PLEX (programming language)

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Paradigm procedural, imperative
Developer Göran Hemdahl
First appeared 1970s
OS Ericsson APZ
License Proprietary

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.[1] Originally designed in the 1970s, it has been continuously evolving since then.[2] The language has two variants: Plex-C used for the AXE Central Processor (CP) and Plex-M used for Extension Module Regional Processors (EMRP).[3]


Several precompilers or code generators exist, to produce source code in Plex-C from higher level languages or graphical models[citation needed]. These can generate Plex-C from:

Source code in Plex-C is compiled into the assembly language ASA210C. The binary form of ASA210C is either interpreted by a combination of hardware and microcode, or is compiled by a Just-In-Time compiler into native machine code for a high-capacity microprocessor.


Code execution is triggered by specific events, encoded as signals.[3]

See also[edit]


  1. ^ Joe Armstrong. "A History of Erlang" (PDF). Ericsson AB. Retrieved 2009-03-07. 
  2. ^ Johan Erikson and Björn Lisper. "A Formal Semantics for PLEX" (PDF). Mälardalen University. Retrieved 2009-03-07. 
  3. ^ a b Johan Erikson and Bo Lindell. "The Execution Model of APZ/PLEX - An Informal Description" (PDF). Mälardalen University. Retrieved 2009-03-07.