🚀 go-pugleaf

I have an OS/2 protected mode application on an 80386 developed 
with the Microsoft C 6.0 compiler, which I need to port to 
Windows 3.1.  Actually it's a non-GUI application, so what I'm 
really targeting is a DOS box under Windows.  I need to be able 
to dynamically allocate several megabytes of data.  We plan to 
use the Microsoft 7.0 compiler for the Windows version of the 
product.

Under OS/2 I was blissfully ignorant of any behind the scenes
manipulations which had to occur to enable me to access more
than 640K of memory.  I simply malloc'ed to my heart's content,
and everything worked without a hitch.  Well, now it's time to
see how the other half lives...  In looking into what it's going
to take to get from here to there, I've been poring over 
literature describing the DOS 640K barrier, and the DOS extender
products which are supposed to free you from the original 
limitations of DOS.

I talked with people at both Rational Systems and Phar Lap, which
appear to be the two major players in this arena.  Here are the
major points I see for the products offered by each:

Rational Systems:
----------------
  DOS/16M
    - Allows you to use up to 16M of memory for an application
      running in DOS protected mode.
    - Interfaces with the DOS Protected Mode Interface (DPMI)
      memory manager when run under Windows.  Am I correct in
      assuming the DPMI is also available within DOS boxes
      running under Windows?
    - Requires use of Rational's home-grown Instant-D debugger,
      as opposed to Codeview for debugging.
    - Currently supports debugging of global symbols only (no locals)
      for Microsoft 7.0.  (I could continue to use 6.0 if 16M is
      considered the superior product in most other aspects.)

  Ozone (sp?)
    They told be about this over the phone.  It's a lesser-known
    product of theirs that's been out for about a year.  Apparently
    it's geared toward exactly the type of migration I'm looking to
    do -- moving non-GUI, character-based applications from OS/2 to
    DOS protected mode.  They tell me that the conversion should
    take all of 15 minutes to accomplish -- simply graft their
    loader program onto your currently existing OS/2 executable to
    produce a DOS executable which "simulates" OS/2 for your
    original executable.  Additionally you can use Codeview to
    debug such executables.  I'm waiting for further info from
    Rational.

Phar Lap:
--------
  286 DOS Extender
    - Also allows access of up to 16M.
    - Supports MSC 7.0
    - Uses Codeview protected version (cvp) for debugging

All three products apparently require no major modifications, if any,
to my original source code.  I can continue to invoke the compiler's
run-time library routines (malloc, calloc, halloc) and automagically
be given access to extended memory.

Are my perceptions accurate?  Does anyone have any success/failure
stories with any of these, or have recommendations for other tried
and true alternatives?

Advance Thanks.

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|  Ed Fleming                                                     |
|  Intermetrics, Inc.                                             |
|  733 Concord Ave.                                               |
|  Cambridge, MA  02138                                           |
|  (617) 661-1840                                                 |
|  Internet:  fleming@inmet.inmet.com                             |
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