Jim Hall wrote:
> > On Mon, Jan 29, 2024 at 8:07 PM Jim Hall <jh...@freedos.org> wrote:
> >> I am working on an academic project that requires understanding the
> >> MAD programming language so I can pick apart (and faithfully recreate)
> >> an old MAD program. That's the Michigan Algorithm Decoder, from 1959
> >> and the early 1960s.
> >> [..]
> >> Does anyone know of a MAD compiler for DOS?
Ralf Quint wrote:
> Up to your email, I haven't even heard of a MAD compiler. Only the
> magazine... 😛
> (and interesting seeing that mentioned in the Wikipedia article LOL)
Yes, I hadn't heard of it either until a few months ago when I started
researching the RUNOFF source code. It's written about half in MAD and
about half in FAP (FORTRAN Assembly Programming). The RUNOFF program
is written in MAD with some support functions in FAP.
I'm thinking about writing a book about the early history of document
preparation systems, and RUNOFF seemed a good place to start. I want
to faithfully recreate the MAD code in another programming language -
not an automated translation like ESR's translator would do, but an
understandable recreation by a human who understands what the original
code is doing and recreates it in a sensible way in another
programming language. Might do it in C or BASIC. BASIC might be
easier, since I'm seeing some similarities between MAD and BASIC. But
I'd prefer to do it in C.
But step #1 is to understand what's going on in the code. MAD is
mostly readable, but the for-next loop equivalent is a little weird to
me. For example, to loop from 1 to 10 (inclusive) in C, you'd do this:
for (i = 1; i <= 10; i++) {
...
}
Just to compare: in FORTRAN77, it's like "DO label var = start, stop, step":
DO 10 I = 1, 10, 1
...
10 CONTINUE
But in MAD, I *think* it's like "THROUGH label, FOR var = start, step,
failcondition":
THROUGH LOOP, FOR I = 1, 1, I .GT. 10
...
LOOP CONTINUE
And from what I can see, I think "failcondition" gets tested at the
end of each iteration, so it's more like this weird 'while'
construction in C:
i = 1;
do {
...
i++;
} while ( !(i>10) );
That's why I wanted to write some sample code in a real MAD compiler,
to see if I'm correctly understanding that (and a few other odd things
in the language).
_______________________________________________
Freedos-devel mailing list
Freedos-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/freedos-devel
