MI, W-Code and OS/400

 >> What the heck is IBM in the language business for anyway? IBM should
provide ILE and a W-Code compiler.  The rest should be left to the
independents.

Back in the days of the 38 and the pre-ILE 400, "MI" was a published
standard and the translator was well known to many people - witness Leif's
book.  In all that time there were three compilers written by third parties.
Two of them by RM - COBOL and Fortran - and a C compiler by Asna.  None of
them remain in the market as far as I know unless Asna still sell theirs,
and the RM ones would never have happened without heavy funding from IBM.

Compilers are expensive to build and maintain, particularly when your user
base expects code they wrote 20 years ago to still work the same way when
compiled today.  IBM is in the compiler business in part because no one else
wants it.  The market on the 400 is _way_ too small for anyone to make
money.  IBM actively encouraged a number of vendors but it never came to
anything.

Remember also there are _two_ MI's not one.  The old OPM MI which includes
the opcodes you referenced and the new MI-prime which is similar to w-code.
The C compiler generates W-code.  In fact the current 400 C compiler _is_
the AIX compiler with slightly modified code gen to take advantage of
certain platform specific features.  While w-code is not platform specific
it does have a method for "suggesting" to the back end translator how to
optimize certain operations etc.

You can write to Bruce Vining at IBM in Rochester and ask for details of
w-code if you wish to build a compiler.  But don't bother trying to go back
to C - that would be a waste of time since w-code translators are available
for most major platforms.

Jon Paris
Partner400
www.Partner400.com