Re: Why couldn't an operating system be written in ada

[Randy Greene <rgreene1@msmail4.hac.com>]

Robert Dewar wrote:
> 
> Nasser said
> 
> "Building a "real" OS is a very large job, it takes years and years,
> with large teams of people working on it, and very few companies
> can committ to something like this very easily regardless of the
> language used."
> 
> Building a full OS, including all utilities, compilers, etc is indeed
> a very large job, but building just the kernel is not such a  big job
> (Linux for instance is NOT that large). So building an OS kernel
> in Ada would be a reasonably practical project.

My 2 cents...

I agree with Robert that the effort to build an OS kernel in Ada is 
not unreasonably large. The part of Hughes Aircraft that I work for 
has been writing real-time embedded OSs in Ada since 1988, the latest 
having been developed for the F-22 figher. These OSs support multiple 
programs, multi-threaded processes, separate virtual address spaces 
for each program, Multi-level security, etc., and, even with all the 
I/O drivers, these OSs have tended to run around 25,000 lines of code 
or smaller (maybe 15,000 for the kernel itself). This isn't so large 
that its beyond the scope of one person to write. My experience is 
that the other tools needed for a "full" system (compiler, linker, 
debugger, etc.) tend to take far more effort than the kernel itself.


Randy Greene
Hughes Aircraft Company
Radar and Communications Systems