 It was shipped within a year of PL/I F.

Compilers were implemented by several groups in the early 1960s.The Multics project at MIT, one of the first to develop an operating system in a high-level language, used Early PL/I (EPL), a subset dialect of PL/I, as their implementation language in 1964.EPL was developed at Bell Labs and MIT by Douglas McIlroy, Robert Morris, and others.