P R E - D I S
                      -----------------
                         Version 1.1
		         30 Sep 1997
                      Patrick C Sweetman
                    sweetman.p.c@xtra.co.nz

    Pre-disassembler for old Turbo Pascal programs.

    Creates a .DEF disassembler directives file for
    use by the Sourcer disassembler.

    Note:  "Turbo Pascal" and "Sourcer" are trade names
           owned by their respective owners and have nothing
           to do with Patrick C Sweetman or this software
           except as being the subject of discussion.


	This program is copyright of Patrick C Sweetman and is
    hereby released into the public domain where it may be
    used or disposed of without restraint.


This program was written to speed up the first phase of disassembling
some old Pascal programs.  I didn't know the version of Turbo Pascal,
didn't have a copy of it, and didn't have much remaining documentation
from the time that the programs had been written.

The first step was to chose a disassembler and make a first pass at
one of the programs.  "Sourcer" was the disassembler that I chose,
and if you're using a different one you will have to adapt the output
of pre-dis to suit.

Getting the disassembler to produce a clean disassembly involved looking
at the output and adding directives and labels to the .DEF file.  This
took ten days for the first program, and nearly a week for the second,
but by then I had written a number of tools and editor macros to
partially automate the process.

Then I took a break to write this program.  It incorporates all of the
lessons I gained through manually configuring the disassembler and
includes tentative names for some of the Pascal library routines which
are called by the user code.

As well as labelling some calls to the library, it finds and labels all
Pascal strings and many other data structures.  These are given labels
based on their type and address, and one of the first things which you
should do is to replace these labels with meaningful ones based on your
assessment of their function in the disassembly.

To use this program specify the .exe file to be pre-disassembled
on the command line.

    eg.   pre-dis    test

    or    pre-dis test.exe

The program will create two files:

    1.  Directives file with .def extension  eg: test.def

    2.  Comments file with .rem extension    eg: test.rem

Then run the Sourcer disassembler, specifying the directives file
on the command line.

    eg.   sr  test.def

After the disassembly you should replace the .def file by renaming
the .sdf file which was created by Sourcer.  Then manually modify
this on the basis of your examination of the disassembly listing.

With this procedure you should very quickly achieve a clean
disassembly and you can then proceed with assigning meaningful
names until the project reaches the stage where you can begin
to reverse-engineer or produce a functional specification for
the program.

Notes:
    1. pre-dis may not be able to identify many library routines
       if the version of Turbo pascal is different, but it should
       still be very useful.

       If someone can provide me with a more fully documented
       disassembly of the library routines I can incorporate
       those labels into the next version of this program, and
       that will make it much more useful.  Similarly for other
       versions of Turbo Pascal.

    2. Although I create a comments file (with .rem extension) I
       did not get around to using it.  Maybe in the next version,
       if there is call, I will automatically generate comments on
       the basis of the contents of Pascal strings, and maybe for
       library calls.  But for now I don't see much need.

    3. If a .def file or a .rem file larger than the empty one exists
       already, then pre-dis exits with an error message.  The last
       thing you want is for your work of the last fortnight to be
       overwritten.  So rename them, or delete them if you want them
       replaced.

    4. On a slower machine, please be patient.  A 200k program took
       about one minute on a 686 P166+ based PC.

    5. All comments and suggestions: email sweetman.p.c@xtra.co.nz
                       or, if suitable, in comp.lang.pacsal.borland

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