Re: naval systems

[David Gillon <david.gillon@baesystems.com>]

Andrew Swallow wrote:

> ADA, officially, did not have any Input/Output statements. 

So Chapter 14, Input-Output, of Mil-Std 1815A is a figment of my
imagination?

> ADA compilers were very large, which made them very slow.  

Early Ada compilers, maybe (a lot depended on how good a job you did of
designing your code). Later ones, definitely not.

>  The runtime support code
> needed more memory than most embedded computers had. 

Only if you didn't tailor it. And how has the embedded market reacted to
this supposed limitation? Gone all out for run-time operating
systems.....

> ADA is only used where cost and time scales are
> unimportant - such as cost plus contracts.

Nonsense. Boeing _chose_ to use Ada for it's development of the 777,
which had extremely tight schedules and where contracts were
risk-sharing, not cost-plus. The FAA couldn't have cared less what
language they used, so they gained nothing there, but Boeing saw enough
gains in the language to pursue it for its own sake. 

> ADA is a bureaucrat, the only things that ADA does not double
> check are those it triple checks. 

Pragma Suppress etc..... Ada checking is configurable and quite capable
of being turned off entirely.

> Hence, ADA is unsafe in any application that requires fast reaction
> times like missile guidance systems, airborne radars or nuclear
> reactor shut down systems.

This would be why it is the language of choice for nuclear reactor
safety systems and fly by wire, then? Ada is quite capable of generating
precisely the same machine code as C for the identical task, so
statements it is inherently slow fly in the face of reality. What it is
is markedly more maintainable and inherently safer to code.

-- 

David Gillon