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guspnp(4)                 NetBSD Programmer's Manual                 guspnp(4)


NAME

     guspnp - Am78C201 device driver


SYNOPSIS

     guspnp* at isapnp?
     audio*  at guspnp?

     There should be no limit caused by the driver on the number of drivers or
     cards active in the system.


DESCRIPTION

     The guspnp driver provides support for audiosubsystems using the Inter-
     wave (Am78C20x) family of ICs, usually the Gravis Ultrasound Plug and
     Play. Unlike the gus driver guspnp driver does not require any local mem-
     ory for the IC, but uses the codec for both playback and recording. The
     guspnp driver can simultaneously playback and record 8- and 16-bit sam-
     ples at frequencies from 5.51kHz to 48kHz.

     The guspnp driver relies on isapnp to allocate suitable resources for it.
     This version of the driver only uses the first logical device of 5 the
     interwave IC has. The 4 Unused logical devices are ATAPI CD-ROM device,
     PnP Joystick device, Legacy soundcard emulation device (Soundblaster) and
     MIDI serial device. Support for atleast ATAPI CD-ROM and Joystick is be-
     ing worked on.  This version of the driver will use 1 IRQ and 2 DRQs.


BUGS

     Sometimes you can cause a hiss on either left or right channel, or both.
     You can usually make it disappear by playing random data, however this
     might not be a very nice thing to your audio equipment, but it is the on-
     ly way I have found out to be effective.

     Only the Codec is used in this version of the driver, therefore only 2
     channels are supported (left and right). Also sound quality is propably
     worse at lower kHz compared to playing through the synthesizer which does
     interpolation.

     If the implementation has a 'bad' oscillator, using frequencies 44.8kHz
     and 38.4kHz will result in incorrect playback frequency. The author has a
     GUS PnP Pro which displays this behaviour.

     Other members of the Interwave family have not been tested and don't have
     the glue needed to make them work. Should someone need to implement it,
     not many changes in the existing code are needed. Output voltage control
     in register CFIG2 [7] should be set differently for some other members of
     the family.

     Other architectures than i386 haven't been tested. The bus_space abstrac-
     tion has been used from the beginning, so it should work.


SEE ALSO

     audio(4),  isapnp(4),  gus(4)


AUTHOR

     Kari Mettinen (Kari.Mettinen@helsinki.fi), University of Helsinki.


REFERENCES

     Interwave(tm) IC Am78C201/202 Programmer's Guide Rev. 2. 1996. Advanced
     Micro Devices.


HISTORY

     The guspnp driver appeared in NetBSD 1.3.