Re: Ada and embedded applications

["Chris Campbell" <chris.danx@ntlworld.com>]

"Robert A Duff" <bobduff@world.std.com> wrote in message
news:wccsnhg6j6v.fsf@world.std.com...
> "Chris Campbell" <chris.danx@ntlworld.com> writes:
>
> > One poster claimed that Ada was not used in some embedded devices because of
> > memory overheads for exception handling.
>
> Sounds like nonsense, but it's not completely clear what that poster
> meant.

This is the exact text (and not my regurgutation of it which is vague).

--
[ ... ]

> This is what I meant with "worship". Of course you're right, it's almost
> sure, that there exists a C compiler for that hand-holdable device.
> But why there is _only_ a C compiler for it? And not Pascal? Or Ada?
> Perhaps even Java could be possible?

Pascal (or at least something that looks roughly like Pascal) would
be a reasonable possibility if everybody agreed exactly what that
"roughly like Pascal" language really ought to be.

Ada probably is not reasonable for _most_ such devices.  Ada requires
exception handling, which takes up quite a bit of memory.  In
embedded devices, price matters a LOT, and more memory means a higher
price.  Ada _does_ get used in embedded systems with budgets to
support it (e.g. the aerospace industry) but in the lower-end of the
market, exception handling makes it unusable (and the same goes for
C++).

Consider that at work right now, I'm working on some code for a PIC
16C55, which has a total of 512 bytes (no, not Kbytes, but bytes) of
program memory available.  It might be possible to get an Ada program
to run in that, but if so it'll take somebody a LOT smarter than me
to do it.

In addition, Ada is a large, complex language so porting it to a new
processor tends to be a relatively slow, expensive process.  If a
company has a choice between using C and waiting 6 months for an Ada
compiler to get finished, there's often little real choice at all.
--
-- Jerry Coffin on alt.os.development in post Re: using C to develop an OS
--




Chris Campbell