47 p.m.
Ken Thompson writes:
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.
OK then. You *would* be the expert.
11:17 p.m.
It's a just-so story. We have nostalgia for Unix, C, and the PDP-11
and its instruction set, and we combine them all into the story about
why it all succeeded. But nostalgia can mislead.
I loved the PDP-11 and its instruction set, I loved C, and I loved
Unix. Memory has put causation in there that is not altogether true.
The PDP-11 as an affordable commercial computer, now _that_ was important.
-rob
On Mon, Nov 29, 2021 at 8:50 AM Jon Steinhart <jon(a)fourwinds.com> wrote:
Ken Thompson writes:
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.
OK then. You *would* be the expert. 
29 Nov
29 Nov
1:19 a.m.
Rob, I offer a small tweak to your statement, that I hope you will consider
On Sun, Nov 28, 2021 at 5:20 PM Rob Pike <robpike(a)gmail.com> wrote:
The PDP-11 as an affordable commercial computer, now
_that_ was important.
s/computer/mini-computer/
I really believe that this distinction is important. Bell coined the term
in the late 1950s/early 1960s when he called it a minicomputer. The key is
that he meant >>minimal computer - in function and price<< (not small).
(This would event eventual lead to Bell's law for the birth and death of
computer classes).
To me, the PDP-111 ISA is the epitome the *minimal computer architecture*
- just want you to need to get the job done be it commercial or scientific
and it was affordable as you said. The solution is elegant, nothing fancy,
little extra added - just the right set of features for a system to do real
work. It was also extremely regular as Larry points out, so it was not
filled with a ton of special cases. It did have a few more features like
addressing modes, and multiple registers that made it more complex than say an
accumulator-based PDP-8. But the small set of new features made sense and
were* of** use for almost all programmers*. [FWIW: IMHO, most new features
we add to Intel*64 is all for some special cases for a specific customer].
I note that the VAX (was is the epitome of the CISC and while
extraordinarily successful), has always been an easy target as way too
complicated, filled with many special cases (just for the Fortran compiler,
or for Cutler's as an assembly programmer).
IMHO: C is also made from the same minimal ideal. It took the simplicity
of the B and added typing and better data structures, but did not overdo
it. Again, what was added was useful to almost all programmers.
I note that while the follow-on to both the 11 (the Vax) and C (C++) became
working horses, but both are ugly as can be, and neither would I call
elegant. I've used them both, however, I have moved on since that time. I
do pine for something more like a 64-bit PDP-11 (more in a minute), and
still use C when I can in the kernel or Go when in userspace.
Having kicked around DEC during some of the Alpha discussions, other than
the original lack of byte addressing, I think the PDP-11 influenced the
Alpha more than VAX did. There was a definition -- why is the needed --
thinking. Keep it simple a minimal.
As for Unix (since this is a Unix history list), again I think it is the
minimal view I miss from Sixth and Seventh Edition. I look at Linux and
mostly turn green with how much has been lost from those days. But like
the PDP-11, I can not really go back. My hope is that something will
appear that is "good enough" and '"simple enough" to get people
excited
again.
my 2 cents,
Clem
ᐧ
ᐧ
2:12 a.m.
On Sun, Nov 28, 2021 at 07:19:08PM -0500, Clem Cole wrote:
To me, the PDP-111 ISA is the epitome the *minimal
computer architecture*
- just want you to need to get the job done be it commercial or scientific
and it was affordable as you said. The solution is elegant, nothing fancy,
little extra added - just the right set of features for a system to do real
work. It was also extremely regular as Larry points out, so it was not
filled with a ton of special cases.
I remember Ken Witte (my TA for the PDP-11 class) trying to get me to see
how easy it was to read the octal. If I remember correctly (and I probably
don't, this was ~40 years ago), the instructions were divided into fields,
so instruction, operand, operand and it was all regular, so you could see
that this was some form of an add or whatever, it got the values from
these registers and put it in that register. I remember Ken trying to
get me to see how uniform it all was and I guess I sort of got it but
what I remember the most is his passion for it. We were pretty friendly
and if I had some big octal listing that wasn't working, he'd come over
and drink a beer and read through it. For him, it was just faster to
read the octal than to look at my tortured assembly.
64 bit PDP-11
That would be pretty cool. Your comments about minimalist approaches ring
really true for me. The last conversation I had with Greg Chesson was
a 2 hour rant from him about the fact that nobody who is doing anything
these days understands the value of a minimalist approach, it's one
complex framework or whatever after another.
