4THGL code

[whtaylor@primenet.com (Warren Taylor)]

As a subcontractor to Boeing on ISS (aka ISSA aka SSF), we (Orbital Sciences) 
have been mandated by Boeing to use the MatrixX (ISI) system for all of our 
deliverable software, and have been working with the system for the last 5 or 
6 years.  In our case, the generated ADA code is not the deliverable, and in 
fact we don't even CM it.  The MatrixX diagrams, along with some human coded 
Ada and a very small amount of assembler (IPL and boot code) are the "source" 
code for this system.  As far as I know, all space station software from all 
subcontractors is to be developed under this environment.  As far as the 
choice of intermediate language goes, I can only relate that MatrixX does 
sometimes produce buggy Ada code, which is usually caught by the compiler.  I 
vote for Ada as the intermediate language for this reason.  All of our I/O and 
self test code with hardware interfaces was coded in Ada, including interrupt 
handlers.  By the way, the system is very far along in testing at this point, 
and no "show stoppers" have developed in any part of the system.

Warren Taylor
Senior Principal Engineer, OSC