The GameBoy is a hand-held game console developed and manufactured by Nintendo and was first released in 1989. It uses a 4 grey scale LCD display and an extended 8080 CPU, taking inspiration from the Z80, but also adding its own instructions not seen in either.
The sound card has 2 pulse wave channels, the first with an additional sliding effect, a 32-sample 4-bit Freewave PCM channel and a noise channel. The speaker is mono but stereo is available through headphones.
'[i[6]
ROM cartridges varied in size from 256kbit to 8Mbit.
The GameBoy remains the most successful hand-held console in history and came originally bundled with the famous Tetris puzzle game.
'[#[Specifications]
'[tab[CPU] 4.19MHz custom '[[8-bit] core along the lines of the '[[Intel 8080] and the Zilog '[[Z80].
'[tab[RAM] 8KB
'[tab[Video RAM] 8KB
'[tab[Display] 160 x 144 pixels
'[tab[Frame Rate] 59.73 frames per second
'[tab[Color Palette] 4 (off and LCD intensity levels 1-3)
'[tab[Sound] 2 '[[Pulse Wave[pulse waves], 1 4-bit '[[PCM] wave, 1 '[[white noise], and an audio input for ROM use.
The Game Boy Color has 32KB of RAM and 16KB of VRAM, both implemented via bankswitching. It has a colour gamut of 32768 colours (5:5:5 RGB) but the scale is NONLINEAR (half-way is still quite bright).
The GBC also has a facility for ROM/RAM-to-VRAM DMA transfers (as well as the ROM/RAM-to-OAM DMA facility) and the CPU has a double-speed mode.
GameBoys can also communicated via built-in serial ports. The connector type of this unique cable is not generally manufactured.
'[#[Modifications]
...changing the hardware of the Gameboy
Pro Audio, overclocking, underclocking, midi control . . .
Someone might want to mention Prosound here.
'[#[More on sound]
(basically just deriving from pandocs here though some stuff is from memory)
The Game Boy has stereo sound with 4 channels built in, plus an extra pin on the cartridge for sound expansion. The panning is quite coarse: you have 3-bit master volumes for the left and right channels, and you can set each of the 4 channels (plus the external channel) to go either on the left, the right, both, or neither.
There are two channels for pulse waves (channels 1 and 2), each with a selectable duty from {12.5%, 25%, 50%, 75%}, just like the '[[NES]. Both channels have a 4-bit volume level, hardware volume slide ("sweep"), an optional note cutoff length, and an 11 bit period, each. The first pulse channel also has a note slide ("tone sweep"). These are most likely not completely necessary, but could simplify some things.
The Game Boy also has a wave channel (channel 3) with a 16-byte / 32-sample, 4-bit user-definable waveform. This also has an 11-bit period and a note cutoff length, but only 4 volume settings: 100%, 50%, 25%, and off - the volume settings are simply right-shifts of the sample data, and will probably make it sound quite bad. You WILL need to turn the channel off BEFORE you write to the wave data, and RESTART the channel afterwards!
Finally, there is a noise channel. It uses at least the equivalent of a Fibonacci LFSR with taps on the bottom two bits - the length of the LFSR can be either 15 bits or 7 bits (user-selected). There are 128 period values that can be used (16 * 8), although as expected there is some overlap. This has 4-bit volume plus a volume envelope and a note cutoff length.
See pandocs (listed below) for more information.
'[#[Programming]
'[l[http://sourceforge.net/projects/gbdk/[Gameboy Development Kit] on sourceforge and a '[l[http://www.loirak.com/gameboy/gbprog.php[quick tutorial].
Some of you may prefer to use '[l[http://www.villehelin.com/wla.html[WLA-DX] as an assembler, which also contains Z80 and 6502 compilers along with a few others.
There are some very good docs known as the '[l[http://nocash.emubase.de/pandocs.htm[pandocs]. You must have that stupid Nintendo logo in your ROM, though, otherwise your code won't run on the real thing!