There is a reason that the people I respect the most tend to spend a lot
of time on what not to put in, rather than what to put in. I became
friends with Linus Torvalds because we spent probably almost a year
talking about what not to put in to LMbench, we wanted to get it right.
I know people look at Linux and recoil in horror, it's a long way from
v6 or v7. But v7 was a uniprocessor Unix that had no networking. Linux
scales pretty well on SMPs with lots of CPUs, it has generalized NUMA
support, it has a /proc that I'd argue is way more true to Unix than
the SysV /proc (I don't know Ron Gomes but I was friends with Rodger
Faulkner), the Linux /proc is all strings, it's so useful. Linux
just handles way way way way way more than v7 could even imagine
handling. Pretty much all of the supercomputers are Linux so it
scales up and it scales down to a rasberry pi.
A thing that blew my mind in Linux was drivers. PCI drivers.
They were portable to different byte order machines. I was so
used to drivers being specific to the CPU, that was eye opening.
I'd say more but the wife is calling, I just wanted you to know
that Linus definitely understands the minimalist approach, Linux
started that way but it has been asked to do a lot so you get what
you get.
--lm
3:23 a.m.
On Nov 28, 2021, at 5:12 PM, Larry McVoy <lm(a)mcvoy.com> wrote:
On Sun, Nov 28, 2021 at 07:19:08PM -0500, Clem Cole wrote:
Indeed.
As far as processor design is concerned, I believe one of the
problems is that there are fewer and fewer people who can do
both h/w and s/w design competently. This is why I think more
programmers should roll up their sleeves and design a
processor and understand the issues involved, especially now
that programming FPGAs is becoming common. May be start with
an existing RISC-V core in some HDL, and push and pull it
into (what you think is) an ideal minimalist design. Even
adding a codegen target for such a processor (to at least tcc
or Ken's C compiler) won't be all that hard. I believe this
sort of co-design is what is needed to move past the current
designs. It will likely be some young whippersnapper who
doesn't know what is impossible, rather than one of us
greybeards!
64 bit PDP-11
That would be pretty cool. Your comments about minimalist approaches ring
really true for me. The last conversation I had with Greg Chesson was
a 2 hour rant from him about the fact that nobody who is doing anything
these days understands the value of a minimalist approach, it's one
complex framework or whatever after another. 
30 Nov
30 Nov
8:27 p.m.
Hi Bakul,
As far as processor design is concerned, I believe one
of the problems
is that there are fewer and fewer people who can do both h/w and s/w
design competently.
The ARM chip came about because the UK's Acorn Computers couldn't find a
decent cost:performance 16-bit CPU to replace the 6502 in new models.
Furber and Wilson realised from a visit to Bill Mensch's WDC that chip
design could be done by a small outfit. The recent UCB reports on RISC
suggested a simple design could still have high performance so they set
about skipping 16-bit CPUs and rolling their own 32-bit RISC CPU, the
Acorn RISC Machine.
The point of that bit of history is they were not chip designers, but
knew electronics and programming. Wilson designed the ARM's instruction
set and it was a delight to code: very orthogonal, and every instruction
had four-bits of condition-flag test, e.g. Carry Set, and a bit to
indicate if this instruction should set the condition flags. Thus
several instructions in a row could test the condition flags set by an
instruction a few earlier and unaltered since; this cut the need for
quite a few branches.
I think Wilson did such a good job because she had coded extensively in
assembler on several different architectures. Not just the odd device
driver or context-switch but 16 KiB of 6502 instructions which were BBC
BASIC, a structured BASIC with WHILE, PROC, integers, floats, etc.
(The BASIC ROM remains a good test of any 6502 emulator today because of
all the corner cases the hand-written assembly exercised.) This was
just for the BASIC interpreter; the OS, file system, etc., were all in
other 16 KiB ROMs of hand-written assembly.
The ability to add a co-processor to the BBC Microcomputer meant Z80 and
other implementations followed. So with all that experience it's not
surprising that the instruction set, though RISC, gave just what the
assembly writer wanted, nothing more, whilst being easy to learn and
remember. I don't think a hardware-chip designer could have done such a
good job.
The later pressure to drop 32-bit instructions for a mixture of 16-bit
and 32-bit due to mobile's small flash capacity beget Thumb, still used
today as Thumb-2, which dropped much of the nice features which made
hand-written assembly such a pleasure, but then by then compilers were
better quality and more common.
