Ada in Embedded Systems Programming.

Ada in Embedded Systems Programming.

[whiting_ms@corning.com (Matt Whiting)]

Has anyone other than me read the most recent edition of "Embedded Systems
Programming" magazine (Vol. 7, Number 11, Nov. 94)?  It contains two
interesting articles: one about Ada directly, and one that uses Ada as the
vehicle to illustrate another point.  I found both very good reading.

I'm a long-time Ada fan trapped in a corporation that went from marginal
to worse (FORTRAN to C).  I found these two articles very refreshing. 
They didn't come across to me as the usual obnoxious "my language is better
than yours" drivel, but rather made some very calm and factual arguments as to
why Ada was chosen for the specific application.

I'm beginning to think that the DOD mandate is very counter productive as a lot
of people seem to get their jollies from telling Uncle Sam to take a hike. 
Maybe if DOD dropped the mandate they would actually ENCOURAGE the commercial
use of Ada (many commercial companies want no association at all with the
military) and maybe even the DOD use.  The military can always simply offer
more promotions to program managers that choose Ada if they really feel the
need for an external incentive.  If the military is anything like civilian
companies, the word will soon get around and people will soon get the hint!  :-)

So ... maybe all you vocal Ada supporters should consider lobbying for
elimination of the mandate and the use of more "personal" incentives for the
use of Ada where it makes good sense.

Maybe we need a few more carrots and a few less sticks...

--
Matthew S. Whiting, P.E.   | PP-ASEL-IA | All opinions expressed herein are
Corning Incorporated       |            | strictly personal.
whiting_ms@corning.com     |            |

Re: Ada in Embedded Systems Programming.

[John M. Mills]

In article <1994Oct27.080032.1@corning.com>,
whiting_ms@corning.com (Matt Whiting) <whiting_ms@corning.com> wrote:
>
>Has anyone other than me read the most recent edition of "Embedded Systems
>Programming" magazine (Vol. 7, Number 11, Nov. 94)?  It contains two
>interesting articles: one about Ada directly, and one that uses Ada as the
>vehicle to illustrate another point.  I found both very good reading.

Yes, I enjoyed reading these articles.  Each was useful, but the article
on system engineering an automobile cruise control was particularly
gratifying in that it addressed realities of what I consider "software
engineering" as contrasted to "computer science."  On the other hand,
the satellite-borne controller described in the cover article (by Richard
Riehle) describe a system actually realized in Ada, whereas the cruise
control would presumably be recoded for smaller targets than supported
by most Ada compilers:  "I wrote the Ada design with an assembly language
solution in mind." -[author]  He also specifically refers to Ada typing
models which will enhance the protability and/or focus attention on
implementation requirements for the eventual targets [i.e., multi-precision
fixed-point arithmetic].  I find this a quite useful insight.

I believe the "all or nothing" approach to Ada's design has shut it out of
a lot of this class of applications, quite aside from Ada's other qualities
as a development language: by that, I mean that I am unaware of
a compiler which would target (say) an 8051, following code development and
analysis on a larger platform.  I'm afraid I consider the common "Show me a
design that couldn't be done in Ada" response to be foolish and immaterial if
the application environment can't accept the targets which Ada compilers can
support.  The Riehle article mentions some [Ada legal] suppressions which
enable them to target a 64Kw memory space.  In retrospect, more elaborate
switches to turn Ada language features on and off might have been a good
design approach.

(Nomex gloves and safety glasses are now in place!)

Regards --jmm--

-- 
John M. Mills, SRE -- john.m.mills@gtri.gatech.edu -- (404)528-3258 (voice)
   Georgia Tech/ GTRI/ SDL, 7220 Richardson Rd., Smyrna, GA 30080
     Inez Has Tiny Fuzzy Poodles - II'67

Re: Ada in Embedded Systems Programming.

[Ted Dennison]

In article <38orsv$1sv@siberia.gatech.edu>, jmills@ccrf-news.gatech.edu (John M. Mills) writes:
|> I believe the "all or nothing" approach to Ada's design has shut it out of
|> a lot of this class of applications, quite aside from Ada's other qualities

There are a TON of validated Ada cross-compilers. I have done an embedded 
project in Ada, with no real problems. I think there is a lot more embedded
Ada programming than you may be aware of. 

