DOS Defender (Ludum Dare #31)
C C++ Makefile
Permalink
Failed to load latest commit information.
.gitignore Get libraries checked in. Dec 6, 2014
Makefile More warnings. Dec 10, 2014
README.md Update README. Dec 9, 2014
UNLICENSE Add UNLICENSE. Dec 7, 2014
alloc.h
com.ld Rename _main() to dosmain(). Dec 9, 2014
dosdef.c
init.h
int.h Get libraries checked in. Dec 6, 2014
joystick.h
keyboard.h Add keyboard end game input. Dec 6, 2014
math.h Get libraries checked in. Dec 6, 2014
port.h Get libraries checked in. Dec 6, 2014
print.h
rand.h
speaker.h
time.h
tone.h
vga.h Get libraries checked in. Dec 6, 2014
vga_font.h

README.md

DOS Defender

DOS Defender is an x86 real mode DOS game for Ludum Dare #31 (December, 2014). Since few DOS machines still exist, the target platform is actually DOSBox, though it should work to some extent on any DOS system. The game can be played with a mouse but it's intended to be played with a joystick/gamepad.

Playing

Just point DOSBox at the COM binary.

$ dosbox DOSDEF.COM

There are no external assets, so mounting isn't necessary.

Building

All you need is a GCC compiler that can target i386. In theory, it doesn't matter if it's for Linux, Windows, etc., nor is there a need for something like DJGPP. The compiled code will be packaged as a COM file using a linker script (e.g. --oformat=binary). Unfortunately, there's a long-standing bug in MinGW that prevents this from working correctly without objdump.

The final game is a 10kB executable. To run, all it needs is 64kB of RAM and 64kB of video memory. With some tweaking, it could even run without a need for any OS.

DOS Defender is written in GCC's dialect of C and probably can't be built with any other compiler. The host platform is treated like an embedded system, so there's no intention of actually building the game from within DOS itself. Compilation is done as a single translation unit to allow the optimizer full reign in minimizing the code size (COM files are limited to 64kB).