On our journey through the programming languages of the 60s, we can of course not skip the B programming language, one of the more influential predecessors of C. Both B and C, being developed at Bell Labs by Ken Thompson and Dennis Ritchie, exhibit large similarities in their syntax, yet B ended up being quickly succeeded by C and was therefore never used widely. This made it quite challenging to find a B compiler that runs on modern systems. The few systems that still use B target mainframes rather than mainstream x86_64/ARM hardware.
Fortunately, a few hobbyists have taken on the challenge of building a B compiler based on the Ken Thompson book, in particular C. Smith, whose implementation I will use for this challenge. To quote the website:
It is implemented by compiling to machine code for a fictitious machine (actually a family of machines) which is then run by an instruction set simulator. The reason I mention a family of machines is because although it primarily supports the version of B described by Ken Thompson in his original reference manual for B on the 16-bit PDP-11 minicomputer (which I have followed as rigorously as possible)
With a little bit of patching, most notably pinning down the C++ standard to C++03, this compiler runs more or less out-of-the-box on modern POSIX systems such as macOS or Linux. By targeting bytecode rather than native code the compiler also sidesteps the portability issues with assembly or machine code generation.