PL/P

The PL/P programming language (an acronym of "Programming Language for Prime (computers)") is a medium-level language developed by Prime Computer to serve as their second primary operating system programming language after Fortran IV.

Additions to the PRIMOS operating system for Prime 50 Series computers was written mostly in PL/P in later years. Certain PRIMOS modules written during PRIMOS's early years in Fortran IV were rewritten in PL/P. PL/P was the most widespread compiled programming language used for commercial PRIMOS applications, outpacing the use of the Prime C compiler, the CPL scripting language, and the Fortran IV compiler in commercial applications.