[Info-vax] Ada on VMS, was: Re: Free Pascal for VMS ?

[Scott Dorsey]

Chris  <xxx.syseng.yyy at gfsys.co.uk> wrote:
>On 05/13/18 01:36, Scott Dorsey wrote:
>
>> Ada83 was a monster, it just grew into a bigger one.
>
>Fwir, The whole point about ADA was that it was formally verifiable,
>together with it's internal real time time executive. 

Yes, although you could get an Ada subset that was verified but lacked
any of the realtime features, for more general purpose business programming.
The DoD intention was to eventually move all programming of every sort to
Ada, which didn't happen in the long run.

>It  had
>rigorous run time checking capability, concurrency and more. It was and
>perhaps still is widely used for aerospace, avionics, safety critical
>etc and of course military projects. Both those markets have a lot of
>money behind them and it might be missing that market by not having
>a working compiler. 

Yes.  Although it should be said that there were other programming languages
like JOVIAL that were dominant in those markets and which still struggle
along to some extent there.  It is amazing the extent to which
all of that has disappeared in the past 20 years, though, and the extent
to which C has taken over in that market in spite of being inherently unsuited
for that sort of work.

>VMS historically was  used in that market
>alongside ADA because of it's reliability and security. It was never
>relevant to the sort of embedded systems work done here, but can
>understand the reasoning behind it. Complex, yes, but most other
>languages get nowhere near it's capabilities. More of a system than
>a programming language...

Yes, and this was part of the problem behind it.  Also, as you'll note,
it was used quite a bit as an embedded programming language and so 
frequently used with a cross-compiler running under VMS that generated
code to run on the embedded architecture.  Such cross-compilers are
comparatively easy to port to x86 since the back end doesn't have to change.
--scott

-- 
"C'est un Nagra. C'est suisse, et tres, tres precis."