So what is the problem with Ada for embedded applications?

|> as a development language: by that, I mean that I am unaware of
|> a compiler which would target (say) an 8051, following code development and

Well, a quick search through the list of validated compilers confirms your 
suspicions; I couldn't find any validated 8051 cross compiler. The 8051 is WAY
obsolete though. Nonetheless, I'm sure someone will port GNAT to it if there is
any kind of demand.

|> analysis on a larger platform.  I'm afraid I consider the common "Show me a
|> design that couldn't be done in Ada" response to be foolish and immaterial if
|> the application environment can't accept the targets which Ada compilers can
|> support.  The Riehle article mentions some [Ada legal] suppressions which
|> enable them to target a 64Kw memory space.  In retrospect, more elaborate
|> switches to turn Ada language features on and off might have been a good
|> design approach.
|> 

Cross compiler vendors commonly use a reduced version of the the Ada runtime
(eg: no tasking or dynamic memory allocation/deallocation). Is this the kind
of thing you are thinking of?

T.E.D.

Re: Ada in Embedded Systems Programming.

[Norman H. Cohen]

In article <1994Oct27.080032.1@corning.com>, whiting_ms@corning.com
(whiting_ms@corning.com (Matt Whiting)) writes: 

|> I'm beginning to think that the DOD mandate is very counter productive as a lot
|> of people seem to get their jollies from telling Uncle Sam to take a hike.
|> Maybe if DOD dropped the mandate they would actually ENCOURAGE the commercial
|> use of Ada (many commercial companies want no association at all with the
|> military) and maybe even the DOD use.

Corporations whose decisions are made with this level of maturity are
bound to be short-lived anyway, so it shouldn't matter much to anybody
which programming language they use.

--
Norman H. Cohen    ncohen@watson.ibm.com

Re: Ada in Embedded Systems Programming.

[John M. Mills]

In article <38qt85$as2@theopolis.orl.mmc.com>,
Ted Dennison <dennison@romulus23.DAB.GE.COM> wrote:
>.. I think there is a lot more embedded
>Ada programming than you may be aware of. 

I'm sure there are many I'm unaware of, but it is interesting how many folks
suggest that we are pioneers for doing it.  Actually we don't use any radical
tools, and many better ones [than what we use] are now available.

>So what is the problem with Ada for embedded applications?

Nothing, if you can afford enough target processor.  My point was that more
applications would _benefit_ from Ada if some reduced-function compilers
could target common microcontrollers and fit executables into a few tens of
KBytes of RAM and ROM.  You could benefit from the compile-time qualities,
if you forwent some run-time features and libraries.

>Well, a quick search through the list of validated compilers confirms your 
>suspicions; I couldn't find any validated 8051 cross compiler. The 8051 is WAY

This doesn't explain the ads I see every couple of months for newer and faster
8-bit microcontrollers, including 8051-variants and compatibles, nor the number
of ads for cross-compilers (C, of course), emulators, and related tools.  The
fire alarm/security system just installed  in our building uses two 8085 CPUs.
Appalling from a technical standpoint, but obviously current technology.  (The
last 80xx code I wrote was for 8085s, ten years ago.  It's probably still
running, however.)

I would settle for a 16-bit target with small ROM and RAM partitions.  I expect
the processor chip isn't such a driver as the support silicon.  Recently we
were asked to identify Ada tools to transition a 16-bit single-card missile
telemetry controller from assembly language.  After hearing the price, the
client was overjoyed to hear about the target memory requirement, since that
was so much larger than their hardware, it allowed them to instantly dismiss
the expen$ive Ada tools.  (Our recommendations matched frequently-given
advice here -- don't bother to flame me for not reading the validated compilers
list.  We also talked to support engineers identified by the vendors.)

>Nonetheless, I'm sure someone will port GNAT to it if there is
>any kind of demand.

I've always thought of FSF and the GNU project as the one successful example
of Supply Side Economics!

>Cross compiler vendors commonly use a reduced version of the the Ada runtime
>(eg: no tasking or dynamic memory allocation/deallocation). Is this the kind
>of thing you are thinking of?

Yes -- There are probably ways to address this and come out with smaller
executables.

This problem isn't restricted to Ada -- I managed one project with Intel
FORTRAN 77 (extended) on a '286 processor.  Our in-house-code size estimates
were within about 20%, but Intel's libraries linked about five times what they
had estimated for us.  Fortunately it was no bell-ringer in that application.

Regards --jmm--

-- 
John M. Mills, SRE -- john.m.mills@gtri.gatech.edu -- (404)528-3258 (voice)
   Georgia Tech/ GTRI/ SDL, 7220 Richardson Rd., Smyrna, GA 30080
     Inez Has Tiny Fuzzy Poodles - II'67