From: Steve Lionel [Steve.Lionel@COMPAQ.COM]
Sent: Friday, August 04, 2000 1:06 PM
To: Info-VAX@Mvb.Saic.Com
Subject: Updated FORRTL_TV - Translated VAX Fortran RTL

As some of you are aware, there has been a problem with VAX Fortran
programs translated by DECmigrate (VAX) and run on Alpha, where if you
install OpenVMS Alpha 7.2 or Compaq Fortran 7.2 (or later), the
translated programs stop working (typically, they get an ACCVIO.)

The reason this occurs is that the translated VAX Fortran RTL
(FORRTL_TV), as supplied by OpenVMS, is not a simple translation of
the VAX RTL.  Instead, an attempt was made to support mixed translated
and native I/O on the same Fortran unit.  To use this, you would have
to have a VAX Fortran shareable image which you then brought to Alpha
and translated, wrote some native Alpha Fortran code which called the
translated shareable image, and attempted to do I/O to the same
Fortran LUN in both the native and translated code.  If you simply had
a VAX executable which you translated, you would not have used this
feature.

This must have seemed like a good idea at the time, but the engineers
who implemented it (they worked for the Alpha Migration group, not
Fortran), decided to take a short cut.  Rather than turning the VAX
RTL I/O code into "jackets" for calls into the public entry points of
the native RTL, they had the translated RTL share the native RTL's
internal data structures.  This worked as long as the native RTL
didn't change the layout or use of its internal structures, but with
the added support of 64-bit addressing, these structures changed
significantly and the translated RTL was unable to deal with this.

The solution I have implemented is to simply translate the latest
version of the VAX Fortran RTL, eliminating support for the
cross-architecture I/O.   An added advantage of this approach is that
the new translated RTL is compatible with VAX Fortran V6 and later,
and supports the non-native data in I/O feature.  Note however that
the math library has NOT been updated to include new routines that the
V6 compiler used, so you would have to compile with /MATH_LIBRARY=V5.

A kit to install the updated translated FORRTL_TV is available at
ftp://ftp.compaq.com/pub/products/fortran/OpenVMS/FORRTL_TV-T0100-1.zipexe

RUN this to unpack and then install as follows:

$ PRODUCT INSTALL FORRTL_TV /SOURCE=[]/HELP

OpenVMS Alpha 7.1-2 is the minimum version supported.  (If someone
needs support for an earlier version, let me know.)

The files updated are FORRTL_D56_TV.EXE and FORRTL.IIF, both in
SYS$LIBRARY:.  If you have worked around the problem by using an older
copy of DEC$FORRTL.EXE, the Alpha Fortran RTL, you no longer need to
do that, as this translated image doesn't reference DEC$FORRTL.EXE

If you try this, please let me know, by mail, the results of your
testing.  It seemed to work ok for me - I ran it through a number of
the VAX Fortran test suites.  If enough people seem satisfied with it,
I'll ask OpenVMS Engineering to include it in future releases (and to
create a remedial kit for it.)

Lastly, if you DO use the mixed-architecture I/O feature, I'd be
interested in hearing from you and seeing a description of your
application.  I can pretty much guarantee that we will NEVER restore
the mixed-architecture I/O feature, but there are reasonable
workarounds.

Steve Lionel (mailto:Steve.Lionel@compaq.com)
Fortran Engineering
Compaq Computer Corporation, Nashua NH

Compaq Fortran web site: http://www.compaq.com/fortran