+Building with DJGPP
+-------------------
+The DJGPP port of GCC is the recommended toolchain to use for building the demo,
+either natively or cross-compiled on UNIX.
+
+For native DOS builds add the DJGPP bin directory to the path (usually
+`c:\djgpp\bin`) and set the DJGPP environment variable to point to the
+`djgpp.env` file.
+
+For cross-compiling on UNIX simply source the `setenv` file which comes with
+DJGPP, which will set the `PATH` and `DJDIR` variables as necessary.
+
+In both cases, run `make -f Makefile.dj` to build. To run the resulting
+`demo.exe` you'll need to copy `cwsdpmi.exe` to the same directory. You can find
+it here: ftp://ftp.fu-berlin.de/pc/languages/djgpp/current/v2misc/csdpmi7b.zip
+
+When building natively on an old computer, and encounter a huge amount of disk
+swapping, and corresponding ridiculously long compile times, make sure to
+disable any memory managers and try again. `EMM386` may interfere with
+`CWSDPMI`'s ability to use more than 32mb of RAM, and modern versions of GCC
+need way more than that. Disable the memory manager with `emm386 off`, and
+verify the amount of usable RAM with `go32-v2`.
+
+Another problem is the MS-DOS version of `HIMEM.SYS` which only reports up to
+64mb. To use more than that, which is necessary for modern versions of GCC, you
+can either disable `HIMEM.SYS` completely, or use the `HIMEM.SYS` driver that
+comes with Windows 9x (DOS >= 7). Here's a copy in case you need it:
+http://mutantstargoat.com/~nuclear/tmp/d7himem.sys
+