This is why I think more programmers should roll up
their sleeves and
design a processor and understand the issues involved, especially now
that programming FPGAs is becoming common. May be start with an
existing RISC-V core in some HDL, and push and pull it into (what you
think is) an ideal minimalist design.
I agree with the sentiment, but it sounds quite a big leap for most
programmers. I knew assembly and logic but not how to fill the gap to
create a CPU. The popular book from a few years ago which plugged the
hole for me was ‘The Elements of Computing Systems’, which I see has now
had a second edition: ISBN 0-262-53980-2, https://amzn.to/3xE0IZo
It's a book of two halves: the first builds a simple CPU for a primitive
computer from nothing but NAND gates; the second half writes an
assembler, then a compiler for a language targeting a VM and then
implements the VM on the CPU built in part one. It's the reader who has
to do all this. Initially in the book's HDL run against the provided
simulators and test cases. Then in the programming language of his
choice as just text I/O is required.
So to start the other binary-operator logic gates have to be build with
NANDs, then multiplexers, etc. There's a target of how many gates to
use so an efficient design has to be produced. By chapter two we're
implementing the ALU. After the sequential logic of chapter three the
instruction set is introduced in chapter four. It proceeds at pace,
just giving the barest tuition needed to understand each conceptual
part. Any discussion of subtleties or alternative approaches is
eschewed for weightier textbooks.
I think it's a better introduction to CPU design and from that one can
read up on Verilog, etc., and start experimenting with little CPU
designs on FPGAs.
--
Cheers, Ralph.
1 Dec
1 Dec
9:46 a.m.
On Nov 30, 2021, at 11:27, Ralph Corderoy
<ralph(a)inputplus.co.uk> wrote:
... The point of that bit of history is they were not chip designers, but
knew electronics and programming. Wilson designed the ARM's instruction
set and it was a delight to code: very orthogonal, and every instruction
had four-bits of condition-flag test, e.g. Carry Set, and a bit to
indicate if this instruction should set the condition flags. Thus
several instructions in a row could test the condition flags set by an
instruction a few earlier and unaltered since; this cut the need for
quite a few branches. ...
I wrote a fair amount of PDP-11 assembler, back in the early 70's (about 10K LOC). I
was particularly happy with a routine that moved a cell between a pair of doubly-linked,
circular linked lists (a "free" list and a "busy" list).
The routine only had to modify six pointers, which isn't a hard problem. The cute
part was that it was able to do so using (IIRC) only eight or nine instructions. The
PDP-11's auto-increment mode obviated the need for separate index modification code.
I had previously written a fair amount of code for a Varian 620i, which had an AQX
architecture. The 620i wasn't _hard_ to program, but it _was_ a bit tedious. The
PDP-11, by comparison, was a programmer's delight.
Which brings me to a historical notion:
The DG Nova (https://en.wikipedia.org/wiki/Data_General_Nova) came out in 1969, just a bit
before the PDP-11 (https://en.wikipedia.org/wiki/PDP-11) My impression, when I (later
on) looked at the Nova ISA, was that they had moved in the right direction from the AQX
approach, but not quite far enough. DEC, IMNSHO, got it right. (ducking).
-r
1:28 p.m.
On 12/1/21 12:46 AM, Rich Morin wrote:
The DG Nova
(https://en.wikipedia.org/wiki/Data_General_Nova) came out in 1969, just a bit before the
PDP-11 (https://en.wikipedia.org/wiki/PDP-11) My impression, when I (later on) looked at
the Nova ISA, was that they had moved in the right direction from the AQX approach, but
not quite far enough. DEC, IMNSHO, got it right. (ducking).
https://history-computer.com/dec-pdp-11-computer/
is a concise summary of where the pdp-11 architecture came from
(Harold McFarland at CMU) and the origins of the nova from the
and the connection to the dec pdp-x
original source documents can be found at bitsavers
30 Nov
30 Nov
4:18 a.m.
On Sun, Nov 28, 2021 at 05:12:44PM -0800, Larry McVoy wrote:
I remember Ken Witte (my TA for the PDP-11 class)
trying to get me to see
how easy it was to read the octal. If I remember correctly (and I probably
don't, this was ~40 years ago), the instructions were divided into fields,
so instruction, operand, operand and it was all regular, so you could see
that this was some form of an add or whatever, it got the values from
these registers and put it in that register.
