🚀 go-pugleaf

	About a month ago, I posted a question about
porting Pascal from VMS to a VAX running BSD 4.2.  I was
having problems with open/rewrite()ing files and with
separate compilation.  I would like to thank all of the
people who offered suggestions.  Most of them worked, and
my program set is now on BSD and running fine.  The rest of
this message is a review of the differences in file opening
and separate compilation.

1)	For file "output", Unix defaults to it open.  A
rewrite will cause your output to go to a wierdly named
file.  On VMS, the rewrite just restarts output to the
terminal again (useful to clear possible error bits).
Comment out a rewrite() from VMS to Unix, add one from Unix
to VMS.

2)	For files other than "output", VMS seems to be more
forgiving about forgetting to open them somehow.  I'm not
sure exactly what the difference was, though.

3)	For separate compilation, Unix uses a syntax very
similar to the "forward" keyword in Jensen-Wirth, but in
the modules, there is no "program" statement or anything
like that.  Instead of "forward", use "external", and put
those declarations in an include file.  VMS builds a module
very similarly to a program, but the new keyword "MODULE"
is used in place of "program".  Also, where the
"begin top-level-code end." would be in a program there is
an "end;".  The "forward" syntax is NOT required.  From Unix
to VMS, add the "module foo(input...);" to the front, the
"end;" to the end, and change all of your "external"s to
"forward"s.  From VMS to Unix, you have to make sure that
ALL of your routines are declared with "forward" first,
then cut off the "module..." and "end;", change the
"forward"s to "external"s, and cut them out into an include
file.

4)	Other changes: To Unix, flush the case to lower and
remove "_" and "$" from all names.  To VMS, probably change
rewrite()s to complicated open()s that look like ForTran
open statements.

Doug Freyburger		DOUG@JPL-VLSI, DOUG@JPL-ROBOTICS,
JPL 171-235		...escher!doug, doug@aerospace,
Pasadena, CA 91109	etc.

Disclaimer: The opinions expressed above are far too
ridiculous to be associated with my employer.

Unix is a trademark of Bell Labs, VMS is a trade mark of
DEC, and there are others that I'm probably forgeting to
mention.
-- 

Doug Freyburger		DOUG@JPL-VLSI, DOUG@JPL-ROBOTICS,
JPL 171-235		...escher!doug, doug@aerospace,
Pasadena, CA 91109	etc.

Disclaimer: The opinions expressed above are far too
ridiculous to be associated with my employer.

Unix is a trademark of Bell Labs, VMS is a trade mark of
DEC, and there are others that I'm probably forgeting to
mention.