I couldn't disagree more. Here is some background.

I didn't have much experience with COBOL or Algol -- Bell Labs was a FORTRAN shop. And we had a strong need to run FORTRAN programs on many different kinds of computers. So the portability of FORTRAN programs was very important. Barbara Ryder built a program (in FORTRAN!) called the PFORT verifier that verified that a FORTRAN program could be run on any of the six dominant machines of the day (this was an inspiration for Lint, by the way). It was incredible what differences she found in this "portable" language when different implementations encountered the programs. My favorite was a bug in one compiler that would cause a program that began with 50 comment cards to abort. The FORTRAN program produced a title line on the listing (remember those?) that was printed out, and it used the first function name to get the title. 50 lines => new page, no title => blam.   The subtle bugs caused by copy-in/copy-out argument passing were especially icky.

So portability was much in our minds in the late sixties and early seventies. As Unix began to catch on, there was a desire to move some utilities to other systems. Neither B nor the original C was really up to the job. Remember that machines of the day had different character sets, different floating point implementations, and different byte and word sizes, word address vs. byte addressed, and with different word orders. It was a zoo. Moving programs in any language was difficult, not least because the operating systems were so different (remember JCL?).

Late in 1974, as I recall, Dennis mused "You know, I think it would be easier to move Unix to a new machine than to change a large application to run on another operating system." I thought about this for a few minutes, and then offered to write a portable C compiler. I had already moved B and/or C from the PDP-11 to the Honeywell (36-bit words, 9 bit bytes, word addressed) and the IBM/360 (32-bits, byte addressed, but bizarre difficulties accessing memory in a reasonable fashion), so I had some idea what I was getting into.   We also persuaded the company to buy us a 32-bit minicomputer (the Interdata 4/32) with the goal of porting C and Unix to it.

With so many different kinds of opcodes and data formats, Dennis made what I think was an inspired solution.   + meant "add" on whatever computer it was running on.   int was the natural word size. etc. This had three very good properties:
1) it kept the language simple.   In particular, it kept us from having to specify bit widths for everything, which would then need to be changed when the program was ported to avoid inefficiency.
2) It kept the compiler simple. This was essential on the small PDP-11.
3) It turned out that with the addition of Lint, many problems that could result from porting could be found, without preventing the program from running well on the host system.

So C was indisputably intended to be portable, at least in that sense. And in practice it was highly portable while sacrificing little in performance on different systems (unlike some other languages).

There were drawbacks -- it wasn't perfect. Cross compiling from one machine to a much different one still had its challenges. Adopting the target machine's byte order made networking code harder to write. And machines that considered character constants to be signed produced a lot of irritation (and a lot of Lint messages). But it wasn't from lack of trying...

Steve

----- Original Message -----
From:
"Greg 'groggy' Lehey" <grog@lemis.com>

To:
"Noel Chiappa" <jnc@mercury.lcs.mit.edu>
Cc:
<tuhs@minnie.tuhs.org>
Sent:
Mon, 27 Feb 2017 07:49:00 +1100
Subject:
[TUHS] Portability (was: BSDi Imaging)

On Sunday, 26 February 2017 at 7:50:50 -0500, Noel Chiappa wrote:
>
> There were in theory portable languages beforehand (e.g. PL/1), but
> I think it probably over-specified things - e.g. it would be
> impossible to port Multics to another architecture without almost
> completely re-writing it from scratch, the code is shot through with
> "fixed bin(18)"'s every other line...

That may be coloured by your perspective. C was never designed to be
portable, while much older languages like Algol and Cobol were. There
were quite different reasons for C's success.

To quote "The Programmer's ABC'sâ from Datamation, April 1976:

C is for Cobol
What a pity
It was designed
By a committee

Greg
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