PL-11 is a high-level machine-oriented programming language

Programming language

A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....

 for the PDP-11

PDP-11

The PDP-11 was a series of 16-bit minicomputers sold by Digital Equipment Corporation from 1970 into the 1990s, one of a succession of products in the PDP series. The PDP-11 replaced the PDP-8 in many real-time applications, although both product lines lived in parallel for more than 10 years...

, developed by R.D. Russell of CERN

CERN

The European Organization for Nuclear Research , known as CERN , is an international organization whose purpose is to operate the world's largest particle physics laboratory, which is situated in the northwest suburbs of Geneva on the Franco–Swiss border...

 in 1971. Written in Fortran IV, it is similar to PL360

PL360

PL360 is a programming language designed by Niklaus Wirth for the IBM System/360 computer. It provides facilities for specifying exact machine language instructions and registers similar to assembly language, but also provides features commonly found in high-level languages, such as complex...

and is cross-compiled on other machines.

PL-11 was originally developed as part of the Omega project, a particle physics facility operational at CERN (Geneva, Switzerland) during the 1970s. The first version was written for the CII 10070, a clone of the XDS Sigma 7 built in France. Towards the end of the 1970s it was ported to the IBM 370/168, then part of CERN's computer centre.

A report describing the language is available from CERN.