Re: Ada Operating System

["Randy Brukardt" <randy@rrsoftware.com>]

>Sometime ago, I was thrown a question while giving talks in
>Universities. "What language do they use to build the Ada compiler?"
>and an (assumed) answer from the audience was "C". Then raised another
>question: "If Ada has many safety features that C does not have and
>the Ada compiler was written in C, how exactly safe is Ada?"
>
>I know there is ACVC test suite out there to certify Ada compilers
>before they reach out the market. But then, why still use C to write
>an Ada compiler?

For what its worth, Janus/Ada is 99.5% written in Ada, and always has
been (since June 1981, long before it was first released). There is a
small amount of assembler in the compiler (for performance reasons; we
have Ada equivalent code that we use when porting the compiler to
another platform). The runtime is also all in Ada except for about 8000
lines of assembler that do things not possible in Ada 83, including task
context switching, implementing the heap, exception handling, and so on.
Much of that could be written in Ada 95; we haven't done so mainly
because it isn't broken (important rule of computing: "If it ain't
broke, don't fix it!"). We've also built all of the compiler's tools
(Make, Debugger, etc.) in Ada. The only exception is the programming
environment, which we acquired from another company; we're planning to
replace it with a Claw application as we can't fix it (no source code),
which will eliminate that as non-Ada code.

I believe at least one other Ada compiler is virtually all in Ada.

                    Randy.