I've looked it up and it is pretty much as Ken described. The weird thing
is that there is no need to do it like the PDP-11 did it, you could use
random numbers for each instruction and lots of processors did pretty
much that. The PDP-11 didn't, it was very uniform to the point that
Ken's ability to read octal made perfect sense. I was never that good
but a little google and reading and I can see how he got there.
Charles Sauer contacted me off list and sent me this:
https://notes.technologists.com/notes/2008/01/10/a-brief-history-of-dell-un…
Turns out that Ken was a big deal there. Not surprised at all.
--lm
29 Nov
29 Nov
2:18 a.m.
I suspect because we believed we understood the pdp11 we felt we'd
understand a good operating system on it.
If more tertiary education people had been on other hardware of the day,
we'd probably have invented the same myths for that host.
G
On Mon, 29 Nov 2021, 10:22 am Clem Cole, <clemc(a)ccc.com> wrote:
Rob, I offer a small tweak to your statement, that I
hope you will consider
On Sun, Nov 28, 2021 at 5:20 PM Rob Pike <robpike(a)gmail.com> wrote:
The PDP-11 as an affordable commercial computer,
now _that_ was important.
s/computer/mini-computer/
I really believe that this distinction is important. Bell coined the term
in the late 1950s/early 1960s when he called it a minicomputer. The key is
that he meant >>minimal computer - in function and price<< (not small).
(This would event eventual lead to Bell's law for the birth and death of
computer classes).
To me, the PDP-111 ISA is the epitome the *minimal computer architecture*
- just want you to need to get the job done be it commercial or
scientific and it was affordable as you said. The solution is elegant,
nothing fancy, little extra added - just the right set of features for a
system to do real work. It was also extremely regular as Larry points out,
so it was not filled with a ton of special cases. It did have a few more
features like addressing modes, and multiple registers that made it more
complex than say an accumulator-based PDP-8. But the small set of new
features made sense and were* of** use for almost all programmers*.
[FWIW: IMHO, most new features we add to Intel*64 is all for some special
cases for a specific customer].
I note that the VAX (was is the epitome of the CISC and while
extraordinarily successful), has always been an easy target as way too
complicated, filled with many special cases (just for the Fortran
compiler, or for Cutler's as an assembly programmer).
IMHO: C is also made from the same minimal ideal. It took the
simplicity of the B and added typing and better data structures, but did
not overdo it. Again, what was added was useful to almost all programmers.
I note that while the follow-on to both the 11 (the Vax) and C (C++)
became working horses, but both are ugly as can be, and neither would I
call elegant. I've used them both, however, I have moved on since that
time. I do pine for something more like a 64-bit PDP-11 (more in a
minute), and still use C when I can in the kernel or Go when in userspace.
Having kicked around DEC during some of the Alpha discussions, other than
the original lack of byte addressing, I think the PDP-11 influenced the
Alpha more than VAX did. There was a definition -- why is the needed --
thinking. Keep it simple a minimal.
As for Unix (since this is a Unix history list), again I think it is the
minimal view I miss from Sixth and Seventh Edition. I look at Linux and
mostly turn green with how much has been lost from those days. But like
the PDP-11, I can not really go back. My hope is that something will
appear that is "good enough" and '"simple enough" to get people
excited
again.
my 2 cents,
Clem
ᐧ
ᐧ
2:36 a.m.
On Nov 28, 2021, at 4:19 PM, Clem Cole <clemc(a)ccc.com> wrote:
My hope is that something will appear that is "good enough" and
'"simple enough" to get people excited again
My hope is for "Unix as a service". Just another service for
programs that need a Unix API. I think KeyNIX (Unix on top of
KeyKOS) had the right idea but the problem was and is that
typically hardware is not optimized for IPC & fast context
switching. That may change when we can put zillions of core
on a chip but can't speed up individual cores. UAAS may even
facilitate a move to a sea-of-cores architecture!
2:47 a.m.
Was B, or rather BCPL, influenced by Algol68? It too had
<var> <op>:= <value>
as a shorthand for
<var> := <var> op <value>
Its declaration
<type> <name>
is the same as in C. Though in A68 this was a shorthand for
ref <type> <name> = loc <type>
On Nov 28, 2021, at 1:31 PM, Ken Thompson
<kenbob(a)gmail.com> wrote:
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(a)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 
8:46 a.m.
