A thought...

[Chuck Tomlinson]

> From: tom cloud <cloud at peaches.ph.utexas.edu>
> 
> I haven't worked on process control or related in a while, but there
> were always public domain OS's (and boot routines) available for
> the 8-bit genre.  I'll bet if you look you'll find the same thing
> exists for the 80x86 types.  The advantage is there's cheap hardware
> already available.  You don't normally want all that DOS crap hanging
> around your neck -- it's too unwieldy, it's for a different purpose.

I really haven't had any problems with DOS.  Once the app is loaded and 
initialized, our DOS-based controllers really don't call any DOS or 
BIOS services at all.  The DOS compilers manage to translate all our 
core code to "straight" '386 assembly.

> There's too much stuff you don't need.  If you can find a simple OS
> written to work on the PC hardware it'll make a great platform to
> build any data logger, controller, etc.

I agree that DOS has tons of stuff that isn't necessary for the
controller, but one huge benefit of DOS is that you can use industrial
strength (but cheap) optimizing C compilers, and do all the debug and 
development on the same machine.  

Also, the same compiler can be used to write a powerful user interface 
for data logging and parameter tuning.  If the controller is running 
stand-alone, you can disable the user interface. Then the extra DOS 
baggage is all passive, and doesn't create any overhead.

Even when I write 68332 controller code, I do all the code maintenance 
and syntax-checking in a PC development environment, usually the 
Borland C++ Windows IDE.  I only run the '332 compiler and linker when 
I'm ready to run the code.  

Maybe it means I'm not a "real" programmer, but I like my development 
environment to be as effortless as possible (to save my brain-power for 
the algorithm :-).  I also like to keep far away from assembly language.  
The PC compilers support all sorts of handy macros that allow you to 
write 100% C code.

--
Chuck Tomlinson