Add aica firmware

[linux-libre-firmware.git] / aica / Dreamcast_sound.txt

diff --git a/aica/Dreamcast_sound.txt b/aica/Dreamcast_sound.txt
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+SOUND ON THE SEGA DREAMCAST
+
+The Sega Dreamcast includes an ARM7 processor that separately handles sound
+playback. The ARM7 processor has its own address space which is only partially
+accessible to the main SH4 processor.
+
+The ALSA driver loads data to the ARM7 address space using DMA (which will
+run at a good speed). The old OSS driver did not use DMA and so showed
+very poor performance at high bit rates.
+
+The driver also loads some simple firmware (separately licenced under a 
+modified BSD licence) which controls the ARM7 processor. Without the 
+firmware the driver would merely fill the ARM7's address space and would 
+not playback any sound.
+
+The firmware, by default, should be loaded to /lib/firmware/ and should
+be named aica_firmware.bin.