Bakul Shah <bakul(a)iitbombay.org> wrote:
Was B, or rather BCPL, influenced by Algol68? It too
had
<var> <op>:= <value>
as a shorthand for
<var> := <var> op <value>
Its declaration
<type> <name>
is the same as in C. Though in A68 this was a shorthand for
ref <type> <name> = loc <type>
I don't know if it was purposeful or not, but Algol 68 had the notion
of deproceduring - i.e. function call, which seems to have carried over
into C where the name of function is a pointer to it. You can do
void myproc();
void (*functptr) = myproc;
...
funcptr()
to call through the pointer. (Even though the K&R book taught us
to use (*funcptr)(), the syntax above worked at least as far back
as PCC.)
Did C pick this up from Algol 68? I have no idea, but it would not
surprise me if it had.
Arnold
3:44 p.m.
On Mon, Nov 29, 2021 at 12:52:06AM -0700, arnold(a)skeeve.com wrote:
arnold(a)skeeve.com wrote:
Function pointers are the one part of C that I have to relearn every time.
--
---
Larry McVoy lm at mcvoy.com http://www.mcvoy.com/lm
void myproc();
void (*functptr) = myproc;
...
funcptr()
Make that
void (*funcptr)() = myproc.
Sorry. 
1:11 p.m.
On 28 Nov 2021 17:47 -0800, from bakul(a)iitbombay.org (Bakul Shah):
Was B, or rather BCPL, influenced by Algol68? It too
had
<var> <op>:= <value>
as a shorthand for
<var> := <var> op <value>
The already mentioned https://www.bell-labs.com/usr/dmr/www/chist.html
states that
"For example, B introduced generalized assignment operators, using
x=+y to add y to x. The notation came from Algol 68 [Wijngaarden 75]
via McIlroy, who had incorporated it into his version of TMG."
--
Michael Kjörling • https://michael.kjorling.se • michael(a)kjorling.se
“Remember when, on the Internet, nobody cared that you were a dog?”
28 Nov
28 Nov
10:23 p.m.
I heard that the null terminated string was a 11-build-in.
--- ------------------------------
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
10:39 p.m.
On Sun, 28 Nov 2021, Thomas Paulsen wrote:
I heard that the null terminated string was a
11-build-in.
It's a fairly good fit for 6502, too. When I write 6502 code, all my
messages are stored as C strings. Because on an Apple, something like
this...
putch = $FDED
entry: ldy #$00
@1: lda msg, y
beq @2
eor #$80
jsr putch
iny
bne @1
@2: rts
msg: .byte "Hello, cruel world.", 13, 0
...is pretty easy to do.
-uso.
11:41 p.m.
The ++ operator appears to have been. The PDP-11 had addressing modes to so predecrement
and postincrement.
On Nov 28, 2021, at 16:41, Steve Nickolas
<usotsuki(a)buric.co> wrote:
On Sun, 28 Nov 2021, Thomas Paulsen wrote:
I heard that the null terminated string was a
11-build-in.
It's a fairly good fit for 6502, too. When I write 6502 code, all my messages are
stored as C strings. Because on an Apple, something like this...
putch = $FDED
entry: ldy #$00
@1: lda msg, y
beq @2
eor #$80
jsr putch
iny
bne @1
@2: rts
msg: .byte "Hello, cruel world.", 13, 0
...is pretty easy to do.
-uso.
10:40 p.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
29 Nov
29 Nov
4:37 p.m.
I had ordered a used copy of the 2nd edition of the book (came from
the Cherry Hill Public Library!) before the plug for it on the list
came out (because it looked like it covered/credited MIT/Lincoln and
DEC systems in shaping interactive computing).
I found the book a mile wide, and a millimeter deep, and while I've
only randomly scanned it (mostly looking up index references), the
organization by time period shatters the stories of each manufacturer
into snippets, to a point that I'm hard pressed to believe that most
readers would be able to stitch back together in a way that would give
them a coherent idea of any particular strain of computing history.
Nonetheless, I'd be happy to hear that it was assigned reading for CS
students.
1082
days inactive
1085
days old
24 comments
16 participants
participants (16)
-
Al Kossow -
arnold＠skeeve.com -
Bakul Shah -
Clem Cole -
George Michaelson -
Jon Steinhart -
Ken Thompson -
Larry McVoy -
Michael Kjörling -
Phil Budne -
Ralph Corderoy -
Rich Morin -
Rob Pike -
Ron Natalie -
Steve Nickolas -
Thomas Paulsen