[TUHS] The origins of portability in C

[christopher fujino via TUHS]

I have often read things like, "`int`s in C are of unfixed size so that
Unix could be ported." So I was surprised to read in Dennis Ritchie's "The
Development of the C Language" that:

PL/I, the implementation language of Multics, was not much to our
> tastes, but we were also using other languages, including BCPL, and we
> regretted losing the
> advantages of writing programs in a language above the level of assembler,
> such as ease of writ-
> ing and clarity of understanding. At the time we did not put much weight
> on portability; interest
> in this arose later.
>

Brian Kernighan quotes Steve Johnson in "Unix: A History and a Memoir":

There was another pressure to make Unix portable. A number of DEC's
> competitors were beginning to grumble that regulated AT&T had too cozy a
> relationship with DEC. We pointed out that there were no other machines
> like the PDP-11 on the market, but this argument  was getting weaker.
> Dennis hooked me into the portability effort with one sentence: 'I think
> that it would be easier to move Unix to another piece of hardware than to
> rewrite an application to run under a different operating system.' I was
> all in from that point on.


A few questions:

1. Was Johnson's Portable C Compiler developed explicitly to port Unix, or
was it already around?
2. And if it was already around, what was the initial motivation for
creating a portable C compiler?
3. Am I right to assume that prior to the Portable C Compiler, C's
primitives were thought of as PDP-11 specific?

Thanks!

Chris