The Drivers

The hardware drivers themself are located in the `DEVS:AHI' drawer, and are named as `<name>.audio'. They are actually libraries, in spite of being located under the `DEVS:' assign, and will be flushed out from memory when not in use and the system needs more RAM. Many of the drivers require additional files; see below. These extra files are not delivered with AHI.

delfina.audio

Requires delfina.library.

paula.audio

On startup, the file `ENV:CyberSound/SoundDrivers/14Bit_Calibration' is read and used for the 14 bit DAC calibration. The environment variable `AHIpaulaFilterFreq' is also checked, and should be set to a frequency in Hertz. If the mixing frequency is higher than this value, the internal low-pass filter will be turned off. If it is lower, the filter will be activated. The default is 0 Hz, which means that the filter will always be turned off. Example:

SetEnv AHIpaulaFilterFreq 16000
Copy ENV:AHIpaulaFilterFreq ENVARC:

toccata.audio

Requires toccata.library. This driver also reads the environment variable `AHItoccataNoTask'. If set to `1', all mixing will be done in a Software Interrupt which means the sound output will not suffer when multitasking is turned off. The back side is that it requires a faster CPU. Example:

SetEnv AHItoccataNoTask 1
Copy ENV:AHItoccataNoTask ENVARC:

Please note that this driver is used for both the DraCo Motion and Toccata.

wavetools.audio

Requires dad_audio.device.

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