+=head1 BUILDING AND INSTALLING MODULES ON DOS
+
+=head2 Building Prerequisites for Perl on DOS
+
+For building and installing non-XS modules, all you need is a working
+perl under DJGPP. Non-XS modules do not require re-linking the perl
+binary, and so are simpler to build and install.
+
+XS-type modules do require re-linking the perl binary, because part of
+an XS module is written in "C", and has to be linked together with the
+perl binary to be executed. This is required because perl under DJGPP
+is built with the "static link" option, due to the lack of "dynamic
+linking" in the DJGPP environment.
+
+Because XS modules require re-linking of the perl binary, you need both
+the perl binary distribution and the perl source distribution to build
+an XS extension module. In addition, you will have to have built your
+perl binary from the source distribution so that all of the components
+of the perl binary are available for the required link step.
+
+=head2 Unpacking CPAN Modules on DOS
+
+First, download the module package from CPAN (e.g., the "Comma Separated
+Value" text package, Text-CSV-0.01.tar.gz). Then expand the contents of
+the package into some location on your disk. Most CPAN modules are
+built with an internal directory structure, so it is usually safe to
+expand it in the root of your DJGPP installation. Some people prefer to
+locate source trees under /usr/src (i.e., C<($DJDIR)/usr/src>), but you may
+put it wherever seems most logical to you, *EXCEPT* under the same
+directory as your perl source code. There are special rules that apply
+to modules which live in the perl source tree that do not apply to most
+of the modules in CPAN.
+
+Unlike other DJGPP packages, which are normal "zip" files, most CPAN
+module packages are "gzipped tarballs". Recent versions of WinZip will
+safely unpack and expand them, *UNLESS* they have zero-length files. It
+is a known WinZip bug (as of v7.0) that it will not extract zero-length
+files.
+
+From the command line, you can use the djtar utility provided with DJGPP
+to unpack and expand these files. For example:
+
+ C:\djgpp>djtarx -v Text-CSV-0.01.tar.gz
+
+This will create the new directory C<($DJDIR)/Text-CSV-0.01>, filling
+it with the source for this module.
+
+=head2 Building Non-XS Modules on DOS
+
+To build a non-XS module, you can use the standard module-building
+instructions distributed with perl modules.
+
+ perl Makefile.PL
+ make
+ make test
+ make install
+
+This is sufficient because non-XS modules install only ".pm" files and
+(sometimes) pod and/or man documentation. No re-linking of the perl
+binary is needed to build, install or use non-XS modules.
+
+=head2 Building XS Modules on DOS
+
+To build an XS module, you must use the standard module-building
+instructions distributed with perl modules *PLUS* three extra
+instructions specific to the DJGPP "static link" build environment.
+
+ set FNCASE=y
+ perl Makefile.PL
+ make
+ make perl
+ make test
+ make -f Makefile.aperl inst_perl MAP_TARGET=perl.exe
+ make install
+
+The first extra instruction sets DJGPP's FNCASE environment variable so
+that the new perl binary which you must build for an XS-type module will
+build correctly. The second extra instruction re-builds the perl binary
+in your module directory before you run "make test", so that you are
+testing with the new module code you built with "make". The third extra
+instruction installs the perl binary from your module directory into the
+standard DJGPP binary directory, C<($DJDIR)/bin>, replacing your
+previous perl binary.
+
+Note that the MAP_TARGET value *must* have the ".exe" extension or you
+will not create a "perl.exe" to replace the one in C<($DJDIR)/bin>.
+
+When you are done, the XS-module install process will have added information
+to your "perllocal" information telling that the perl binary has been replaced,
+and what module was installed. You can view this information at any time
+by using the command:
+
+ perl -S perldoc perllocal
+