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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Would this be logical for embedded hardware?
Date: Mon, 02 Jul 2012 12:19:36 +0100
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Date: 2012-07-02T12:19:36+01:00
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Austin Obyrne <austin.obyrne@hotmail.com> writes:

> Can I slap my soul on the table here and say I am not at all sure what
> an embedded system really means - as an engineer I immediately
> envisage some piece of equipment that is triggered into action by a
> controlling signal that then runs the equipment according to the
> embedded sytem algorithm.  The most dramatic one I can think of is say
> putting down the landing gear of an aircraft (that I happen to be on)
> just when it is needed and the extremme case also of launching a
> nuclear weapon say.

In an Ada context, "embedded system" would almost always mean this sort
of system.

> But there is another instance also that I am not at all sure about and
> that is an embedded program within a piece of software written in the
> same language or even a different language - is this just a figment of
> my imagination or does it exist - even under another name = like say a
> task package?

This too is possible, though less common.

As an example, TclAdaShell[1] allows you to embed a Tcl interpreter in
an Ada program. 

I've used this to provide a functional testbed; I made the
software-under-tests's services and dependencies visible from Ada, and
the test scripts were written in Tcl. This was highly cost-effective.

Another use might be to use Tk to implement the GUI of an Ada program.

I would never refer to this kind of system as "embedded", though.

[1] http://tcladashell.sf.net