Re: New GNAT ports (was Re: Ada and Automotive Industry)

[ok@goanna.cs.rmit.edu.au (Richard A. O'Keefe)]

>  >"   Amen!  If it wasn't clear before, that was exactly my point.  The
>  >cost of the port can be academic if you can't guarantee that the
>  >compiler will be ready in time.  I'd want a lot of time for an 8051
>  >GNAT target,

I've been studying the 8051 recently.
I've convinced myself that with the aid of one more pragma [%]
an Ada *subset* can straightforwardly do everything that assembler
can do.  (Given a machine with 4k of code ROM (and _maybe_ up to
64k of external RAM) and < 256 bytes of data RAM (and _maybe_ up
to 64k of clumsily accessed external RAM) you clearly aren't going
to bother with interfaces to COBOL or floating point (my estimate
is that a good FP package would eat the entire ROM) and given the
way the 8051 does subroutine calls it's probably going to be a good
idea to ban recursion and so on.

It would of course be possible to achieve assembly code efficiency
using such an Ada subset, because with the aid of machine code
inserts your "Ada" code could *be* "assembler" code.  It would
still be useful to do because of packages and such.

Would there be any point in writing this up?
I've had wistful thoughts about a possible product.
Given that the two smart cards I've seen used 8051-like processors,
and given the range of applications for smart cards and "postage
stamp" computers (my word, the smart card chips are cheaper than
the concrete blocks my office is made from; the possibilities for
instrumentation are *awesome*) I suspect that the 8051 lookalikes
still have some useful lifespan, and that there is a bigger market
than one might think.  Example:  a lot of money hereabouts goes into
gambling.  How about hand-held bingo machines?  Or hand-held pokies?
What would happen if you had phone cards where you could gamble, and
the winnings would be free calls and the losses would be dead cards?
What about smart buildings with polymer-based chemical sensors hooked
up to postage stamp computers communicating over twisted pairs that
can *cheaply* monitor internal air pollutants?  I mean, we're talking
about systems where the wire would be the most expensive part!

[%] The pragma is
	pragma Origin(non-negative constant integer expression);
    saying that the first byte of the textually following statement
    is to be at the given address.  That was the only thing I saw in
    the 8051 book I was reading that I couldn't do in a reasonable
    Ada subset.

-- 
My tertiary education cost a quarter of a million in lost income
(assuming close-to-minimum wage); why make students pay even more?
Richard A. O'Keefe; http://www.cs.rmit.edu.au/%7Eok; RMIT Comp.Sci.