GBA Service Manual
Page 3
2.6 Audio section
The audio section includes part of the CPU, an audio amplifier IC, speaker and headphone
jack heard. There are 4 channels for GB Color compatible audio, plus two DMA channels
used in the GB Advance mode to provide continuous playback.
Audio 1 (Sound 1): Allows the generation of rectangular waveforms with scanning functions
(frequency variation) and envelope (volume variation).
Audio 2 (Sound 2): Allows the generation of rectangular waveforms with envelope functions.
Audio 3 (Sound 3): It allows the reproduction of any waveform recorded in RAM.
Audio 4 (Sound 4): Can generate white noise with envelope functions.
Direct Audio A and B: Allows playback of 8-bit linear audio data.
2.7 Cartridge Interface
For the cartridge interface, a 32-pin connector is used. A key has been incorporated into this
connector to determine how the system should be started (GBA or GBC).
2.8 Controls Input
The CPU processes the parallel data, directly from the controls. Each control is connected to
the ground through an open contact on the PCI. When the key is pressed, a conductive
blanket is pressed against the open contact, closing the circuit.
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