PLEX and AXE system

PLEX (Programming Language for EXchanges) is a special-purpose, pseudo-parallel and event-driven real-time programming language. Dedicated for AXE telephone exchanges, it was developed by Göran Hemdahl at Ericsson. Originally designed in the 1970s, it has been continuously evolving since then. The language has two variants: Plex-C used for AXE Central Processors (CP) and Plex-M used for Extension Module Regional Processors (EMRP).

PLEX-C programming language

PLEX is an acronym for Programming Language for EXchanges and is a highlevel language developed by Ericsson in the 1970s, and extended in 1983. Programs in the AXE central processors use the Plex version Plex-C. The EMRP, which controls the subscriber stage, runs programs in Plex-M, a different dialect of Plex.

Plex is a high-level, real-time, language with very strict requirements regarding execution time.