Reading through [1], there are documents offered by
AT&T for the "Level II COBOL" system, which some further research indicates
is a product from Convergent (same folks as the UNIX PC.) There's also the LPI-COBOL
which appears to be a Language Processor Inc. product.
Ryan-McFarland comes to mind: in my recollection they were the leading Cobol on small
machines in the early 80’s. Ryan-McFarland’s predecessor company Digitek was contracted to
do the PL/I compiler for Multics, but failed. It seems they later did Bell Labs PL/I (says
https://en.wikipedia.org/wiki/Digitek) I think they did a Unix version of their Cobol in
the mid/late 80’s as well.
A few years ago I tried to find out more about RM-Cobol as it existed in the late 70’s and
early 80’s, but with little success. As a product it survived till the present day under
the ownership of Micro-Focus and most web mentions are for more recent versions.
It would seem to me that compilers on machines with small memories and word sizes in the
60’s, 70’s and even 80’s tended to compile to a virtual machine / intermediate code --
sometimes with the option to compile to native from there. Think BCPL and o-code, Pascal
and p-code, the Amsterdam Compiler Kit and m-code, the Microsoft “revenue bomb” p-code C
compiler, etc. According to the above Wikipedia article RM-Cobol used the same approach. I
did once see the source for another 80’s Cobol compiler and it compiled to a virtual
machine with 60-bit words.
By the way, I loved the recent posts on B and NB. THUS at its best!