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From: granoff@decwin.enet.dec.com (Mark H. Granoff)
Newsgroups: comp.lang.pascal
Subject: Turbo Pascal 5.5 and Overlays
Keywords: turbo pascal 5.5 overlays units
Message-ID: <6458@shlump.nac.dec.com>
Date: 29 Nov 89 20:39:30 GMT
Sender: newsdaemon@shlump.nac.dec.com
Reply-To: granoff@decwin.enet.dec.com (Mark H. Granoff)
Organization: Digital Equipment Corporation
Lines: 54


    I have a large application, which is only about half done, and is getting
    larger.  Since memory is at a premium, I've decided that the only (?)
    solution is to use overlays.  Fortunately, related functions and
    procedures are already separated into various include files.  So,
    converting these large chunks of code into overlayable units should not
    be difficult.

    Here's the problem.  I decided to check out this overlay business with
    a little test program (included after this text, from memory).  The
    problem is that when I run the .EXE, I get a runtime error 208 (which
    means that I haven't init'd the Overlay manager).  This doesn't make
    sense though because the error occurs at the BEGIN for the main
    program, before the program would have had a *chance* to init the
    overlay manager!  What am I missing?  Thanks.

    OVRUNIT.PAS
         UNIT ovrunit;
         {$O+,F+}
         INTERFACE
         procedure ovrjunk;
         IMPLEMENTATION
         procdure ovrjunk;
           begin
             writeln('procedure ovrjunk called.');
           end;
         BEGIN
         END.

         I compile this and get a .TPU file, as expected.

    OVRTEST.PAS
         PROGRAM ovrtest;
         {$F+}
         USES Overlay,ovrunit;
         {$O ovrunit}
         BEGIN   { <------- Run time error occurs here!? }
           OvrInit('ovrtest.ovr');
           { examine OvrResult here as appropriate...}
           ovrjunk; { call procedure in overlay }
         END.

         I compile this and get .EXE and .OVR files, as expected.

    When I run OVRTEST, I get Runtime error 208.  Could it be that I since
    I have only one unit overlayed, the overlay manager is getting confused
    or something?  I probably missed something obvious...  Thanks for your
    help, and be kind. :-)

    Please respond directly to me, since I don't get to read this group
very often,
    at granoff@decwin.dec.com --or-- granoff@vaxwrk.dec.com.

    -Mark