I personally am not aware of another any earlier, so if you asked me that is what I would have said. I'd be curious if you discover an earlier one and the story behind it.

On Thu, Apr 15, 2021 at 7:20 AM Lars Brinkhoff <lars@nocrew.org> wrote:

Hello,

Which was the first C compiler written outside Bell Labs?

I have a candidate in mind. Alan Snyder interned at Bell Labs in 1973.
Later at MIT, we wrote a C compiler for the PDP-10. This would have
been 1974-1975.