I noticed the "non-bell C" thread on TUHS and can add a data point
from datamuseum.dk:

The Danish Company "Christian Rovsing A/S" evidently had a C-compiler
for their CR80 mini computer, and my guess is that they created it
in order to qualify for DoD contracts in the POSIX regime.

Example C source:

        https://datamuseum.dk/aa//cr80/80/802c73092.html

Listing file from the compiler:

        https://datamuseum.dk/aa//cr80/ef/ef65339dc.html

Listing file from the assembler:

        http://datamuseum.dk/aa/cr80/32/32ef5456f.html

Listing from the linker:

        https://datamuseum.dk/aa//cr80/17/170304129.html

So far we have not spotted the actual compiler anywhere
in the media we have read.

Mention of C being used for project delivery:

        http://datamuseum.dk/aa/cr80/1c/1c0b47f0e.html

And btw:  That one is from a CDC disc-pack which a father+son
team has read by building a SMD-USB converter.

That project may be interesting in the TUHS domain as well:

        https://github.com/Datamuseum-DK/pico-smd-controller


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