THE ESTEREL V4_45 SYSTEM IS NOW AVAILABLE
                 -----------------------------------------
     
The release Esterel v4_45 of the Esterel v4 system is now available.  
Esterel v4_45 is fully compatible at source code level with the
previous version Esterel v4_41 and v3_23.

Esterel v4_45 differs from its predecessor Esterelv4_41 in the following ways:

  - A new causal interpretation scheme has been added (option -I). This
  interpretation option produces an object C code that is much simpler
  and much faster than the one produced by option -I of esterelv4_41,
  which uses the Esterel v3 technology. The interpreter is based on a
  new semantics called the constructive semantics.
  It is able to handle programs that were flagged as causally
  incorrect by v3_xx and v4_4x. Interpretation fails for non-causal programs.
  In that case, there is an error message in simulation mode and a return 
  code of -1 in normal mode.
  The underlying theory of constructive causality is reported in a research
  paper available by ftp from server
                   cma.cma.fr 
as 
          esterel/constructiveness.ps.gz
  
  - The Motif-based graphical simulator xsimul is replaced by a new
  Tcl/Tk based simulator called xes (X Esterel Simulator). Xes is
  directly included in the esterelv4_45 distribution tape, unlike xsimul that 
  was distributed separately. Xes is developed by Jean-Paul Marmorat.

  - Generation of hardware circuits from Pure Esterel programs is possible
  by using the -Lblif option (esterel -Lblif foo.strl).
  The circuits are generated in Berkeley Logic Interchange format (blif).
  Contact us if you want to use this possibility; you will then need 
  additional documentation and specific optimizers.

  - The wristwatch example is included in the distribution tape. Use it to try
    xes!

Esterel v4_45 is in fact an intermediate version that will later be
replaced by Esterel v5 described below. Even if it is yet incomplete,
we make it available to let users experiment with the new interpreter
and with the xes simulator.


To get Esterel v4_45
- --------------------

 If you already ftp'ed an Esterel v4_4x compiler, you will find v4_45 at
the same place on cma.cma.fr, with xes included. Just ftp it; 
you won't need another licence.
Otherwise, please write to esterel-request@cma.cma.fr.


Towards Esterel v5
- ------------------

 Esterel v4_45 should be the last compiler of the Esterel v4 series. 
Then we shall distribute a new generation Esterel v5 compiler
that will include the following features:

  - Exact causality analysis, both at interpretation and compilation
  time. This will remove one of the most annoying limitations of v3 and v4.
  All programs accepted so far will remain accepted. The new acceptance
  criterion will be much simpler and semantically well-defined
  by a clean restriction of the behavioral semantics called the
  constructive behavioral semantics. This will be the main improvement.

  - More elaborate symbolic simulation: when running xes, the
  instructions executed during a transition will be highlited on the
  screen. Causality problems will be shown directly on source code 
  using an appropriate coloring scheme. (There is an approximation of this 
feature
  in esterelv4_45 when using xes with the -I option, but it is yet imperfect 
and
  not documented).

Gerard Berry, Xavier Fornari, Jean-Paul Marmorat