The "original" Colossal Cave Adventure for DOS
==============================================

A few days ago I stumbled upon Dan Nelson's port of the original PDP-10
FORTRAN source code by Crowther and Woods /1/ to ANSI FORTRAN 77 /2/ in
the Interactive Fiction Archive.

As I couldn't find a pre-compiled Windows binary for this port, I used
gfortran 9.2.0 for building my own Windows executables. Please have a
look at the content of advent-orig-nelson-win.zip for the executables,
updated source files and further information.

Then I thought, why not try building executables for DOS. Maybe sometime
in the future I would reactivate my old computers and would like to play
adventure in pure MS-DOS 5.0 environment. One should have a dream...

On the internet I found a g77 implementation for DOS bundled with the
EMX DOS-extender (GNU Fortran 0.5.19 (EMX)). It was possible to compile
the port after commenting out one line in advent.for (line 3250) and the
same line in wiz.for (line 41):

C     INTRINSIC TIME,LTIME

During compilation of advent.for using the optimization parameter -O2, I
did receive the error message: 'virtual memory exhausted'. Without
optimization the compilation finished successfully.

The final build required the EMX DOS-extender at runtime. Honestly, I
did not like this build.

Then I remembered from the 90s that there was DJGPP, a port of GCC by DJ
Delorie, where I could possibly find a more suitable g77 implementation.

What a surprise! The DJGPP project seems to be well alive /3/. I found a
suitable version of g77 as well as several versions of gfortran. I tried
only two of the available compilers:

g77     : GNU Fortran (GCC) 3.4.6
gfortran: GNU Fortran (GCC) 9.2.0

I finally compiled the port using gfortran 9.2.0*. I copied cwsdpmi5
stub and coff files together**. The executables have been packed with
UPX 3.95d /4/.

Due to cwsdpmi at least a 80386 processor and DOS 3.0 or higher are
required for running the executables.

The executables have only been tested in DOSBox 0.74 /5/ as I was to
lazy to reactivate my old machines just now. 

This archive contains following files:

advent.dat        data file converted by Dan Nelson
advent.exe        pre-compiled executable for advent
advent.for        updated source file for advent
make.bat          batch file for compiling advent and wiz (gfortran)
make-g77.bat      batch file for compiling advent and wiz (g77)
README            README by Dan Nelson
README.dos        this file
wiz.exe           pre-compiled executable for wiz
wiz.for           updated source file for wiz

The included source files for advent and wiz are the same ones, which I
used for compilation of the windows binaries.

All credits for the source port of the original adventure and, again,
big thanks go to Dan Nelson.

Hartmut Kuehne
Dec 15, 2019


Update: "You fell into a pit..."
================================

Of course, it had to happen: When compiling the sources with gfortran
9.2.0, I did fall, full of confidence, into a pit prepared only for me
by the developers of the gfortran compiler. I did not break my neck, but
the random number generator. No dwarfs, no pirate, no escape from Witt's
End...

According to the documentation of gfortran 9.2.0 /6/, the compiler does
provide an intrinsic function RAN as alias for RAND for compatibility
with HP FORTRAN 77/iX. This intrinsic function has been called instead
of advent's own random number generator function RAN. After declaring
RAN as external procedure (EXTERNAL RAN) the dwarfs did return!

This archive contains now the updated sources and binaries.

Jan 04, 2020.


References:

/1/ https://www.ifarchive.org/if-archive/games/source/advent-original.tar.gz
/2/ https://www.ifarchive.org/if-archive/games/source/advent-orig-nelson.tar.gz
/3/ http://www.delorie.com/djgpp/
/4/ https://upx.github.io/
/5/ https://www.dosbox.com/
/6/ https://gcc.gnu.org/onlinedocs/gfortran/RAN.html


Notes below:

*)  I downloaded following files from DJGPP project:

    Base installation:
        v2gnu\bnu2331b.zip
        v2misc\csdpmi5b.zip
        v2\djdev205.zip
        v2\djtzn205.zip
        v2\faq230b.zip
        v2gnu\mak421b.zip
        v2\readme.1st
        v2gnu\txi413br3.zip

    g77: GNU Fortran (GCC) 3.4.6
        v2gnu\g77346b.zip
        v2gnu\gcc346b.zip

    gfortran: GNU Fortran (GCC) 9.2.0
        v2gnu\gcc920b.zip
        v2gnu\gfor920b.zip

    I did extract the zip archives into the directory C:\DJGPP using

        pkunzip -d *.zip

    After setting the default environment variables we are good to go:

        SET DJGPP=C:\DJGPP\DJGPP.ENV
        SET PATH=C:\DJGPP\BIN;%PATH% 

**) If you want to compile the game by yourself in DOSBox, a real DOS
    command shell (e.g. COMMAND.COM from original MS-DOS distribution)
    is necessary. The copy command of DOSBox does not support the /b
    parameter required for combining cwsdstub.exe and the coff files to
    standalone executables. You would compile the source files using
    gfortran issuing following command:

        c:\command.com /c make.bat