To compile DGD, you will have to set HOST in src/Makefile to the
proper value:
SUNOS4		SunOS 4.x, the default.  Should compile immediately with gcc.
MINIX_68K	Minix 1.5 for 68K computers, probably works with Minix 1.6
		as well.  Copy src/host/minix68k/Makefile to src/host.
ATARI_ST	Atari ST with MiNT and gcc.  See src/host/atarist/README.
GENERIC_BSD	BSD Unix.  Copy src/host/Makefile.bsd to src/host/Makefile.
GENERIC_SYSV	SYSV Unix.  Copy src/host/Makefile.sysv to src/host/Makefile.
BSD386		The same as GENERIC_BSD; set LIBS to -lcrypt.
LINUX		The same as GENERIC_SYSV.

   For other platforms, you can either try to use the closest of the above,
or add your own host support to the src/host.h file.  There are some systems
which I don't support directly yet, but for which porting is easy:
NeXT	use GENERIC_BSD, but in host/Makefile replace dirent.* by direct.*
Solaris	use GENERIC_SYSV, set LIBS to -lsocket -lnsl
ULTRIX	use GENERIC_BSD, but define ALLOCA as ALLOC and AFREE as FREE
AIX	use GENERIC_SYSV, but change the definitions of UCHAR and SCHAR to
	the outcommented versions in the MINIX_68K entry (AIX characters
	are unsigned), also add #include <sys/select.h> to host/unix/connect.c

   Things may become more difficult if you want to port DGD to a different
type of host.  I planned a port to the Mac and MSDOS myself, but so far
haven't been able to do this because I don't have those machines; I do
have an XT but DGD is now too big to fit in 640K, alas (this also means that
I won't do the planned port to the Sinclair QL).  If you want to do your own
port and you need some advice, contact me.
   In general, platforms must meet the following requirements:
 - shorts should be 2 bytes wide
 - integers should be either 2 or 4 bytes wide
 - longs should be at least as wide as pointers
 - two's complement should be used to represent negative numbers
 - the value of NULL must be 0.
For each port, one should only have to modify src/host.h, the makefiles and
the files in the src/host directory.