7 Welcome to gnuboy, one of the few pieces of Free Software to emulate
8 the Game Boy handheld game console. Written in ANSI C with a few
9 optional assembler optimizations for particular cpus, gnuboy supports
10 a wide range of host systems, and has been tested successfully on:
16 Linux/390 (IBM S/390 Mainframe)
26 Additionally, gnuboy should run on any other *nix variants that have
27 ANSI C compilers and that are remotely POSIX compliant. As gnuboy is
28 Free Software, you're welcome to fix any problems you encounter
29 building it for a particular system, or to port it to entirely new
35 gnuboy emulates nearly all aspects of the (Color) Gameboy, including
36 all of the following and much more:
38 Full GBZ80 instruction set.
39 Scanline-based LCD engine.
40 Ten sprites per scanline limit.
41 Support for all CGB graphics extensions.
42 Sprite DMA, HDMA, and GDMA.
43 All four sound channels including digital samples.
44 MBC1, MBC2, MBC3 (including clock), and MBC5 mappers.
45 Wave pattern memory corruption when sound channel 3 is played.
46 Pad, timer, divide counter, and other basic hardware registers.
47 CGB double-speed CPU mode.
49 Aspects not emulated at this time include:
51 * Serial IO (link cable).
52 Undocumented 'extra' ram in OAM space on Gameboy Color.
53 All Super Gameboy extensions.
54 * GBC, HuC1, and HuC3 IR ports.
55 * Obscure mappers such as TAMA5.
56 Sorting sprites by X coordinate in DMG mode.
57 HALT instruction skipping in DMG mode.
58 CPU stalls during HDMA and GDMA.
60 Only the two marked by * are known to affect the playability of
61 actual games or demos; the rest are just listed for completeness'
67 In addition to basic emulation, gnuboy provides the following
70 Highly flexible keybinding and configuration subsystem.
71 State saving and loading at any point.
72 Very precise timing/synchronization, preserved across save/load.
73 Joystick support on Linux, DOS, and all SDL-based ports.
74 Fully customizable palettes for DMG games.
75 Screen scaling by a factor of 2, 3, or 4 in all ports.
76 Hardware-based screen scaling on platforms where it's available.
77 Debug traces to stdout.
78 Dynamic palette allocation when run in 256-color modes...
79 OR simulated 3/3/2 bits per channel in 256-color modes.
81 For information on configuring and using these features, see the
82 additional documentation in the "docs" directory.
87 Out of over 300 results reported by testers, all games are known to
88 work perfectly on gnuboy with the following exceptions:
90 Fighting Phoenix (Japanese) may or may not work since it uses the
91 HuC1 memory controller, which is not implemented properly. There has
92 been no report either way so far.
94 Pocket Bomberman (Japanese version, which uses HuC1) runs, but can
95 be made to crash if the player jumps into the ceiling in the first
96 level. It's not clear whether this bug is MBC-related, something
97 else, or an actual bug in the original game.
99 Monster Go! Go! Go! (Japanese) is unplayable. The cause of the
100 problem is not fully known, but it's either a very bad dump or it's
101 using some sort of specialized MBC that's not documented.
103 Final Fantasy Adventure has visual problems with the fade between
104 screens. Does not affect gameplay.
106 Bubble Bobble 2 has some minor tile glitches right before gameplay
107 actually begins. Cause unknown. Does not affect gameplay.
109 Alone in the Dark is reported to have minor visual glitches. I
110 haven't seen it myself so I can't judge their severity.
112 Both new Zelda games are reported to have a visual glitch at the
113 beginning of the game, and on certain other screens. I haven't seen
114 the problem myself, but supposedly it impacts gameplay to some
117 Please report any other incompatibilities discovered directly to
118 gnuboy@unix-fu.org, so that they can be documented and hopefully
124 Here's a brief list of what may appear in gnuboy in the future:
128 Super Gameboy support.
129 Serial link over the internet.
130 Serial link to a real Gameboy with a custom cable.
131 Configurable color filters to provide more authentic LCD look.
132 Custom colorization of DMG games on a per-tile basis.
133 Support for more colorspaces in the hardware scaler.
135 GBS player built from the same source tree.
136 Full recording and playback of emulation.
137 So-called "high level emulation" of certain typical dumb loops.
139 Features that are not likely to appear soon or at all include:
141 Rumble support - this would be nice, but SDL doesn't seem to support
142 force-feedback yet. We'll see about it in the long-term though.
144 Eagle/2xSaI/etc. - probably not feasible since these libraries don't
145 appear to be compatible with the terms of the GPL. We might work on
146 our own interpolation engine eventually, but that's low priority.
148 GUI/GUI-like features - such things are best handled by external
149 front-ends. We might eventually add a mechanism for external
150 programs to communicate with gnuboy and reconfigure it while it's
153 Plugins - NO! The way I see it, plugins are just an attempt to work
154 around the GPL. In any case, even if you are adding plugin support
155 yourself, you are bound by the terms of the GPL when linking ANY
156 code to gnuboy, including dynamic-linked modules. However we'd
157 rather not deal with this mess to begin with.
159 Compressed ROMs/Saves - this one is very iffy. On most systems, this
160 is redundant; *nix users can just pipe the rom through a
161 decompression program, and Windows users can just double-click or
162 drag files from their favorite GUI unzipper program. Linking to zlib
163 isn't really acceptable since it's massively bloated and we don't
164 want to include it with gnuboy or add external dependencies. We may,
165 however, write our own tiny decompressor to use at some point.
167 Ideas and suggestions for other features are welcome, but won't
168 necessarily be used. You're of course also free to add features
169 yourself, and if they fit well into the main tree they may eventually
170 get included in the official release. See the file HACKING for more
171 details on modifying and/or contributing.
176 Thanks goes out to everyone who's expressed interest in gnuboy by
177 writing -- users, porters, authors of other emulators, and so forth.
178 Apologies if we don't get a personal response out to everyone, but
179 either way, consider your feedback appreciated.
184 OK, that looks like about it. More to come, stick around...
188 -Laguna <laguna@aerifal.cx>