mapping of tasking to the OS

[Michiel Perdeck <perdeck.via@sni.de>]

I am gathering ammunition to propagate the use of Ada in my company 
(CMG plc) and I have the following question:

Ada supports tasking (multithreading) on the level of the language 
itself, as opposed to most other languages which leave this to OS calls 
who's semantics are not part of the language definition. I think that 
the Ada approach has the great advantage of making it possible to 
formally specify (a program is a formal specification) the concurrency 
aspect of a system. But...

How does the Ada tasking map to a particular operating system? Are there 
standard ways for this mapping in e.g. Unix (with and without 
lightweight processes), OS/2, Win95, NT, etc.? And what about some of 
the well-know C/Unix constructs like fork/exec, does that have an 
equivalent in Ada? I know that some of my collegues (specifically the 
Unix affictionado's) will want to be certain how specific multi-tasking 
constructs are mapped onto the OS! (And don't tell me that one can of 
course use OS calls in Ada.)

Regards,
Michiel Perdeck
----------------------
michiel.perdeck@cmg.nl
michiel.perdeck@tip.nl