HARMONY(4)

NAME
harmony - CS4215/AD1849 audio interface

SYNOPSIS
harmony* at gsc?
audio* at harmony?

DESCRIPTION
The harmony device uses the Crystal Semiconductor CS4215 16-Bit Multimedia Audio Codec or Analog Devices AD1849 SoundPort(R) Stereo Codec chip to implement the audio device interface described in audio(4). This device is found on most HP PA-RISC workstations. The harmony has a maximum precision of 16 bits and has a stereo input and stereo output.

On HP 9000/712 models harmony also provides two additional channels for an add-on card with two fax/voice modems.

One of the hardware registers reflects the state of the CHI bus that is used to communicate with the codec and thus being sampled at a low accuracy secondary frequency (such as timeout(9)) produces poor quality random bit stream that is fed into the entropy pool of rnd(4).

MACHINES
An incomplete list of machines that feature harmony audio:

•   712/*
•   715/*
•   725/*
•   735/*
•   755/*
•   B132L[+], B160L, B180L+
•   C100, C110, C132L, C160[L], C180, C200, C240, C360
•   J200, J210[XC], J280, J282, J2240

SEE ALSO
ioctl(2), audio(4), gsc(4), intro(4), rnd(4)

HISTORY
Support for harmony first appeared in OpenBSD 3.3. It was ported to NetBSD 1.6 by Chuck Silvers.

CAVEATS
To trigger entropy collection CHI bus has to be programmed into the data mode that happens once a single buffer of data has been played or recorded.