[DougMerritt]

Yes. But the Burroughs architecture was literally designed to support the high level language (it was heavily CISC), so that solution did not extend to any other computer systems, whereas C of course was relatively portable.

(To head off complaints about what "portable means": portable enough that people did port Unix and C programs to many architectures, unlike the case with the Burroughs OS and programs.)

So the Unix claims of firsts need qualifiers to be absolutely true, but are true in spirit even when phrased casually: the earlier exceptions are mostly just curiosities.