29 Nov
2021
29 Nov
'21
12:12 a.m.
The ++ operator appears to have been.
One would expect that most people on this list would have read "The
Development of the C Language", by Dennis Ritchie, which makes perfectly clear
(at 'More History') that the PDP-11 had nothing to do with it:
Thompson went a step further by inventing the ++ and -- operators, which
increment or decrement; their prefix or postfix position determines whether
the alteration occurs before or after noting the value of the operand. They
were not in the earliest versions of B, but appeared along the way. People
often guess that they were created to use the auto-increment and
auto-decrement address modes provided by the DEC PDP-11 on which C and Unix
first became popular. This is historically impossible, since there was no
PDP-11 when B was developed.
https://www.bell-labs.com/usr/dmr/www/chist.html
thereby alleviating the need for Ken to chime in (although they do allow a
very efficient implementation of it).
Too much to hope for, I guess.
Noel
29 Nov
29 Nov
12:35 a.m.
New subject: A New History of Modern Computing - my thoughts
Getting a bit far afield from Unixes, but A Quick Rundown Of Instruction
Sets I Have Known, more or less in the order I learned them:
6502: you never forget your first love, and, sure, it's constrained, but
it's elegant and concise and I still adore it.
68k: Lovely. I used it before I ever used the PDP-11, but in retrospect
it's like the PDP-11 but more so. Roomy, comfortable, regular. Too bad it
lost to x86 in the marketplace.
8051: I mean, OK, I get it, you need a low-cost embedded architecture and
it's the 1980s, but...yuck.
x86-and-descendents: the less said the better. Maybe I just don't like
Intel's designs?
SPARC: It's not bad. Having lots of registers is nice. But by the time it
came along compilers were good enough that I never actually needed to use
it in anger.
S/360-and-descendents: The S/360 is OK, even nice, in a very 1960s IBM
way. And then its evolution just KEPT adding ever more baroque filigrees
onto it. Don't get me wrong, I love SIE, because I love VM, but even that
is kind of a bag on the side, and by the time you get to System z...this is
what happens when you don't start over from a clean sheet every so often.
PDP-11: There's a very good reason it was used as a model architecture in
coursework for decades. Also regular and comfortable.
TI-99/4A (more or less TI 9900): I like microcode as much as anyone but
honestly this is pretty silly here, folks.
These days I'm kinda sorta poking at RISC-V and ARM. Not that I need to,
but they seem nifty.
Adam
On Sun, Nov 28, 2021 at 4:15 PM Noel Chiappa <jnc(a)mercury.lcs.mit.edu>
wrote:
The ++
operator appears to have been.
One would expect that most people on this list would have read "The
Development of the C Language", by Dennis Ritchie, which makes perfectly
clear
(at 'More History') that the PDP-11 had nothing to do with it:
Thompson went a step further by inventing the ++ and -- operators, which
increment or decrement; their prefix or postfix position determines
whether
the alteration occurs before or after noting the value of the operand.
They
were not in the earliest versions of B, but appeared along the way.
People
often guess that they were created to use the auto-increment and
auto-decrement address modes provided by the DEC PDP-11 on which C and
Unix
first became popular. This is historically impossible, since there was no
PDP-11 when B was developed.
https://www.bell-labs.com/usr/dmr/www/chist.html
thereby alleviating the need for Ken to chime in (although they do allow a
very efficient implementation of it).
Too much to hope for, I guess.
Noel
2:53 a.m.
New subject: A New History of Modern Computing - my thoughts
On Sun, Nov 28, 2021 at 6:37 PM Adam Thornton <athornton(a)gmail.com> wrote:
PDP-11: There's a very good reason it was used as
a model architecture in
coursework for decades. Also regular and comfortable.
MIPS II / MIPS32 has also been used as a model architecture: it's 32-bit
and supported by current gcc (as is the PDP-11). A short paper on running
C programs on the JVM is at <http://www.xwt.org/mips2java/>: you compiled
them to MIPS R2K statically linked executables and then compiled the
resulting executables to Java. The regularity of the MIPS ISA made the
compiled code decently fast even before the JVM JIT.
>
2:48 p.m.
New subject: A New History of Modern Computing - my thoughts
On 11/28/21 6:35 PM, Adam Thornton wrote:
Getting a bit far afield from Unixes, but A Quick
Rundown Of
Instruction Sets I Have Known, more or less in the order I learned them:
6502: you never forget your first love, and, sure, it's constrained,
but it's elegant and concise and I still adore it.
68k: Lovely. I used it before I ever used the PDP-11, but in
retrospect it's like the PDP-11 but more so. Roomy, comfortable,
regular. Too bad it lost to x86 in the marketplace.
8051: I mean, OK, I get it, you need a low-cost embedded architecture
and it's the 1980s, but...yuck.
x86-and-descendents: the less said the better. Maybe I just don't
like Intel's designs?
SPARC: It's not bad. Having lots of registers is nice. But by the
time it came along compilers were good enough that I never actually
needed to use it in anger.
S/360-and-descendents: The S/360 is OK, even nice, in a very 1960s IBM
way. And then its evolution just KEPT adding ever more baroque
filigrees onto it. Don't get me wrong, I love SIE, because I love VM,
but even that is kind of a bag on the side, and by the time you get to
System z...this is what happens when you don't start over from a clean
sheet every so often.
PDP-11: There's a very good reason it was used as a model architecture
in coursework for decades. Also regular and comfortable.
TI-99/4A (more or less TI 9900): I like microcode as much as anyone
but honestly this is pretty silly here, folks.
When I was in high school, I loved reading about instruction sets. I
recommend the first five volumes of Annual Review in Automatic
Programming, if you are interested.
The DEC instructions sets were all quite elegant, from the minimal PDP-8
(nee PDP-5) 12-bit machine to the PDP-10 (nee 6). I maintained the BCPL
compiler at BBN for a while in the 1970's, and it was a pleasure to
figure out what machine code to generate.
Then there was RISC vs CISC, where the VAX was a major punching bag. I
was at Berkeley for RISC-I, and was a part of the small student group
that did its register windows scheme.
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jnc＠mercury.lcs.mit.edu -
John Cowan